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Sample records for vastus lateralis activity

  1. Activities of the Vastus Lateralis and Vastus Medialis Oblique Muscles during Squats on Different Surfaces.

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    Hyong, In Hyouk; Kang, Jong Ho

    2013-08-01

    [Purpose] The purpose of the present study was to examine the effects of squat exercises performed on different surfaces on the activity of the quadriceps femoris muscle in order to provide information on support surfaces for effective squat exercises. [Subjects and Method] Fourteen healthy subjects performed squat exercises for five seconds each on three different support surfaces: hard plates, foam, and rubber air discs. Their performance was measured using electromyography. As the subjects performed the squat exercises on each surface, data on the activity of the vastus medialis oblique and the vastus lateralis, and the vastus medials oblique/vastus lateralis ratio, were collected. [Results] The activity of the vastus medialis oblique and the vastus medialis oblique/vastus lateralis ratio were found to be statistically significantly higher on rubber air discs than when the squats were performed on hard plates or foam. [Conclusion] To activate the vastus medialis obilique, and to enhance the vastus medialis oblique/vastus lateralis ratio, unstable surfaces that are highly unstable should be selected.

  2. VASTUS LATERALIS OBLIQUE ACTIVITY DURING GAIT OF SUBJECTS WITH PATELLOFEMORAL PAIN

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    Gilmar Moraes Santos

    Full Text Available ABSTRACT Introduction: So far, little is known about the behavior of electromyographic activity of vastus lateralis oblique muscle during treadmill gait in subjects with and without patellofemoral pain syndrome. Objective: The purpose of this study was to investigate the electromyographic activity of the patellar stabilizers muscles and the angle of the knee joint flexion in subjects with and without patellofemoral pain syndrome. Method: Fifteen subjects without (21 ± 3 years and 12 with patellofemoral pain syndrome (20 ± 2 years were evaluated. The electromyographic activity and flexion angle of the knee joint were obtained during gait on the treadmill with a 5 degree inclination. Results: The knee flexion angle was significantly lower in the subjects with patellofemoral pain syndrome when compared with the healthy controls. The electromyographic activity of vastus lateralis longus was significantly greater during gait on the treadmill with inclination in subjects with patellofemoral pain syndrome. The results also showed that the electromyographic activity of vastus lateralis oblique and vastus medialis oblique were similar in both groups, regardless of the condition (with/without inclination. Conclusion: We have shown that knee kinematics during gait differs among patients with and without patellofemoral pain syndrome and healthy controls and that a different motor strategy persists even when the pain is no longer present. In addition, the findings suggested that the vastus lateralis oblique has a minor role in patellar stability during gait.

  3. The effect of hip abduction on the EMG activity of vastus medialis obliquus, vastus lateralis longus and vastus lateralis obliquus in healthy subjects

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    Arakaki Juliano

    2006-07-01

    Full Text Available Abstract Study design Controlled laboratory study. Objectives The purposes of this paper were to investigate (d whether vastus medialis obliquus (VMO, vastus lateralis longus (VLL and vastus lateralis obliquus (VLO EMG activity can be influenced by hip abduction performed by healthy subjects. Background Some clinicians contraindicate hip abduction for patellofemoral patients (with based on the premise that hip abduction could facilitate the VLL muscle activation leading to a VLL and VMO imbalance Methods and measures Twenty-one clinically healthy subjects were involved in the study, 10 women and 11 men (aged X = 23.3 ± 2.9. The EMG signals were collected using a computerized EMG VIKING II, with 8 channels and three pairs of surface electrodes. EMG activity was obtained from MVIC knee extension at 90° of flexion in a seated position and MVIC hip abduction at 0° and 30° with patients in side-lying position with the knee in full extension. The data were normalized in the MVIC knee extension at 50° of flexion in a seated position, and were submitted to ANOVA test with subsequent application of the Bonferroni multiple comparisons analysis test. The level of significance was defined as p ≤ 0.05. Results The VLO muscle demonstrated a similar pattern to the VMO muscle showing higher EMG activity in MVIC knee extension at 90° of flexion compared with MVIC hip abduction at 0° and 30° of abduction for male (p Conclusion The results showed that no selective EMG activation was observed when comparison was made between the VMO, VLL and VLO muscles while performing MVIC hip abduction at 0° and 30° of abduction and MVIC knee extension at 90° of flexion in both male and female subjects. Our findings demonstrate that hip abduction do not facilitated VLL and VLO activity in relation to the VMO, however, this study included only healthy subjects performing maximum voluntary isometric contraction contractions, therefore much remains to be discovered by

  4. Anatomy of vastus lateralis muscle flap.

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    Tayfur, Volkan; Magden, Orhan; Edizer, Mete; Atabey, Atay

    2010-11-01

    A vastus lateralis muscle flap is used as a pedicled and free flap. In this study, the vastus lateralis muscles of 15 adult formalin-fixed cadavers (30 cases) were dissected. The dominant pedicle was found to be descending branch of the lateral circumflex femoral artery. The mean diameter of the artery was found to be 2.1 mm. This pedicle was located 119.4 mm distal to the pubic symphysis. The mean length of the major pedicle was found to be 56.8 mm when the dominant pedicle was chosen to nourish the flap. The dominant pedicle entered the muscle 155.8 and 213.7 mm from the greater trochanter and the anterior superior iliac spine, respectively. The muscle had proximal minor pedicles from the ascending and transverse branches of lateral circumflex femoral artery. These arteries had mean diameters of 1.8 and 2.0 mm, respectively. The distal minor branches were present in all of the dissections. The distal branch had a mean diameter of 1.8 mm. The origin of this distal branch was located 83.7 mm proximal to the intercondylar line. The motor nerve of the vastus lateralis was found to be originating from femoral nerve. The nerve entered the muscle 194.6 mm from the anterior superior iliac spine.

  5. Protein intake does not increase vastus lateralis muscle protein synthesis during cycling

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    Hulston, CJ; Wolsk, Emil; Grøndahl, Thomas Sahl

    2011-01-01

    PURPOSE: This study aimed to investigate the effect of protein ingestion on leg protein turnover and vastus lateralis muscle protein synthesis during bicycle exercise and recovery. METHODS: Eight healthy males participated in two experiments in which they ingested either a carbohydrate solution...... sampling, and blood flow measurements. Muscle protein synthesis was calculated from the incorporation of l-[ring-C6]phenylalanine into protein. RESULTS: Consuming protein during exercise increased leg protein synthesis and decreased net leg protein breakdown; however, protein ingestion did not increase...... protein synthesis within the highly active vastus lateralis muscle (0.029%·h(-1), ± 0.004%·h(-1), and 0.030%·h(-1), ± 0.003%·h(-1), in CHO and CHO + P, respectively; P = 0.88). In contrast, consuming protein, during exercise and recovery, increased postexercise vastus lateralis muscle protein synthesis...

  6. Vastus Lateralis Motor Unit Firing Rate Is Higher in Women With Patellofemoral Pain.

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    Gallina, Alessio; Hunt, Michael A; Hodges, Paul W; Garland, S Jayne

    2018-05-01

    To compare neural drive, determined from motor unit firing rate, in the vastus medialis and lateralis in women with and without patellofemoral pain. Cross-sectional study. University research laboratory. Women (N=56) 19 to 35 years of age, including 36 with patellofemoral pain and 20 controls. Not applicable. Participants sustained an isometric knee extension contraction at 10% of their maximal voluntary effort for 70 seconds. Motor units (N=414) were identified using high-density surface electromyography. Average firing rate was calculated between 5 and 35 seconds after recruitment for each motor unit. Initial firing rate was the inverse of the first 3 motor unit interspike intervals. In control participants, vastus medialis motor units discharged at higher rates than vastus lateralis motor units (P=.001). This was not observed in women with patellofemoral pain (P=.78) because of a higher discharge rate of vastus lateralis compared with control participants (P=.002). No between-group differences were observed for vastus medialis (P=.93). Similar results were obtained for the initial motor unit firing rate. These findings suggest that women with patellofemoral pain have a higher neural drive to vastus lateralis but not vastus medialis, which may be a contributor of the altered patellar kinematics observed in some studies. The different neural drive may be an adaptation to patellofemoral pain, possibly to compensate for decreased quadriceps force production, or a precursor of patellofemoral pain. Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  7. Effects of visibility and types of the ground surface on the muscle activities of the vastus medialis oblique and vastus lateralis

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    Park, Jeong-ki; Lee, Dong-yeop; Kim, Jin-Seop; Hong, Ji-Heon; You, Jae-Ho; Park, In-mo

    2015-01-01

    [Purpose] The purpose of this study was to compare the effects of visibility and types of ground surface (stable and unstable) during the performance of squats on the muscle activities of the vastus medialis oblique (VMO) and vastus lateralis (VL). [Subjects and Methods] The subjects were 25 healthy adults in their 20s. They performed squats under four conditions: stable ground surface (SGS) with vision-allowed; unstable ground surface (UGS) with vision-allowed; SGS with vision-blocked; and UGS with vision-blocked. The different conditions were performed on different days. Surface electromyogram (EMG) values were recorded. [Results] The most significant difference in the activity of the VMO and VL was observed when the subjects performed squats on the UGS, with their vision blocked. [Conclusion] For the selective activation of the VMO, performing squats on an UGS was effective, and it was more effective when subjects’ vision was blocked. PMID:26356407

  8. Effect of shoe heel height on vastus medialis and vastus lateralis electromyographic activity during sit to stand

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    Hodgson David

    2008-01-01

    Full Text Available Abstract Background It has been proposed that high-heeled shoes may contribute to the development and progression of knee pain. However, surprisingly little research has been carried out on how shoe heel height affects muscle activity around the knee joint. The purpose of this study was to investigate the effect of differing heel height on the electromyographic (EMG activity in vastus medialis (VM and vastus lateralis (VL during a sit to stand activity. This was an exploratory study to inform future research. Methods A repeated measures design was used. Twenty five healthy females carried out a standardised sit to stand activity under 4 conditions; barefoot, and with heel wedges of 1, 3, and 5 cm in height. EMG activity was recorded from VM and VL during the activity. Data were analysed using 1 × 4 repeated measures ANOVA. Results Average rectified EMG activity differed with heel height in both VM (F2.2, 51.7 = 5.24, p 3, 72 = 5.32, p 3, 72 = 0.61, p = 0.609. Conclusion We found that as heel height increased, there was an increase in EMG activity in both VM and VL, but no change in the relative EMG intensity of VM and VL as measured by the VM: VL ratio. This showed that no VM: VL imbalance was elicited. This study provides information that will inform future research on how heel height affects muscle activity around the knee joint.

  9. Female PFP patients present alterations in eccentric muscle activity but not the temporal order of activation of the vastus lateralis muscle during the single leg triple hop test.

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    Kalytczak, Marcelo Martins; Lucareli, Paulo Roberto Garcia; Dos Reis, Amir Curcio; Bley, André Serra; Biasotto-Gonzalez, Daniela Aparecida; Correa, João Carlos Ferrari; Politti, Fabiano

    2018-04-07

    This study aimed to compare the concentric and eccentric activity and the temporal order of peak activity of the hip and knee muscles between women with patellofemoral pain (PFP) and healthy women during the single leg triple hop test (SLTHT). Electromyographic (EMG) and Kinematic data were collected from 14 healthy women (CG) and 14 women diagnosed with PFP (PFG) during a single session of the single leg triple hop test. Integral surface electromyography (iEMG) data of the hip and knee muscles in eccentric and concentric phases and the length of time that each muscle needed to reach the maximal peak of muscle activity were calculated. The iEMG in the eccentric phase was significantly higher (p < 0.05) than the concentric phase, for the gluteus maximus and gluteus medius muscles (CG and PFG) and for the vastus lateralis muscle (PFG). The vastus lateralis muscle was the first muscle to reach the highest peak of activity in the PFG, and the third to reach this peak in the CG. In the present study, the activity of the vastus lateralis muscle during the eccentric phase of the jump was greater than concentric phase, as a temporal anticipation of its peak in activity among women with PFP. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. THE CHIMERIC ALT-VASTUS LATERALIS FREE FLAP IN RECONSTRUCTION OF ADVANCED BRONJ OF THE MAXILLA

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    Francesca Toia

    2015-04-01

    Full Text Available ntroduction Bisphosphonate-related osteonecrosis of the jaw (BRONJ is a dangerous complication of bisphosphonates, a class of pharmaceutical agents used in numerous bone disorders. No gold standard therapy exists, but recent literature suggests that, in advanced stages, the best results are achieved with aggressive debridement. In this paper, we report our experience of treatment of stage 3 BRONJ of the maxilla with extensive surgical debridement and reconstruction with a chimeric ALT-Vastus lateralis flap. Methods Five selected patients with stage 3 BRONJ underwent partial maxillectomy with disease-free margins followed by immediate reconstruction with a chimeric ALT-Vastus lateralis free flap. Results Only two patients experienced minor complications. All other patients healed uneventfully within two weeks and donor site morbidity was minimal. Conclusions Our data suggest that aggressive debridement and reconstruction with a chimeric ALT -Vastus lateralis flap is an effective option for the treatment of stage III BRONJ of the maxilla.

  11. Characteristics of myosin profile in human vastus lateralis muscle in relation to training background.

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    Zawadowska, B; Majerczak, J; Semik, D; Karasinski, J; Kolodziejski, L; Kilarski, W M; Duda, K; Zoladz, J A

    2004-01-01

    Twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg) of different training background were investigated and classified into three groups according to their physical activity and sport discipline: untrained students (group A), national and sub-national level endurance athletes (group B, 7.8+/-2.9 years of specialised training) and sprint-power athletes (group C, 12.8+/-8.7 years of specialised training). Muscle biopsies of vastus lateralis were analysed histochemically for mATPase and SDH activities, immunohistochemically for fast and slow myosin, and electrophoretically followed by Western immunoblotting for myosin heavy chain (MyHC) composition. Significant differences (Pski-jumping, volleyball, soccer and modern dance. Furthermore, the relative amount of the fastest MyHCIIX isoform in vastus lateralis muscle was significantly lower in the athletes from group C than in students (group A). We conclude that the myosin profile in the athletes belonging to group C was unfavourable for their sport disciplines. This could be the reason why those athletes did not reach international level despite of several years of training.

  12. The vastus lateralis neuromuscular activity during all-out cycling exercise.

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    Bercier, Stephane; Halin, Renaud; Ravier, Philippe; Kahn, Jean-Francois; Jouanin, Jean-Claude; Lecoq, Anne-Marie; Buttelli, Olivier

    2009-10-01

    The objective of this work was to study modifications in motor control through surface electromyographic (sEMG) activity during a very short all-out cycling exercise. Twelve male cyclists (age 23+/-4 years) participated in this study. After a warm-up period, each subject performed three all-out cycling exercises of 6s separated by 2 min of complete rest. This protocol was repeated three times with a minimum of 2 days between each session. The braking torque imposed on cycling motion was 19 Nm. The sEMG of the vastus lateralis was recorded during the first seven contractions of the sprint. Time-frequency analysis of sEMG was performed using continuous wavelet transform. The mean power frequency (MPF, qualitative modifications in the recruitment of motor units) and signal energy (a quantitative indicator of modifications in the motor units recruitment) were computed for the frequency range 10-500 Hz. sEMG energy increased (P0.05) between contraction number 1 and 2, decreased (P recruitment of motor units (MUs) at the beginning of the sprint followed by a preferential recruitment of faster MUs at the end of the sprint, respectively.

  13. Neural and morphological adaptations of vastus lateralis and vastus medialis muscles to isokinetic eccentric training

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    Rodrigo de Azevedo Franke

    2014-09-01

    Full Text Available Vastus lateralis (VL and vastus medialis (VM are frequently targeted in conditioning/rehabilitation programs due to their role in patellar stabilization during knee extension. This study assessed neural and muscular adaptations in these two muscles after an isokinetic eccentric training program. Twenty healthy men underwent a four-week control period followed by a 12-week period of isokinetic eccentric training. Ultrasound evaluations of VL and VM muscle thickness at rest and electromyographic evaluations during maximal isometric tests were used to assess the morphological and neural properties, respectively. No morphological and neural changes were found throughout the control period, whereas both muscles showed significant increases in thickness (VL = 6.9%; p .05 post-training. Isokinetic eccentric training produces neural and greater morphological adaptations in VM compared to VL, which shows that synergistic muscles respond differently to an eccentric isokinetic strength training program

  14. Muscle Activation of Vastus Medialis Oblique and Vastus Lateralis in Sling-Based Exercises in Patients with Patellofemoral Pain Syndrome: A Cross-Over Study

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    Wen-Dien Chang

    2015-01-01

    Full Text Available Objectives. To examine what changes are caused in the activity of the vastus medialis oblique (VMO and vastus lateralis (VL at the time of sling-based exercises in patients with patellofemoral pain syndrome (PFPS and compare the muscular activations in patients with PFPS among the sling-based exercises. Methods. This was a cross-over study. Sling-based open and closed kinetic knee extension and hip adduction exercises were designed for PFPS, and electromyography was applied to record maximal voluntary contraction during the exercises. The VMO and VL activations and VMO : VL ratios for the three exercises were analyzed and compared. Results. Thirty male (age = 21.19 ± 0.68 y and 30 female (age = 21.12 ± 0.74 y patients with PFPS were recruited. VMO activations during the sling-based open and closed kinetic knee extension exercises were significantly higher (P=0.04 and P=0.001 than those during hip adduction exercises and VMO : VL ratio for the sling-based closed kinetic knee extension and hip adduction exercises approximated to 1. Conclusions. The sling-based closed kinetic knee extension exercise produced the highest VMO activation. It also had an appropriate VMO : VL ratio similar to sling-based hip adduction exercise and had beneficial effects on PFPS.

  15. The Effect of Increasing Volume of Exercise on Activation Pattern of Vastus Medialis and Lateralis and its Correlation With Anterior Knee Pain in Karate Elites.

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    Safar Cherati, Afsaneh; Lotfian, Sara; Jamshidi, Aliashraf; Sanjari, Mohammad Ali; Razi, Mohammad

    2016-09-01

    The effects of exercise volume on the pattern of muscle activity is one of the most important factors in training management and injury risk reduction. In the lower limb, the quadriceps muscle which plays a determining role in performing the stance and other karate techniques could be injured in intensive exercise and may induce anterior knee pain in athletes. The aim of this study was to determine the relationship between training volume and muscle activity of vastus medialis and vastus lateralis and its association with anterior knee pain in karate elites. Male and female athletes from national junior and cadet karate team (14 to 18 years) were invited to participate in the study at the beginning and the end of the training camps. Studies involved measurement of electromyographic muscle activity of vastus medialis and vastus lateralis in both lower extremities with surface electromyography device and assessment of movement by electrogoniometery. Muscle activity was recorded in three tests of dachi, walking up and walking down stairs. Simultaneously, anterior knee pain was evaluated using visual analogue scale and anterior knee pain scale questionnaire. Eight athletes of a total number of 23 reported increased ratings of pain in their right knees. No differences in muscle activity were observed in tests of Dachi and stairs between the groups with and without pain. Comparing Dachi task pattern at the beginning and end of training camps, there was no significant difference in pattern of biomechanical movement; however, reducing the amount of muscle activity in early and late phases of tasks was observed in electromyographic assessment. The results showed that performing the same task after a six-week training period, less muscle activity was required in all phases in two groups of tasks, including karate-specific movement (dachi) and activities of daily living (up or down stairs).

  16. Oxygenation and EMG in the proximal and distal vastus lateralis during submaximal isometric knee extension

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    Crenshaw, Albert G.; Bronee, Lars; Krag, Ida

    2010-01-01

    /or (2) fatigue development. Nine males performed 2-min sustained isometric knee extensions at 15% and 30% maximum voluntary contraction during which oxygenation and EMG were recorded simultaneously from proximal and distal locations of the vastus lateralis muscle. Near infrared spectroscopy variables...

  17. Effects of squats accompanied by hip joint adduction on the selective activity of the vastus medialis oblique.

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    Hyong, In Hyouk

    2015-06-01

    [Purpose] This study evaluated the effective selective activation method of the vastus medialis oblique for knee joint stabilization in patients with patellofemoral pain syndrome. [Subjects and Methods] Fifteen healthy college students (9 males, 6 females); mean age, height, and weight: 22.2 years, 167.8 cm, and 61.4 kg, respectively) participated. The knee angle was held at 60°. Muscle activities were measured once each during an ordinary squat and a squat accompanied by hip joint adduction. The muscle activities of the vastus medialis oblique and vastus lateralis were measured by electromyography for five seconds while maintaining 60° knee flexion. Electromyography signals were obtained at a sampling rate of 1,000 Hz and band pass filtering at 20-50 Hz. The obtained raw root mean square was divided by the maximal voluntary isometric contraction and expressed as a percentage. The selective activity of the vastus medialis oblique was assessed according to the muscle activity ratio of the vastus medialis oblique to the vastus lateralis. [Results] The activity ratio of the vastus medialis oblique was higher during a squat with hip joint adduction than without. [Conclusion] A squat accompanied by hip joint adduction is effective for the selective activation of the vastus medialis oblique.

  18. Lactate dehydrogenase is not a mitochondrial enzyme in human and mouse vastus lateralis muscle

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    Rasmussen, Hans N; van Hall, Gerrit; Rasmussen, Ulla F

    2002-01-01

    The presence of lactate dehydrogenase in skeletal muscle mitochondria was investigated to clarify whether lactate is a possible substrate for mitochondrial respiration. Mitochondria were prepared from 100 mg samples of human and mouse vastus lateralis muscle. All fractions from the preparation...... procedure were assayed for marker enzymes and lactate dehydrogenase (LDH). The mitochondrial fraction contained no LDH activity (detection limit approximately 0.05 % of the tissue activity) and the distribution of LDH activity among the fractions paralleled that of pyruvate kinase, i.e. LDH was fractionated...... as a cytoplasmic enzyme. Respiratory experiments with the mitochondrial fraction also indicated the absence of LDH. Lactate did not cause respiration, nor did it affect the respiration of pyruvate + malate. The major part of the native cytochrome c was retained in the isolated mitochondria, which, furthermore...

  19. Muscle fibre type shifting in the vastus lateralis of patients with COPD is associated with disease severity: a systematic review and meta-analysis.

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    Gosker, Harry R; Zeegers, Maurice P; Wouters, Emiel F M; Schols, Annemie M W J

    2007-11-01

    Skeletal muscle dysfunction is a common feature in chronic obstructive pulmonary disease (COPD) which is associated with intrinsic muscular abnormalities. One of the most consistently reported alterations is a shift from fibre type I to II in the vastus lateralis of these patients. Surprisingly, the relationship between this shift and the severity and phenotype of COPD remains unclear. A study was conducted to determine whether vastus lateralis muscle fibre type proportions are associated with COPD disease severity and to provide reference values for the proportions of fibre types in the vastus lateralis in COPD. A systematic review and a meta-analysis were conducted in which muscle fibre type data and markers of disease severity were collected from the literature. The forced expiratory volume in 1 s (FEV(1)), the ratio of FEV(1) to forced vital capacity (FVC) and body mass index were positively associated with the proportion of type I fibres in COPD. A proportion of 51% for vastus lateralis fibre type I and 13% for fibre type IIX were calculated from the combined data as normal values for patients with typical GOLD stage 3-4 COPD aged 60-70 years. Based on these reference values, a proportion of fibre type I 29% were defined as pathologically abnormal. This review sheds new light on the relationship between skeletal muscle abnormalities and important hallmarks of the disease in severe COPD, and identifies absence of data in GOLD stages 1-2. This review also provides reference values on fibre type composition for diagnostic purposes in COPD.

  20. Variability and reliability of the vastus lateralis muscle anatomy.

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    D'Arpa, Salvatore; Toia, Francesca; Brenner, Erich; Melloni, Carlo; Moschella, Francesco; Cordova, Adriana

    2016-08-01

    The aims of this study are to investigate the variability of the morphological and neurovascular anatomy of the vastus lateralis (VL) muscle and to describe the relationships among its intramuscular partitions and with the other muscles of the quadriceps femoris. Clinical implications in its reliability as a flap donor are also discussed. In 2012, the extra- and intramuscular neurovascular anatomy of the VL was investigated in 10 cadaveric lower limbs. In three specimens, the segmental arterial pedicles were injected with latex of different colors to point out their anastomotic connections. The morphological anatomy was investigated with regard to the mutual relationship of the three muscular partitions and the relation of the VL with the other muscles of the quadriceps femoris. The VL has a segmental morphological anatomy. However, the fibers of its three partitions interconnect individually and with the other bellies of the quadriceps femoris, particularly, in several variable portions with the vastus intermedius and mainly in the posterior part of the VL. The lateral circumflex femoral artery and its branches have variable origin, but demonstrate constant segmental distribution. Intramuscular dissection and colored latex injections show a rich anastomotic vascular network among the three partitions. Moderate variability exists in both the myological and the neurovascular anatomy of the VL. Despite this variability, the anatomy of the VL always has a constant segmental pattern, which makes the VL a reliable flap donor. Detailed knowledge of the VL anatomy could have useful applications in a broad clinical field.

  1. The Vastus Medialis Oblique: Vastus Lateralis Electromyographic Intensity Ratio During Squat with Hip Adduction in Athletes with and Without Patellofemoral Pain Syndrome

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    Farhad Reza-zadeh

    2012-07-01

    Full Text Available Objective: This study was designed to compare vastus medialis oblique (VMO: vastus lateralis longus (VLL electromyographic intensity ratio during squat with hip adduction in athletes with and without patellofemoral pain syndrome (PFPS. Materials & Methods: In this non-experimental and case-control study, 16 male athletes with PFPS were selected purposefully and 16 healthy male athletes aged 18-30 years from national teams (Volleyball, Handball and Taekwondo were matched based on variables such as weight, height, age, dominancy. All subjects selected based on inclusion and exclusion criteria. EMG activity of VMO and VLL muscles was recorded by surface electrodes with Telemetric EMG System at 15, 30 and 45 degrees of squat and VMO: VLL ratio was calculated. One way ANOVA was used to compare these muscles ratio between two groups. Results: The ratio of VMO: VLL in both groups with and without PFPS in almost all angles were lower than one. However, healthy athletes had lower ratios. Also, there were no significant differences in VMO: VLL ratio at various angles. Conclusion: It seems that sports activities prevent VMO weakening in athletes. However, VMO: VLL ratio in athletes with and without patellofemoral pain does not influence by this syndrome.

  2. Organization of metabolic pathways in vastus lateralis of patients with chronic obstructive pulmonary disease.

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    Green, Howard J; Bombardier, Eric; Burnett, Margaret; Iqbal, Sobia; D'Arsigny, Christine L; O'Donnell, Dennis E; Ouyang, Jing; Webb, Katherine A

    2008-09-01

    The objective of this study was to determine whether patients with chronic obstructive lung disease (COPD) display differences in organization of the metabolic pathways and segments involved in energy supply compared with healthy control subjects. Metabolic pathway potential, based on the measurement of the maximal activity (V(max)) of representative enzymes, was assessed in tissue extracted from the vastus lateralis in seven patients with COPD (age 67 +/- 4 yr; FEV(1)/FVC = 44 +/- 3%, where FEV(1) is forced expiratory volume in 1 s and FVC is forced vital capacity; means +/- SE) and nine healthy age-matched controls (age 68 +/- 2 yr; FEV(1)/FVC = 75 +/- 2%). Compared with control, the COPD patients displayed lower (P chain and glycogenolysis and glycolysis relative to beta-oxidation.

  3. Characteristics of myosin profile in human vastus lateralis muscle in relation to training background.

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    J A Zoladz

    2004-10-01

    Full Text Available Twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg of different training background were investigated and classified into three groups according to their physical activity and sport discipline: untrained students (group A, national and sub-national level endurance athletes (group B, 7.8+/-2.9 years of specialised training and sprint-power athletes (group C, 12.8+/-8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase and SDH activities, immunohistochemically for fast and slow myosin, and electrophoretically followed by Western immunoblotting for myosin heavy chain (MyHC composition. Significant differences (P<0.05 regarding composition of muscle fibre types and myosin heavy chains were found only between groups A (41.7+/-1.6% of MyHCI, 40.8+/-4.0% of MyHCIIA and 17.5+/-4.0% of MyHCIIX and B (64.3+/-0.8% of MyHCI, 34.0+/-1.4% of MyHCIIA and 1.7+/-1.4% of MyHCIIX and groups A and C (59.6+/-1.6% of MyHCI, 37.2+/-1.3% of MyHCIIA and 3.2+/-1.3% of MyHCIIX. Unexpectedly, endurance athletes (group B such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance. Furthermore, the relative amount of the fastest MyHCIIX isoform in vastus lateralis muscle was significantly lower in the athletes from group C than in students (group A. We conclude that the myosin profile in the athletes belonging to group C was unfavourable for their sport disciplines. This could be the reason why those athletes did not reach international level despite of several years of training.

  4. Muscle morphology of the vastus lateralis is strongly related to ergometer performance, sprint capacity and endurance capacity in Olympic rowers

    NARCIS (Netherlands)

    van der Zwaard, Stephan; Weide, Guido; Levels, Koen; Eikelboom, Michelle R.I.; Noordhof, Dionne A.; Hofmijster, Mathijs J.; van der Laarse, Willem J.; de Koning, Jos J.; de Ruiter, Cornelis J.; Jaspers, Richard T.

    2018-01-01

    Rowers need to combine high sprint and endurance capacities. Muscle morphology largely explains muscle power generating capacity, however, little is known on how muscle morphology relates to rowing performance measures. The aim was to determine how muscle morphology of the vastus lateralis relates

  5. Training induced decrease in oxygen cost of cycling is accompanied by down-regulation of SERCA expression in human vastus lateralis muscle.

    Science.gov (United States)

    Majerczak, J; Karasinski, J; Zoladz, J A

    2008-09-01

    We have examined the effect of 5 week cycling endurance training program on the sarco(endo)plasmic reticulum Ca2+ ATPase isoforms (SERCA1 and 2) and myosin heavy chain (MyHC) in the vastus lateralis muscle as well as on the oxygen uptake to power output ratio (VO2/PO) during incremental cycling. Fifteen untrained men performed an incremental cycling exercise until exhaustion before and after moderate intensity training. Muscle biopsies were taken from vastus lateralis before and after training program. Training resulted in higher (P = 0.048) maximal oxygen uptake (VO(2max)) as well as in higher power output reached at VO(2max) (P = 0.0001). Moreover, lower (P = 0.02) VO2/PO ratio determined during incremental moderate intensity cycling (i.e. 30-120 W) as well as lower (P = 0.003) VO2/PO ratio reached at VO(2max) were observed after the training. A significant down regulation of SERCA2 protein (P = 0.03) and tendency (P = 0.055) to lower SERCA1 content accompanied by lower (P<10(-4)) plasma thyroid hormone concentration, with no changes (P = 0.67) in MyHC composition in vastus lateralis muscle were found after training. We have concluded that the increase in mechanical efficiency of cycling occurring during first weeks of endurance training is not related to changes in MyHC composition but it may be due to down-regulation of SERCA pumps.

  6. Effect of pedaling rates and myosin heavy chain composition in the vastus lateralis muscle on the power generating capability during incremental cycling in humans.

    Science.gov (United States)

    Majerczak, J; Szkutnik, Z; Duda, K; Komorowska, M; Kolodziejski, L; Karasinski, J; Zoladz, J A

    2008-01-01

    In this study, we have determined power output reached at maximal oxygen uptake during incremental cycling exercise (P(I, max)) performed at low and at high pedaling rates in nineteen untrained men with various myosin heavy chain composition (MyHC) in the vastus lateralis muscle. On separate days, subjects performed two incremental exercise tests until exhaustion at 60 rev min(-1) and at 120 rev min(-1). In the studied group of subjects P(I, max) reached during cycling at 60 rev min(-1) was significantly higher (p=0.0001) than that at 120 rev min(-1) (287+/-29 vs. 215+/-42 W, respectively for 60 and 120 rev min(-1)). For further comparisons, two groups of subjects (n=6, each) were selected according to MyHC composition in the vastus lateralis muscle: group H with higher MyHC II content (56.8+/-2.79 %) and group L with lower MyHC II content in this muscle (28.6+/-5.8 %). P(I, max) reached during cycling performed at 60 rev min(-1) in group H was significantly lower than in group L (p=0.03). However, during cycling at 120 rev min(-1), there was no significant difference in P(I, max) reached by both groups of subjects (p=0.38). Moreover, oxygen uptake (VO(2)), blood hydrogen ion [H(+)], plasma lactate [La(-)] and ammonia [NH(3)] concentrations determined at the four highest power outputs completed during the incremental cycling performed at 60 as well as 120 rev min(-1), in the group H were significantly higher than in group L. We have concluded that during an incremental exercise performed at low pedaling rates the subjects with lower content of MyHC II in the vastus lateralis muscle possess greater power generating capabilities than the subjects with higher content of MyHC II. Surprisingly, at high pedaling rate, power generating capabilities in the subjects with higher MyHC II content in the vastus lateralis muscle did not differ from those found in the subjects with lower content of MyHC II in this muscle, despite higher blood [H(+)], [La(-)] and [NH(3

  7. Changes in force, surface and motor unit EMG during post-exercise development of low frequency fatigue in vastus lateralis muscle

    NARCIS (Netherlands)

    de Ruiter, C.J.; Elzinga, M.J.; Verdijk, P.W.L.; van Mechelen, W.; de Haan, A.

    2005-01-01

    We investigated the effects of low frequency fatigue (LFF) on post-exercise changes in rectified surface EMG (rsEMG) and single motor unit EMG (smuEMG) in vastus lateralis muscle (n=9). On two experimental days the knee extensors were fatigued with a 60-s-isometric contraction (exercise) at 50%

  8. Capillary density and capillary-to-fibre ratio in vastus lateralis muscle of untrained and trained men.

    Science.gov (United States)

    Zoladz, J A; Semik, D; Zawadowska, B; Majerczak, J; Karasinski, J; Kolodziejski, L; Duda, K; Kilarski, W M

    2005-01-01

    Muscle fibre profile area (Af), volume density (Vv), capillary-to-fibre ratio (CF) and number of capillaries per fibre square millimetre (CD) were determined from needle biopsies of vastus lateralis of twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg) of different training background. Seven subjects were untrained students (group A), nine were national and sub-national level endurance athletes (group B) with the background of 7.8+/-2.9 years of specialised training, and eight subjects were sprint-power athletes (group C) with 12.8+/-8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase. Capillaries were visualized and counted using CD31 antibodies against endothelial cells. There were significant differences in the Vv of type I and type II muscle fibres in both trained groups, B (51.8%; 25.6%) and C (50.5%; 26.4%). However, in untrained group A that was treated as a reference group, the difference between Vv of type I and type II fibres was less prominent, nevertheless statistically significant (42.1%; 35.1%). There was also a significant difference in CF: 1.9 in group A and 2.1 in groups B and C. The number of capillaries per mm2 (CD) was 245 (group A), 308 (group B) and 325 (group C). Significant differences (Pski-jumping, volleyball, soccer and modern dance.

  9. Motor units in vastus lateralis and in different vastus medialis regions show different firing properties during low-level, isometric knee extension contraction.

    Science.gov (United States)

    de Souza, Leonardo Mendes Leal; Cabral, Hélio Veiga; de Oliveira, Liliam Fernandes; Vieira, Taian Martins

    2018-04-01

    Architectural differences along vastus medialis (VM) and between VM and vastus lateralis (VL) are considered functionally important for the patellar tracking, knee joint stability and knee joint extension. Whether these functional differences are associated with a differential activity of motor units between VM and VL is however unknown. In the present study, we, therefore, investigate neuroanatomical differences in the activity of motor units detected proximo-distally from VM and from the VL muscle. Nine healthy volunteers performed low-level isometric knee extension contractions (20% of their maximum voluntary contraction) following a trapezoidal trajectory. Surface electromyograms (EMGs) were recorded from VM proximal and distal regions and from VL using three linear adhesive arrays of eight electrodes. The firing rate and recruitment threshold of motor units decomposed from EMGs were then compared among muscle regions. Results show that VL motor units reached lower mean firing rates in comparison with VM motor units, regardless of their position within VM (P motor units (P = .997). Furthermore, no significant differences in the recruitment threshold were observed for all motor units analysed (P = .108). Our findings possibly suggest the greater potential of VL to generate force, due to its fibres arrangement, may account for the lower discharge rate observed for VL then either proximally or distally detected motor units in VM. Additionally, the present study opens new perspectives on the importance of considering muscle architecture in investigations of the neural aspects of motor behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Comparison of oscillations of skin blood flow and deoxygenation in vastus lateralis in light exercise.

    Science.gov (United States)

    Yano, T; Lian, C-S; Afroundeh, R; Shirakawa, K; Yunoki, T

    2014-03-01

    The purpose of the present study was to compare oscillation of skin blood flow with that of deoxygenation in muscle during light exercise in order to determine the physiological significance of oscillations in deoxygenation. Prolonged exercise with 50% of peak oxygen uptake was performed for 60 min. Skin blood flow (SBF) was measured using a laser blood flow meter on the right vastus lateralis muscle. Deoxygenated haemoglobin/myoglobin (DHb/Mb) concentration in the left vastus lateralis were measured using a near-infrared spectroscopy system. SBF and DHb/Mb during exercise were analysed by fast Fourier transform. We classified frequency bands according to previous studies (Kvernmo et al. 1999, Kvandal et al. 2006) into phase I (0.005-0.0095 and 0.0095-0.02 Hz), phase II (0.02-0.06 Hz: phase II) and phase III (0.06-0.16 Hz). The first peak of power spectra density (PSD) in SBF appeared at 0.0078 Hz in phase I. The second peak of PSD in SBF appeared at 0.035 Hz. The third peak of PSD in SBF appeared at 0.078 Hz. The first peak of PSD in DHb/Mb appeared at 0.0039 Hz, which was out of phase I. The second peak of PSD in DHb/Mb appeared at 0.016 Hz. The third peak of PSD in DHb/Mb appeared at 0.035 Hz. The coefficient of cross correlation was very low. Cross power spectra density showed peaks of 0.0039, 0.016 and 0.035 Hz. It is concluded that a peak of 0.016 Hz in oscillations of DHb/Mb observed in muscle during exercise is associated with endothelium-dependent vasodilation (phase I) and that a peak of 0.035 Hz in DHb/Mb is associated with sympathetic nerve activity (phase II). It is also confirmed that each peak of SBF oscillations is observed in each phase.

  11. COMPARISON OF OSCILLATIONS OF SKIN BLOOD FLOW AND DEOXYGENATION IN VASTUS LATERALIS IN LIGHT EXERCISE

    Directory of Open Access Journals (Sweden)

    T. Yano

    2014-07-01

    Full Text Available The purpose of the present study was to compare oscillation of skin blood flow with that of deoxygenation in muscle during light exercise in order to determine the physiological significance of oscillations in deoxygenation. Prolonged exercise with 50% of peak oxygen uptake was performed for 60 min. Skin blood flow (SBF was measured using a laser blood flow meter on the right vastus lateralis muscle. Deoxygenated haemoglobin/myoglobin (DHb/Mb concentration in the left vastus lateralis were measured using a near-infrared spectroscopy system. SBF and DHb/Mb during exercise were analysed by fast Fourier transform. We classified frequency bands according to previous studies (Kvernmo et al. 1999, Kvandal et al. 2006 into phase I (0.005-0.0095 and 0.0095-0.02 Hz, phase II (0.02-0.06 Hz: phase II and phase III (0.06-0.16 Hz. The first peak of power spectra density (PSD in SBF appeared at 0.0078 Hz in phase I. The second peak of PSD in SBF appeared at 0.035 Hz. The third peak of PSD in SBF appeared at 0.078 Hz. The first peak of PSD in DHb/Mb appeared at 0.0039 Hz, which was out of phase I. The second peak of PSD in DHb/Mb appeared at 0.016 Hz. The third peak of PSD in DHb/Mb appeared at 0.035 Hz. The coefficient of cross correlation was very low. Cross power spectra density showed peaks of 0.0039, 0.016 and 0.035 Hz. It is concluded that a peak of 0.016 Hz in oscillations of DHb/Mb observed in muscle during exercise is associated with endothelium-dependent vasodilation (phase I and that a peak of 0.035 Hz in DHb/Mb is associated with sympathetic nerve activity (phase II. It is also confirmed that each peak of SBF oscillations is observed in each phase.

  12. Myosin heavy chain composition in the vastus lateralis muscle in relation to oxygen uptake and heart rate during cycling in humans.

    Science.gov (United States)

    Majerczak, J; Nieckarz, Z; Karasinski, J; Zoladz, J A

    2014-04-01

    In this study we examined the relationship between fast myosin heavy chain (MyHC2) content in the vastus lateralis and the rate of oxygen uptake (VO2) and heart rate (HR) increase during an incremental exercise in 38, young, healthy men. Prior to the exercise test, muscle biopsies were taken in order to evaluate the MyHC composition. It was found that during cycling performed below the lactate threshold (LT), a positive relationship between MyHC2 and the intercept of the oxygen uptake and power output (VO2-PO) relationship existed (r=0.49, P=0.002), despite no correlation between MyHC2 and the slope value of the VO2-PO relationship (r= -0.18, P=0.29). During cycling performed above the LT, MyHC2 correlated positively with the magnitude of the nonlinearity in the VO2-PO relationship; i.e. with the accumulated VO2'excess' (r=0.44, P=0.006) and peak VO2'excess' (r=0.44, P=0.006), as well as with the slope of the HR-PO relationship (r=0.49, P=0.002). We have concluded that a greater MyHC2 content in the vastus lateralis is accompanied by a higher oxygen cost of cycling during exercise performed below the LT. This seems to be related to the higher energy cost of the non-cross-bridge activities in the muscles possessing a greater proportion of MyHC2 content. In the case of heavy-intensity exercise, a higher MyHC2 content in the vastus lateralis is accompanied by greater non-linearity in the VO2-PO relationship, as well as a steeper increase in HR in the function of an increase of PO. This relationship can be explained by greater disturbances in metabolic stability in type II muscle fibres during exercise, resulting in a decrease of muscle mechanical efficiency and greater increase of heart rate at a given power output. Therefore, MyHC composition has an impact on the oxygen cost of cycling both below and above the LT.

  13. Neuromuscular partitioning, architectural design, and myosin fiber types of the M. vastus lateralis of the llama (Lama glama).

    Science.gov (United States)

    Graziotti, Guillermo H; Palencia, Pablo; Delhon, Gustavo; Rivero, José-Luis L

    2004-11-01

    The llama (Lama glama) is one of the few mammals of relatively large body size in which three fast myosin heavy chain isoforms (i.e., IIA, IIX, IIB) are extensively expressed in their locomotory muscles. This study was designed to gain insight into the morphological and functional organization of skeletal musculature in this peculiar animal model. The neuromuscular partitioning, architectural design, and myosin fiber types were systematically studied in the M. vastus lateralis of adult llamas (n = 15). Four nonoverlapping neuromuscular partitions or compartments were identified macroscopically (using a modified Sihler's technique for muscle depigmentation), although they did not conform strictly to the definitions of "neuromuscular compartments." Each neuromuscular partition was innervated by primary branches of the femoral nerve and was arranged within the muscle as paired partitions, two in parallel (deep-superficial compartmentalization) and the other two in-series (proximo-distal compartmentalization). These neuromuscular partitions of the muscle varied in their respective architectural designs (studied after partial digestion with diluted nitric acid) and myosin fiber type characteristics (identified immunohistochemically with specific anti-myosin monoclonal antibodies, then examined by quantitative histochemistry and image analysis). The deep partitions of the muscle had longer fibers, with lower angles of pinnation, and higher percentages of fast-glycolytic fibers than the superficial partitions of the muscle. These differences clearly suggest a division of labor in the whole M. vastus lateralis of llamas, with deep partitions exhibiting features well adapted for dynamic activities in the extension of stifle, whereas superficial portions seem to be related to the antigravitational role of the muscle in preserving the extension of the stifle during standing and stance phase of the stride. This peculiar structural and functional organization of the llama M

  14. Comparison of the EMG Activities in the Vastus Medialis Oblique ...

    African Journals Online (AJOL)

    omoyemi

    (VMO) and vastus lateralis (VL) muscles during two open chain exercises commonly used ... or gender, but the terminal knee extension exercise type x gender interaction effect was ... believe PFPS is caused by differences in the timing during.

  15. Specific force of the vastus lateralis in adults with achondroplasia.

    Science.gov (United States)

    Sims, David T; Onambélé-Pearson, Gladys L; Burden, Adrian; Payton, Carl; Morse, Christopher I

    2018-03-01

    Achondroplasia is a clinical condition defined by shorter stature and disproportionate limb length. Force production in able-bodied individuals (controls) is proportional to muscle size, but given the disproportionate nature of achondroplasia, normalizing to anatomical cross-sectional area (ACSA) is inappropriate. The aim of this study was to assess specific force of the vastus lateralis (VL) in 10 adults with achondroplasia (22 ± 3 yr) and 18 sex-matched controls (22 ± 2 yr). Isometric torque (iMVCτ) of the dominant knee extensors (KE) and in vivo measures of VL muscle architecture, volume, activation, and patella tendon moment arm were used to calculate VL physiological CSA (PCSA), fascicle force, and specific force in both groups. Achondroplasic muscle volume was 53% smaller than controls (284 ± 36 vs. 604 ± 102 cm 3 , P 0.05), but coactivation of bicep femoris of achondroplasic subjects was 70% more than controls (43 ± 20 vs. 13 ± 5%, P force (702 ± 235 vs. 1704 ± 303 N, P force than control subjects (17 ± 6 vs. 24 ± 6 N⋅cm -2 , P = 0.012). The smaller VL specific force in achondroplasia may be attributed to infiltration of fat and connective tissue, rather than to any difference in myofilament function. NEW & NOTEWORTHY The novel observation of this study was the measurement of normalized force production in a group of individuals with disproportionate limb length-to-torso ratios.

  16. Do epigenetic events take place in the vastus lateralis of patients with mild chronic obstructive pulmonary disease?

    Directory of Open Access Journals (Sweden)

    Ester Puig-Vilanova

    Full Text Available Muscle dysfunction is a major comorbidity in Chronic Obstructive Pulmonary Disease (COPD. Several biological mechanisms including epigenetic events regulate muscle mass and function in models of muscle atrophy. Investigations conducted so far have focused on the elucidation of biological mechanisms involved in muscle dysfunction in advanced COPD. We assessed whether the epigenetic profile may be altered in the vastus lateralis of patients with mild COPD, normal body composition, and mildly impaired muscle function and exercise capacity. In vastus lateralis (VL of mild COPD patients with well-preserved body composition and in healthy age-matched controls, expression of DNA methylation, muscle-enriched microRNAs, histone acetyltransferases (HTAs and deacetylases (HDACs, protein acetylation, small ubiquitin-related modifier (SUMO ligases, and muscle structure were explored. All subjects were clinically evaluated. Compared to healthy controls, in the VL of mild COPD patients, muscle function and exercise capacity were moderately reduced, DNA methylation levels did not differ, miR-1 expression levels were increased and positively correlated with both forced expiratory volume in one second (FEV1 and quadriceps force, HDAC4 protein levels were increased, and muscle fiber types and sizes were not different. Moderate skeletal muscle dysfunction is a relevant feature in patients with mild COPD and preserved body composition. Several epigenetic events are differentially expressed in the limb muscles of these patients, probably as an attempt to counterbalance the underlying mechanisms that alter muscle function and mass. The study of patients at early stages of their disease is of interest as they are a target for timely therapeutic interventions that may slow down the course of the disease and prevent the deleterious effects of major comorbidities.

  17. Relationship between electromyographic activity of the vastus lateralis while standing and the extent of bilateral simulated knee-flexion contractures.

    Science.gov (United States)

    Potter, P J; Kirby, R L

    1991-12-01

    The effect of simulated bilateral knee-flexion contractures (KFC) on the electromyographic (EMG) activity of the vastus lateralis was studied by testing 10 normal subjects using surface EMG to test the hypothesis that the activity of the knee extensors would increase as a function of the severity of the contracture. The root mean square of the EMG activity was determined from four 4-s samples taken at 30-s intervals, during 2 min of standing in each of five positions of simulated KFC (0 degree, 10 degrees, 20 degrees, 30 degrees and 40 degrees). A randomly balanced order of conditions was used. KFC were simulated in each subject by means of an adjustable line from the subject's waist to the sole of each foot. An analysis of variance was used to contrast EMG activity, and a significant difference was found between each of the positions (P less than 0.05). The mean (+/- 1 SD) EMG activity, expressed as a percentage of the maximum voluntary contraction, was 0.3% (+/- 0.2) at 0 degree, 7.6% (+/- 5.6) at 10 degrees, 10.9% (+/- 7.6) at 20 degrees, 16.6% (+/- 12.4) at 30 degrees and 24.0% (+/- 14.0) at 40 degrees. A linear relationship was found (r2 = 0.986), expressed by the equation y = 0.62 + 0.56 x, where y represents EMG activity and x represents the extent of simulated KFC (P = 0.0007). The results provide insight into the increased knee extensor activity necessary to stand with KFC and underline the importance of treating this common disorder.

  18. Effects of Barbell Deadlift Training on Submaximal Motor Unit Firing Rates for the Vastus Lateralis and Rectus Femoris

    Science.gov (United States)

    Stock, Matt S.; Thompson, Brennan J.

    2014-01-01

    Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units. PMID:25531294

  19. Effects of barbell deadlift training on submaximal motor unit firing rates for the vastus lateralis and rectus femoris.

    Directory of Open Access Journals (Sweden)

    Matt S Stock

    Full Text Available Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC assessment. Twenty-four previously untrained men (mean age  = 24 years were randomly assigned to training (n = 15 or control (n = 9 groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC and y-intercepts (pps of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70, but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units.

  20. Effects of barbell deadlift training on submaximal motor unit firing rates for the vastus lateralis and rectus femoris.

    Science.gov (United States)

    Stock, Matt S; Thompson, Brennan J

    2014-01-01

    Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units.

  1. Capillary density and capillary-to-fibre ratio in vastus lateralis muscle of untrained and trained men

    Directory of Open Access Journals (Sweden)

    W. M. Kilarski

    2011-08-01

    Full Text Available Muscle fibre profile area (Af, volume density (Vv, capillary-to-fibre ratio (CF and number of capillaries per fibre square millimetre (CD were determined from needle biopsies of vastus lateralis of twenty-four male volunteers (mean ± SD: age 25.4±5.8 years, height 178.6±5.5 cm, body mass 72.1±7.7 kg of different training background. Seven subjects were untrained students (group A, nine were national and sub-national level endurance athletes (group B with the background of 7.8±2.9 years of specialised training, and eight subjects were sprint-power athletes (group C with 12.8±8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase. Capillaries were visualized and counted using CD31 antibodies against endothelial cells. There were significant differences in the Vv of type I and type II muscle fibres in both trained groups, B (51.8%; 25.6% and C (50.5%; 26.4%. However, in untrained group A that was treated as a reference group, the difference between Vv of type I and type II fibres was less prominent, nevertheless statistically significant (42.1%; 35.1%. There was also a significant difference in CF: 1.9 in group A and 2.1 in groups B and C. The number of capillaries per mm2 (CD was 245 (group A, 308 (group B and 325 (group C. Significant differences (P<0.05 in CF and CD, were found only between group A (1.9; 245 and both groups of trained men, B and C (2.1; 308 and 325. However, endurance athletes (group B, such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance.

  2. History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

    Science.gov (United States)

    Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

    2018-06-01

    In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the

  3. Recruitment order of motor units in human vastus lateralis muscle is maintained during fatiguing contractions.

    Science.gov (United States)

    Adam, Alexander; De Luca, Carlo J

    2003-11-01

    Motor-unit firing patterns were studied in the vastus lateralis muscle of five healthy young men [21.4 +/- 0.9 (SD) yr] during a series of isometric knee extensions performed to exhaustion. Each contraction was held at a constant torque level, set to 20% of the maximal voluntary contraction at the beginning of the experiment. Electromyographic signals, recorded via a quadrifilar fine wire electrode, were processed with the precision decomposition technique to identify the firing times of individual motor units. In repeat experiments, whole-muscle mechanical properties were measured during the fatigue protocol using electrical stimulation. The main findings were a monotonic decrease in the recruitment threshold of all motor units and the progressive recruitment of new units, all without a change of the recruitment order. Motor units from the same subject showed a similar time course of threshold decline, but this decline varied among subjects (mean threshold decrease ranged from 23 to 73%). The mean threshold decline was linearly correlated (R2 >or= 0.96) with a decline in the elicited peak tetanic torque. In summary, the maintenance of recruitment order during fatigue strongly supports the notion that the observed common recruitment adaptations were a direct consequence of an increased excitatory drive to the motor unit pool. It is suggested that the increased central drive was necessary to compensate for the loss in force output from motor units whose muscle fibers were actively contracting. We therefore conclude that the control scheme of motor-unit recruitment remains invariant during fatigue at least in relatively large muscles performing submaximal isometric contractions.

  4. Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings.

    Science.gov (United States)

    Malfait, Bart; Dingenen, Bart; Smeets, Annemie; Staes, Filip; Pataky, Todd; Robinson, Mark A; Vanrenterghem, Jos; Verschueren, Sabine

    2016-01-01

    The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (phamstrings medialis activity) during the preparatory and initial contact phase and an increased lateral neuromuscular activation (dominant vastus lateralis activity) during the peak loading phase.

  5. Increased Interstitial Concentrations of Glutamate and Pyruvate in Vastus Lateralis of Women with Fibromyalgia Syndrome Are Normalized after an Exercise Intervention - A Case-Control Study.

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    Björn Gerdle

    Full Text Available Fibromyalgia syndrome (FMS is associated with central alterations, but controversies exist regarding the presence and role of peripheral factors. Microdialysis (MD can be used in vivo to study muscle alterations in FMS. Furthermore for chronic pain conditions such as FMS, the mechanisms for the positive effects of exercise are unclear. This study investigates the interstitial concentrations of algesics and metabolites in the vastus lateralis muscle of 29 women with FMS and 28 healthy women before and after an exercise intervention.All the participants went through a clinical examination and completed a questionnaire. In addition, their pressure pain thresholds (PPTs in their upper and lower extremities were determined. For both groups, MD was conducted in the vastus lateralis muscle before and after a 15-week exercise intervention of mainly resistance training of the lower limbs. Muscle blood flow and interstitial muscle concentrations of lactate, pyruvate, glutamate, glucose, and glycerol were determined.FMS was associated with significantly increased interstitial concentrations of glutamate, pyruvate, and lactate. After the exercise intervention, the FMS group exhibited significant decreases in pain intensity and in mean interstitial concentrations of glutamate, pyruvate, and glucose. The decrease in pain intensity in FMS correlated significantly with the decreases in pyruvate and glucose. In addition, the FMS group increased their strength and endurance.This study supports the suggestion that peripheral metabolic and algesic muscle alterations are present in FMS patients and that these alterations contribute to pain. After an exercise intervention, alterations normalized, pain intensity decreased (but not abolished, and strength and endurance improved, all findings that suggest the effects of exercise are partially peripheral.

  6. Effect of knee joint angle on neuromuscular activation of the vastus intermedius muscle during isometric contraction.

    Science.gov (United States)

    Watanabe, K; Akima, H

    2011-12-01

    The purpose of this study was to compare the relationship between surface electromyography (EMG) and knee joint angle of the vastus intermedius muscle (VI) with the synergistic muscles in the quadriceps femoris (QF) muscle group. Fourteen healthy men performed maximal voluntary contractions during isometric knee extension at four knee joint angles from 90°, 115°, 140°, and 165° (180° being full extension). During the contractions, surface EMG was recorded at four muscle components of the QF muscle group: the VI, vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles. The root mean square of the surface EMG at each knee joint angle was calculated and normalized by that at a knee joint angle of 90° for individual muscles. The normalized RMS of the VI muscle was significantly lower than those of the VL and RF muscles at the knee joint angles of 115° and 165° and those of the VL, VM, and RF muscles at the knee joint angle of 140° (Pneuromuscular activation of the VI muscle is regulated in a manner different from the alteration of the knee joint angle compared with other muscle components of the QF muscle group. © 2011 John Wiley & Sons A/S.

  7. Morphometric study of tensor of vastus intermedius in South Indian population.

    Science.gov (United States)

    Veeramani, Raveendranath; Gnanasekaran, Dhivyalakshmi

    2017-03-01

    Tensor of vastus intermedius is a newly discovered muscle located between vastus lateralis and vastus intermedius. The purpose of this study was to investigate the detailed morphology of tensor of vastus intermedius, specifically to provide data pertaining to the attachments, innervations, variation in the types and its morphometry in South Indian population. The tensor of vastus intermedius was studied in thirty six cadaveric lower limbs using macrodissection techniques. The origin of the muscle was from upper part of intertrochanteric line and anterior part of greater trochanter of femur inserted to medial aspect of upper border of patella. The muscle was classified into four types based on the origin and also the aponeurosis course with independent type (type 1) being common. The mean and standard deviation of the length of tensor of vastus intermedius and aponeurosis were 145.40±37.55 mm and 193.55±42.32 mm, respectively. The results of the study suggest that tensor of vastus intermedius is variable and the information provided regarding the attachments, types and quantitative data will contribute to the existing knowledge of the muscle.

  8. Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

    Science.gov (United States)

    Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

    2011-05-01

    This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

  9. Immediate effect of selective neuromuscular electrical stimulation on the electromyographic activity of the vastus medialis oblique muscle

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    Denise DalAva Augusto

    2008-07-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2008v10n2p155 The Patellofemoral pain syndrome (PFPS is described as an anterior or retropatellar knee pain in the absence of other associated diseases, and has often been associated with dysfunction of the vastus medialis oblique muscle (VMO. However, several studies have demonstrated the impossibility of selectively activating this muscle with exercises. The aim of the present study was to analyze the immediate effect of neuromuscular electrical stimulation of VMO muscle by means of monitoring the electromyographic activity of the vastus medialis oblique (VMO and vastus lateralis (VL muscles. Eighteen healthy women with a mean age of 23.2 years and mean BMI of 20 Kg/m2 were evaluated. The study protocol included electromyographic analysis of VMO and VL muscles, before and immediately after neuromuscular electrical stimulation of the VMO muscle. During the electromyographic analysis, the volunteers performed maximal voluntary isometric contraction in a 60° knee extension on an isokinetic dynamometer. “Russian current” apparatus was used for electrical stimulation. Results: The data analysis demonstrated a signifi cant increase in VMO activation intensity immediately after it had been electrically stimulated (p=0.0125, whereas VL activation intensity exhibited no signifi cant increase (p=0.924. Moreover, a significant increase in the VMO/VL ratio was also detected (p=0.048. In this study it was observed that electrical stimulation modifiedthe VMO/VL ratio, which suggests electrical stimulation has a benefi cial effect on VMO muscle strength.

  10. High content of MYHC II in vastus lateralis is accompanied by higher VO2/power output ratio during moderate intensity cycling performed both at low and at high pedalling rates.

    Science.gov (United States)

    Majerczak, J; Szkutnik, Z; Karasinski, J; Duda, K; Kolodziejski, L; Zoladz, J A

    2006-06-01

    The aim of this study was to examine the relationship between the content of various types of myosin heavy chain isoforms (MyHC) in the vastus lateralis muscle and pulmonary oxygen uptake during moderate power output incremental exercise, performed at low and at high pedalling rates. Twenty one male subjects (mean +/- SD) aged 24.1 +/- 2.8 years; body mass 72.9 +/- 7.2 kg; height 179.1 +/- 4.8 cm; BMI 22.69 +/- 1.89 kg.m(-2); VO2max 50.6 +/- 5.3 ml.kg.min(-1), participated in this study. On separate days, they performed two incremental exercise tests at 60 rev.min(-1) and at 120 rev.min(-1), until exhaustion. Gas exchange variables were measured continuously breath by breath. Blood samples were taken for measurements of plasma lactate concentration prior to the exercise test and at the end of each step of the incremental exercise. Muscle biopsies were taken from the vastus lateralis muscle, using Bergström needle, and they were analysed for the content of MyHC I and MyHC II using SDS--PAGE and two groups (n=7, each) were selected: group H with the highest content of MyHC II (60.7 % +/- 10.5 %) and group L with the lowest content of MyHC II (27.6 % +/- 6.1 %). We have found that during incremental exercise at the power output between 30-120 W, performed at 60 rev.min(-1), oxygen uptake in the group H was significantly greater than in the group L (ANCOVA, p=0.003, upward shift of the intercept in VO2/power output relationship). During cycling at the same power output but at 120 rev.min(-1), the oxygen uptake was also higher in the group H, when compared to the group L (i.e. upward shift of the intercept in VO2/power output relationship, ANCOVA, p=0.002). Moreover, the increase in pedalling rate from 60 to 120 rev.min(-1) was accompanied by a significantly higher increase of oxygen cost of cycling and by a significantly higher plasma lactate concentration in subjects from group H. We concluded that the muscle mechanical efficiency, expressed by the VO2/PO ratio

  11. Collagen content in the vastus lateralis and the soleus muscle following a 90-day bed rest period with or without resistance exercises

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Oestergaard; Schjerling, Peter; Tesch, Per

    2015-01-01

    training serves as a proxy for the conditions in space. Therefore, ground-based studies may improve the understanding of the consequences of long-term inactivity. PURPOSE: the purpose is to compare the change in collagen protein in the vastus lateralis (VL) and the soleus (SOL) muscle amongst persons......INTRODUCTION: spaceflight seems associated with deterioration of the function of the skeletal muscles. Since muscle collagen is critical for muscle function, an improved understanding of the content of the muscle collagen during long-term inactivity seems important. Bed-rest with in-bed resistance...... collagen/mg protein [95% CI: -25.6; 12.6], p=0.50). There was no difference in the effect of BR versus BRE over time (mean difference -2.78 μg collagen/mg protein [95% CI: -29.7; 24.1], p=0.82). CONCLUSION: muscle collagen content in the VL or SOL muscle does not seem to differ after a 90-day bed rest...

  12. Effect of 5-week moderate intensity endurance training on the oxidative stress, muscle specific uncoupling protein (UCP3) and superoxide dismutase (SOD2) contents in vastus lateralis of young, healthy men.

    Science.gov (United States)

    Majerczak, J; Rychlik, B; Grzelak, A; Grzmil, P; Karasinski, J; Pierzchalski, P; Pulaski, L; Bartosz, G; Zoladz, J A

    2010-12-01

    In the present study fifteen male subjects (age: 22.7 ± 0.5 years; BMI: 23.5 ± 0.6 kg x m⁻²; VO₂(max) 46.0 ± 1.0 mL x kg⁻¹ x min⁻¹) performed 5 week moderate intensity endurance training. The training resulted in a significant increase in maximal oxygen uptake (VO₂(max)) (P=0.048) and power output reached at VO₂(max) (P=0.0001). No effect of training on the uncoupling protein 3 (UCP3) content in the vastus lateralis was found (P>0.05). The improvement of physical capacity was accompanied by no changes in cytochrome-c and cytochrome-c oxidase contents in the vastus lateralis (P>0.05). However, the training resulted in an increase (P=0.02) in mitochondrial manganese superoxide dismutase (SOD2) content in this muscle. Moreover, a significant decrease (P=0.028) in plasma basal isoprostanes concentration [F₂isoprostanes](pl) accompanied by a clear tendency to lower (P=0.08) gluthatione disulfide concentration [GSSG](pl) and tendency to higher (P=0.08) total antioxidant capacity (TAC) was observed after the training. We have concluded that as little as 5 weeks of moderate intensity endurance training is potent to improve physical capacity and antioxidant protection in humans. Surprisingly, these effects occur before any measurable changes in UCP3 protein content. We postulate that the training-induced improvement in the antioxidant protection at the muscle level is due to an increase in SOD2 content and that therefore, the role of UCP3 in the enhancement of physical capacity and antioxidant protection, at least in the early stage of training, is rather questionable.

  13. Effect of a patella support brace on myoelectric activity of knee joint muscles during single leg landing

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    Fatemeh Salariesker

    2013-06-01

    Full Text Available Introduction: Patellfemoral pain syndrome is one of the most common knee joint problems that affect athletes and non-athletes. Knee brace is often used as a treatment method for patellar realignment. The aim of the present study was to determine the effects of a patella support brace on myoelectric activity of selected knee muscles during single leg landing in healthy females. Materials and Methods: 19 healthy female students (Mean age: 23.6±1.98 years, height: 163.5±5.88 cm, weight: 62.3±3.6 kg participated in this study. Myoelectric activity of biceps femoris, semitendinosus, vastus medialis and vastus lateralis were collected during single leg landing in with and without using the patella support brace conditions.Results: Use of the patella support brace had no significant effect on myoelectric activity for the semitendinosus (p=0.668, vastus medialis (VM (p=0.915 and vastus lateralis (VL (P=0.134, while myoelectric activity for biceps femoris (p=0.005 and ratio of VM/VL myoelectric activity significantly increased (p=0.045. Conclusion: Our results revealed that biceps femoris activity and vastus medialis/vastus lateralis ratio increased after using patella support brace during single leg landing. Further studies on kinematic and kinetic variables are needed to describe these changes in muscular activity when using the patella support brace.

  14. Relationship between skin temperature and muscle activation during incremental cycle exercise.

    Science.gov (United States)

    Priego Quesada, Jose I; Carpes, Felipe P; Bini, Rodrigo R; Salvador Palmer, Rosario; Pérez-Soriano, Pedro; Cibrián Ortiz de Anda, Rosa M

    2015-02-01

    While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings.

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    Bart Malfait

    Full Text Available The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ.Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM,vastus lateralis(VL}, {vastus medialis(VM,hamstring medialis(HM}, {hamstring medialis(HM,hamstring lateralis(HL} and the {vastus lateralis(VL,hamstring lateralis(HL}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping.The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05. Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001. The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05. Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001. Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001.This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an increased medial and posterior

  16. Dexamethasone up-regulates skeletal muscle maximal Na+,K+ pump activity by muscle group specific mechanisms in humans

    DEFF Research Database (Denmark)

    Nordsborg, Nikolai; Goodmann, Craig; McKenna, Michael J.

    2005-01-01

    Dexamethasone, a widely clinically used glucocorticoid, increases human skeletal muscle Na+,K+ pump content, but the effects on maximal Na+,K+ pump activity and subunit specific mRNA are unknown. Ten healthy male subjects ingested dexamethasone for 5 days and the effects on Na+,K+ pump content......, maximal activity and subunit specific mRNA level (a1, a2, ß1, ß2, ß3) in deltoid and vastus lateralis muscle were investigated. Before treatment, maximal Na+,K+ pump activity, as well as a1, a2, ß1 and ß2 mRNA levels were higher (P ... increased Na+,K+ pump maximal activity in vastus lateralis and deltoid by 14 ± 7% (P Na+,K+ pump content by 18 ± 9% (P

  17. Changes in force, surface and motor unit EMG during post-exercise development of low frequency fatigue in vastus lateralis muscle.

    Science.gov (United States)

    de Ruiter, C J; Elzinga, M J H; Verdijk, P W L; van Mechelen, W; de Haan, A

    2005-08-01

    We investigated the effects of low frequency fatigue (LFF) on post-exercise changes in rectified surface EMG (rsEMG) and single motor unit EMG (smuEMG) in vastus lateralis muscle (n = 9). On two experimental days the knee extensors were fatigued with a 60-s-isometric contraction (exercise) at 50% maximal force capacity (MFC). On the first day post-exercise (15 s, 3, 9, 15, 21 and 27 min) rsEMG and electrically-induced (surface stimulation) forces were investigated. SmuEMG was obtained on day two. During short ramp and hold (5 s) contractions at 50% MFC, motor unit discharges of the same units were followed over time. Post-exercise MFC and tetanic force (100 Hz stimulation) recovered to about 90% of the pre-exercise values, but recovery with 20 Hz stimulation was less complete: the 20-100 Hz force ratio (mean +/- SD) decreased from 0.65+/-0.06 (pre-exercise) to 0.56+/-0.04 at 27 min post-exercise (Pexercise rsEMG (% pre-exercise maximum) and motor unit discharge rate were 51.1 +/- 12.7% and 14.1 +/- 3.7 (pulses per second; pps) respectively, 15 s post-exercise the respective values were 61.4 +/- 15.4% (P0.05). Thereafter, rsEMG (at 50% MFC) remained stable but motor unit discharge rate significantly increased to 17.7 +/- 3.9 pps 27 min post-exercise. The recruitment threshold decreased (Pexercise to 25.2 +/- 6.7% 27 min post-exercise. The increase in discharge rate was significantly greater than could be expected from the decrease in recruitment threshold. Thus, post-exercise LFF was compensated by increased motor unit discharge rates which could only partly be accounted for by the small decrease in motor unit recruitment threshold.

  18. Regulation of PDH in human arm and leg muscles at rest and during intense exercise

    DEFF Research Database (Denmark)

    Kiilerich, Kristian; Birk, Jesper Bratz; Damsgaard, Rasmus

    2008-01-01

    To test the hypothesis that pyruvate dehydrogenase (PDH) is differentially regulated in specific human muscles, regulation of PDH was examined in triceps, deltoid, and vastus lateralis at rest and during intense exercise. To elicit considerable glycogen use, subjects performed 30 min of exhaustive...... arm cycling on two occasions and leg cycling exercise on a third day. Muscle biopsies were obtained from deltoid or triceps on the arm exercise days and from vastus lateralis on the leg cycling day. Resting PDH protein content and phosphorylation on PDH-E1 alpha sites 1 and 2 were higher (P ....05) in vastus lateralis than in triceps and deltoid as was the activity of oxidative enzymes. Net muscle glycogen utilization was similar in vastus lateralis and triceps ( approximately 50%) but less in deltoid (likely reflecting less recruitment of deltoid), while muscle lactate accumulation was approximately...

  19. Ergonomic assessment of brake and accelerator mechanisms of MF285 and MF399 tractors using electromyography method

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    A Nikkhah

    2016-04-01

    Full Text Available Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than that of developed countries. Attention to ergonomic condition of agricultural machinery drivers is one of the goals of agricultural mechanization. Therefore, in this study the ergonomic conditions of brake and accelerator mechanisms for MF285 and MF399 tractor's drivers were investigated using a new method. Materials and Methods: 25 people were selected for experiment. The electrical activity of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus medialis, Vastus lateralis, Quadratus Lumborum and Trapezius muscles of drivers before and during pressing the pedal and after rest time were recorded using Biovision device. Measurements were performed for each person on each muscle 30 seconds before pressing the pedal, 60 seconds after pressing the pedal and after 60 seconds of rest. For all drivers, the muscles on the right side (brake and accelerator side have been selected and tested. The measurements were performed in compliance with appropriate time intervals between the measurements. Results and Discussion: Ergonomic assessment of brake pedal: The results showed that the RMS electrical activity of muscles of Vastus medialis and Medial gastrocnemius, during 60 seconds braking were 2.47 and 1.97. So, Vastus medialis and Medial gastrocnemius had the highest stress during pressing the MF399 tractor's brake pedal. Moreover, the Medial gastrocnemius and Lateral gastrocnemius with RMS electrical activity ratio of 2.47 and 1.74 had the highest RMS electrical activity ratio respectively, during 60 seconds braking compared to before braking of MF285 tractor. The comparison of results showed that the Vastus medialis and Trapezius had the higher stress

  20. Electromyographic investigation of unstable patella before and after its realignment operation

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    D D Baksi

    2011-01-01

    Full Text Available Background: Patellar dislocations are either due to superolateral contracture of the soft tissue or imbalance of the power between the vastus medialis (VM and the vastus lateralis (VL. The imbalance of muscle power as an etiology of patellar dislocation has not been studied. Hence, we studied the recurrent, habitual and permanent dislocations of the patella with an electromyogram (EMG of the vastus medialis, vastus lateralis, and pes anserinus, before and after realignment operations, to document the muscle imbalance and effectiveness of the realignment operation. Materials and Methods: An electromyographic investigation was carried out on the vastus medialis and vastus lateralis in nine recurrent, 20 habitual, and 13 permanent dislocations of the patella, before and after their realignment operations. Pes anserinus transposition, which acted as a medial stabilizer of the patella, was also investigated with an EMG study, to understand its role on patellar stability at 0΀, 30΀, 60΀, 90΀, 120΀, 150΀, and full flexion of the knee. The age of the patients varied from nine to 30 (mean 15 years. There were 24 males and 18 females. Twenty-six patellar dislocations were on the right and 16 were on the left side. Results: Electromyographic pictures reveal subnormal activity of the vastus medialis in all types of dislocations and similar activities of the vastus lateralis in permanent and habitual dislocations recorded pre operatively, which recovered to almost normal values postoperatively, at the mean one-year follow-up. Pes anserinus, which was used for medial stabilization of the patella after its realignment, maintained normal EMG activity before and after the operation. Conclusion: This study is significant for understanding the imbalance of muscle activities in patients with an unstable patella, which can be rectified without recurrence after pes anserinus transposition.

  1. The interaction between the vastus medialis and vastus intermedius and its influence on the extensor apparatus of the knee joint.

    Science.gov (United States)

    Grob, Karl; Manestar, Mirjana; Filgueira, Luis; Kuster, Markus S; Gilbey, Helen; Ackland, Timothy

    2018-03-01

    Although the vastus medialis (VM) is closely associated with the vastus intermedius (VI), there is a lack of data regarding their functional relationship. The purpose of this study was to investigate the anatomical interaction between the VM and VI with regard to their origins, insertions, innervation and function within the extensor apparatus of the knee joint. Eighteen human cadaveric lower limbs were investigated using macro-dissection techniques. Six limbs were cut transversely in the middle third of the thigh. The mode of origin, insertion and nerve supply of the extensor apparatus of the knee joint were studied. The architecture of the VM and VI was examined in detail, as was their anatomical interaction and connective tissue linkage to the adjacent anatomical structures. The VM originated medially from a broad hammock-like structure. The attachment site of the VM always spanned over a long distance between: (1) patella, (2) rectus femoris tendon and (3) aponeurosis of the VI, with the insertion into the VI being the largest. VM units were inserted twice-once on the anterior and once on the posterior side of the VI. The VI consists of a complex multi-layered structure. The layers of the medial VI aponeurosis fused with the aponeuroses of the tensor vastus intermedius and vastus lateralis. Together, they form the two-layered intermediate layer of the quadriceps tendon. The VM and medial parts of the VI were innervated by the same medial division of the femoral nerve. The VM consists of multiple muscle units inserting into the entire VI. Together, they build a potential functional muscular complex. Therefore, the VM acts as an indirect extensor of the knee joint regulating and adjusting the length of the extensor apparatus throughout the entire range of motion. It is of clinical importance that, besides the VM, substantial parts of the VI directly contribute to the medial pull on the patella and help to maintain medial tracking of the patella during knee

  2. Reference values for vastus lateralis fiber size and type in healthy subjects over 40 years old: a systematic review and metaanalysis.

    Science.gov (United States)

    Gouzi, Fares; Maury, Jonathan; Molinari, Nicolas; Pomiès, Pascal; Mercier, Jacques; Préfaut, Christian; Hayot, Maurice

    2013-08-01

    Skeletal muscle atrophy is a major systemic impairment in chronic diseases. Yet its determinants have been hard to identify because a clear research definition has not been agreed upon. The reduction in muscle fiber cross-sectional area (CSA) is a widely acknowledged marker of muscle atrophy, but no reference values for the muscle fiber CSA at the age of the onset of chronic disease have ever been published. Thus, we aimed to systematically review the studies providing data on fiber CSA and fiber type proportion in the vastus lateralis of the quadriceps of healthy subjects (age >40 yr) and then to pool and analyze the data from the selected studies to determine reference values for fiber CSA. We followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and identified 19 studies, including 423 subjects that matched the inclusion criteria. On the basis of fiber type and gender, the mean fiber CSA and the lower limits of normal (LLNs) were (%type I*60) + 1,743 μm(2) and (%type I*60) - 718 μm(2), respectively, for men; and (%type I*70) + 139 μm(2) and (%type I*70) - 1,485 μm(2), respectively, for women. There was no significant heterogeneity among subgroups of fiber type and gender. The pooled type I fiber proportion was 50.3% (LLN = 32.9%). In multivariate analysis, fiber CSA was significantly correlated with Vo2 peak (r = 190.92; P = 0.03), and type I fiber proportion was correlated with age (r = -0.024; P = 0.005), body mass index (r = 0.096; P = 0.005), and Vo2 peak (r = -0.053; P = 0.005). Our metaanalysis of a homogeneous set of studies is the first to provide valuable LLNs for fiber CSA according to fiber type and gender. This analysis will be improved by prospective assessment in well-characterized healthy subjects.

  3. Atividade eletromiográfica do vasto medial oblíquo em portadoras da síndrome da dor patelofemoral Electromyographyc activity of the vastus medialis oblique muscle in female patients with patellofemoral syndrome

    Directory of Open Access Journals (Sweden)

    Sâmia Najara Freitas Bessa

    2008-01-01

    Full Text Available A síndrome da dor patelofemoral (SDPF é uma das afecções que mais acometem a articulação do joelho. Embora sua etiologia não seja completamente conhecida, uma disfunção do músculo vasto medial oblíquo (VMO tem sido apontada como possível fator desencadeante. Este estudo visou avaliar, por meio de eletromiografia, se algum exercício, dentre dez exercícios resistidos usuais, produz ativação seletiva do VMO, com vistas a sua utilização clínica. Vinte voluntárias do sexo feminino, sendo dez com SDPF (24,7±4,35 anos e dez saudáveis, controle (22,5±1,58 anos, foram submetidas à avaliação eletromiográfica dos músculos VMO, vasto lateral longo e vasto lateral oblíquo (VLO durante a realização de 10 exercícios, incluindo cadeia cinética aberta e fechada, em diferentes angulações do joelho e posições do quadril. Os resultados mostram que nenhum dos exercícios se revelou seletivo para o VMO, tendo alguns mostrado ativação seletiva do VLO. No grupo com SDPF observou-se menor atividade eletromiográfica de todos os vastos em oito dos dez exercícios propostos, quando comparado ao controle; observou-se ainda, no grupo SDPF, menor relação VMO/VLO (0,63 do que no grupo controle (0,82, pThe patellofemoral pain syndrome (PFPS is among the most common knee pathologies. Although its etiology is not fully known, a dysfunction of the vastus medialis oblique (VMO muscle has been pointed out as a possible cause. This study aimed at assessing, by means of electromyography, whether one or more, among ten usual resisted exercises, might produce VMO selective activation, in view of its clinic application. Twenty female volunteers, ten with PFPS (aged 24.7±4.35 and ten healthy ones (aged 22.5±1.58 were submitted to electromyographic evaluation of VMO, vastus lateralis longus and vastus lateralis oblique (VLO muscles during ten exercises, including open and closed kinetic chain, at different degrees of knee flexion and of hip

  4. Magnetic resonance imaging of the tensor vastus intermedius: A topographic study based on anatomical dissections.

    Science.gov (United States)

    Grob, Karl; Manestar, Mirjana; Gascho, Dominic; Ackland, Timothy; Gilbey, Helen; Fretz, Christian; Kuster, Markus S

    2017-11-01

    The tensor of the vastus intermedius (TVI) is a newly described component of the extensor apparatus of the knee joint. The objective of this study was to evaluate the appearance of the TVI on magnetic resonance (MR) imaging and its association with the adjacent vastus lateralis (VL) and vastus intermedius (VI) muscles and to compare these findings with the corresponding anatomy. MR images were analyzed from a cadaveric thigh where the TVI, as part of the extensor apparatus of the knee joint, had been dissected. The course of the TVI in relation to the adjacent VL and VI was studied. The anatomic dissection and MR imaging revealed a multilayered organization of the lateral extensor apparatus of the knee joint. The TVI is an intervening muscle between the VL and VI that combined into a broad flat aponeurosis in the midthigh and merged into the quadriceps tendon. Dorsally, the muscle fibers of the TVI joined those of the VL and VI and blended into the attachment at the lateral lip of the linea aspera. In this area, distinguishing between these three muscles was not possible macroscopically or virtually by MR imaging. In the dorsal aspect, the onion-like muscle layers of the VL, TVI, and VI fuse to a hardly separable muscle mass indicating that these muscles work in conjunction to produce knee extension torque when knee joint action is performed. Clin. Anat. 30:1096-1102, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. Hip position and sex differences in motor unit firing patterns of the vastus medialis and vastus medialis oblique in healthy individuals.

    Science.gov (United States)

    Peng, Yi-Ling; Tenan, Matthew S; Griffin, Lisa

    2018-06-01

    Weakness of the vastus medialis oblique (VMO) has been proposed to explain the high prevalence of knee pain in female subjects. Clinicians commonly use exercises in an attempt to preferentially activate the VMO. Recently, our group found evidence to support clinical theory that the VMO is neurologically distinct from the vastus medialis (VM). However, the ability to voluntarily activate these muscle subsections is still disputed. The aim of this study was to determine if VM and VMO activation varies between sexes and if control of the two muscles is different between rehabilitation exercises. Thirteen men and 13 women performed isometric straight leg raises in two hip positions, neutral hip rotation and 30 degrees lateral hip rotation. Bipolar intramuscular fine-wire electrodes were inserted into the VM and VMO to obtain motor unit recruitment thresholds and initial firing rates at recruitment. Linear mixed models and Tukey post hoc tests were used to assess significant differences in 654 motor units. Women demonstrated faster motor unit firing rate at recruitment, 1.18 ± 0.56 Hz higher than men. Motor units fired 0.47 ± 0.19 Hz faster during neutral hip rotation compared with lateral hip rotation. The VMO motor units were recruited 2.92 ± 1.28% earlier than the VM. All motor units were recruited 3.74 ± 1.27% earlier during neutral hip rotation than lateral hip rotation. Thus the VM and the VMO can be activated differentially, and their motor unit recruitment properties are affected by sex and hip position. NEW & NOTEWORTHY This is the first study to reveal differential activation of the vastus medialis oblique from the vastus medialis in clinical exercise protocols. Our research group used fine-wire electrodes to examine EMG signals of the vastus medialis oblique and vastus medialis to avoid possible cross talk. We also consider the effect of sex on motor unit firing patterns because of higher prevalence of knee pain in women, and yet few

  6. Menstrual cycle mediates vastus medialis and vastus medialis oblique muscle activity.

    Science.gov (United States)

    Tenan, Matthew S; Peng, Yi-Ling; Hackney, Anthony C; Griffin, Lisa

    2013-11-01

    Sports medicine professionals commonly describe two functionally different units of the vastus medialis (VM), the VM, and the vastus medialis oblique (VMO), but the anatomical support is equivocal. The functional difference of the VMO is principle to rehabilitation programs designed to alleviate anterior knee pain, a pathology that is known to have a greater occurrence in women. The purpose of this study was to determine whether the motor units of the VM and VMO are differentially recruited and if this recruitment pattern has an effect of sex or menstrual cycle phase. Single motor unit recordings from the VM and VMO were obtained for men and women during an isometric ramp knee extension. Eleven men were tested once. Seven women were tested during five different phases of the menstrual cycle, determined by basal body temperature mapping. The recruitment threshold and the initial firing rate at recruitment were determined from 510 motor unit recordings. The initial firing rate was lower in the VMO than that in the VM in women (P recruitment thresholds for the VM and VMO in either sex or across the menstrual cycle. There was a main effect of menstrual phase on initial firing rate, showing increases from the early follicular to late luteal phase (P = 0.003). The initial firing rate in the VMO was lower than that in the VM during ovulatory (P = 0.009) and midluteal (P = 0.009) phases. The relative control of the VM and VMO changes across the menstrual cycle. This could influence patellar pathologies that have a higher incidence in women.

  7. Neuromuscular Activation of the Vastus Intermedius Muscle during Isometric Hip Flexion.

    Directory of Open Access Journals (Sweden)

    Akira Saito

    Full Text Available Although activity of the rectus femoris (RF differs from that of the other synergists in quadriceps femoris muscle group during physical activities in humans, it has been suggested that the activation pattern of the vastus intermedius (VI is similar to that of the RF. The purpose of present study was to examine activation of the VI during isometric hip flexion. Ten healthy men performed isometric hip flexion contractions at 25%, 50%, 75%, and 100% of maximal voluntary contraction at hip joint angles of 90°, 110° and 130°. Surface electromyography (EMG was used to record activity of the four quadriceps femoris muscles and EMG signals were root mean square processed and normalized to EMG amplitude during an isometric knee extension with maximal voluntary contraction. The normalized EMG was significantly higher for the VI than for the vastus medialis during hip flexion at 100% of maximal voluntary contraction at hip joint angles of 110° and 130° (P < 0.05. The onset of VI activation was 230-240 ms later than the onset of RF activation during hip flexion at each hip joint angle, which was significantly later than during knee extension at 100% of maximal voluntary contraction (P < 0.05. These results suggest that the VI is activated later than the RF during hip flexion. Activity of the VI during hip flexion might contribute to stabilize the knee joint as an antagonist and might help to smooth knee joint motion, such as in the transition from hip flexion to knee extension during walking, running and pedaling.

  8. Quantitative Skeletal Muscle MRI: Part 2, MR Spectroscopy and T2 Relaxation Time Mapping-Comparison Between Boys With Duchenne Muscular Dystrophy and Healthy Boys.

    Science.gov (United States)

    Kim, Hee Kyung; Serai, Suraj; Lindquist, Diana; Merrow, Arnold C; Horn, Paul S; Kim, Dong Hoon; Wong, Brenda L

    2015-08-01

    The purpose of this study is to validate the use of MR spectroscopy (MRS) in measuring muscular fat and to compare it with T2 maps in differentiating boys with Duchenne muscular dystrophy (DMD) from healthy boys. Forty-two boys with DMD and 31 healthy boys were evaluated with MRI with (1)H-MRS and T2 maps. Grading of muscle fat and edema on conventional images, calculation of fat fractions ([fat / fat] + water) on MRS, and calculation of T2 fat values on T2 maps of the gluteus maximus and vastus lateralis muscles were performed. Group comparisons were made. The 95% reference interval (RI) of fat fraction for the control group was applied and compared with T2 map results. Minimal fat on T1-weighted images was seen in 90.3% (gluteus maximus) and 71.0% (vastus lateralis) of healthy boys, versus 33.3% (gluteus maximus) and 52.4% (vastus lateralis) of boys with DMD. Muscle edema was seen in none of the healthy boys versus 52.4% (gluteus maximus) and 57.1% (vastus lateralis) of the boys with DMD. Fat fractions were higher in the DMD group (52.7%, gluteus maximus; 27.3%, vastus lateralis) than in the control group (12.8%, gluteus maximus; 13.7%, vastus lateralis) (p muscle edema in DMD.

  9. Effect of a Short Time Concentric Versus Eccentric Training Program on Electromyography Activity and Peak Torque of Quadriceps

    DEFF Research Database (Denmark)

    Carvalho, Alberto; Caserotti, Paolo; Carvalho, C.

    2014-01-01

    The purpose of this study was to examine the effect of an 8-week concentric (CON) versus eccentric (ECC) isokinetic training program on the electromyography (EMG) signal amplitude of vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF). Also, the isometric (ISO) and dynamic maximum...

  10. Muscle ion transporters and antioxidative proteins have different adaptive potential in arm than in leg skeletal muscle with exercise training

    DEFF Research Database (Denmark)

    Mohr, Magni; Nielsen, Tobias Schmidt; Weihe, Pál

    2017-01-01

    for 15 weeks, and pre- and postintervention biopsies were obtained from deltoideus and vastus lateralis muscle. Before training, monocarboxylate transporter 4 (MCT4), Na(+)/K(+) pump α2, and superoxide dismutase 2 (SOD2) expressions were lower (P ... occurred exclusively in vastus lateralis muscle. The increased (P MCT4 and SOD2 in deltoid muscle after HIS and vastus lateralis muscle after SOC were similar. In conclusion, arm musculature displays lower basal ROS, La(-), K(+) handling capability but higher Na(+)-dependent H...

  11. Immediate effect of selective neuromuscular electrical stimulation on the electromyographic activity of the vastus medialis oblique muscle

    Directory of Open Access Journals (Sweden)

    Jamilson Simões Brasileiro

    2008-04-01

    Full Text Available The Patellofemoral pain syndrome (PFPS is described as an anterior or retropatellar knee pain in the absence of other associated diseases, and has often been associated with dysfunction of the vastus medialis oblique muscle (VMO. However, several studies have demonstrated the impossibility of selectively activating this muscle with exercises. The aim of the present study was to analyze the immediate effect of neuromuscular electrical stimulation of VMO muscle by means of monitoring the electromyographic activity of the vastus medialis oblique (VMO and vastus lateralis (VL muscles. Eighteen healthy women with a mean age of 23.2 years and mean BMI of 20 Kg/m2 were evaluated. The study protocol included electromyographic analysis of VMO and VL muscles, before and immediately after neuromuscular electrical stimulation of the VMO muscle. During the electromyographic analysis, the volunteers performed maximal voluntary isometric contraction in a 60° knee extension on an isokinetic dynamometer. “Russian current” apparatus was used for electrical stimulation. Results: The data analysis demonstrated a signifi cant increase in VMO activation intensity immediately after it had been electrically stimulated (p=0.0125, whereas VL activation intensity exhibited no signifi cant increase (p=0.924. Moreover, a significant increase in the VMO/VL ratio was also detected (p=0.048. In this study it was observed that electrical stimulation modifiedthe VMO/VL ratio, which suggests electrical stimulation has a benefi cial effect on VMO muscle strength. Resumo A Síndrome da dor patelofemoral (SDPF é descrita como dor anterior ou retro-patelar do joelho na ausência de outras patologias associadas, sendo freqüentemente associada à disfunção do Vasto Medial Oblíquo (VMO. Entretanto, diversos estudos têm demonstrado a impossibilidade de ativar seletivamente este músculo através de exercícios. O objetivo do presente estudo foi analisar o efeito imediato da

  12. Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

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    Pantoja Patrícia Dias

    2014-07-01

    Full Text Available This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.

  13. Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

    Science.gov (United States)

    Pantoja, Patrícia Dias; Mello, André; Liedtke, Giane Veiga; Kanitz, Ana Carolina; Cadore, Eduardo Lusa; Pinto, Stephanie Santana; Alberton, Cristine Lima; Kruel, Luiz Fernando Martins

    2014-01-01

    This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions. PMID:25114728

  14. Leptin signaling in skeletal muscle after bed rest in healthy humans

    DEFF Research Database (Denmark)

    Guerra, Borja; Ponce-Gonzalez, Jesus Gustavo; Morales-Alamo, David

    2014-01-01

    . Leptin receptor isoforms (OB-Rs), suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) protein expression and signal transducer and activator of transcription 3 (STAT3) phosphorylation were analyzed by Western blot. RESULTS: After bed rest basal insulin concentration.......4-fold after bed rest (P PTP1B in the deltoid. PTP1B was increased by 90% with bed rest in the vastus lateralis (P ... between the increase in vastus lateralis PTP1B and the increase in both basal insulin concentrations (r = 0.66, P

  15. Biomechanical characteristics of skeletal muscles and associations between running speed and contraction time in 8- to 13-year-old children.

    Science.gov (United States)

    Završnik, Jernej; Pišot, Rado; Šimunič, Boštjan; Kokol, Peter; Blažun Vošner, Helena

    2017-02-01

    Objective To investigate associations between running speeds and contraction times in 8- to 13-year-old children. Method This longitudinal study analyzed tensiomyographic measurements of vastus lateralis and biceps femoris muscles' contraction times and maximum running speeds in 107 children (53 boys, 54 girls). Data were evaluated using multiple correspondence analysis. Results A gender difference existed between the vastus lateralis contraction times and running speeds. The running speed was less dependent on vastus lateralis contraction times in boys than in girls. Analysis of biceps femoris contraction times and running speeds revealed that running speeds of boys were much more structurally associated with contraction times than those of girls, for whom the association seemed chaotic. Conclusion Joint category plots showed that contraction times of biceps femoris were associated much more closely with running speed than those of the vastus lateralis muscle. These results provide insight into a new dimension of children's development.

  16. Effects of neuromuscular training on knee joint stability after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Shim, Jae-Kwang; Choi, Ho-Suk; Shin, Jun-Ho

    2015-12-01

    [Purpose] This study examined the effects of neuromuscular training on knee joint stability after anterior cruciate ligament reconstruction. [Subjects and Methods] The subjects were 16 adults who underwent arthroscopic anterior cruciate reconstruction and neuromuscular training. The Lysholm scale was used to assess functional disorders on the affected knee joint. A KT-2000 arthrometer was used to measure anterior displacement of the tibia against the femur. Surface electromyography was used to detect the muscle activation of the vastus medialis oblique, vastus lateralis, biceps femoris, and semitendinosus before and after neuromuscular training. [Results] There was significant relaxation in tibial anterior displacement of the affected and sound sides in the supine position before neuromuscular training. Furthermore, the difference in the tibial anterior displacement of the affected knee joints in the standing position was reduced after neuromuscular training. Moreover, the variation of the muscle activation evoked higher muscle activation of the vastus medialis oblique, vastus lateralis, biceps femoris, and semitendinosus. [Conclusion] Neuromuscular training may improve functional joint stability in patients with orthopedic musculoskeletal injuries in the postoperative period.

  17. Functional and morphological adaptations to aging in knee extensor muscles of physically active men.

    Science.gov (United States)

    Baroni, Bruno Manfredini; Geremia, Jeam Marcel; Rodrigues, Rodrigo; Borges, Marcelo Krás; Jinha, Azim; Herzog, Walter; Vaz, Marco Aurélio

    2013-10-01

    It is not known if a physically active lifestyle, without systematic training, is sufficient to combat age-related muscle and strength loss. Therefore, the purpose of this study was to evaluate if the maintenance of a physically active lifestyle prevents muscle impairments due to aging. To address this issue, we evaluated 33 healthy men with similar physical activity levels (IPAQ = 2) across a large range of ages. Functional (torque-angle and torque-velocity relations) and morphological (vastus lateralis muscle architecture) properties of the knee extensor muscles were assessed and compared between three age groups: young adults (30 ± 6 y), middle-aged subjects (50 ± 7 y) and elderly subjects (69 ± 5 y). Isometric peak torques were significantly lower (30% to 36%) in elderly group subjects compared with the young adults. Concentric peak torques were significantly lower in the middle aged (18% to 32%) and elderly group (40% to 53%) compared with the young adults. Vastus lateralis thickness and fascicles lengths were significantly smaller in the elderly group subjects (15.8 ± 3.9 mm; 99.1 ± 25.8 mm) compared with the young adults (19.8 ± 3.6 mm; 152.1 ± 42.0 mm). These findings suggest that a physically active lifestyle, without systematic training, is not sufficient to avoid loss of strength and muscle mass with aging.

  18. Quantitative ultrasound tissue characterization in shoulder and thigh muscles – a new approach

    Directory of Open Access Journals (Sweden)

    Jørgensen Kurt

    2006-01-01

    Full Text Available Abstract Background The echogenicity patterns of ultrasound scans contain information of tissue composition in muscles. The aim was: (1 to develop a quantitative ultrasound image analysis to characterize tissue composition in terms of intensity and structure of the ultrasound images, and (2 to use the method for characterization of ultrasound images of the supraspinatus muscle, and the vastus lateralis muscle. Methods Computerized texture analyses employing first-order and higher-order grey-scale statistics were developed to objectively characterize ultrasound images of m. supraspinatus and m. vastus lateralis from 9 healthy participants. Results The mean grey-scale intensity was higher in the vastus lateralis muscle (p -2 and for m. supraspinatus: 0.016 mm-2. Conclusion The higher intensity and the higher number of blobs in the vastus lateralis muscle indicates that the thigh muscle contained more non-contractile components than the supraspinatus muscle, and that the muscle was coarser. The image analyses supplemented each other and gave a more complete description of the tissue composition in the muscle than the mean grey-scale value alone.

  19. Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

    Science.gov (United States)

    Erdag, Deniz

    2017-01-01

    The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM). Electromyographic (EMG) activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition system (Myomonitor IV, Delsys Inc., Boston, MA, USA). Kinematical data were analyzed by using saSuite 2D kinematical analysis program. Data were analyzed with repeated measures analysis of variance (p squat may not be necessary for focusing on knee extensor improvement and may increase the lumbar injury risk. PMID:28546738

  20. Changes of pedaling technique and muscle coordination during an exhaustive exercise.

    Science.gov (United States)

    Dorel, Sylvain; Drouet, Jean-Marc; Couturier, Antoine; Champoux, Yvan; Hug, François

    2009-06-01

    Alterations of the mechanical patterns during an exhaustive pedaling exercise have been previously shown. We designed the present study to test the hypothesis that these alterations in the biomechanics of pedaling, which occur during exhaustive exercise, are linked to changes in the activity patterns of lower limb muscles. Ten well-trained cyclists were tested during a limited time to exhaustion, performing 80% of maximal power tolerated. Pedal force components were measured continuously using instrumented pedals and were synchronized with surface EMG signals measured in 10 lower limb muscles. The results confirmed most of the alterations of the mechanical patterns previously described in the literature. The magnitude of the root mean squared of the EMG during the complete cycle (RMScycle) for tibialis anterior and gastrocnemius medialis decreased significantly (P < 0.05) from 85% and 75% of Tlim, respectively. A higher RMScycle was obtained for gluteus maximus (P < 0.01) and biceps femoris (P < 0.05) from 75% of Tlim. The k values that resulted from the cross-correlation technique indicated that the activities of six muscles (gastrocnemius medialis, gastrocnemius lateralis, tibialis anterior, vastus lateralis, vastus medialis, and rectus femoris) were shifted forward in the cycle at the end of the exercise. The large increases in activity for gluteus maximus and biceps femoris, which are in accordance with the increase in force production during the propulsive phase, could be considered as instinctive coordination strategies that compensate for potential fatigue and loss of force of the knee extensors (i.e., vastus lateralis and vastus medialis) by a higher moment of the hip extensors.

  1. Dynamic factors and electromyographic activity in a sprint start

    Directory of Open Access Journals (Sweden)

    M Čoh

    2009-07-01

    Full Text Available The aim of the study was to establish the major dynamic parameters as well as the EMG activation of muscles in a sprint start as the first derivative of sprint velocity. The subject of the analysis was block velocity, the production of force in the front and rear starting blocks, the block acceleration in the first two steps and the electromyographic activity (EMG of the following muscles: the erector spinae muscle, gluteus maximus muscle, rectus femoris muscle, vastus medialis muscle, vastus lateralis muscle, biceps femoris muscle and gastrocnemius–medialis muscle. One international-class female sprinter participated in the experiment. She performed eight starts in constant laboratory conditions. The 3-D kinematic analysis was made using a system of nine Smart-e 600 cameras operating at a frame rate of 60 Hz. Dynamic parameters were established by means of two separate force platforms to which the starting blocks were fixed. A 16-channel electromyograph was used to analyse electromyographic activity (EMG. It was established that the block velocity depended on the absolute force produced in the front and rear starting blocks and that it was 2.84±0.21 m.s-1. The maximal force on the rear and front blocks was 628±34 N and 1023±30 N, respectively. In view of the total impulse (210±11 Ns the force production/time ratio in the rear and front blocks was 34%:66%. The erector spinae muscle, vastus lateralis muscle and gastrocnemius–medialis muscle generate the efficiency of the start. The block acceleration in the first two steps primarily depends on the activation of the gluteus maximus muscle, rectus femoris muscle, biceps femoris muscle and gastrocnemius–medialis muscle. A sprint start is a complex motor stereotype requiring a high degree of integration of the processes of central movement regulation and an optimal level of biomotor abilities.

  2. The effects of body weight unloading on kinetics and muscle activity of overweight males during Overground walking.

    Science.gov (United States)

    Fischer, Arielle G; Wolf, Alon

    2018-02-01

    Excess body weight has become a major worldwide health and social epidemic. Training with body weight unloading, is a common method for gait corrections for various neuromuscular impairments. In the present study we assessed the effects of body weight unloading on knee and ankle kinetics and muscle activation of overweight subjects walking overground under various levels of body weight unloading. Ten overweight subjects (25 ≤ BMI weight unloading experimental conditions. Gait parameters assessed under these conditions included knee and ankle flexion moments and the Electromygraphic activity of the Tibialis Anterior, Lateral Gastrocnemius and Vastus Lateralis. Increasing body weight unloading levels from 0% to 30% was found to significantly reduce the peak knee flexion and ankle plantarflexion moments. Also observed was a significant reduction in muscle activity of the Tibialis Anterior, Lateral Gastrocnemius and Vastus Lateralis under the three body-weight unloading conditions. Our results demonstrate that a reduction of up to 30% overweight subjects' body weight during gait is conducive to a reduction in the knee and ankle flexion moments and in the balancing net quadriceps moment and ankle flexors moment. The newly devised body weight unloading device is therefore an effective method for reducing joint loads allowing overweight people who require controlled weight bearing scenarios to retrain their gait while engaging in sustained walking exercise. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Immediate effects of neuromuscular joint facilitation intervention after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Wang, Lei

    2016-07-01

    [Purpose] The aim of this study was to examine the immediate effects of neuromuscular joint facilitation (NJF) on the functional activity level after rehabilitation of anterior cruciate ligament (ACL) reconstruction. [Subjects and Methods] Ten young subjects (8 males and 2 females) who underwent ACL reconstruction were included in the study. The subjects were divided into two groups, namely, knee joint extension muscle strength training (MST) group and knee joint extension outside rotation pattern of NJF group. Extension strength was measured in both groups before and after the experiment. Surface electromyography (sEMG) of the vastus medialis and vastus lateralis muscles and joint position error (JPE) test of the knee joint were also conducted. [Results] JPE test results and extension strength measurements in the NJF group were improved compared with those in the MST group. Moreover, the average discharge of the vastus medialis and vastus lateralis muscles on sEMG in the NJF group was significantly increased after MST and NJF treatments. [Conclusion] The obtained results suggest that NJF training in patients with ACL reconstruction can improve knee proprioception ability and muscle strength.

  4. Gender variability in electromyographic activity, in vivo behaviour of the human gastrocnemius and mechanical capacity during the take-off phase of a countermovement jump.

    Science.gov (United States)

    Rubio-Arias, Jacobo Ángel; Ramos-Campo, Domingo Jesús; Peña Amaro, José; Esteban, Paula; Mendizábal, Susana; Jiménez, José Fernando

    2017-11-01

    The purpose of this study was to analyse gender differences in neuromuscular behaviour of the gastrocnemius and vastus lateralis during the take-off phase of a countermovement jump (CMJ), using direct measures (ground reaction forces, muscle activity and dynamic ultrasound). Sixty-four young adults (aged 18-25 years) participated voluntarily in this study, 35 men and 29 women. The firing of the trigger allowed obtainment of data collection vertical ground reaction forces (GRF), surface electromyography activity (sEMG) and dynamic ultrasound gastrocnemius of both legs. Statistically significant gender differences were observed in the jump performance, which appear to be based on differences in muscle architecture and the electrical activation of the gastrocnemius muscles and vastus lateralis. So while men developed greater peak power, velocity take-offs and jump heights, jump kinetics compared to women, women also required a higher electrical activity to develop lower power values. Additionally, the men had higher values pennation angles and muscle thickness than women. Men show higher performance of the jump test than women, due to significant statistical differences in the values of muscle architecture (pennation angle and thickness muscle), lower Neural Efficiency Index and a higher amount of sEMG activity per second during the take-off phase of a CMJ. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  5. Rate of Torque Development and Feedforward Control of the Hip and Knee Extensors: Gender Differences.

    Science.gov (United States)

    Stearns-Reider, Kristen M; Powers, Christopher M

    2017-10-06

    The purpose of this study was to determine whether women demonstrate decreased rate of torque development (RTD) of the hip and knee extensors and altered onset timing of the vastus lateralis and gluteus maximus during a drop-jump task when compared with men. On average, women demonstrated significantly lower normalized RTD of the hip extensors (women: 11.6 ± 1.3 MVT.s -1 , men: 13.1 ± 0.9 MVT.s -1 ; p ≤ .01); however, there was no significant difference in knee extensor RTD. Women also demonstrated significantly earlier activation of their vastus lateralis (women: 206.0 ± 130.6 ms, men: 80.9 ± 69.6 ms; p ≤ .01) and gluteus maximus (women: 85.7 ± 58.6 ms, men: 54.5 ± 35.4 ms; p = .02). In both men and women, there was a significant negative correlation between the hip extensor RTD and the vastus lateralis electromyographic onset time (men: r = -.386, p = .046; women: r = -.531, p = .008). The study findings suggest that women may utilize a feedforward control strategy in which they activate their knee extensors earlier than men to compensate for deficits in hip extensor RTD. The impaired capacity to rapidly stabilize the hip and knee joints during dynamic maneuvers may contribute to the increased risk of anterior cruciate ligament injury observed in women.

  6. The Effect of Local Anesthetic Volume Within the Adductor Canal on Quadriceps Femoris Function Evaluated by Electromyography

    DEFF Research Database (Denmark)

    Grevstad, Ulrik; Jæger, Pia; Kløvgaard, Johan

    2016-01-01

    BACKGROUND: Single-injection adductor canal block (ACB) provides analgesia after knee surgery. Which nerves that are blocked by an ACB and what influence-if any-local anesthetic volume has on the effects remain undetermined. We hypothesized that effects on the nerve to the vastus medialis muscle......, they received a femoral nerve block and a placebo ACB. The effect on the vastus medialis (primary endpoint) and the vastus lateralis was evaluated using noninvasive electromyography (EMG). Quadriceps femoris muscle strength was evaluated using a dynamometer. RESULTS: There was a statistically significant......L was used (P = 0.0001). No statistically significant differences were found between volume and effect on the vastus lateralis (P = 0.81) or in muscle strength (P = 0.15). CONCLUSIONS: For ACB, there is a positive correlation between local anesthetic volume and effect on the vastus medialis muscle. Despite...

  7. Effect of exercise therapy on neuromuscular activity and knee strength in female adolescents with patellofemoral pain

    DEFF Research Database (Denmark)

    Rathleff, Michael S.; Samani, Afshin; Olesen, Jens L.

    2016-01-01

    . A random subsample of 57 female adolescents was included and tested at baseline and after 3months. Neuromuscular control of the knee was quantified as the complexity of surface electromyography of the vastus lateralis and vastus medialis during stair descent. Secondary outcomes were complexity of knee...... during stair descent than those receiving patient education alone. This suggest that exercise therapy has an effect not only on self-reported outcome measures but also on objective measures of thigh muscle function in female adolescents with patellofemoral pain....

  8. Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

    Directory of Open Access Journals (Sweden)

    Hasan U. Yavuz

    2017-01-01

    Full Text Available The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM. Electromyographic (EMG activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition system (Myomonitor IV, Delsys Inc., Boston, MA, USA. Kinematical data were analyzed by using saSuite 2D kinematical analysis program. Data were analyzed with repeated measures analysis of variance (p<0.05. Overall muscle activities increased with increasing loads, but significant increases were seen only for vastus medialis and gluteus maximus during 90% and 100% of 1RM compared to 80% while there was no significant difference between 90% and 100% for any muscle. The movement pattern in the hip joint changed with an increase in forward lean during maximal loading. Results may suggest that maximal loading during squat may not be necessary for focusing on knee extensor improvement and may increase the lumbar injury risk.

  9. The mRNA expression profile of metabolic genes relative to MHC isoform pattern in human skeletal muscles

    DEFF Research Database (Denmark)

    Plomgaard, Peter; Penkowa, Milena; Leick, Lotte

    2006-01-01

    The metabolic profile of rodent muscle is generally reflected in the myosin heavy chain (MHC) fiber-type composition. The present study was conducted to test the hypothesis that metabolic gene expression is not tightly coupled with MHC fiber-type composition for all genes in human skeletal muscle....... Triceps brachii, vastus lateralis quadriceps, and soleus muscle biopsies were obtained from normally physically active, healthy, young male volunteers, because these muscles are characterized by different fiber-type compositions. As expected, citrate synthase and 3-hydroxyacyl dehydrogenase activity...... of a broad range of metabolic genes. The triceps muscle had two- to fivefold higher MHC IIa, phosphofructokinase, and LDH A mRNA content and two- to fourfold lower MHC I, lipoprotein lipase, CD36, hormone-sensitive lipase, and LDH B and hexokinase II mRNA than vastus lateralis or soleus. Interestingly...

  10. Plantar pressure and EMG activity of simulated and actual ski jumping take-off.

    Science.gov (United States)

    Virmavirta, M; Komi, P V

    2001-10-01

    Plantar pressures and activation of the four muscles (VL - vastus lateralis, GL - gluteus, TA - tibialis anterior and GA - lat. gastrocnemius) were measured from ten ski jumpers under simulated laboratory conditions with training shoes (Lab TS) and with jumping boots (Lab JB) as well as in actual hill jumping conditions (Hill). The most significant differences between measured conditions were found in muscle activation patterns and plantar pressures prior to take-off. The centrifugal force due to the curvature of the inrun under actual hill jumping conditions caused extra pressure under the fore and rear parts of the feet (Pknee and hip extensor muscles.

  11. Patellar stabilization: a quantitative evaluation of the vastus medialis obliquus muscle

    NARCIS (Netherlands)

    Raimondo, R. A.; Ahmad, C. S.; Blankevoort, L.; April, E. W.; Grelsamer, R. P.; Henry, J. H.

    1998-01-01

    Twenty-one cadaveric knees were dissected to analyze the functional anatomy of the vastus medialis complex (VMC), which is composed of the vastus medialis obliquus (VMO) and the vastus medialis longus (VML) muscles. The physiologic cross-sectional area of the VMO for 20 of the knees was 29% of the

  12. Influence of Lateral Muscle Loading in the Proximal Femur after Fracture Stabilization with a Trochanteric Gamma Nail (TGN)

    Science.gov (United States)

    Sitthiseripratip, Kriskrai; Mahaisavariya, Banchong; Suwanprateeb, Jintamai; Bohez, Erik; Vander Sloten, Jos

    The purpose of this study was to investigate the influence of lateral muscle loading on the stress/strain distributions of the trochanteric Gamma nail (TGN) fixation within the healed, trochanteric and subtrochanteric femoral fractures by means of a finite element method. The effect of three muscle groups, the abductors (ABD), the vastus lateralis (VL) and the iliotibial band (ITB), were investigated. The analytical results showed that addition of lateral muscle forces, iliotibial band and vastus lateralis, produced compensation of forces and reduction of bending moments in the bone and in the trochanteric Gamma nail especially in the lateral aspect. The iliotibial band produced a higher impact as compared to the vastus lateralis. Therefore in the finite element analysis of the proximal femur with the trochanteric Gamma nail fracture fixation should include the lateral muscle forces to simulate load condition with maximal physiological relevance to the closed nailing technique.

  13. Muscle fibre type composition of a number of limb muscles in different types of horse.

    Science.gov (United States)

    Snow, D H; Guy, P S

    1980-03-01

    Skeletal muscle of the equine was differentiated into three fibre types according to myosin ATPase (pH 9.4) and succinic dehydrogenase activity. The percentage of these types was determined in the musculus deltoideus, m triceps brachii caput longum, m gluteus medius, m semitendinosis, m biceps femoris and m vastus lateralis of the thoroughbred, Shetland pony, pony, heavy hunter and donkey. In addition the m gluteus medius was examined in the arab and American racing quarterhorse. High myosin ATPase activity fibres varied from a mean of 93.2 per cent in the m gluteus medius of the quarterhorse to 58.2 per cent in the m vastus lateralis of the donkey. In the m gluteus medius it was found that the percentage of high mycosin ATPase (pH 9.4) fibres varied significantly among breeds and these differences were related to the sprinting speed of the breed.

  14. Oral glucose ingestion attenuates exercise-induced activation of 5'-AMP-activated protein kinase in human skeletal muscle

    DEFF Research Database (Denmark)

    Åkerström, Thorbjörn; Birk, Jesper Bratz; Klein, Ditte Kjærsgaard

    2006-01-01

    5'-AMP-activated protein kinase (AMPK) has been suggested to be a 'metabolic master switch' regulating various aspects of muscle glucose and fat metabolism. In isolated rat skeletal muscle, glucose suppresses the activity of AMPK and in human muscle glycogen loading decreases exercise-induced AMPK...... activation. We hypothesized that oral glucose ingestion during exercise would attenuate muscle AMPK activation. Nine male subjects performed two bouts of one-legged knee-extensor exercise at 60% of maximal workload. The subjects were randomly assigned to either consume a glucose containing drink or a placebo...... drink during the two trials. Muscle biopsies were taken from the vastus lateralis before and after 2 h of exercise. Plasma glucose was higher (6.0 +/- 0.2 vs. 4.9 +/- 0.1 mmol L-1, P

  15. The Role of Botulinum Toxin Type A in the Clinical Management of Refractory Anterior Knee Pain

    Directory of Open Access Journals (Sweden)

    Barbara J. Singer

    2015-08-01

    Full Text Available Anterior knee pain is a highly prevalent condition affecting largely young to middle aged adults. Symptoms can recur in more than two thirds of cases, often resulting in activity limitation and reduced participation in employment and recreational pursuits. Persistent anterior knee pain is difficult to treat and many individuals eventually consider a surgical intervention. Evidence for long term benefit of most conservative treatments or surgical approaches is currently lacking. Injection of Botulinum toxin type A to the distal region of vastus lateralis muscle causes a short term functional “denervation” which moderates the influence of vastus lateralis muscle on the knee extensor mechanism and increases the relative contribution of the vastus medialis muscle. Initial data suggest that, compared with other interventions for anterior knee pain, Botulinum toxin type A injection, in combination with an active exercise programme, can lead to sustained relief of symptoms, reduced health care utilisation and increased activity participation. The procedure is less invasive than surgical intervention, relatively easy to perform, and is time- and cost-effective. Further studies, including larger randomized placebo-controlled trials, are required to confirm the effectiveness of Botulinum toxin type A injection for anterior knee pain and to elaborate the possible mechanisms underpinning pain and symptom relief.

  16. Fatigue-related changes in motor-unit synchronization of quadriceps muscles within and across legs

    NARCIS (Netherlands)

    Boonstra, T.W.; Daffertshofer, A.; van Ditshuizen, J.C.; van den Heuvel, M.R.C.; Hofman, C.; Willigenburg, N.W.; Beek, P.J.

    2008-01-01

    Two experiments were conducted to examine effects of muscle fatigue on motor-unit synchronization of quadriceps muscles (rectus femoris, vastus medialis, vastus lateralis) within and between legs. We expected muscle fatigue to result in an increased common drive to different motor units of

  17. The Hsp72 and Hsp90α mRNA Responses to Hot Downhill Running Are Reduced Following a Prior Bout of Hot Downhill Running, and Occur Concurrently within Leukocytes and the Vastus Lateralis

    Directory of Open Access Journals (Sweden)

    James A. Tuttle

    2017-07-01

    Full Text Available The leukocyte heat shock response (HSR is used to determine individual's thermotolerance. The HSR and thermotolerance are enhanced following interventions such as preconditioning and/or acclimation/acclimatization. However, it is unclear whether the leukocyte HSR is an appropriate surrogate for the HSR in other tissues implicated within the pathophysiology of exertional heat illnesses (e.g., skeletal muscle, and whether an acute preconditioning strategy (e.g., downhill running can improve subsequent thermotolerance. Physically active, non-heat acclimated participants were split into two groups to investigate the benefits of hot downhill running as preconditioning strategy. A hot preconditioning group (HPC; n = 6 completed two trials (HPC1HOTDOWN and HPC2HOTDOWN of 30 min running at lactate threshold (LT on −10% gradient in 30°C and 50% relative humidity (RH separated by 7 d. A temperate preconditioning group (TPC; n = 5 completed 30 min running at LT on a −1% gradient in 20°C and 50% (TPC1TEMPFLAT and 7 d later completed 30 min running at LT on −10% gradient in 30°C and 50% RH (TPC2HOTDOWN. Venous blood samples and muscle biopsies (vastus lateralis; VL were obtained before, immediately after, 3, 24, and 48 h after each trial. Leukocyte and VL Hsp72, Hsp90α, and Grp78 mRNA relative expression was determined via RT-QPCR. Attenuated leukocyte and VL Hsp72 (2.8 to 1.8 fold and 5.9 to 2.4 fold; p < 0.05 and Hsp90α mRNA (2.9 to 2.4 fold and 5.2 to 2.4 fold; p < 0.05 responses accompanied reductions (p < 0.05 in physiological strain [exercising rectal temperature (−0.3°C and perceived muscle soreness (~ −14%] during HPC2HOTDOWN compared to HPC1HOTDOWN (i.e., a preconditioning effect. Both VL and leukocyte Hsp72 and Hsp90α mRNA increased (p < 0.05 simultaneously following downhill runs and demonstrated a strong relationship (p < 0.01 of similar magnitudes with one another. Hot downhill running is an effective preconditioning strategy

  18. Cytokine genes as potential biomarkers for muscle weakness in OPMD

    DEFF Research Database (Denmark)

    Riaz, Muhammad; Raz, Yotam; van der Slujis, Barbara

    2016-01-01

    is a dominant, late-onset myopathy, caused by an alanine-expansion mutation in the gene encoding for poly(A) binding protein nuclear 1 (expPABPN1). Here, we investigated the hypothesis that cytokines could mark OPMD disease state. We determined cytokines levels the vastus lateralis muscle from genetically...... confirmed expPABPN1 carriers at a symptomatic or a presymptomatic stage. We identified cytokine-related genes candidates from a transcriptome study in a mouse overexpressing exp PABPN1 Six cytokines were found to be consistently down-regulated in OPMD vastus lateralis muscles. Expression levels...

  19. Low muscle glycogen and elevated plasma free fatty acid modify but do not prevent exercise-induced PDH activation in human skeletal muscle

    DEFF Research Database (Denmark)

    Kiilerich, Kristian; Gudmundsson, Mikkel; Birk, Jesper Bratz

    2010-01-01

    to the contra-lateral leg (CON) the day before the experiment day. On the experimental days, plasma FFA was ensured normal or remained elevated by consuming breakfast rich (low FFA) or poor (high FFA) in carbohydrate, 2 hours before performing 20 min of two-legged knee extensor exercise. Vastus lateralis...

  20. Chronic Effects of Different Rest Intervals Between Sets on Dynamic and Isometric Muscle Strength and Muscle Activity in Trained Older Women.

    Science.gov (United States)

    Jambassi Filho, José Claudio; Gurjão, André Luiz Demantova; Ceccato, Marilia; Prado, Alexandre Konig Garcia; Gallo, Luiza Herminia; Gobbi, Sebastião

    2017-09-01

    This study investigated the chronic effects of different rest intervals (RIs) between sets on dynamic and isometric muscle strength and muscle activity. We used a repeated-measures design (pretraining and posttraining) with independent groups (different RI). Twenty-one resistance-trained older women (66.4 ± 4.4 years) were randomly assigned to either a 1-minute RI group (G-1 min; n = 10) or 3-minute RI group (G-3 min; n = 11). Both groups completed 3 supervised sessions per week during 8 weeks. In each session, participants performed 3 sets of 15 repetitions of leg press exercise, with a load that elicited muscle failure in the third set. Fifteen maximum repetitions, maximal voluntary contraction, peak rate of force development, and integrated electromyography activity of the vastus lateralis and vastus medialis muscles were assessed pretraining and posttraining. There was a significant increase in load of 15 maximum repetitions posttraining for G-3 min only (3.6%; P 0.05). The findings suggest that different RIs between sets did not influence dynamic and isometric muscle strength and muscle activity in resistance-trained older women.

  1. Asymmetry and Thigh Muscle Coactivity in Fatigued Anterior Cruciate Ligament-Reconstructed Elite Skiers

    DEFF Research Database (Denmark)

    Jordan, Matthew J; Aagaard, Per; Herzog, Walter

    2017-01-01

    PURPOSE: The acute effects of fatigue on functional interlimb asymmetry and quadriceps/hamstring muscle activity levels, including preparatory coactivation during squat jump takeoff and landing, were evaluated in elite alpine ski racers with/without anterior cruciate ligament reconstruction (ACLR......). METHODS: Twenty-two elite ski racers (ACLR, n = 11; control, n = 11) performed an 80-s repeated squat jump test (jump test) on a dual force plate system with simultaneous EMG recordings in vastus lateralis, vastus medialis, semitendinosus, and biceps femoris. Asymmetry index (AI) and jump height of body...

  2. Comparative analysis of speed's impact on muscle demands during partial body weight support motor-assisted elliptical training.

    Science.gov (United States)

    Burnfield, Judith M; Irons, Sonya L; Buster, Thad W; Taylor, Adam P; Hildner, Gretchen A; Shu, Yu

    2014-01-01

    Individuals with walking limitations often experience challenges engaging in functionally relevant exercise. An adapted elliptical trainer (motor to assist pedal movement, integrated body weight harness, ramps/stairs, and grab rails) has been developed to help individuals with physical disabilities and chronic conditions regain/retain walking capacity and fitness. However, limited published studies are available to guide therapeutic interventions. This repeated measures study examined the influence of motor-assisted elliptical training speed on lower extremity muscle demands at four body weight support (BWS) levels commonly used therapeutically for walking. Electromyography (EMG) and pedal trajectory data were recorded as ten individuals without known disability used the motor-assisted elliptical trainer at three speeds [20,40, 60 revolutions per minute (RPM)] during each BWS level (0%, 20%, 40%, 60%). Overall, the EMG activity (peak, mean, duration) in key stabilizer muscles (i.e., gluteus medius, gluteus maximus, vastus lateralis, medial gastrocnemius and soleus) recorded at 60 RPM exceeded those at 40 RPM, which were higher than values at 20 RPM in all but three situations (gluteus medius mean at 0% BWS, vastus lateralis mean at 20% BWS, soleus duration at 40% BWS); however, these differences did not always achieve statistical significance. Slower motor-assisted speeds can be used to accommodate weakness of gluteus medius, gluteus maximus, vastus lateralis, medial gastrocnemius and soleus. As strength improves, training at faster motor-assisted speeds may provide a means to progressively challenge key lower extremity stabilizers. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Trunk muscle activity increases with unstable squat movements.

    Science.gov (United States)

    Anderson, Kenneth; Behm, David G

    2005-02-01

    The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).

  4. Effect of Seat Tube Angle and Exercise Intensity on Muscle Activity Patterns in Cyclists

    Science.gov (United States)

    DUGGAN, WILL; DONNE, BERNARD; FLEMING, NEIL

    2017-01-01

    Previous studies have reported improved efficiency at steeper seat tube angle (STA) during ergometer cycling; however, neuromuscular mechanisms have yet to be fully determined. The current study investigated effects of STA on lower limb EMG activity at varying exercise intensities. Cyclists (n=11) were tested at 2 workloads; 160W and an individualised workload (IWL) equivalent to lactate threshold (TLac) minus 10%δ (derived from maximal incremental data), using 3 STA (70, 75 and 80°). Electromyographic data from Vastus Medialis (VM), Rectus Femoris (RF), Vastus Lateralis (VL) and Biceps Femoris (BF) were assessed. The timing and magnitude of activation were quantified and analysed using a two-way ANOVA. STA had significant (P pedal stroke is generated during the mid-section of the down-stroke, movement of the activation range of knee extensors into the predominantly power phase of the pedal stroke would potentially account for increased efficiency and decreased cardio-respiratory costs. Greater activity of bi-articular RF, in the first 108º of the crank cycle at IWL (80 vs. 70º) may more closely resemble the pelvic stabilising activity of RF in running biomechanics; and potentially explain the more effective transition from cycling to running reported in triathletes using steeper STA. PMID:29399245

  5. Effects of treadmill inclination on electromyographic activity and hind limb kinematics in healthy hounds at a walk.

    Science.gov (United States)

    Lauer, Susanne K; Hillman, Robert B; Li, Li; Hosgood, Giselle L

    2009-05-01

    To evaluate the effect of treadmill incline on muscle activity and joint range of motion (ROM) in hind limbs of dogs. 8 purpose-bred healthy adult hounds. Activities of the hamstring (semimembranosus, semitendinosus, and biceps femoris muscles), gluteal (superficial, middle, and deep gluteal muscles), and quadriceps (femoris, vastus lateralis, vastus intermedius, and vastus medialis muscles) muscle groups and hip and stifle joint ROM were measured with surface electrogoniometric and myographic sensors in hounds walking on a treadmill at 0.54 m/s at inclines of 5%, 0%, and -5% in random order. Mean electromyographic activities and mean ROMs at each inclination were compared for swing and stance phases. Treadmill inclination did not affect duration of the stance and swing phases or the whole stride. When treadmill inclination was increased from -5% to 5%, hip joint ROM increased and the degree of stifle joint extension decreased significantly. In the beginning of the stance phase, activity of the hamstring muscle group was significantly increased when walking at a 5% incline versus a 5% decline. In the end of the stance phase, that activity was significantly increased when walking at a 5% incline versus at a 5% decline or on a flat surface. Activity of the gluteal and quadriceps muscle groups was not affected when treadmill inclination changed. Treadmill inclination affected joint kinematics only slightly. Walking on a treadmill at a 5% incline had more potential to strengthen the hamstring muscle group than walking on a treadmill with a flat or declined surface.

  6. Decreased torque and electromyographic activity in the extensor thigh muscles in chondromalacia patellae.

    Science.gov (United States)

    Väätäinen, U; Airaksinen, O; Jaroma, H; Kiviranta, I

    1995-01-01

    The alterations in thigh muscle properties of chondromalacia patellae patients during isometric and dynamic endurance tests were studied using a variokinetic knee testing system linked to surface EMG. A total of 41 patients (chondromalacia group) with arthroscopically certified chondromalacia of the patella were studied. The control group consisted of 31 healthy adult volunteers with no history of knee pain or trauma. Peak torque values were 21% (p chondromalacia group than in the control group. The decrease in the ratio between integrated EMG (IEMG) and measured force were found in all parts of the quadriceps femoris muscle in patients with chondromalacia of the patella in isometric extension. No change in the normalized IEMG levels of the thigh muscles were found between chondromalacia patients and controls in dynamic endurance test. The severity of the chondromalacia of the patella did not affect the level of electromyographic activation in thigh muscles. The ratio of normalized EMG levels of vastus medialis and vastus lateralis did not differ between the groups. The present study showed that chondromalacia patellae patients have reduced force and electromyographic activation levels of quadriceps femoris muscle. Especially, the explosive strength of the quadriceps femoris muscle is reduced.

  7. Effects of combined high intensity arm and leg training on performance and cardio-respiratory measures.

    Science.gov (United States)

    Zinner, Christoph; Sperlich, Billy; Born, Dennis-Peter; Michels, Guido

    2017-01-01

    The purpose of this study was to investigate the effects of combined arm and leg high-intensity low-volume interval training (HIITarm+leg) on maximal oxygen uptake, myocardial measures (i.e. stroke volume, cardiac output, ejection fraction), Tissue Oxygenation Index (TOI) of the vastus lateralis and triceps brachii, as well as power output in comparison to leg HIIT (HIITleg) only. The 20 healthy, male and female volunteers completed six sessions of either HIITleg on a cycle ergometer or HIITarm+leg on an arm and leg cycle ergometer. During pre- and post-testing, the volunteers completed a submaximal and incremental test to exhaustion on a cycle ergometer. Magnitude based interference revealed likely to very likely beneficial effects for HIITarm+leg compared to HIITleg in maximal oxygen uptake, cardiac measures as well peak power output. The TOI following HIITarm+leg demonstrated likely to very likely increased oxygenation in the triceps brachii or the vastus lateralis when compared to HIITleg. The results suggest that six sessions of HIITarm+leg may likely to very likely improve maximal oxygen uptake, some inotropy-related cardiac measures with improved tissue oxygenation of the triceps brachii and vastus lateralis muscles resulting in greater leg peak power output.

  8. A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury

    DEFF Research Database (Denmark)

    Husted, Rasmus S; Bencke, Jesper; Andersen, Lars Louis

    2016-01-01

    phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests. METHODS: Sixty-two adolescent female elite......BACKGROUND: Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular...... football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored...

  9. Inter- and intramuscular differences in training-induced hypertrophy of the quadriceps femoris: association with muscle activation during the first training session.

    Science.gov (United States)

    Wakahara, Taku; Ema, Ryoichi; Miyamoto, Naokazu; Kawakami, Yasuo

    2017-07-01

    The purpose of this study was to examine whether inter- and intramuscular differences in hypertrophy induced by resistance training correspond to differences in muscle activation during the first training session. Eleven young men completed 12 weeks of training intervention for knee extension. Before and after the intervention, T1-weighted magnetic resonance (MR) images were recorded to determine the volume and anatomical cross-sectional area (CSA) along the length of the individual muscles of the quadriceps femoris. The T2-weighted MR images were also acquired before and immediately after the first training session. The T2 was calculated for each pixel within the quadriceps femoris, from which the muscle activation was evaluated as %activated volume and area. The results showed that the %activated volume after the first training session was significantly higher in the vastus intermedius than the vastus medialis. However, the relative change in muscle volume after the training intervention was significantly greater in the rectus femoris than the vasti muscles (vastus lateralis, intermedius and medialis). Within the rectus femoris, both the %activated area and relative increase in CSA were significantly greater in the distal region than the proximal region. In contrast, the %activated area and relative increase in CSA of the vasti were nearly uniform along each muscle. These results suggest that the muscle activation during the first training session is associated with the intramuscular difference in hypertrophy induced by training intervention, but not with the intermuscular difference. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  10. Quantitative Skeletal Muscle MRI: Part 1, Derived T2 Fat Map in Differentiation Between Boys With Duchenne Muscular Dystrophy and Healthy Boys.

    Science.gov (United States)

    Johnston, Jennifer H; Kim, Hee Kyung; Merrow, Arnold C; Laor, Tal; Serai, Suraj; Horn, Paul S; Kim, Dong Hoon; Wong, Brenda L

    2015-08-01

    The purpose of this study was to validate derived T2 maps as an objective measure of muscular fat for discrimination between boys with Duchenne muscular dystrophy (DMD) and healthy boys. Forty-two boys with DMD (mean age, 9.9 years) and 31 healthy boys (mean age, 11.4 years) were included in the study. Age, body mass index, and clinical function scale grade were evaluated. T1-weighted MR images and T2 maps with and without fat suppression were obtained. Fatty infiltration was graded 0-4 on T1-weighted images, and derived T2 fat values (difference between mean T2 values from T2 maps with and without fat suppression) of the gluteus maximus and vastus lateralis muscles were calculated. Group comparisons were performed. The upper limit of the 95% reference interval of T2 fat values from the control group was applied. There was no significant difference in age or body mass index between groups. All healthy boys and 19 boys (45.2%) with DMD had a normal clinical function scale grade. Grade 1 fatty infiltration was seen in 90.3% (gluteus maximus) and 71.0% (vastus lateralis) of healthy boys versus 33.3% (gluteus maximus) and 52.4% (vastus lateralis) of boys with DMD. T2 fat values of boys with DMD were significantly longer than in the control group (p < 0.001). Using a 95% reference interval for healthy boys for the gluteus maximus (28.3 milliseconds) allowed complete separation from boys with DMD (100% sensitivity, 100% specificity), whereas the values for the vastus lateralis (7.28 milliseconds) resulted in 83.3% sensitivity and 100% specificity. Measurement of muscular fat with T2 maps is accurate for differentiating boys with DMD from healthy boys.

  11. Pectoral fin beat frequency predicts oxygen consumption during spontaneous activity in a labriform swimming fish (Embiotoca lateralis)

    DEFF Research Database (Denmark)

    Tudorache, Christian; Jordan, Anders D.; Svendsen, Jon Christian

    2009-01-01

    The objective of this study was to identify kinematic variables correlated with oxygen consumption during spontaneous labriform swimming. Kinematic variables (swimming speed, change of speed, turning angle, turning rate, turning radius and pectoral fin beat frequency) and oxygen consumption (MO2......) of spontaneous swimming in Embiotoca lateralis were measured in a circular arena using video tracking and respirometry, respectively. The main variable influencing MO2 was pectoral fin beat frequency (r (2) = 0.71). No significant relationship was found between swimming speed and pectoral fin beat frequency....... Complementary to other methods within biotelemetry such as EMG it is suggested that such correlations of pectoral fin beat frequency may be used to measure the energy requirements of labriform swimming fish such as E. lateralis in the field, but need to be taken with great caution since movement and oxygen...

  12. The Effect of Exercise on the Skeletal Muscle Phospholipidome of Rats Fed a High-Fat Diet

    Directory of Open Access Journals (Sweden)

    Jong Sam Lee

    2010-10-01

    Full Text Available The aim of this study was to examine the effect of endurance training on skeletal muscle phospholipid molecular species from high-fat fed rats. Twelve female Sprague-Dawley rats were fed a high-fat diet (78.1% energy. The rats were randomly divided into two groups, a sedentary control group and a trained group (125 min of treadmill running at 8 m/min, 4 days/wk for 4 weeks. Forty-eight hours after their last training bout phospholipids were extracted from the red and white vastus lateralis and analyzed by electrospray-ionization mass spectrometry. Exercise training was associated with significant alterations in the relative abundance of a number of phospholipid molecular species. These changes were more prominent in red vastus lateralis than white vastus lateralis. The largest observed change was an increase of ~30% in the abundance of 1-palmitoyl-2-linoleoyl phosphatidylcholine ions in oxidative fibers. Reductions in the relative abundance of a number of phospholipids containing long-chain n-3 polyunsaturated fatty acids were also observed. These data suggest a possible reduction in phospholipid remodeling in the trained animals. This results in a decrease in the phospholipid n-3 to n-6 ratio that may in turn influence endurance capacity.

  13. Static stretching does not alter pre and post-landing muscle activation

    Directory of Open Access Journals (Sweden)

    Moss Wesley R

    2011-05-01

    Full Text Available Abstract Background Static stretching may result in various strength and power deficiencies. Prior research has not determined, however, if static stretching causes a change in muscle activation during a functional task requiring dynamic stability. The purpose of this study was to determine if static stretching has an effect on mean pre and postlanding muscle (vastus medialis VM, vastus lateralis VL, medial hamstring MH, and biceps femoris BF activity. Methods 26 healthy, physically active subjects were recruited, from which 13 completed a 14-day static stretching regimen for the quadriceps and hamstrings. Using the data from the force plate and EMG readings, a mean of EMG amplitude was calculated for 150 msec before and after landing. Each trial was normalized to an isometric reference position. Means were calculated for the VM, VL, MH, and BF from 5 trials in each session. Measures were collected pre, immediately following the 1st stretching session, and following 2 weeks of stretching. Results A 14-day static stretching regimen resulted in no significant differences in pre or postlanding mean EMG amplitude during a drop landing either acutely or over a 14-day period. Conclusions Static stretching, done acutely or over a 14-day period does not result in measurable differences of mean EMG amplitude during a drop landing. Static stretching may not impede dynamic stability of joints about which stretched muscles cross.

  14. Age-Related Increase in Electromyography Burst Activity in Males and Females

    Directory of Open Access Journals (Sweden)

    Olga Theou

    2013-01-01

    Full Text Available The rapid advancement of electromyography (EMG technology facilitates measurement of muscle activity outside the laboratory during daily life. The purpose of this study was to determine whether bursts in EMG recorded over a typical 8-hour day differed between young and old males and females. Muscle activity was recorded from biceps brachii, triceps brachii, vastus lateralis, and biceps femoris of 16 young and 15 old adults using portable surface EMG. Old muscles were active 16–27% of the time compared to 5–9% in young muscles. The number of bursts was greater in old than young adults and in females compared to males. Burst percentage and mean amplitude were greater in the flexor muscles compared with the extensor muscles. The greater burst activity in old adults coupled with the unique activity patterns across muscles in males and females provides further understanding of how changes in neuromuscular activity effects age-related functional decline between the sexes.

  15. Insulin receptor binding and tyrosine kinase activity in skeletal muscle from normal pregnant women and women with gestational diabetes

    DEFF Research Database (Denmark)

    Damm, P.; Handberg, A.; Kühl, C.

    1993-01-01

    OBJECTIVE: To ascertain whether the decreased glucose tolerance and insulin resistance found in normal and gestational diabetic pregnancy might be associated with changes in insulin receptor function. METHODS: Eight nonpregnant healthy women (nonpregnant controls), eight healthy pregnant women...... (pregnant controls), and eight women with gestational diabetes were investigated. All were non-obese. Muscle biopsies were obtained from the vastus lateralis muscle, and insulin binding and tyrosine kinase activities in partially purified skeletal muscle insulin receptors were studied. The pregnant controls...... with gestational diabetes compared to nonpregnant controls (P pregnant women did not differ from the other two groups. Postpartum, no differences in insulin binding were found between the groups. Basal and maximal tyrosine kinase activities toward the exogenous substrate poly(Glu4Tyr1) were...

  16. Long latency postural responses are functionally modified by cognitive set.

    Science.gov (United States)

    Beckley, D J; Bloem, B R; Remler, M P; Roos, R A; Van Dijk, J G

    1991-10-01

    We examined how cognitive set influences the long latency components of normal postural responses in the legs. We disturbed the postural stability of standing human subjects with sudden toe-up ankle rotations. To influence the subjects' cognitive set, we varied the rotation amplitude either predictably (serial 4 degrees versus serial 10 degrees) or unpredictably (random mixture of 4 degrees and 10 degrees). The subjects' responses to these ankle rotations were assessed from the EMG activity of the tibialis anterior, the medial gastrocnemius, and the vastus lateralis muscles of the left leg. The results indicate that, when the rotation amplitude is predictable, only the amplitude of the long latency (LL) response in tibialis anterior and vastus lateralis varied directly with perturbation size. Furthermore, when the rotation amplitude is unpredictable, the central nervous system selects a default amplitude for the LL response in the tibialis anterior. When normal subjects are exposed to 2 perturbation amplitudes which include the potential risk of falling, the default LL response in tibialis anterior appropriately anticipates the larger amplitude perturbation rather than the smaller or an intermediate one.

  17. Exercise induces transient transcriptional activation of the PGC-1a gene in human skeletal muscle

    DEFF Research Database (Denmark)

    Pilegaard, Henriette; Saltin, Bengt; Neufer, P. Darrell

    2003-01-01

    Endurance exercise training induces mitochondrial biogenesis in skeletal muscle. The peroxisome proliferator activated receptor co-activator 1a (PGC-1a) has recently been identified as a nuclear factor critical for coordinating the activation of genes required for mitochondrial biogenesis in cell...... culture and rodent skeletal muscle. To determine whether PGC-1a transcription is regulated by acute exercise and exercise training in human skeletal muscle, seven male subjects performed 4 weeks of one-legged knee extensor exercise training. At the end of training, subjects completed 3 h of two......-legged knee extensor exercise. Biopsies were obtained from the vastus lateralis muscle of both the untrained and trained legs before exercise and after 0, 2, 6 and 24 h of recovery. Time to exhaustion (2 min maximum resistance), as well as hexokinase II (HKII), citrate synthase and 3-hydroxyacyl...

  18. MID-VASTUS VS MEDIAL PARA-PATELLAR APPROACH IN TOTAL KNEE REPLACEMENT—TIME TO DISCHARGE

    Science.gov (United States)

    Mukherjee, P.; Press, J.; Hockings, M.

    2009-01-01

    Background It has been shown before that when compared with the medial para-patellar approach, the mid-vastus approach for TKR results in less post-operative pain for patients and more rapid recovery of straight leg raise. As far as we are aware the post-operative length of stay of the two groups of patients has not been compared. We postulated that the reduced pain and more rapid recovery of straight leg raise would translate into an earlier, safe, discharge home for the mid-vastus patients compared with those who underwent a traditional medial para-patellar approach. Methods Twenty patients operated on by each of five established knee arthroplasty surgeons were evaluated prospectively with regard to their pre and post-operative range of movement, time to achieve straight leg raise post-operatively and length of post-operative hospital stay. Only one of the surgeons performed the mid-vastus approach, and the measurements were recorded by physiotherapists who were blinded as to the approach used on each patient. Results The results were analysed using a standard statistical software package, and although the mean length of stay was lower for the mid-vastus patients, the difference did not reach a level of significance (p = 0.13). The time taken to achieve straight leg raise post-operatively was significantly less in the mid-vastus group (p<0.001). Conclusion Although this study confirms previous findings that the mid-vastus approach reduces the time taken for patients to achieve straight leg raise, when compared with the medial para-patellar approach, on its own it does not translate into a significantly shorter length of hospital stay. In order to reduce the length of post-operative hospital stay with an accelerated rehabilitation program for TKR, a multi-disciplinary approach is required. Patient expectations, GP support, physiotherapists and nursing staff all have a role to play and the mid-vastus approach, in permitting earlier straight leg raising

  19. A comparison of muscle activation between back squats and belt squats.

    Science.gov (United States)

    Evans, Thomas W; McLester, Cherilyn N; Howard, Jonathan H; McLester, John R; Calloway, Jimmy P

    2017-06-08

    A machine belt squat is a piece of equipment designed to allow the performance of squats while loading weight on the lifter's hips using a belt. The purpose of this investigation was to determine if belt squats differ from back squats in activation of the primary movers, and to determine the predictive capabilities of back squat load, training status, and anthropometric data on belt squat load. Thirty-one participants (16 males and 15 females) completed anthropometric measurements, a demographic questionnaire, a familiarization visit, and two testing visits, completing a 5 repetition maximum test for back squat and belt squat. Surface electromyography was used to measure muscle activation for the left and right vastus medialis (VMO), vastus lateralis (VLO), rectus femoris (RF), and gluteus maximus (GM). Comparison of muscle activation between the two exercises showed significant differences in the left GM (back squat: 0.84 ± 0.45, belt squat: 0.69 ± 0.22, p=0.015) and right GM (back squat: 0.86 ± 0.45, belt squat: 0.71 ± 0.29, p=0.004). Regression analysis computed significant prediction equations for belt squat load for general population, males, females, and advanced lifters. Overall, results indicate that belt squats may significantly differ in GM activation from back squats. Back squat load, as well as other variables, may be effective in accurately estimating appropriate belt squat load. These findings may help to more appropriately program for training with machine belt squats as a back squat alternative.

  20. Dynamic Neuromuscular Control of the Lower Limbs in Response to Unexpected Single-Planar versus Multi-Planar Support Perturbations in Young, Active Adults.

    Science.gov (United States)

    Malfait, Bart; Staes, Filip; de Vries, Aijse; Smeets, Annemie; Hawken, Malcolm; Robinson, Mark A; Vanrenterghem, Jos; Verschueren, Sabine

    2015-01-01

    An anterior cruciate ligament (ACL) injury involves a multi-planar injury mechanism. Nevertheless, unexpected multi-planar perturbations have not been used to screen athletes in the context of ACL injury prevention yet could reveal those more at risk. The objective of this study was to compare neuromuscular responses to multi-planar (MPP) and single-planar perturbations (SPP) during a stepping-down task. These results might serve as a basis for future implementation of external perturbations in ACL injury screening programs. Thirteen young adults performed a single leg stepping-down task in eight conditions (four MPP and four SPP with a specified amplitude and velocity). The amplitudes of vastus lateralis (VL), vastus medialis (VM), hamstrings lateralis (HL), hamstrings medialis (HM) EMG activity, medio-lateral and anterior-posterior centre of mass (COM) displacements, the peak knee flexion and abduction angles were compared between conditions using an one-way ANOVA. Number of stepping responses were monitored during all conditions. Significantly greater muscle activity levels were found in response to the more challenging MPP and SPP compared to the less challenging conditions (p neuromuscular activity were found between the MPP conditions and their equivalents in the SPP. Eighteen stepping responses were monitored in the SPP versus nine in the MPP indicating that the overall neuromuscular control was even more challenged during the SPP which was supported by greater COM displacements in the SPP. The more intense MPP and SPP evoked different neuromuscular responses resulting in greater muscle activity levels compared to small perturbations. Based on the results of COM displacements and based on the amount of stepping responses, dynamic neuromuscular control of the knee joint appeared less challenged during the MPP. Therefore, future work should investigate extensively if other neuromuscular differences (i.e. co-activation patterns and kinetics) exist between MPP

  1. RAPID KNEE-EXTENSIONS TO INCREASE QUADRICEPS MUSCLE ACTIVITY IN PATIENTS WITH TOTAL KNEE ARTHROPLASTY

    DEFF Research Database (Denmark)

    Husted, Rasmus Skov; Wilquin, Lousia; Jakobsen, Thomas Linding

    2017-01-01

    rapid knee-extensions were associated with greater voluntary quadriceps muscle activity during an experimental strength training session, compared to that elicited using slow knee-extensions. STUDY DESIGN: A randomized cross-over study. METHODS: Twenty-four patients (age 66.5) 4-8 weeks post total knee...... agonist muscle activity, especially if the exercise is conducted using rapid muscle contractions. PURPOSE: The purpose of this study was to examine if patients with total knee arthroplasty could perform rapid knee-extensions using a 10 RM load four to eight weeks after surgery, and the degree to which...... arthroplasty randomly performed one set of five rapid, and one set of five slow knee-extensions with the operated leg, using a load of their 10 repetition maximum, while surface electromyography recordings were obtained from the vastus medialis and lateralis of the quadriceps muscle. RESULTS: Data from 23...

  2. Rapid knee-extensions to increase quadriceps muscle activity in patients with total knee arthroplasty

    DEFF Research Database (Denmark)

    Husted, Rasmus Skov; Wilquin, Lousia; Jakobsen, Thomas Linding

    2017-01-01

    rapid knee-extensions were associated with greater voluntary quadriceps muscle activity during an experimental strength training session, compared to that elicited using slow knee-extensions. STUDY DESIGN: A randomized cross-over study. METHODS: Twenty-four patients (age 66.5) 4-8 weeks post total knee...... agonist muscle activity, especially if the exercise is conducted using rapid muscle contractions. PURPOSE: The purpose of this study was to examine if patients with total knee arthroplasty could perform rapid knee-extensions using a 10 RM load four to eight weeks after surgery, and the degree to which...... arthroplasty randomly performed one set of five rapid, and one set of five slow knee-extensions with the operated leg, using a load of their 10 repetition maximum, while surface electromyography recordings were obtained from the vastus medialis and lateralis of the quadriceps muscle. RESULTS: Data from 23...

  3. A single bout of whole-leg, peristaltic pulse external pneumatic compression upregulates PGC-1α mRNA and endothelial nitric oxide sythase protein in human skeletal muscle tissue.

    Science.gov (United States)

    Kephart, Wesley C; Mobley, C Brooks; Fox, Carlton D; Pascoe, David D; Sefton, JoEllen M; Wilson, Trent J; Goodlett, Michael D; Kavazis, Andreas N; Roberts, Michael D; Martin, Jeffrey S

    2015-07-01

    What is the central question of this study? Does 60 min of peristaltic pulse external pneumatic compression (EPC) alter gene and protein expression patterns related to metabolism, vascular biology, redox balance and inflammation in vastus lateralis biopsy samples? What is the main finding and its importance? A single bout of EPC transiently upregulates PGC-1α mRNA, while also upregulating endothelial nitric oxide synthase protein and nitric oxide metabolite concentrations in vastus lateralis biopsy samples. We investigated whether a single 60 min bout of whole-leg, lower pressure external pneumatic compression (EPC) altered select vascular, metabolic, antioxidant and inflammation-related mRNAs. Ten participants (eight male, two female; aged 22.0 ± 0.4 years) reported to the laboratory 4 h postprandial, and vastus lateralis muscle biopsies were obtained before (PRE) and 1 and 4 h after EPC treatment. Messenger RNA expression was analysed using real-time RT-PCR, and significant mRNA findings were investigated further by Western blot analysis of respective protein concentrations. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA increased by 77% 1 h following EPC compared with PRE levels (P = 0.005), but no change in protein concentration 1 or 4 h post-EPC was observed. Increases in endothelial nitric oxide sythase (eNOS) mRNA (+44%) and superoxide dismutase 2 (SOD2) mRNA (+57%) 1 h post-EPC as well as an increase in interleukin-10 mRNA (+132%) 4 h post-EPC compared with PRE levels were observed, but only approached significance (P = 0.076, 0.077 and 0.074, respectively). Interestingly, eNOS protein (+40%, P = 0.025) and nitrate and nitrite (NOx) concentrations (+69%, P = 0.025) increased 1-4 h post-EPC. Moreover, SOD2 protein tended to increase from PRE to 4 h post-EPC (+43%, P = 0.074), although no changes in tissue 4-hydroxnonenal levels was observed. An acute bout of EPC transiently upregulates PGC-1α mRNA, while also upregulating e

  4. Net joint moments and muscle activation in barbell squats without and with restricted anterior leg rotation.

    Science.gov (United States)

    Chiu, Loren Z F; vonGaza, Gabriella L; Jean, Liane M Y

    2017-01-01

    Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P squat depth, ankle plantar flexor (P squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.

  5. Underwater Near-Infrared Spectroscopy: Muscle Oxygen Changes in the Upper and Lower Extremities in Club Level Swimmers and Triathletes.

    Science.gov (United States)

    Jones, B; Cooper, C E

    2016-01-01

    To date, measurements of oxygen status during swim exercise have focused upon systemic aerobic capacity. The development of a portable, waterproof NIRS device makes possible a local measurement of muscle hemodynamics and oxygenation that could provide a novel insight into the physiological changes that occur during swim exercise. The purpose of this study was to observe changes in muscle oxygenation in the vastus lateralis (VL) and latissimus dorsi (LD) of club level swimmers and triathletes. Ten subjects, five club level swimmers and five club level triathletes (three men and seven women) were used for assessment. Swim group; mean±SD=age 21.2±1.6 years; height 170.6±7.5 cm; weight 62.8±6.9 kg; vastus lateralis skin fold 13.8±5.6 mm; latissimus dorsi skin fold 12.6±3.7. Triathlete group; mean±SD=age 44.0±10.5 years; height 171.6±7.0 cm; weight 68.6±12.7 kg; vastus lateralis skin fold 11.8±3.5 mm; latissimus dorsi skin fold 11.2±3.1. All subjects completed a maximal 200 m freestyle swim, with the PortaMon, a portable NIR device, attached to the subject's dominant side musculature. ΔTSI% between the vastus lateralis and latissimus dorsi were analysed using either paired (2-tailed) t-tests or Wilcoxon signed rank test. The level of significance for analysis was set at pswim significantly faster (p=0.04) than club level triathletes. Club level swimmers use both the upper and lower muscles to a similar extent during a maximal 200 m swim. Club level triathletes predominately use the upper body for propulsion during the same exercise. The data produced by NIRS in this study are the first of their kind and provide insight into muscle oxygenation changes during swim exercise which can indicate the contribution of one muscle compared to another. This also enables a greater understanding of the differences in swimming techniques seen between different cohorts of swimmers and potentially within individual swimmers.

  6. EFFECT OF MODERATE ALTITUDE ON PERIPHERAL MUSCLE OXYGENATION DURING LEG RESISTANCE EXERCISE IN YOUNG MALES

    Directory of Open Access Journals (Sweden)

    Toshio Matsuoka

    2004-09-01

    Full Text Available Training at moderate altitude (~1800m is often used by athletes to stimulate muscle hypoxia. However, limited date is available on peripheral muscle oxidative metabolism at this altitude (1800AL. The purpose of this study was to determine whether acute exposure to 1800AL alters muscle oxygenation in the vastus lateralis muscle during resistance exercise. Twenty young active male subjects (aged 16 - 21 yr performed up to 50 repetitions of the parallel squat at 1800AL and near sea level (SL. They performed the exercise protocol within 3 h after arrival at 1800 AL. During the exercise, the changes in oxygenated hemoglobin (OxyHb in the vastus lateralis muscle, arterial oxygen saturation (SpO2, and heart rate were measured using near infrared continuous wave spectroscopy (NIRcws and pulse oximetry, respectively. Changes in OxyHb were expressed by Deff defined as the relative index of the maximum change ratio (% from the resting level. OxyHb in the vastus lateralis muscle decreased dramatically from the resting level immediately after the start of exercise at both altitudes. The Deff during exercise was significantly (p < 0.001 lower at 1800AL (60.4 ± 6.2 % than at near SL (74.4 ± 7.6 %. SpO2 during exercise was significantly (p < 0.001 lower at 1800AL (92.0 ± 1.7 % than at near SL (96.7 ± 1.2 %. Differences (SL - 1800AL in Deff during exercise correlated fairly strongly with differences in SpO2 during exercise (r = 0.660. These results suggested that acute exposure to moderate altitude caused a more dramatical decrease in peripheral muscle oxygenation during leg resistance exercise. It is salient to note, therefore , that peripheral muscle oxygenation status at moderate altitude could be evaluated using NIRcws and that moderate altitudes might be effectively used to apply hypoxic stress on peripheral muscles.

  7. The immediate intervention effects of robotic training in patients after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Ye, Miao

    2016-07-01

    [Purpose] The purpose of this study was to examine the immediate effects of robot-assisted therapy on functional activity level after anterior cruciate ligament reconstruction. [Subjects and Methods] Participants included 10 patients (8 males and 2 females) following anterior cruciate ligament reconstruction. The subjects participated in robot-assisted therapy and treadmill exercise on different days. The Timed Up-and-Go test, Functional Reach Test, surface electromyography of the vastus lateralis and vastus medialis, and maximal extensor strength of isokinetic movement of the knee joint were evaluated in both groups before and after the experiment. [Results] The results for the Timed Up-and-Go Test and the 10-Meter Walk Test improved in the robot-assisted rehabilitation group. Surface electromyography of the vastus medialis muscle showed significant increases in maximum and average discharge after the intervention. [Conclusion] The results suggest that walking ability and muscle strength can be improved by robotic training.

  8. Neuromuscular Alterations After Ankle Sprains: An Animal Model to Establish Causal Links After Injury.

    Science.gov (United States)

    Lepley, Lindsey K; McKeon, Patrick O; Fitzpatrick, Shane G; Beckemeyer, Catherine L; Uhl, Timothy L; Butterfield, Timothy A

    2016-10-01

    The mechanisms that contribute to the development of chronic ankle instability are not understood. Investigators have developed a hypothetical model in which neuromuscular alterations that stem from damaged ankle ligaments are thought to affect periarticular and proximal muscle activity. However, the retrospective nature of these studies does not allow a causal link to be established. To assess temporal alterations in the activity of 2 periarticular muscles of the rat ankle and 2 proximal muscles of the rat hind limb after an ankle sprain. Controlled laboratory study. Laboratory. Five healthy adult male Long Evans rats (age = 16 weeks, mass = 400.0 ± 13.5 g). Indwelling fine-wire electromyography (EMG) electrodes were implanted surgically into the biceps femoris, medial gastrocnemius, vastus lateralis, and tibialis anterior muscles of the rats. We recorded baseline EMG measurements while the rats walked on a motor-driven treadmill and then induced a closed lateral ankle sprain by overextending the lateral ankle ligaments. After ankle sprain, the rats were placed on the treadmill every 24 hours for 7 days, and we recorded postsprain EMG data. Onset time of muscle activity, phase duration, sample entropy, and minimal detectable change (MDC) were assessed and compared with baseline using 2-tailed dependent t tests. Compared with baseline, delayed onset time of muscle activity was exhibited in the biceps femoris (baseline = -16.7 ± 54.0 milliseconds [ms]) on day 0 (5.2 ± 64.1 ms; t 4 = -4.655, P = .043) and tibialis anterior (baseline = 307.0 ± 64.2 ms) muscles on day 3 (362.5 ± 55.9 ms; t 4 = -5.427, P = .03) and day 6 (357.3 ± 39.6 ms; t 4 = -3.802, P = .02). Longer phase durations were observed for the vastus lateralis (baseline = 321.9 ± 92.6 ms) on day 3 (401.3 ± 101.2 ms; t 3 = -4.001, P = .03), day 4 (404.1 ± 93.0 ms; t 3 = -3.320, P = .048), and day 5 (364.6 ± 105.2 ms; t 3 = -3.963, P = .03) and for the tibialis anterior (baseline = 103.9 ± 16.4 ms

  9. A rare knee extensor mechanism injury: Vastus intermedius tendon rupture

    Directory of Open Access Journals (Sweden)

    Engin Cetinkaya

    2015-01-01

    Conclusion: We report the first case of isolated rupture of the vastus intermedius tendon in the literature and we claim that disorder may be succesfully treated with conservative treatment and adequate physiotheraphy.

  10. Vastus Medialis advancement: clinical results and correlation with tangential X-rays of the patellofemoral joint

    International Nuclear Information System (INIS)

    O'Beirne, J.; O'Connell, R.J.; White, M.

    1986-01-01

    Thirteen patients who had recurrent dislocation of the patella treated by vastus medialis advancement were reviewed, and tangential X-rays of the patellofemoral joint were taken at the time of review. Clinically the results were excellent or good in ten (77%). However, the X-ray appearances were similar to what would be expected in a group of patients with untreated recurrent dislocation, probably because the corrective action of the vastus medialis did not apply with the quadriceps relaxed for X-ray. We conclude that vastus medialis advancement is a successful operation for recurrent patellar dislocation but that tangential X-rays of the patellofemoral joint are not an indicator of the outcome of surgery. (author)

  11. Larval habitat choice in still water and flume flows by the opportunistic bivalve Mulinia lateralis

    Science.gov (United States)

    Grassle, Judith P.; Snelgrove, Paul V. R.; Butman, Cheryl Ann

    Competent pediveligers of the coot clam Mulinia lateralis (Say) clearly preferred an organically-rich mud over abiotic glass beads in 24-h flume experiments, and often demonstrated the same choice in still-water experiments. We hypothesize that peediveligers with characteristic helical swimming paths above the bottom can exercise habitat choice in both still water nad flow, but that the limited swimming ambits of physiologically older periveligers require near-bottom flows to move the larvae between sediment patches so that they can exercise habitat choice. Although M. lateralis larvae are planktotrophic, their ability to delay metamorphosis in the absence of a preferred sediment cue is limited to about five days, a shorter time than the lecithotrophi larvae of the opportunistic polychaete species, Capitella spp. I and II. Field distributions of all three opportunistic species may result, at least in part, from active habitat selection for high-organic sediments by settling larvae.

  12. Effects of prior heavy exercise on VO(2) kinetics during heavy exercise are related to changes in muscle activity.

    Science.gov (United States)

    Burnley, Mark; Doust, Jonathan H; Ball, Derek; Jones, Andrew M

    2002-07-01

    We hypothesized that the elevated primary O(2) uptake (VO(2)) amplitude during the second of two bouts of heavy cycle exercise would be accompanied by an increase in the integrated electromyogram (iEMG) measured from three leg muscles (gluteus maximus, vastus lateralis, and vastus medialis). Eight healthy men performed two 6-min bouts of heavy leg cycling (at 70% of the difference between the lactate threshold and peak VO(2)) separated by 12 min of recovery. The iEMG was measured throughout each exercise bout. The amplitude of the primary VO(2) response was increased after prior heavy leg exercise (from mean +/- SE 2.11 +/- 0.12 to 2.44 +/- 0.10 l/min, P exercise (491 +/- 108 vs. 604 +/- 151% increase above baseline values, P exercise is related to a greater recruitment of motor units at the onset of exercise.

  13. The activity of satellite cells and myonuclei following 8 weeks of strength training in young men with suppressed testosterone levels

    DEFF Research Database (Denmark)

    Kvorning, T; Kadi, F; Schjerling, P

    2015-01-01

    AIM: To investigate how suppression of endogenous testosterone during an 8-week strength training period influences the activity of satellite cells and myonuclei. METHODS: Twenty-two moderately trained young men participated in this randomized, placebo-controlled, and double-blinded intervention...... from the mid-portion of the vastus lateralis muscle. RESULTS: Testosterone resting level in goserelin was 10-20 times lower compared with placebo, and the training-induced increase in the level of testosterone was abolished in goserelin. Training increased satellite cells number in type II fibres by 20...... of testosterone. The data indicate that low testosterone levels could reduce the differentiation of satellite cells to myonuclei via the bone morphogenetic proteins signalling pathway, resulting in reduced increases in lean leg mass....

  14. Electromyographic analyses of muscle pre-activation induced by single joint exercise.

    Science.gov (United States)

    Júnior, Valdinar A R; Bottaro, Martim; Pereira, Maria C C; Andrade, Marcelino M; P Júnior, Paulo R W; Carmo, Jake C

    2010-01-01

    To investigate whether performing a low-intensity, single-joint exercises for knee extensors was an efficient strategy for increasing the number of motor units recruited in the vastus lateralis muscle during a subsequent multi-joint exercises. Nine healthy male participants (23.33+/-3.46 yrs) underwent bouts of exercise in which knee extension and 45 degrees , and leg press exercises were performed in sequence. In the low-intensity bout (R30), 15 unilateral knee extensions were performed, followed by 15 repetitions of the leg presses at 30% and 60% of one maximum repetition load (1-MR), respectively. In the high-intensity bout (R60), the same sequence was performed, but the applied load was 60% of 1-MR for both exercises. A single set of 15 repetitions of the leg press at 60% of 1-MR was performed as a control exercise (CR). The surface electromyographic signals of the vastus lateralis muscle were recorded by means of a linear electrode array. The root mean square (RMS) values were determined for each repetition of the leg press, and linear regressions were calculated from these results. The slopes of the straight lines obtained were then normalized using the linear coefficients of the regression equations and compared using one-way ANOVAs for repeated measures. The slopes observed in the CR were significantly lower than those in the R30 and R60 (precruitment of motor units was more effective when a single-joint exercise preceded the multi-joint exercise. Article registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under the number ACTRN12609000413224.

  15. Skeletal muscle myosin heavy chain isoform content in relation to gonadal hormones and anabolic-catabolic balance in trained and untrained men.

    Science.gov (United States)

    Grandys, Marcin; Majerczak, Joanna; Karasinski, Janusz; Kulpa, Jan; Zoladz, Jerzy A

    2012-12-01

    Gonadal hormones and anabolic-catabolic hormone balance have potent influence on skeletal muscle tissue, but little is known about their action with regard to myosin heavy chain (MHC) transformation in humans. We investigated the relationship between skeletal muscle MHC isoform content in the vastus lateralis muscle and basal testosterone (T) concentration in 3 groups of subjects: endurance trained (E), sprint/strength trained (S), and untrained (U) young men. We have also determined basal sex hormone-binding globulin and cortisol (C) concentrations in untrained subjects to examine the relationship between MHC composition and the anabolic-catabolic hormone balance. Moreover, basal free testosterone (fT) and bioavailable testosterone (bio-T) concentrations were calculated for this subgroup. Despite significant differences in MHC isoform content (69.4 ± 2.39%, 61.4 ± 8.04%, and 37.5 ± 13.80% of MHC-2 for groups S, U, and E, respectively, Kruskal-Wallis: H = 18.58, p 0.5). We have also found that in the U group, type 2 MHC in the vastus lateralis muscle is positively correlated with basal fT:C ratio (r = 0.63, p = 0.01). It is concluded that the differences in the training history and training specificity can be distinguished with regard to the MHC composition but not with regard to the basal T concentration. Simultaneously, it has been shown that MHC isoform content in human vastus lateralis muscle may be related to basal anabolic-catabolic hormone balance, and this hypothesis needs further investigation.

  16. Long-term interventions effects of robotic training on patients after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Zhou, Yue; Gu, Rui; Ye, Miao; Ge, Meng; Xu, Yanfeng; Liu, Jianfeng

    2016-08-01

    [Purpose] The aim of this study was to examine the long-term interventions effects of robot-assisted therapy rehabilitation on functional activity levels after anterior cruciate ligament reconstruction. [Subjects and Methods] The subjects were 8 patients (6 males and 2 females) who received anterior cruciate ligament reconstruction. The subjects participated in robot-assisted therapy lasting for one month. The Timed Up-and-Go test, 10-Meter Walk test, Functional Reach Test, surface electromyography of the vastus lateralis and vastus medialis, and extensor strength of isokinetic movement of the knee joint were evaluated before and after the intervention. [Results] The average value of the of vastus medialis EMG, Functional Reach Test, and the maximum and average extensor strength of the knee joint isokinetic movement increased significantly, and the time of the 10-Meter Walk test decreased significantly. [Conclusion] These results suggest that walking ability and muscle strength can be improved by robotic walking training as a long-term intervention.

  17. Action of crude Radix Aconiti Lateralis (Fuzi) and its processed products on splenic lymphocytes growth investigated by microcalorimetry

    International Nuclear Information System (INIS)

    Liu, Tiantian; Zhao, Yanling; Wang, Jiabo; Zhou, Xu; Sun, Zhiyong; Zheng, Quanfu; Li, Ruisheng; Zhang, Ping; Li, Jianyu; Song, Xueai; Xiao, Xiaohe

    2013-01-01

    Highlights: • This article investigated the effects of crude Radix Aconiti Lateralis and its processed products on splenic lymphocytes. • The results showed that bioeffects of crude Radix Aconiti Lateralis could be obtained by thermodynamic parameters. • This study gave the hint that the microcalorimetry is a useful tool to estimate the efficiency and toxicity of medicine. - Abstract: Using the TAM air isothermal microcalorimeter, the HFP–time curves of splenic lymphocytes growth were measured, and the effects of crude Radix Aconiti Lateralis and its processed products including Yanfuzi, Danfupian, Baifupian on splenic lymphocytes growth were investigated. Some quantitative information, such as k, P max etc. was obtained from the HFP–time curves. The results revealed that crude Radix Aconiti Lateralis and Yanfuzi had inhibitory effect on mice splenic lymphocytes growth: crude Radix Aconiti Lateralis with IC 50 of 18 mg mL −1 showed stronger inhibitory effect than Yanfuzi with IC 50 of 32 mg mL −1 . Danfupian and Baifupian promoted splenic lymphocytes growth: Baifupian with EC 50 of 25 mg mL −1 showed a little stronger promotion effect than Danfupian with EC 50 of 28 mg mL −1 . The result may be related to their toxicity and we could evaluate different bioeffects of crude Radix Aconiti Lateralis and its processed products on splenic lymphocytes growth from microcalorimetric measurement

  18. [Selective training of the vastus medialis muscle using electrical stimulator for chondromalacia patella].

    Science.gov (United States)

    Guo, K; Ye, Q; Lin, J; Shen, J; Yang, X

    1996-04-01

    Chondromalacia patella is closely related with subluxation and tilt of patella, as well as with muscular atrophy of quadriceps, especially in vastus medialis muscle. 364 cases of chondromalacia patella were treated with selective training of the vastus medialis muscle using electrical stimulator in our hospital. 211 cases were followed up after treatment from 6 months to 3 years. Among them excellent and good results were seen in 130 cases (62%), fair results were seen in 69 cases (33%) and no change was seen in 12 cases (5%). Significant reduction of CA (P chondromalacia patella.

  19. Vastus lateralis surface and single motor unit EMG following submaximal shortening and lengthening contractions

    NARCIS (Netherlands)

    Altenburg, T.M.; de Ruiter, C.J.; Verdijk, P.W.L.; van Mechelen, W.; de Haan, A.

    2008-01-01

    A single shortening contraction reduces the force capacity of muscle fibers, whereas force capacity is enhanced following lengthening. However, how motor unit recruitment and discharge rate (muscle activation) are adapted to such changes in force capacity during submaximal contractions remains

  20. Expression of interleukin-15 in human skeletal muscle effect of exercise and muscle fibre type composition

    DEFF Research Database (Denmark)

    Nielsen, Anders Rinnov; Mounier, Remi; Plomgaard, Peter

    2007-01-01

    The cytokine interleukin-15 (IL-15) has been demonstrated to have anabolic effects in cell culture systems. We tested the hypothesis that IL-15 is predominantly expressed by type 2 skeletal muscle fibres, and that resistance exercise regulates IL-15 expression in muscle. Triceps brachii, vastus...... lateralis quadriceps and soleus muscle biopsies were obtained from normally physically active, healthy, young male volunteers (n = 14), because these muscles are characterized by having different fibre-type compositions. In addition, healthy, normally physically active male subjects (n = 8) not involved...

  1. Vastus medialis motor unit properties in knee osteoarthritis

    Directory of Open Access Journals (Sweden)

    Chess David G

    2011-09-01

    Full Text Available Abstract Background Maximal isometric quadriceps strength deficits have been widely reported in studies of knee osteoarthritis (OA, however little is known about the effect of osteoarthritis knee pain on submaximal quadriceps neuromuscular function. The purpose of this study was to measure vastus medialis motor unit (MU properties in participants with knee OA, during submaximal isometric contractions. Methods Vastus medialis motor unit potential (MUP parameters were assessed in 8 patients with knee OA and 8 healthy, sex and age-matched controls during submaximal isometric contractions (20% of maximum isometric torque. Unpaired t-tests were used to compare groups for demographic and muscle parameters. Results Maximum knee extension torque was ~22% lower in the OA group, a difference that was not statistically significantly (p = 0.11. During submaximal contractions, size related parameters of the needle MUPs (e.g. negative peak duration and amplitude-to-area ratio were greater in the OA group (p Conclusions Changes in MU recruitment and rate coding strategies in OA may reflect a chronic reinnervation process or a compensatory strategy in the presence of chronic knee pain associated with OA.

  2. Muscular power, neuromuscular activation, and performance in shot put athletes at preseason and at competition period.

    Science.gov (United States)

    Kyriazis, Thomas A; Terzis, Gerasimos; Boudolos, Konstantinos; Georgiadis, Georgios

    2009-09-01

    The aim of this study was to investigate changes in shot put performance, muscular power, and neuromuscular activation of the lower extremities, between the preseason and the competition period, in skilled shot put athletes using the rotational technique. Shot put performance was assessed at the start of the pre-season period as well as after 12 weeks, at the competition period, in nine shot putters. Electromyographic (EMG) activity of the right vastus lateralis muscle was recorded during all shot put trials. Maximum squat strength (1RM) and mechanical parameters during the countermovement jump (CMJ) on a force platform were also determined at pre-season and at competition period. Shot put performance increased 4.7% (p phase was increased significantly (p training period. Shot put performance was significantly related with muscular power and takeoff velocity during the CMJ, at competition period (r = 0.66, p competition period.

  3. Skeletal muscle architectural adaptations to marathon run training.

    Science.gov (United States)

    Murach, Kevin; Greever, Cory; Luden, Nicholas D

    2015-01-01

    We assessed lateral gastrocnemius (LG) and vastus lateralis (VL) architecture in 16 recreational runners before and after 12 weeks of marathon training. LG fascicle length decreased 10% while pennation angle increased 17% (p training can modify skeletal muscle architectural features.

  4. POST-INJECTION SCIATIC NEUROPATHY: A FIVE-YEAR REVIEW ...

    African Journals Online (AJOL)

    Alonge Ibidunni

    Each patient was evaluated for the limb affected, the health care centre where the injection was given and the health care ... disability depending on the timing and duration of corrective .... The upper part of the lateral thigh. (vastus lateralis ...

  5. A comparison of free weight squat to Smith machine squat using electromyography.

    Science.gov (United States)

    Schwanbeck, Shane; Chilibeck, Philip D; Binsted, Gordon

    2009-12-01

    The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.

  6. Muscle Activity in Single- vs. Double-Leg Squats.

    Science.gov (United States)

    DeFOREST, Bradley A; Cantrell, Gregory S; Schilling, Brian K

    Muscular activity, vertical displacement and ground reaction forces of back squats (BS), rear-leg elevated split squats (RLESS) and split squats (SS) were examined. Nine resistance-trained men reported for two sessions. The first session consisted of the consent process, practice, and BS 1-repetition maximum testing. In the second session, participants performed the three exercises while EMG, displacment and ground reaction force data (one leg on plate) were collected. EMG data were collected from the gluteus maximus (GMX), biceps femoris (BF), semitendinosus (ST), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), tibialis anterior (TA), and medial gastrocnemius (MGas) of the left leg (non-dominant, front leg for unilateral squats). Load for BS was 85% one repetition maximum, and RLESS and SS were performed at 50% of BS load. Repeated measures ANOVA was used to compare all variables for the three exercises, with Bonferroni adjustments for post hoc multiple comparisons, in addition to calculation of standardized mean differences (ES). Muscle activity was similar between exercises except for biceps femoris, which was significantly higher during RLESS than SS during both concentric and eccentric phases (ES = 2.11; p=0.012 and ES= 2.19; p=0.008), and significantly higher during BS than the SS during the concentric phase (ES = 1.78; p=0.029). Vertical displacement was similar between all exercises. Peak vertical force was similar between BS and RLESS and significantly greater during RLESS than SS (ES = 3.03; p=0.001). These findings may be helpful in designing resistance training programs by using RLESS if greater biceps femoris activity is desired.

  7. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

    Directory of Open Access Journals (Sweden)

    Juliette Ropars

    Full Text Available The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD. Dynamic surface electromyography recordings (EMGs of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF, vastus lateralis (VL, medial hamstrings (HS, tibialis anterior (TA and gastrocnemius soleus (GAS muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity.

  8. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

    Science.gov (United States)

    Ropars, Juliette; Lempereur, Mathieu; Vuillerot, Carole; Tiffreau, Vincent; Peudenier, Sylviane; Cuisset, Jean-Marie; Pereon, Yann; Leboeuf, Fabien; Delporte, Ludovic; Delpierre, Yannick; Gross, Raphaël; Brochard, Sylvain

    2016-01-01

    The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity.

  9. Insulin receptor binding and protein kinase activity in muscles of trained rats

    International Nuclear Information System (INIS)

    Dohm, G.L.; Sinha, M.K.; Caro, J.F.

    1987-01-01

    Exercise has been shown to increase insulin sensitivity, and muscle is quantitatively the most important tissue of insulin action. Since the first step in insulin action is the binding to a membrane receptor, the authors postulated that exercise training would change insulin receptors in muscle and in this study they have investigated this hypothesis. Female rats initially weighing ∼ 100 g were trained by treadmill running for 2 h/day, 6 days/wk for 4 wk at 25 m/min (0 grade). Insulin receptors from vastus intermedius muscles were solubilized by homogenizing in a buffer containing 1% Triton X-100 and then partially purified by passing the soluble extract over a wheat germ agglutinin column. The 4 wk training regimen resulted in a 65% increase in citrate synthase activity in red vastus lateralis muscle, indicating an adaptation to exercise [ 125 I]. Insulin binding by the partially purified receptor preparations was approximately doubled in muscle of trained rats at all insulin concentrations, suggesting an increase in the number of receptors. Training did not alter insulin receptor structure as evidenced by electrophoretic mobility under reducing and nonreducing conditions. Basal insulin receptor protein kinase activity was higher in trained than untrained animals and this was likely due to the greater number of receptors. However, insulin stimulation of the protein kinase activity was depressed by training. These results demonstrate that endurance training does alter receptor number and function in muscle and these changes may be important in increasing insulin sensitivity after exercise training

  10. Effects of an 8-weeks erythropoietin treatment on mitochondrial and Whole body fat oxidation capacity during exercise in healthy males

    DEFF Research Database (Denmark)

    Guadalupe Grau, Amelia; Plenge, Ulla; Bønding, Signe Helbo

    2015-01-01

    fat oxidation were measured. Biopsies of the vastus lateralis muscle were obtained before and after the intervention. Recombinant erythropoietin treatment increased mitochondrial O2 flux during ADP stimulated state 3 respiration in the presence of complex I and II substrates (malate, glutamate...

  11. Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication

    DEFF Research Database (Denmark)

    Mackey, Abigail L; Rasmussen, Lotte Klejs; Kadi, Fawzi

    2016-01-01

    muscles of one leg. Muscle biopsies were collected from the vastus lateralis muscles before and after stimulation (2.5 h and 2, 7, and 30 d) and were assessed for satellite cells and regeneration by immunohistochemistry and real-time RT-PCR, and we also measured telomere length. After injury, and compared...... activation of satellite cells and muscle remodeling during large-scale regeneration of injured human skeletal muscle.-Mackey, A. L., Rasmussen, L. K., Kadi, F., Schjerling, P., Helmark, I. C., Ponsot, E., Aagaard, P., Durigan, J. L. Q., Kjaer, M. Activation of satellite cells and the regeneration of human......With this study we investigated the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in human skeletal muscle regeneration. Young men ingested NSAID [1200 mg/d ibuprofen (IBU)] or placebo (PLA) daily for 2 wk before and 4 wk after an electrical stimulation-induced injury to the leg extensor...

  12. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance.

    Science.gov (United States)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Bandholm, Thomas; Thorborg, Kristian; Zebis, Mette K; Andersen, Lars L

    2012-12-01

    While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participated. Electromyographic (EMG) activity was recorded in 10 muscles during the concentric and eccentric contraction phase of a knee extension exercise performed with elastic tubing and in training machine and normalized to maximal voluntary isometric contraction (MVC) EMG (nEMG). Knee joint angle was measured during the exercises using electronic inclinometers (range of motion 0-90°). When comparing the machine and elastic resistance exercises there were no significant differences in peak EMG of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) during the concentric contraction phase. However, during the eccentric phase, peak EMG was significantly higher (ptubing (5.7±0.6) compared with knee extensions performed in training machine (5.9±0.5). Knee extensions performed with elastic tubing induces similar high (>70% nEMG) quadriceps muscle activity during the concentric contraction phase, but slightly lower during the eccentric contraction phase, as knee extensions performed using an isotonic training machine. During the concentric contraction phase the two different conditions displayed reciprocal EMG-angle patterns during the range of motion. 5.

  13. Altered expression of cyclin A 1 in muscle of patients with facioscapulohumeral muscle dystrophy (FSHD-1.

    Directory of Open Access Journals (Sweden)

    Anna Pakula

    Full Text Available OBJECTIVES: Cyclin A1 regulates cell cycle activity and proliferation in somatic and germ-line cells. Its expression increases in G1/S phase and reaches a maximum in G2 and M phases. Altered cyclin A1 expression might contribute to clinical symptoms in facioscapulohumeral muscular dystrophy (FSHD. METHODS: Muscle biopsies were taken from the Vastus lateralis muscle for cDNA microarray, RT-PCR, immunohistochemistry and Western blot analyses to assess RNA and protein expression of cyclin A1 in human muscle cell lines and muscle tissue. Muscle fibers diameter was calculated on cryosections to test for hypertrophy. RESULTS: cDNA microarray data showed specifically elevated cyclin A1 levels in FSHD vs. other muscular disorders such as caveolinopathy, dysferlinopathy, four and a half LIM domains protein 1 deficiency and healthy controls. Data could be confirmed with RT-PCR and Western blot analysis showing up-regulated cyclin A1 levels also at protein level. We found also clear signs of hypertrophy within the Vastus lateralis muscle in FSHD-1 patients. CONCLUSIONS: In most somatic human cell lines, cyclin A1 levels are low. Overexpression of cyclin A1 in FSHD indicates cell cycle dysregulation in FSHD and might contribute to clinical symptoms of this disease.

  14. Muscle force output and electromyographic activity in squats with various unstable surfaces.

    Science.gov (United States)

    Saeterbakken, Atle H; Fimland, Marius S

    2013-01-01

    The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e., floor), power board, BOSU ball, and balance cone. Fifteen healthy men (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external, and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed before the experimental test. Compared with stable surface (749 ± 222 N), the force output using power board was similar (-7%, p = 0.320) but lower for BOSU ball (-19%, p = 0.003) and balance cone (-24%, p ≤ 0.001). The force output using BOSU ball and balance cone was approximately 13% (p = 0.037) and approximately 18% (p = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than did the other exercises (p = 0.004-0.030). Lower EMG activity was observed in the rectus femoris using balance cone compared with the BOSU ball (p = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower-limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, because similar muscle activity can be achieved with reduced loads.

  15. Nitric oxide increases cyclic GMP levels, AMP-activated protein kinase (AMPK)alpha1-specific activity and glucose transport in human skeletal muscle

    DEFF Research Database (Denmark)

    Deshmukh, A S; Long, Y C; de Castro Barbosa, T

    2010-01-01

    -nitrosohydrazino)-1,2-ethylenediamine (spermine NONOate) would increase intracellular cyclic GMP (cGMP) levels and promote glucose transport. METHODS: Skeletal muscle strips were prepared from vastus lateralis muscle biopsies obtained from seven healthy men. Muscle strips were incubated in the absence or presence...... of 5 mmol/l spermine NONOate or 120 nmol/l insulin. The L6 muscle cells were treated with spermine NONOate (20 micromol/l) and incubated in the absence or presence of insulin (120 nmol/l). The direct effect of spermine NONOate and insulin on glucose transport, cGMP levels and signal transduction...... was determined. RESULTS: In human skeletal muscle, spermine NONOate increased glucose transport 2.4-fold (p GMP levels (80-fold, p

  16. NUTRITIONAL VALUE AND HEAVY METALS CONTENTS OF THE DRIED SEA CUCUMBER Stichopus vastus FROM SALEMO ISLAND, INDONESIA

    Directory of Open Access Journals (Sweden)

    Abdullah Rasyid

    2018-01-01

    Full Text Available The dried sea cucumber Stichopus vastus is one of the commercially species harvested in Indonesian waters. This study aims to highlight the nutritional value and heavy metals content of dried sea cucumber S. vastus. Proximate (moisture, ash, protein, fat and carbohydrate, mineral (sodium, calcium, potassium and iron and heavy metal (mercury, cadmium, arsenic and lead were determined by standard method of AOAC, while phosphorous was determined by spectrophotometric method. Chondroitin sulphate was determined by UPLC method, glucosamine sulphate and vitamin (A, B1, B2 and E by HPLC method. Results show that protein was the major component in proximate analysis of dried sea cucumber S. vastus in the present study. The protein content was 38.70%. Moisture, ash, fat and carbohydrate content were 19.46%, 34.04%, 0.38% and 7.42% respectively. All vitamins and heavy metals examined in this study were not detected. The sodium content was 8054.36 mg/100 g higher than other minerals. Calcium, potassium, phosphorus and iron content were 2449.9 mg/100 g, 159.77 mg/100 g, 5085.2 mg/100 g and 520.8 mg/100 g respectively. Glucosamine sulphate content was found to be 2.429 g/100 g, whereas chondroitin sulphate was found to be 1.115 g/100 g. It can therefore, be concluded that the dried sea cucumber S. vastus from Salemo Island is safe for human consumption and hence can be used as a source of food supplement in the future. Keywords: food supplement, Salemo island, Stichopus vastus

  17. Erythropoietin treatment enhances muscle mitochondrial capacity in humans

    DEFF Research Database (Denmark)

    Plenge, Ulla; Belhage, Bo; Guadalupe-Grau, Amelia

    2012-01-01

    in humans. In six healthy volunteers rhEpo was administered by sub-cutaneous injection over 8 weeks with oral iron (100 mg) supplementation taken daily. Mitochondrial OXPHOS was quantified by high-resolution respirometry in saponin-permeabilized muscle fibers obtained from biopsies of the vastus lateralis...

  18. Long-term skeletal muscle mitochondrial dysfunction is associated with hypermetabolism in severely burned children

    Science.gov (United States)

    The long-term impact of burn trauma on skeletal muscle bioenergetics remains unknown. Here, we determined respiratory capacity and function of skeletal muscle mitochondria in healthy individuals and in burn victims for up to two years post-injury. Biopsies were collected from the m. vastus lateralis...

  19. The contribution of the in-vivo fate of an oil depot to drug absorption

    NARCIS (Netherlands)

    Kalicharan, R. W.; Oussoren, C; Schot, Peter; Rijk, de, E.; Vromans, H.

    2017-01-01

    Sustained release of lipophilic compounds can be achieved with oil depots. These parenteral formulations are generally injected in the vastus lateralis and deltoid muscle. It is known that the absorption rate differs between these two muscles. The reason for this is not fully understood. The aim of

  20. Severe insulin-resistant diabetes mellitus in patients with congenital muscle fiber type disproportion myopathy

    DEFF Research Database (Denmark)

    Vestergaard, H; Klein, H H; Hansen, T

    1995-01-01

    Congenital muscle fiber type disproportion myopathy (CFTDM) is a chronic, nonprogressive muscle disorder characterized by universal muscle hypotrophy and growth retardation. Histomorphometric examination of muscle shows a preponderance of smaller than normal type 1 fibers and overall fiber size....... Insulin receptor function and glycogen synthase (GS) activity and expression were examined in biopsies of vastus lateralis muscle. Despite a 45-90-fold increase in both fasting and postprandial serum insulin levels, both CFTDM patients had diabetes mellitus. Clamp studies revealed that the oldest boy had...

  1. Lifelong endurance training attenuates age-related genotoxic stress in human skeletal muscle

    OpenAIRE

    Cobley, James N; Sakellariou, George K; Murray, Scott; Waldron, Sarah; Gregson, Warren; Burniston, Jatin G; Morton, James P; Iwanejko, Lesley A; Close, Graeme L

    2013-01-01

    Background The aim of the present study was to determine the influence of age and habitual activity level, at rest and following a single bout of high-intensity exercise, on the levels of three proteins poly(ADP-ribose) polymerase-1 (PARP-1), cleaved-PARP-1 and poly(ADP-ribose) glycohydrolase (PARG), involved in the DNA repair and cell death responses to stress and genotoxic insults. Muscle biopsies were obtained from the vastus lateralis of young trained (22 ± 3 years, n = 6), young untraine...

  2. Methods for screening Port-Orford-cedar for resistance to Phytophthora lateralis

    Science.gov (United States)

    Everett M. Hansen; Paul Reeser; Wendy Sutton; Richard A. Sniezko

    2012-01-01

    Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) (POC) is an economically and ecologically valuable tree in the forests of southwest Oregon and northern California and in the horticultural trade worldwide. Phytophthora lateralis, the aggressive, invasive cause of POC root disease, was introduced to the native...

  3. Bilateral differences in muscle architecture and increased rate of injury in national basketball association players.

    Science.gov (United States)

    Mangine, Gerald T; Hoffman, Jay R; Gonzalez, Adam M; Jajtner, Adam R; Scanlon, Tyler; Rogowski, Joseph P; Wells, Adam J; Fragala, Maren S; Stout, Jeffrey R

    2014-01-01

    Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries. To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (%MISS) in professional basketball players. Cross-sectional study. Setting : Human Performance Laboratory. Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n = 4, height = 203.2 ± 5.5 cm, mass = 105 ± 7.5 kg, age = 25.0 ± 2.8 years) and those who remained healthy (n = 5, height = 200.2 ± 12.2 cm, mass = 100.1 ± 16.6 kg, age = 22.4 ± 1.9 years) during the season. Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and %MISS, as well as between injured and healthy athletes. The data indicated likely relationships between %MISS and age (r = 0.772), and between %MISS and bilateral differences in rectus femoris cross-sectional area (7.8% ± 6.4%; r = 0.657) and vastus lateralis cross-sectional area (6.2% ± 4.8%; r = 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9% ± 8.9%; r = 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0% ± 2.4%) versus healthy athletes (3.2% ± 2.0%). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W), these differences were not statistically significant (P = .20). In the present

  4. Bilateral Differences in Muscle Architecture and Increased Rate of Injury in National Basketball Association Players

    Science.gov (United States)

    Mangine, Gerald T.; Hoffman, Jay R.; Gonzalez, Adam M.; Jajtner, Adam R.; Scanlon, Tyler; Rogowski, Joseph P.; Wells, Adam J.; Fragala, Maren S.; Stout, Jeffrey R.

    2014-01-01

    Context Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries. Objective To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (%MISS) in professional basketball players. Design Cross-sectional study. Setting Human Performance Laboratory. Patients or Other Participants Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n = 4, height = 203.2 ± 5.5 cm, mass = 105 ± 7.5 kg, age = 25.0 ± 2.8 years) and those who remained healthy (n = 5, height = 200.2 ± 12.2 cm, mass = 100.1 ± 16.6 kg, age = 22.4 ± 1.9 years) during the season. Main Outcome Measure(s) Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and %MISS, as well as between injured and healthy athletes. Results The data indicated likely relationships between %MISS and age (r = 0.772), and between %MISS and bilateral differences in rectus femoris cross-sectional area (7.8% ± 6.4%; r = 0.657) and vastus lateralis cross-sectional area (6.2% ± 4.8%; r = 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9% ± 8.9%; r = 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0% ± 2.4%) versus healthy athletes (3.2% ± 2.0%). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W

  5. Muscle activity of leg muscles during unipedal stance on therapy devices with different stability properties.

    Science.gov (United States)

    Wolburg, Thomas; Rapp, Walter; Rieger, Jochen; Horstmann, Thomas

    2016-01-01

    To test the hypotheses that less stable therapy devices require greater muscle activity and that lower leg muscles will have greater increases in muscle activity with less stable therapy devices than upper leg muscles. Cross-sectional laboratory study. Laboratory setting. Twenty-five healthy subjects. Electromyographic activity of four lower (gastrocnemius medialis, soleus, tibialis anterior, peroneus longus) and four upper leg muscles (vastus medialis and lateralis, biceps femoris, semitendinosus) during unipedal quiet barefoot stance on the dominant leg on a flat rigid surface and on five therapy devices with varying stability properties. Muscle activity during unipedal stance differed significantly between therapy devices (P < 0.001). The order from lowest to highest relative muscle activity matched the order from most to least stable therapy device. There was no significant interaction between muscle location (lower versus upper leg) and therapy device (P = 0.985). Magnitudes of additional relative muscle activity for the respective therapy devices differed substantially among lower extremity muscles. The therapy devices offer a progressive increase in training intensity, and thus may be useful for incremental training programs in physiotherapeutic practice and sports training programs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Changes in satellite cells in human skeletal muscle after a single bout of high intensity exercise

    DEFF Research Database (Denmark)

    Crameri, Regina M; Langberg, Henning; Magnusson, Peter

    2004-01-01

    increase in mononuclear cells staining for the neural cell adhesion molecule (N-CAM) and fetal antigen 1 (FA1) were observed within the exercised human vastus lateralis muscle on days 4 and 8 post exercise. In addition, a significant increase in the concentration of the FA1 protein was determined...

  7. Muscle ceramide content in man is higher in type I than type II fibers and not influenced by glycogen content

    DEFF Research Database (Denmark)

    Nordby, P; Prats, C; Kristensen, D

    2010-01-01

    +/- 2 mL O2 min(-1) kg(-1)) participated in the study. On the first day, one leg was glycogen-depleted (DL) by exhaustive intermittent exercise followed by low carbohydrate diet. Next day, in the overnight fasted condition, muscle biopsies were excised from vastus lateralis before and after exhaustive...

  8. Impaired exercise performance and muscle Na(+),K(+)-pump activity in renal transplantation and haemodialysis patients.

    Science.gov (United States)

    Petersen, Aaron C; Leikis, Murray J; McMahon, Lawrence P; Kent, Annette B; Murphy, Kate T; Gong, Xiaofei; McKenna, Michael J

    2012-05-01

    We examined whether abnormal skeletal muscle Na(+),K(+)-pumps underlie impaired exercise performance in haemodialysis patients (HDP) and whether these are improved in renal transplant recipients (RTx). Peak oxygen consumption ( O(2peak)) and plasma [K(+)] were measured during incremental exercise in 9RTx, 10 HDP and 10 healthy controls (CON). Quadriceps peak torque (PT), fatigability (decline in strength during thirty contractions), thigh muscle cross-sectional area (TMCSA) and vastus lateralis Na(+),K(+)-pump maximal activity, content and isoform (α(1)-α(3), β(1)-β(3)) abundance were measured. O(2peak) was 32 and 35% lower in RTx and HDP than CON, respectively (P Na(+),K(+)-pump activity was 28 and 31% lower in RTx and HDP, respectively than CON (P Na(+),K(+)-pump activity (r = 0.45, P = 0.02). O(2peak) and muscle Na(+),K(+)-pump activity were depressed and muscle fatigability increased in HDP, with no difference observed in RTx. These findings are consistent with the possibility that impaired exercise performance in HDP and RTx may be partially due to depressed muscle Na(+),K(+)-pump activity and relative TMCSA.

  9. FAT/CD36 is localized in sarcolemma and in vesicle-like structures in subsarcolemma regions but not in mitochondria

    DEFF Research Database (Denmark)

    Jeppesen, Jacob; Mogensen, Martin; Prats, Clara

    2010-01-01

    was performed on single muscle fibers dissected from soleus muscle of lean and obese Zucker rats and from the vastus lateralis muscle from humans. Co-staining against FAT/CD36 and MitoNEET clearly show that FAT/CD36 is highly present in sarcolemma and it also associates with some vesicle-like intracellular...

  10. Detecting cryptic speciation in the widespread and morphologically conservative carpet chameleon (Furcifer lateralis) of Madagascar.

    Science.gov (United States)

    Florio, A M; Ingram, C M; Rakotondravony, H A; Louis, E E; Raxworthy, C J

    2012-07-01

    Species delimitation within recently evolved groups can be challenging because species may be difficult to distinguish morphologically. Following the General Lineage Concept, we apply a multiple evidence approach to assess species limits within the carpet chameleon Furcifer lateralis, which is endemic to Madagascar and exported in large numbers for the pet trade. Cryptic speciation within F. lateralis was considered likely because this species (1) has a vast distribution, (2) occupies exceptionally diverse habitats and (3) exhibits subtle regional differences in morphology. Phylogenetic trees reconstructed using nuclear and mitochondrial genes recovered three well-supported clades corresponding with geography. Morphological results based on canonical variates analysis show that these clades exhibit subtle differences in head casque morphology. Ecological niche modelling results found that these phylogenetic groups also occupy unique environmental space and exhibit patterns of regional endemism typical of other endemic reptiles. Combined, our findings provide diverse yet consistent evidence for the existence of three species. Consequently, we elevate the subspecies F. lateralis major to species rank and name a new species distributed in northern and western Madagascar. Initial ecological divergence, associated with speciation of F. lateralis in humid eastern habitat, fits the Ecographic Constraint model for species diversification in Madagascar. By contrast, the second speciation event provides some support for the Riverine Barrier model, with the Mangoky River possibly causing initial isolation between species. These findings thus support two contrasting models of speciation within closely related species and demonstrate the utility of applying a combined-evidence approach for detecting cryptic speciation. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  11. Neuromuscular Coordination Deficit Persists 12 Months after ACL Reconstruction But Can Be Modulated by 6 Weeks of Kettlebell Training: A Case Study in Women’s Elite Soccer

    Directory of Open Access Journals (Sweden)

    Mette K. Zebis

    2017-01-01

    Full Text Available The aim of the present single-case study was to investigate the effect of 6 weeks’ kettlebell training on the neuromuscular risk profile for ACL injury in a high-risk athlete returning to sport after ACL reconstruction. A female elite soccer player (age 21 years with no previous history of ACL injury went through neuromuscular screening as measured by EMG preactivity of vastus lateralis and semitendinosus during a standardized sidecutting maneuver. Subsequently, the player experienced a noncontact ACL injury. The player was screened again following postreconstruction rehabilitation, then underwent 6-week kettlebell training, and was subsequently screened again at 6-week follow-up. Prior to and after postreconstruction rehabilitation the player demonstrated a neuromuscular profile during sidecutting known to increase the risk for noncontact ACL injury, that is, reduced EMG preactivity for semitendinosus and elevated EMG preactivity for vastus lateralis. Subsequently, the 6-week kettlebell training increased semitendinosus muscle preactivity during sidecutting by 38 percentage points to a level equivalent to a neuromuscular low-risk profile. An ACL rehabilitated female athlete with a high-risk neuromuscular profile changed to low-risk in response to 6 weeks of kettlebell training. Thus, short-term kettlebell exercise with documented high levels of medial hamstring activation was found to transfer into high medial hamstring preactivation during a sidecutting maneuver.

  12. The hypobaric hypoxia affects the oxidant balance in skeletal muscle regeneration of women

    Directory of Open Access Journals (Sweden)

    Rosa Mancinelli

    2016-07-01

    Full Text Available Aim: The aim of this study was to determine whether a 14-day trekking expeditions, in high altitude hypoxic environment, triggers redox disturbance at the level of satellite cells (adult stem cells in young women.Methods: We collected muscle biopsies from Vastus Lateralis muscle for both single fiber analysis and satellite cells isolation. The samples collected before (PRE-Hypoxia and after (POST-Hypoxia the trekking in the Himalayas were compared. Satellite cells were investigated for oxidative stress (oxidant production, antioxidant enzyme activity and lipid damage, mitochondrial potential variation, gene profile of HIF and myogenic transcription factors (Pax7, MyoD, myogenin and miRNA expression (miR-1, miR-133, miR-206.Results: The nuclear domain analysis showed a significant fusion and consequent reduction of the Pax7+ satellite cells in the single mature fibers. The POST-Hypoxia myoblasts obtained by two out of six volunteers showed high superoxide anion production and lipid peroxidation along with impaired dismutase and catalase and mitochondrial potential. The transcription profile and miRNA expression were different for oxidized and non oxidized cells.Conclusions: The present study supports the phenomenon of hypobaric-hypoxia-induced oxidative stress and its role in the impairment of the regenerative capacity of satellite cells derived from the Vastus Lateralis muscle of young adult female subjects.

  13. Lower extremity muscle functions during full squats.

    Science.gov (United States)

    Robertson, D G E; Wilson, Jean-Marie J; St Pierre, Taunya A

    2008-11-01

    The purpose of this research was to determine the functions of the gluteus maximus, biceps femoris, semitendinosus, rectus femoris, vastus lateralis, soleus, gastrocnemius, and tibialis anterior muscles about their associated joints during full (deep-knee) squats. Muscle function was determined from joint kinematics, inverse dynamics, electromyography, and muscle length changes. The subjects were six experienced, male weight lifters. Analyses revealed that the prime movers during ascent were the monoarticular gluteus maximus and vasti muscles (as exemplified by vastus lateralis) and to a lesser extent the soleus muscles. The biarticular muscles functioned mainly as stabilizers of the ankle, knee, and hip joints by working eccentrically to control descent or transferring energy among the segments during scent. During the ascent phase, the hip extensor moments of force produced the largest powers followed by the ankle plantar flexors and then the knee extensors. The hip and knee extensors provided the initial bursts of power during ascent with the ankle extensors and especially a second burst from the hip extensors adding power during the latter half of the ascent.

  14. [Pharmacokinetic study of six aconitine alkaloids in aconiti lateralis radix praeparata in beagle dogs].

    Science.gov (United States)

    Xiao, Ri-Ping; Lai, Xiao-Ping; Zhao, Yai; Yu, Liang-Wen; Zhu, Yue-Lan; Li, Geng

    2014-02-01

    To study the pharmacokinetics characteristics of six Aconitum alkaloids aconitine (AC), mesaconitine (MA), hypaconitine (HA), benzoylaconine (BAC), benzoylmesaconine (BMA) and benzoylhypaconine (BHA) in beagle dogs. An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for simultaneous quantitation of six Aconitum alkaloids in beagle dog plasma after oral administration of Aconiti Lateralis Radix Praeparata decoction. UPLC/MS/MS system coupled with an electrospray ionization (ESI) source was performed in multiple-reaction monitoring (MRM) mode. Sample preparation was performed with solid-phase extraction(SPE) on a 3 mL HLB cartridge before the analysis. The separation was applied on a Waters C8 column (100 mm x 2.1 mm, 1.7 microm) and a gradient elution of methanol and 0.2% formic acid-water was used as mobile phase. The pharmacokinetic parameters were calculated by the results of the analysis through the DAS 2. 1 software (Drug and Statistics for Windows). The results showed that the fitting model for the six Aconitum alkaloids was the one-compartment model pharmacokinetics. The method is successfully used for the pharmacokinetic evaluation of the six Aconitum alkaloids in beagle dog plasma, it can help monitor the ADME/Tox process when taking Aconiti Lateralis Radix Praeparata by observing the pharmacokinetic process. The results provide a good reference for clinical treatment and safe application of Aconiti Lateralis Radix Praeparata.

  15. Vastus lateralis single motor unit EMG at the same absolute torque production at different knee angles

    NARCIS (Netherlands)

    Altenburg, T.M.; de Haan, A.; Verdijk, P.W.; van Mechelen, W.; de Ruiter, C.J.

    2009-01-01

    Single motor unit electromyographic (EMG) activity of the knee extensors was investigated at different knee angles with subjects (n = 10) exerting the same absolute submaximal isometric torque at each angle. Measurements were made over a 20° range around the optimum angle for torque production

  16. Changes in voluntary activation assessed by transcranial magnetic stimulation during prolonged cycling exercise.

    Directory of Open Access Journals (Sweden)

    Marc Jubeau

    Full Text Available Maximal central motor drive is known to decrease during prolonged exercise although it remains to be determined whether a supraspinal deficit exists, and if so, when it appears. The purpose of this study was to evaluate corticospinal excitability and muscle voluntary activation before, during and after a 4-h cycling exercise. Ten healthy subjects performed three 80-min bouts on an ergocycle at 45% of their maximal aerobic power. Before exercise and immediately after each bout, neuromuscular function was evaluated in the quadriceps femoris muscles under isometric conditions. Transcranial magnetic stimulation was used to assess voluntary activation at the cortical level (VATMS, corticospinal excitability via motor-evoked potential (MEP and intracortical inhibition by cortical silent period (CSP. Electrical stimulation of the femoral nerve was used to measure voluntary activation at the peripheral level (VAFNES and muscle contractile properties. Maximal voluntary force was significantly reduced after the first bout (13 ± 9%, P<0.01 and was further decreased (25 ± 11%, P<0.001 at the end of exercise. CSP remained unchanged throughout the protocol. Rectus femoris and vastus lateralis but not vastus medialis MEP normalized to maximal M-wave amplitude significantly increased during cycling. Finally, significant decreases in both VATMS and VAFNES (∼ 8%, P<0.05 and ∼ 14%, P<0.001 post-exercise, respectively were observed. In conclusion, reductions in VAFNES after a prolonged cycling exercise are partly explained by a deficit at the cortical level accompanied by increased corticospinal excitability and unchanged intracortical inhibition. When comparing the present results with the literature, this study highlights that changes at the cortical and/or motoneuronal levels depend not only on the type of exercise (single-joint vs. whole-body but also on exercise intensity and/or duration.

  17. Delayed presentation of compartment syndrome of the thigh secondary to quadriceps trauma and vascular injury in a soccer athlete

    Directory of Open Access Journals (Sweden)

    Moo Ing How

    2015-01-01

    Conclusion: A high index of suspicion for compartment syndrome is needed in all severe quadriceps contusion. Vascular injury can cause thigh compartment syndrome in sports trauma. MRI findings of deep thigh muscle swelling and “blow-out” tear of the vastus lateralis are strongly suggestive of severe quadriceps injury, and may be a harbinger of delayed thigh compartment syndrome.

  18. Characterization of kinesiological patterns of the frontal kick, mae-geri, in karate experts and non-karate practitioners

    Directory of Open Access Journals (Sweden)

    António M. VencesBrito

    2014-02-01

    Full Text Available Presently, coaches and researchers need to have a better comprehension of the kinesiological parameters that should be an important tool to support teaching methodologies and to improve skills performance in sports. The aim of this study was to (i identify the kinematic and neuromuscular control patterns of the front kick (mae-geri to a fixed target performed by 14 experienced karate practitioners, and (ii compare it with the execution of 16 participants without any karate experience, allowing the use of those references in the analysis of the training and learning process. Results showed that the kinematic and neuromuscular activity during the kick performance occurs within 600 ms. Muscle activity and kinematic analysis demonstrated a sequence of activation bracing a proximal-to-distal direction, with the muscles presenting two distinct periods of activity (1, 2, where the karateka group has a greater intensity of activation – root mean square (RMS and electromyography (EMG peak – in the first period on Rectus Femoris (RF1 and  Vastus Lateralis (VL1 and a lower duration of co-contraction in both periods on Rectus Femoris-Biceps Femoris and Vastus Lateralis-Biceps Femoris (RF-BF; VL-BF. In the skill performance, the hip flexion, the knee extension and the ankle plantar flexion movements were executed with smaller difference in the range of action (ROA in the karateka group, reflecting different positions of the segments. In conclusion, it was observed a general kinesiological pattern, which was similar in karateka and non-karateka practitioners. However, in the karateka group, the training induces a specialization in the muscle activity reflected in EMG and kinematic data, which leads to a better ballistic performance in the execution of the mae-geri kick, associated with a maximum speed of the distal segments, reached closer to the impact moment, possibly representing more power in the contact.

  19. Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata.

    Directory of Open Access Journals (Sweden)

    Alicia M Wells-Berlin

    Full Text Available Decline in surf scoter (Melanitta perspicillata waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum, one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis. The composition (macronutrients, minerals, and amino acids, shell strength (N, and metabolizable energy (kJ of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum, I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

  20. Influence of aging on isometric muscle strength, fat-free mass and electromyographic signal power of the upper and lower limbs in women

    Science.gov (United States)

    Amaral, Josária F.; Alvim, Felipe C.; Castro, Eliane A.; Doimo, Leonice A.; Silva, Marcus V.; Novo, José M.

    2014-01-01

    Background Aging is a multifactorial process that leads to changes in the quantity and quality of skeletal muscle and contributes to decreased levels of muscle strength. Objective This study sought to investigate whether the isometric muscle strength, fat-free mass (FFM) and power of the electromyographic (EMG) signal of the upper and lower limbs of women are similarly affected by aging. Method The sample consisted of 63 women, who were subdivided into three groups (young (YO) n=33, 24.7±3.5 years; middle age (MA) n=15, 58.6±4.2 years; and older adults (OA). n=15, 72.0±4.2 years). Isometric strength was recorded simultaneously with the capture of the electrical activity of the flexor muscles of the fingers and the vastus lateralis during handgrip and knee extension tests, respectively. FFM was assessed using dual-energy X-ray absorptiometry. Results The handgrip strength measurements were similar among groups (p=0.523), whereas the FFM of the upper limbs was lower in group OA compared to group YO (p=0.108). The RMSn values of the hand flexors were similar among groups (p=0.754). However, the strength of the knee extensors, the FFM of the lower limbs and the RMSn values of the vastus lateralis were lower in groups MA (p=0.014, p=0.006 and p=0.013, respectively) and OA (p=0.000, p=0.000 and pisometric muscle strength in MLG and electromyographic activity of the lower limbs are more pronounced with the aging process of the upper limb. PMID:24676705

  1. Effects of the lower extremities muscle activation during muscular strength training on an unstable platform with magneto-rheological dampers

    Science.gov (United States)

    Piao, YongJun; Choi, YounJung; Kim, JungJa; Kwan, TaeKyu; Kim, Nam-Gyun

    2009-03-01

    Adequate postural balance depends on the spatial and temporal integration of vestibular, visual, and somatosensory information. Especially, the musculoskeletal function (range of joint, flexibility of spine, muscular strength) is essential in maintaining the postural balance. Muscular strength training methods include the use of commercialized devices and repeatable resistance training tools (rubber band, ball, etc). These training systems cost high price and can't control of intensity. Thus we suggest a new training system which can adjust training intensity and indicate the center of pressure of a subject while the training was passively controlled by applying controlled electric current to the Magneto- Rheological damper. And we performed experimental studies on the muscular activities in the lower extremities during maintaining, moving and pushing exercises on an unstable platform with Magneto rheological dampers. A subject executed the maintaining, moving and pushing exercises which were displayed in a monitor. The electromyographic signals of the eight muscles in lower extremities were recorded and analyzed in the time and frequency domain: the muscles of interest were rectus femoris, biceps femoris, tensor fasciae latae, vastus lateralis, vastus medialis, gastrocnemius, tibialis anterior, and soleus. The experimental results showed the difference of muscular activities at the four moving exercises and the nine maintaining exercises. The rate of the increase in the muscular activities was affected by the condition of the unstable platform with MR dampers for the maintaining and moving exercises. The experimental results suggested the choice of different maintaining and moving exercises could selectively train different muscles with varying intensity. Furthermore, the findings also suggested the training using this system can improve the ability of postural balance.

  2. Influence of knee joint position and sex on vastus medialis regional architecture.

    Science.gov (United States)

    Gallina, Alessio; Render, Jacqueline N; Santos, Jacquelyne; Shah, Hershal; Taylor, Dayna; Tomlin, Travis; Garland, S Jayne

    2018-06-01

    Ultrasound imaging was used to investigate vastus medialis (VM) architecture in 10 males and 10 females at different knee angles. Increase in muscle thickness occurs predominantly when the knee angle is changed from 0° (full extension) and 45° (p Sex differences in the VM architecture can be observed in the distal (p 0.11).

  3. Does the Dumbbell-Carrying Position Change the Muscle Activity in Split Squats and Walking Lunges?

    Science.gov (United States)

    Stastny, Petr; Lehnert, Michal; Zaatar, Amr M Z; Svoboda, Zdenek; Xaverova, Zuzana

    2015-11-01

    The forward walking lunge (WL) and split squat (SSq) are similar exercises that have differences in the eccentric phase, and both can be performed in the ipsilateral or contralateral carrying conditions. This study aimed to determine the effects of dumbbell-carrying position on the kinematics and electromyographic (EMG) amplitudes of the gluteus medius (Gmed), vastus medialis (VM), vastus lateralis (VL), and biceps femoris during WLs and SSqs. The resistance-trained (RT) and the non-resistance-trained (NT) groups (both n = 14) performed ipsilateral WLs, contralateral WLs, ipsilateral SSqs, and contralateral SSqs in a randomized order in a simulated training session. The EMG amplitude, expressed as a percentage of the maximal voluntary isometric contraction (%MVIC), and the kinematics, expressed as the range of motion (ROM) of the hip and knee, were measured during 5 repetition maximum for both legs. The repeated measure analyses of variance showed significant differences between the RT and NT groups. The NT group showed a smaller knee flexion ROM (p < 0.001, η = 0.36) during both types of WLs, whereas the RT group showed a higher eccentric Gmed amplitude (p < 0.001, η = 0.46) during all exercises and a higher eccentric VL amplitude (p < 0.001, η = 0.63) during contralateral WLs. Further differences were found between contralateral and ipsilateral WLs in both the RT (p < 0.001, η = 0.69) and NT groups (p < 0.001, η = 0.80), and contralateral WLs resulted in higher eccentric Gmed amplitudes. Contralateral WLs highly activated the Gmed (90% MVIC); therefore, this exercise can increase the Gmed maximal strength. The ipsilateral loading condition did not increase the Gmed or VM activity in the RT or NT group.

  4. Moderate-Load Muscular Endurance Strength Training Did Not Improve Peak Power or Functional Capacity in Older Men and Women

    Directory of Open Access Journals (Sweden)

    Simon Walker

    2017-09-01

    Full Text Available The present study determined the effects of muscular endurance strength training on maximum strength and power, functional capacity, muscle activation and hypertrophy in older men and women. Eighty-one men and women acted as an intervention group while 22 acted as non-training controls (age range 64–75 y. Intervention training included super-sets (i.e., paired exercises, immediately performing the second exercises following completion of the first with short rest intervals (30–60 s between sets at an intensity of 50–60% one-repetition maximum (1-RM for 15–20 repetitions. Concentric leg press actions measured maximum strength (1-RM and concentric peak power. Functional capacity was assessed by maximum speed walking tests (i.e., forward walk, backward walk, timed-up-and-go, and stair climb tests. Quadriceps muscle activation was assessed by surface electromyogram and twitch interpolation technique. Vastus lateralis cross-sectional area was measured by panoramic ultrasound. Compared to control, the intervention groups increased maximum strength (1-RM; men: 10 ± 7% vs. 2 ± 3%, women: 14 ± 9% vs. 1 ± 6% both P < 0.01 and vastus lateralis cross-sectional area (men: 6 ± 7% vs. −3 ± 6%, women: 10 ± 10% vs. 0 ± 4% both P < 0.05. But there were no between-group differences in peak power, muscle activation or functional capacity (e.g., stair climb; men: −5 ± 7% vs. −4 ± 3%, women: −5 ± 6% vs. −2 ± 5% both P > 0.05. While benefits occurred during muscular endurance strength training, specific stimuli are probably needed to target all aspects of age-related health.

  5. EFFECTS OF WARM-UP ON VERTICAL JUMP PERFORMANCE AND MUSCLE ELECTRICAL ACTIVITY USING HALF-SQUATS AT LOW AND MODERATE INTENSITY

    Directory of Open Access Journals (Sweden)

    Konstantinos Sotiropoulos

    2010-06-01

    Full Text Available The purpose of this study was to determine the effects of a specific warm-up using half-squats at low and moderate intensity on vertical jump performance and electromyographic activity of the thigh muscles. The subjects were 26 men who were divided into a low intensity group (LIG; n = 13 and a moderate intensity group (MIG; n = 13. The LIG performed a specific warm-up protocol that included the explosive execution of half-squats with loads 25 and 35% of the one repetition maximum (1RM and the MIG with loads 45 and 65% of the 1RM. The two groups performed a countermovement jump (CMJ before and three minutes after the specific warm-up protocols. During the concentric phase of the CMJ a linear encoder connected to an A/D converter interfaced to a PC with a software for data acquisition and analysis allowed the calculation of average mechanical power. The electromyographic (EMG activity of the vastus lateralis (VL, vastus medialis (VM and rectus femoris (RF were recorded during the concentric phase of the jumps. The average quadriceps (Qc activity (mean value of the VL, VM and RF was also calculated. A two way ANOVA (protocols X time with repeated measures on the second factor was used to analyze the data. Following the specific warm-up procedure both groups improved (p < 0.05 CMJ performance and mechanical power by 3.5% and 6.3%, respectively, with no differences observed between the two groups. EMG activity of the Qc and VL increased (p < 0.05 for both groups by 5.9% and 8.5%, respectively. It is concluded that the use of a specific warm-up that includes half-squats, performed explosively with low to moderate intensity, improves CMJ performance. This may be due to increased muscle activation as evaluated by the surface EMG

  6. The effect of exercise and beta2-adrenergic stimulation on glutathionylation and function of the Na,K-ATPase in human skeletal muscle

    DEFF Research Database (Denmark)

    Juel, Carsten; Hostrup, Morten; Bangsbo, Jens

    2015-01-01

    ) on Na,K-ATPase activity. Ten male subjects performed three bouts of 4-min submaximal exercise followed by intense exercise to exhaustion with and without beta2-adrenergic stimulation with terbutaline. Muscle biopsies were obtained from m. vastus lateralis at rest (Control samples) and at exhaustion....... In vitro glutathionylation reduced (P basal glutathionylation in Control samples and no further glutathionylation with exercise and beta......2-adrenergic stimulation. Immunoprecipitation with an anti-GSH antibody and subsequent immunodetection with β1 antibodies showed approximately 20% glutathionylation in Control samples and further glutathionylation after exercise (to 32%) and beta2-adrenergic stimulation (to 38%, P

  7. Increase in vastus medialis cross-sectional area is associated with reduced pain, cartilage loss, and joint replacement risk in knee osteoarthritis.

    Science.gov (United States)

    Wang, Yuanyuan; Wluka, Anita E; Berry, Patricia A; Siew, Terence; Teichtahl, Andrew J; Urquhart, Donna M; Lloyd, David G; Jones, Graeme; Cicuttini, Flavia M

    2012-12-01

    Although there is evidence for a beneficial effect of increased quadriceps strength on knee symptoms, the effect on knee structure is unclear. We undertook this study to examine the relationship between change in vastus medialis cross-sectional area (CSA) and knee pain, tibial cartilage volume, and risk of knee replacement in subjects with symptomatic knee osteoarthritis (OA). One hundred seventeen subjects with symptomatic knee OA underwent magnetic resonance imaging of the knee at baseline and at 2 and 4.5 years. Vastus medialis CSA was measured at baseline and at 2 years. Tibial cartilage volume was measured at baseline and at 2 and 4.5 years. Knee pain was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index at baseline and at 2 years. The frequency of knee joint replacement over 4 years was determined. Regression coefficients (B) and odds ratios were determined along with 95% confidence intervals (95% CIs). After adjusting for confounders, baseline vastus medialis CSA was inversely associated with current knee pain (r = -0.16, P = 0.04) and with medial tibial cartilage volume loss from baseline to 2 years (B coefficient -10.9 [95% CI -19.5, -2.3]), but not with baseline tibial cartilage volume. In addition, an increase in vastus medialis CSA from baseline to 2 years was associated with reduced knee pain over the same time period (r = 0.24, P = 0.007), reduced medial tibial cartilage loss from 2 to 4.5 years (B coefficient -16.8 [95% CI -28.9, -4.6]), and reduced risk of knee replacement over 4 years (odds ratio 0.61 [95% CI 0.40, 0.94]). In a population of patients with symptomatic knee OA, increased vastus medialis size was associated with reduced knee pain and beneficial structural changes at the knee, suggesting that management of knee pain and optimizing vastus medialis size are important in reducing OA progression and subsequent knee replacement. Copyright © 2012 by the American College of Rheumatology.

  8. Is muscle coordination affected by loading condition in ballistic movements?

    Science.gov (United States)

    Giroux, Caroline; Guilhem, Gaël; Couturier, Antoine; Chollet, Didier; Rabita, Giuseppe

    2015-02-01

    This study aimed to investigate the effect of loading on lower limb muscle coordination involved during ballistic squat jumps. Twenty athletes performed ballistic squat jumps on a force platform. Vertical force, velocity, power and electromyographic (EMG) activity of lower limb muscles were recorded during the push-off phase and compared between seven loading conditions (0-60% of the concentric-only maximal repetition). The increase in external load increased vertical force (from 1962 N to 2559 N; P=0.0001), while movement velocity decreased (from 2.5 to 1.6 ms(-1); P=0.0001). EMG activity of tibialis anterior first peaked at 5% of the push-off phase, followed by gluteus maximus (35%), vastus lateralis and soleus (45%), rectus femoris (55%), gastrocnemius lateralis (65%) and semitendinosus (75%). This sequence of activation (P=0.67) and the amplitude of muscle activity (P=0.41) of each muscle were not affected by loading condition. However, a main effect of muscle was observed on these parameters (peak value: Ppush-off phase. Our findings suggest that muscle coordination is not influenced by external load during a ballistic squat jump. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. De novo synthesis of adenine nucleotides in different skeletal muscle fiber types

    International Nuclear Information System (INIS)

    Tullson, P.C.; John-Alder, H.B.; Hood, D.A.; Terjung, R.L.

    1988-01-01

    Management of adenine nucleotide catabolism differs among skeletal muscle fiber types. This study evaluated whether there are corresponding differences in the rates of de novo synthesis of adenine nucleotide among fiber type sections of skeletal muscle using an isolated perfused rat hindquarter preparation. Label incorporation into adenine nucleotides from the [1-14C]glycine precursor was determined and used to calculate synthesis rates based on the intracellular glycine specific radioactivity. Results show that intracellular glycine is closely related to the direct precursor pool. Rates of de novo synthesis were highest in fast-twitch red muscle (57.0 +/- 4.0, 58.2 +/- 4.4 nmol.h-1.g-1; deep red gastrocnemius and vastus lateralis), relatively high in slow-twitch red muscle (47.0 +/- 3.1; soleus), and low in fast-twitch white muscle (26.1 +/- 2.0 and 21.6 +/- 2.3; superficial white gastrocnemius and vastus lateralis). Rates for four mixed muscles were intermediate, ranging between 32.3 and 37.3. Specific de novo synthesis rates exhibited a strong correlation (r = 0.986) with muscle section citrate synthase activity. Turnover rates (de novo synthesis rate/adenine nucleotide pool size) were highest in high oxidative muscle (0.82-1.06%/h), lowest in low oxidative muscle (0.30-0.35%/h), and intermediate in mixed muscle (0.44-0.55%/h). Our results demonstrate that differences in adenine nucleotide management among fiber types extends to the process of de novo adenine nucleotide synthesis

  10. Differential Motor Unit Changes after Endurance or High-Intensity Interval Training.

    Science.gov (United States)

    Martinez-Valdes, Eduardo; Falla, Deborah; Negro, Francesco; Mayer, Frank; Farina, Dario

    2017-06-01

    Using a novel technique of high-density surface EMG decomposition and motor unit (MU) tracking, we compared changes in the properties of vastus medialis and vastus lateralis MU after endurance (END) and high-intensity interval training (HIIT). Sixteen men were assigned to the END or the HIIT group (n = 8 each) and performed six training sessions for 14 d. Each session consisted of 8-12 × 60-s intervals at 100% peak power output separated by 75 s of recovery (HIIT) or 90-120 min continuous cycling at ~65% V˙O2peak (END). Pre- and postintervention, participants performed 1) incremental cycling to determine V˙O2peak and peak power output and 2) maximal, submaximal (10%, 30%, 50%, and 70% maximum voluntary contraction [MVC]), and sustained (until task failure at 30% MVC) isometric knee extensions while high-density surface EMG signals were recorded from the vastus medialis and vastus lateralis. EMG signals were decomposed (submaximal contractions) into individual MU by convolutive blind source separation. Finally, MU were tracked across sessions by semiblind source separation. After training, END and HIIT improved V˙O2peak similarly (by 5.0% and 6.7%, respectively). The HIIT group showed enhanced maximal knee extension torque by ~7% (P = 0.02) and was accompanied by an increase in discharge rate for high-threshold MU (≥50% knee extension MVC) (P 0.05). HIIT and END induce different adjustments in MU discharge rate despite similar improvements in cardiopulmonary fitness. Moreover, the changes induced by HIIT are specific for high-threshold MU. For the first time, we show that HIIT and END induce specific neuromuscular adaptations, possibly related to differences in exercise load intensity and training volume.

  11. Stiffness of individual quadriceps muscle assessed using ultrasound shear wave elastography during passive stretching

    Directory of Open Access Journals (Sweden)

    Jingfei Xu

    2018-04-01

    Full Text Available Background: Until recently it has not been possible to isolate the mechanical behavior of individual muscles during passive stretching. Muscle shear modulus (an index of muscle stiffness measured using ultrasound shear wave elastography can be used to estimate changes in stiffness of an individual muscle. The aims of the present study were (1 to determine the shear modulus–knee angle relationship and the slack angle of the vastus medialis oblique (VMO, rectus femoris (RF, and vastus lateralis (VL muscles; (2 to determine whether this differs between the muscles. Methods: Nine male rowers took part in the study. The shear modulus of VMO, RF, and VL muscles was measured while the quadriceps was passively stretched at 3°/s. The relationship between the muscle shear modulus and knee angle was plotted as shear modulus–knee angle curve through which the slack angle of each muscle was determined. Results: The shear modulus of RF was higher than that of VMO and VL when the muscles were stretched over 54° (all p  0.05. The slack angle was similar among the muscles: 41.3° ± 10.6°, 44.3° ± 9.1°, and 44.3° ± 5.6° of knee flexion for VMO, RF, and VL, respectively (p = 0.626. Conclusion: This is the first study to experimentally determine the muscle mechanical behavior of individual heads of the quadriceps during passive stretching. Different pattern of passive tension was observed between mono- and bi-articular muscles. Further research is needed to determine whether changes in muscle stiffness are muscle-specific in pathological conditions or after interventions such as stretching protocols. Keywords: Muscle tension, Optimal length, Shear modulus, Slack angle, Stretch, Ultrasonography, Vastus lateralis, Vastus medialis

  12. The Effect of Pedaling and Fatigue on Changes of Knee Muscles Co-contraction During Running in Triathletes

    Directory of Open Access Journals (Sweden)

    Mehrdad Anbarian

    2015-09-01

    Full Text Available Objective: The purpose of this study was to determine the effect of cycling fatigue on co-activation of knee muscles during running in novice triathletes. Methods: Twelve novice male triathletes aged 23.7±2.1 years participated in this quasi experimental study. Surface electromyographic activity from gastrocnemius, rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus were recorded during support and non-support phases of running before and after cycling fatigue protocol. General and directed co-activation of the knee muscles were calculated. Paired t-test was used to analyze the data(p<0.05. Results: General co-activation was significantly reduced in propulsion sub-phase, total support and non-support phases after fatigue (p=0.001, but there were not any differences in heel contact and midstance sub-phases. Fatigue only altered directed co-activation of medial and lateral knee muscles during heel contact sub-phase (p=0.034. Extensor and flexor directed co-activation during non-support phase of running significantly decreased after fatigue (p=0.011. Conclusion: Changes in the co-activation during running after cycling fatigue can alter running pattern and reduce the knee function consequently, causing injuries to the lower limbs in novice triathletes.

  13. Creation of a contusion injury in rabbit skeletal muscle using a drop-mass technique

    Directory of Open Access Journals (Sweden)

    Margaret N. Deane

    2013-08-01

    Full Text Available This study reports our experience in developing a simple, minor injury. After reviewing the literature, a ‘drop-mass’ method was selected where a 201 g, elongated oval-shaped weight was dropped up to 15 times through a 1 m tube onto the left vastus lateralis of New Zealand white rabbits. To determine the extent of injury and degree of healing, biopsies were obtained six days after injury from the healing vastus lateralis of each animal. The tissue was fixed in formal saline, embedded in wax, cut and stained with haematoxylin and eosin (H&E and phosphotungstic acid haematoxylin (PTAH and examined by light microscopy (LM. The ‘optimal’ injury was created after seven drops, where quite severe, mild and moderately severe trauma was caused to muscle in the juxta-bone, mid and sub-dermal regions respectively. In each region, the muscle exhibited features of healing six days after injury. The ‘drop-mass’ technique appears to cause a contusion within a single muscle of at least three degrees of severity. This previously unreported observation is of particular importance to other researchers wishing to investigate contusion injury in other animal models.

  14. Electromyographic activity associated with spontaneous functional recovery after spinal cord injury in rats.

    Science.gov (United States)

    Kaegi, Sibille; Schwab, Martin E; Dietz, Volker; Fouad, Karim

    2002-07-01

    This investigation was designed to study the spontaneous functional recovery of adult rats with incomplete spinal cord injury (SCI) at thoracic level during a time course of 2 weeks. Daily testing sessions included open field locomotor examination and electromyographic (EMG) recordings from a knee extensor (vastus lateralis, VL) and an ankle flexor muscle (tibialis anterior, TA) in the hindlimbs of treadmill walking rats. The BBB score (a locomotor score named after Basso et al., 1995, J. Neurotrauma, 12, 1-21) and various measures from EMG recordings were analysed (i.e. step cycle duration, rhythmicity of limb movements, flexor and extensor burst duration, EMG amplitude, root-mean-square, activity overlap between flexor and extensor muscles and hindlimb coupling). Directly after SCI, a marked drop in locomotor ability occurred in all rats with subsequent partial recovery over 14 days. The recovery was most pronounced during the first week. Significant changes were noted in the recovery of almost all analysed EMG measures. Within the 14 days of recovery, many of these measures approached control levels. Persistent abnormalities included a prolonged flexor burst and increased activity overlap between flexor and extensor muscles. Activity overlap between flexor and extensor muscles might be directly caused by altered descending input or by maladaptation of central pattern generating networks and/or sensory feedback.

  15. Rebound boots change lower limb muscle activation and kinematics during different fitness exercises.

    Science.gov (United States)

    Rossato, Mateus; Dellagrana, Rodolfo André; Dos Santos, Juliane Cristine Lopes; Carpes, Felipe P; Gheller, Rodrigo Ghedini; da Silva, De Angelys de Ceselles Seixas; Bezerra, Ewertton de Souza; Dos Santos, João Otacílio Libardoni

    2017-10-01

    The purpose of this study was to evaluate electromyography and kinematic parameters of the lower limbs using rebound boots (RB) and barefoot during a gym workout. This information can be helpful to practitioners to schedule rehabilitation and training programs. Ten women (25 ± 9 years) volunteered for the study; inclusion criteria were as follows: subjects must have experienced the use of RB and the analyzed exercises for at least 6 months, and have no previous injuries in the lower limbs. Seven exercises were performed for 30 s with the RB and subsequently barefoot. Data from muscle activation of vastus lateralis (VL), biceps femoris (BF), lateral gastrocnemius (LG) and 2D kinematics were collected. The use of RB triggered postural changes, characterized by greater hip extension (in 4 of the exercises) and knee extension (in 6 of the exercises) for the landing. RB reduced activation mainly in LG (in 6 of the exercise) while no changes were observed for VL (except in exercise 1) and BF. RB change kinematics and muscle activation suggesting changes in the way the legs absorb and transmit force during jumps. LG was the main muscle affected by the use of RB. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Proboscis lateralis- A 17 years follow-up, a case report

    Directory of Open Access Journals (Sweden)

    Vyas U

    2003-01-01

    Full Text Available Proboscis lateralis is a rare congenital anomaly for which no embryological basis has been established. Besides heminasal aplasia or hypoplasia, various other craniofacial anomalies are also associated with it. It is only uncommonly free of other anomalies. Evaluation of a patient should include CT scan examination to look for growth of facial and skull bones. Reconstruction should start at an early age. Proboscis itself is the best option for heminose formation. Cartilaginous or bony support can be planned later in the late teens to give good aesthetic result.

  17. Whey Protein Ingestion Activates mTOR-dependent Signalling after Resistance Exercise in Young Men: A Double-Blinded Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    David Cameron-Smith

    2009-12-01

    Full Text Available The effect of resistance exercise with the ingestion of supplementary protein on the activation of the mTOR cascade, in human skeletal muscle has not been fully elucidated. In this study, the impact of a single bout of resistance exercise, immediately followed by a single dose of whey protein isolate (WPI or placebo supplement, on the activation of mTOR signalling was analyzed. Young untrained men completed a maximal single-legged knee extension exercise bout and were randomized to ingest either WPI supplement (n = 7 or the placebo (n = 7. Muscle biopsies were taken from the vastus lateralis before, and 2, 4 and 24 hr post-exercise. WPI or placebo ingestion consumed immediately post-exercise had no impact on the phosphorylation of Akt (Ser473. However, WPI significantly enhanced phosphorylation of mTOR (Ser2448, 4E-BP1 (Thr37/46 and p70S6K (Thr389 at 2 hr post-exercise. This study demonstrates that a single dose of WPI, when consumed in modest quantities, taken immediately after resistance exercise elicits an acute and transient activation of translation initiation within the exercised skeletal muscle.

  18. The effect of age and knee osteoarthritis on muscle activation patterns and knee joint biomechanics during dual belt treadmill gait.

    Science.gov (United States)

    Rutherford, Derek; Baker, Matthew; Wong, Ivan; Stanish, William

    2017-06-01

    To compare a group of individuals with moderate medial compartment knee osteoarthritis (OA) to both an age-matched asymptomatic group of older adults and younger adults to determine whether differences in knee joint muscle activation patterns and joint biomechanics exist during gait between these three groups. 20 young adults, 20 older adults, and 40 individuals with moderate knee OA were recruited. Using standardized procedures, surface electromyograms were recorded from the vastus lateralis and medialis, rectus femoris and the medial and lateral hamstrings. All individuals walked on a dual belt instrumented treadmill while segment motions and ground reaction forces were recorded. Sagittal plane motion and net external sagittal and frontal plane moments were calculated. Discrete measures and principal component analyses extracted amplitude and temporal waveform features. Analysis of Variance models using Bonferroni corrections determined between and within group differences in these gait features (α=0.05). Individuals with knee OA have distinct biomechanics and muscle activation patterns when compared to age-matched asymptomatic adults and younger adults whereas differences between the young and older adults were few and included only measures of muscle activation amplitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Influence of wheel size on muscle activity and tri-axial accelerations during cross-country mountain biking.

    Science.gov (United States)

    Hurst, Howard Thomas; Sinclair, Jonathan; Atkins, Stephen; Rylands, Lee; Metcalfe, John

    2017-07-01

    This study aimed to investigate the influence of different mountain bike wheel diameters on muscle activity and whether larger diameter wheels attenuate muscle vibrations during cross-country riding. Nine male competitive mountain bikers (age 34.7 ± 10.7 years; stature 177.7 ± 5.6 cm; body mass 73.2 ± 8.6 kg) participated in the study. Riders performed one lap at race pace on 26, 27.5 and 29 inch wheeled mountain bikes. sEMG and acceleration (RMS) were recorded for the full lap and during ascent and descent phases at the gastrocnemius, vastus lateralis, biceps brachii and triceps brachii. No significant main effects were found by wheel size for each of the four muscle groups for sEMG or acceleration during the full lap and for ascent and descent (P > .05). When data were analysed between muscle groups, significant differences were found between biceps brachii and triceps brachii (P biking. However, more activity was observed in the biceps brachii during 26 inch wheel descending. This is possibly due to an increased need to manoeuvre the front wheel over obstacles.

  20. GLUT4 and glycogen synthase are key players in bed rest-induced insulin resistance

    DEFF Research Database (Denmark)

    Biensø, Rasmus Sjørup; Jørgensen, Stine Ringholm; Kiilerich, Kristian

    2012-01-01

    To elucidate the molecular mechanisms behind physical inactivity-induced insulin resistance in skeletal muscle, 12 young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies obtained before and after. In six of the subjects, muscle biopsies were taken from both...... than before bed rest. This bed rest-induced insulin resistance occurred together with reduced muscle GLUT4, hexokinase II, protein kinase B/Akt1, and Akt2 protein level, and a tendency for reduced 3-hydroxyacyl-CoA dehydrogenase activity. The ability of insulin to phosphorylate Akt and activate....... The present findings demonstrate that physical inactivity-induced insulin resistance in muscle is associated with lower content/activity of key proteins in glucose transport/phosphorylation and storage....

  1. Tricarboxylic acid cycle intermediates accumulate at the onset of intense exercise in man but are not essential for the increase in muscle oxygen uptake

    DEFF Research Database (Denmark)

    Bangsbo, Jens; Gibala, Martin J.; Howarth, Krista R.

    2006-01-01

    dichloroacetate (DCA) in an attempt to alter the level of TCAI. Five men performed strenuous leg kicking exercise (64+/-8 W) under noninfused control (CON) and DCA-supplemented conditions; biopsies (vastus lateralis) were obtained at rest and after 5, 15, and 180 s of exercise. In CON, the total concentration...... seconds of exercise; however, this increase is not essential for the contraction-induced increase in mitochondrial respiration....

  2. THE CONTRIBUTION OF 'RESTING' BODY MUSCLES TO THE SLOW COMPONENT OF PULMONARY OXYGEN UPTAKE DURING HIGH-INTENSITY CYCLING

    Directory of Open Access Journals (Sweden)

    Susan A. Ward

    2012-12-01

    Full Text Available Oxygen uptake (VO2 kinetics during moderate constant- workrate (WR exercise (>lactate-threshold (ӨL are well described as exponential. AboveӨL, these kinetics are more complex, consequent to the development of a delayed slow component (VO2sc, whose aetiology remains controversial. To assess the extent of the contribution to the VO2sc from arm muscles involved in postural stability during cycling, six healthy subjects completed an incremental cycle-ergometer test to the tolerable limit for estimation of ӨL and determination of peak VO2. They then completed two constant-WR tests at 90% of ӨL and two at 80% of ∆ (difference between ӨL and VO2peak. Gas exchange variables were derived breath-by-breath. Local oxygenation profiles of the vastus lateralis and biceps brachii muscles were assessed by near-infrared spectroscopy, with maximal voluntary contractions (MVC of the relevant muscles being performed post-exercise to provide a frame of reference for normalising the exercise-related oxygenation responses across subjects. Above supra-ӨL, VO2 rose in an exponential-like fashion ("phase 2, with a delayed VO2sc subsequently developing. This was accompanied by an increase in [reduced haemoglobin] relative to baseline (∆[Hb], which attained 79 ± 13 % (mean, SD of MVC maximum in vastus lateralis at end-exercise and 52 ± 27 % in biceps brachii. Biceps brachii ∆[Hb] was significantly correlated with VO2 throughout the slow phase. In contrast, for sub- L exercise, VO2 rose exponentially to reach a steady state with a more modest increase in vastus lateralis ∆[Hb] (30 ± 11 %; biceps brachii ∆[Hb] was minimally affected (8 ± 2 %. That the intramuscular O2 desaturation profile in biceps brachii was proportional to that for VO2sc during supra-ӨL cycle ergometry is consistent with additional stabilizing arm work contributing to the VO2sc

  3. Electrically and hybrid-induced muscle activations: effects of muscle size and fiber type

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    Kelly Stratton

    2016-07-01

    Full Text Available The effect of three electrical stimulation (ES frequencies (10, 35, and 50 Hz on two muscle groups with different proportions of fast and slow twitch fibers (abductor pollicis brevis (APB and vastus lateralis (VL was explored. We evaluated the acute muscles’ responses individually and during hybrid activations (ES superimposed by voluntary activations. Surface electromyography (sEMG and force measurements were evaluated as outcomes. Ten healthy adults (mean age: 24.4 ± 2.5 years participated after signing an informed consent form approved by the university Institutional Review Board. Protocols were developed to: 1 compare EMG activities during each frequency for each muscle when generating 25% Maximum Voluntary Contraction (MVC force, and 2 compare EMG activities during each frequency when additional voluntary activation was superimposed over ES-induced 25% MVC to reach 50% and 75% MVC. Empirical mode decomposition (EMD was utilized to separate ES artifacts from voluntary muscle activation. For both muscles, higher stimulation frequency (35 and 50Hz induced higher electrical output detected at 25% of MVC, suggesting more recruitment with higher frequencies. Hybrid activation generated proportionally less electrical activity than ES alone. ES and voluntary activations appear to generate two different modes of muscle recruitment. ES may provoke muscle strength by activating more fatiguing fast acting fibers, but voluntary activation elicits more muscle coordination. Therefore, during the hybrid activation, less electrical activity may be detected due to recruitment of more fatigue-resistant deeper muscle fibers, not reachable by surface EMG.

  4. Alveolar gas exchange and tissue oxygenation during incremental treadmill exercise, and their associations with blood O2 carrying capacity

    Directory of Open Access Journals (Sweden)

    Antti-Pekka E. Rissanen

    2012-07-01

    Full Text Available The magnitude and timing of oxygenation responses in highly active leg muscle, less active arm muscle, and cerebral tissue, have not been studied with simultaneous alveolar gas exchange measurement during incremental treadmill exercise. Nor is it known, if blood O2 carrying capacity affects the tissue-specific oxygenation responses. Thus, we investigated alveolar gas exchange and tissue (m. vastus lateralis, m. biceps brachii, cerebral cortex oxygenation during incremental treadmill exercise until volitional fatigue, and their associations with blood O2 carrying capacity in 22 healthy men. Alveolar gas exchange was measured, and near-infrared spectroscopy (NIRS was used to monitor relative concentration changes in oxy- (Δ[O2Hb], deoxy- (Δ[HHb] and total hemoglobin (Δ[tHb], and tissue saturation index (TSI. NIRS inflection points (NIP, reflecting changes in tissue-specific oxygenation, were determined and their coincidence with ventilatory thresholds (anaerobic threshold (AT, respiratory compensation point (RC; V-slope method was examined. Blood O2 carrying capacity (total hemoglobin mass (tHb-mass was determined with the CO-rebreathing method. In all tissues, NIPs coincided with AT, whereas RC was followed by NIPs. High tHb-mass associated with leg muscle deoxygenation at peak exercise (e.g., Δ[HHb] from baseline walking to peak exercise vs. tHb-mass: r = 0.64, p < 0.01, but not with arm muscle- or cerebral deoxygenation. In conclusion, regional tissue oxygenation was characterized by inflection points, and tissue oxygenation in relation to alveolar gas exchange during incremental treadmill exercise resembled previous findings made during incremental cycling. It was also found out, that O2 delivery to less active m. biceps brachii may be limited by an accelerated increase in ventilation at high running intensities. In addition, high capacity for blood O2 carrying was associated with a high level of m. vastus lateralis deoxygenation at peak

  5. Relação eletromiográfica integrada dos músculos vasto medial oblíquo e vasto lateral longo na marcha em sujeitos com e sem síndrome de dor femoropatelar Relación electromiográfica integrada de los músculos vasto medial oblicuo y vasto lateral largo en marcha en individuos con y sin síndrome de dolor femoropatelar Integrated electromyographic ratio of the vastus medialis oblique and vastus lateralis longus muscles in gait in subjects with and without patellofemoral pain syndrome

    Directory of Open Access Journals (Sweden)

    Gilmar Moraes Santos

    2007-02-01

    actividad eléctrica de los músculos VMO y VLL, en individuos con y sin SDFP es igual en el trote tanto en superficie plana como la que tiene inclinación de 5°.The aim of this study was to determine if there is difference between the vastus medialis oblique and vastus lateralis longus (VMO/VLL muscles activation during treadmill gait level and ascending to 5% degree between healthy subjects and others with patellofemoral pain syndrome. Electromyographic data from the VMO and VLL muscles were obtained in 15 subjects without and 12 with patellofemoral pain syndrome (PFPS during treadmill gait with and without 5 degrees inclination. The value of the VMO/VLL ratio was determined from the mean of 8 strides, in each condition, during 12 s. The t-Student test did not show significant difference in the VMO/VLL ratio between the two groups, regardless the condition. Although there was not significant difference, the subjects of the control group showed higher values in the VMO/VLL ratio in the two tested conditions than the subject of the PFPS group. The findings suggest that the ratio of the electric activity of the VMO and VLL muscles in individuals with and without SDFP is equal in the gait on flat surface as well as slanted to 5 degrees.

  6. Muscle, Skin and Core Temperature after −110°C Cold Air and 8°C Water Treatment

    Science.gov (United States)

    Costello, Joseph Thomas; Culligan, Kevin; Selfe, James; Donnelly, Alan Edward

    2012-01-01

    The aim of this investigation was to elucidate the reductions in muscle, skin and core temperature following exposure to −110°C whole body cryotherapy (WBC), and compare these to 8°C cold water immersion (CWI). Twenty active male subjects were randomly assigned to a 4-min exposure of WBC or CWI. A minimum of 7 days later subjects were exposed to the other treatment. Muscle temperature in the right vastus lateralis (n = 10); thigh skin (average, maximum and minimum) and rectal temperature (n = 10) were recorded before and 60 min after treatment. The greatest reduction (Psporting setting. PMID:23139763

  7. Knee joint angle affects EMG-force relationship in the vastus intermedius muscle.

    Science.gov (United States)

    Saito, Akira; Akima, Hiroshi

    2013-12-01

    It is not understood how the knee joint angle affects the relationship between electromyography (EMG) and force of four individual quadriceps femoris (QF) muscles. The purpose of this study was to examine the effect of the knee joint angle on the EMG-force relationship of the four individual QF muscles, particularly the vastus intermedius (VI), during isometric knee extensions. Eleven healthy men performed 20-100% of maximal voluntary contraction (MVC) at knee joint angles of 90°, 120° and 150°. Surface EMG of the four QF synergists was recorded and normalized by the root mean square during MVC. The normalized EMG of the four QF synergists at a knee joint angle of 150° was significantly lower than that at 90° and 120° (P knee joint angle of 150°. Furthermore, the neuromuscular activation of the VI was the most sensitive to change in muscle length among the four QF synergistic muscles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Evaluation of muscle activity for loaded and unloaded dynamic squats during vertical whole-body vibration.

    Science.gov (United States)

    Hazell, Tom J; Kenno, Kenji A; Jakobi, Jennifer M

    2010-07-01

    The purpose of this investigation was to examine if the addition of a light external load would enhance whole-body vibration (WBV)-induced increases in muscle activity during dynamic squatting in 4 leg muscles. Thirteen recreationally active male university students performed a series of dynamic squats (unloaded with no WBV, unloaded with WBV, loaded with no WBV, and loaded with WBV). The load was set to 30% of body mass and WBV included 25-, 35-, and 45-Hz frequencies with 4-mm amplitude. Muscle activity was recorded with surface electromyography (EMG) on the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GC) and is reported as EMGrms (root mean square) normalized to %maximal voluntary exertion. During unloaded dynamic squats, exposure to WBV (45 Hz) significantly (p squat exercise in all muscles but decreased the TA. This loaded level of muscle activity was further increased with WBV (45 Hz) in all muscles. The WBV-induced increases in muscle activity in the loaded condition (approximately 3.5%) were of a similar magnitude to the WBV-induced increases during the unloaded condition (approximately 2.5%) demonstrating the addition of WBV to unloaded or loaded dynamic squatting results in an increase in muscle activity. These results demonstrate the potential effectiveness of using external loads with exposure to WBV.

  9. Alterations in in vivo knee joint kinematics following a femoral nerve branch block of the vastus medialis: Implications for patellofemoral pain syndrome.

    Science.gov (United States)

    Sheehan, Frances T; Borotikar, Bhushan S; Behnam, Abrahm J; Alter, Katharine E

    2012-07-01

    A potential source of patellofemoral pain, one of the most common problems of the knee, is believed to be altered patellofemoral kinematics due to a force imbalance around the knee. Although no definitive etiology for this imbalance has been found, a weak vastus medialis is considered a primary factor. Therefore, this study's purpose was to determine how the loss of vastus medialis obliquus force alters three-dimensional in vivo knee joint kinematics during a volitional extension task. Eighteen asymptomatic female subjects with no history of knee pain or pathology participated in this IRB approved study. Patellofemoral and tibiofemoral kinematics were derived from velocity data acquired using dynamic cine-phase contrast MRI. The same kinematics were then acquired immediately after administering a motor branch block to the vastus medialis obliquus using 3-5ml of 1% lidocaine. A repeated measures analysis of variance was used to test the null hypothesis that the post- and pre-injection kinematics were no different. The null hypothesis was rejected for patellofemoral lateral shift (P=0.003, max change=1.8mm, standard deviation=1.7mm), tibiofemoral lateral shift (Ppain, but could not account for the full extent of these changes. Thus, vastus medialis weakness is likely a major factor in, but not the sole source of, altered patellofemoral kinematics in such individuals. Published by Elsevier Ltd.

  10. Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Neto Gabriel R.

    2014-07-01

    Full Text Available Strength training combined with blood flow restriction (BFR have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years were randomized into two groups: without Blood Flow Restriction (NFR, n = 6 and With Blood Flow Restriction (WFR, n = 6 that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

  11. Relationship between PPARα mRNA expression and mitochondrial respiratory function and ultrastructure of the skeletal muscle of patients with COPD.

    Science.gov (United States)

    Zhang, Jian-Qing; Long, Xiang-Yu; Xie, Yu; Zhao, Zhi-Huan; Fang, Li-Zhou; Liu, Ling; Fu, Wei-Ping; Shu, Jing-Kui; Wu, Jiang-Hai; Dai, Lu-Ming

    2017-11-02

    Peripheral muscle dysfunction is an important complication in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to explore the relationship between the levels of peroxisome proliferator-activated receptor α (PPARα) mRNA expression and the respiratory function and ultrastructure of mitochondria in the vastus lateralis of patients with COPD. Vastus lateralis biopsies were performed on 14 patients with COPD and 6 control subjects with normal lung function. PPARα mRNA levels in the muscle tissue were detected by real-time PCR. A Clark oxygen electrode was used to assess mitochondrial respiratory function. Mitochondrial number, fractional area in skeletal muscle cross-sections, and Z-line width were observed via transmission electron microscopy. The PPARα mRNA expression was significantly lower in COPD patients with low body mass index (BMIL) than in both COPD patients with normal body mass index (BMIN) and controls. Mitochondrial respiratory function (assessed by respiratory control ratio) was impaired in COPD patients, particularly in BMIL. Compared with that in the control group, mitochondrial number and fractional area were lower in the BMIL group, but were maintained in the BMIN group. Further, the Z-line became narrow in the BMIL group. PPARα mRNA expression was positively related to mitochondrial respiratory function and volume density. In COPD patients with BMIN, mitochondria volume density was maintained, while respiratory function decreased, whereas both volume density and respiratory function decreased in COPD patients with BMIL. PPARα mRNA expression levels are associated with decreased mitochondrial respiratory function and volume density, which may contribute to muscle dysfunction in COPD patients.

  12. Electromyographic evaluation of the lower limbs of patients with Down syndrome in hippotherapy

    Directory of Open Access Journals (Sweden)

    Mariane Fernandes Ribeiro

    2017-05-01

    Full Text Available Hippotherapy is a therapeutic method that uses the horse’s movement to achieve functional results in practitioners with Down syndrome (DS, who present motor and neurophysiological changes that affect the musculoskeletal system. Evaluating the motor behavior related to the control and the improvement of muscle activation in practitioners with Down syndrome subjected to hippotherapy. 10 practitioners were divided into two groups: Down Group (DG – practitioners with DS, and Healthy Group (HG – practitioners with no physical impairment. The muscles gluteus medius, tensor fasciae latae, rectus femoris, vastus medialis, vastus lateralis, biceps femoris, tibialis anterior and gastrocnemius were evaluated by electromyography using gross RMS values, which correspond to muscle activation; the evaluations were performed on the 1st and 10th hippotherapy sessions (frequency: once a week, and after 2 months interval without treatment, they were performed on the 1st and 10th hippotherapy sessions (frequency: twice a week. It was noted that activation of the studied muscles increased with the passing of sessions, regardless the weekly frequency of attendance; however, the period without treatment resulted in reduction of this effect. Practitioners with DS presented satisfactory changes in muscle activation pattern, in learning and in motor behavior during hippotherapy sessions.

  13. Statistical mapping of the effect of knee extension on thigh muscle viscoelastic properties using magnetic resonance elastography

    International Nuclear Information System (INIS)

    Barnhill, Eric; Kennedy, Paul; Van Beek, Edwin J R; Roberts, Neil; Hammer, Steven; Brown, Colin

    2013-01-01

    Skeletal muscle viscoelastic properties reflect muscle microstructure and neuromuscular activation. Elastographic methods, including magnetic resonance elastography, have been used to characterize muscle viscoelastic properties in terms of region of interest (ROI) measurements. The present study extended this approach to create thresholded pixel-by-pixel maps of viscoelastic properties of skeletal muscle during rest and knee extension in eleven subjects. ROI measurements were taken for individual quadricep muscles and the quadriceps region as a whole, and the viscoelastic parameter map pixels were statistically tested at positive false discovery rate q ⩽ 0.25. ROI measurements showed significant (p ⩽ 0.05) increase in storage modulus (G′) and loss modulus (G″), with G″ increasing more than G′, in agreement with previous findings. The q-value maps further identified the vastus intermedius as the primary driver of this change, with greater G″/G′ increase than surrounding regions. Additionally, a cluster of significant decrease in G″/G′ was found in the region of vastus lateralis below the fulcrum point of the lift. Viscoelastic parameter mapping of contracted muscle allows new insight into the relationship between physiology, neuromuscular activation, and human performance. (paper)

  14. Electromyographic Comparison of Squats Using Constant or Variable Resistance.

    Science.gov (United States)

    Andersen, Vidar; Steiro Fimland, Marius; Knutson Kolnes, Maria; Jensen, Susanne; Laume, Martine; Hole Saeterbakken, Atle

    2016-12-01

    Andersen, V, Fimland, MS, Kolnes, MK, Jensen, S, Laume, M and Saeterbakken, AH. Electromyographic comparison of squats using constant or variable resistance. J Strength Cond Res 30(12): 3456-3463, 2016-The aim of the study was to compare the electromyographic (EMG) activity of vastus lateralis, vastus medialis, rectus femoris, and biceps femoris when performing the squat with constant resistance or variable resistance with 2 or 4 elastic bands, respectively, contributing with a mean of 39 and 73% of the total loads. Nineteen resistance-trained women performed 6 repetition maximum using 3 different experimental conditions: free weights (FW), free weights + 2 elastic bands (FW + 2EB), and free weights + 4 elastic bands (FW + 4EB). During analyses, each repetition was divided into 6 phases: upper (more extended knee), middle, and lower phase of the descending and ascending movements. Increased activation in the upper parts of the movement was observed for both variable resistance conditions compared with constant resistance (9-51%, p squat using free weights in combination with elastic bands seems to be preferable compared with free weights alone and more so with a high contribution from variable resistance to the total load.

  15. Interindividual differences in H reflex modulation during normal walking

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Dyhre-Poulsen, Poul; Alkjaer, T

    2002-01-01

    was greater for the S group. The hip joint moment was similar for the groups. The EMG activity in the vastus lateralis and anterior tibial muscles was greater prior to heel strike for the S group. These data indicate that human walking exhibits at least two different motor patterns as evaluated by gating...... of afferent input to the spinal cord, by EMG activity and by walking mechanics. Increasing H reflex excitability during the swing phase appears to protect the subject against unexpected perturbations around heel strike by a facilitated stretch reflex in the triceps surae muscle. Alternatively, in subjects...... with a suppressed H reflex in the swing phase the knee joint extensors seem to form the primary protection around heel strike....

  16. Expression of insulin receptor spliced variants and their functional correlates in muscle from patients with non-insulin-dependent diabetes mellitus

    DEFF Research Database (Denmark)

    Hansen, Torben; Bjørbaek, C; Vestergaard, H

    1993-01-01

    Due to alternative splicing of exon 11 of the receptor gene, the human insulin receptor exists in two forms, that have distinct tissue-specific expression and are functionally different. Needle biopsies obtained from vastus lateralis muscle from 20 patients with noninsulin-dependent diabetes...... kinase activity were examined in wheat germ agglutinin-purified insulin receptors isolated from muscle biopsies. Moreover, insulin-stimulated glucose disposal was studied by means of the euglycemic hyperinsulinemic clamp technique. No difference in the relative expression of spliced variants......, and tyrosine kinase activity toward the exogenous substrate poly(Glu-Tyr(4:1)). Furthermore, no significant relationship was demonstrated between the glucose disposal rate and the relative expression of insulin receptor splice variants. In conclusion, in skeletal muscle from both normal control subjects...

  17. The Associations between Pain Sensitivity and Knee Muscle Strength in Healthy Volunteers

    DEFF Research Database (Denmark)

    Henriksen, Marius; Klokker, Louise; Bartholdy, Cecilie

    2013-01-01

    lateralis, deltoid, and infrapatellar fat pad. Quadriceps and hamstring muscle strength was assessed isometrically at 60-degree knee flexion using a dynamometer. Associations between pain sensitivity and muscle strength were investigated using multiple regressions including age, gender, and body mass index...... as covariates. Results. Knee extension strength was associated with computer-controlled PPT on the vastus lateralis muscle. Computer-controlled PPTs were significantly correlated between sites (r > 0.72) and with cuff PPT (r > 0.4). Saline induced pain intensity and duration were correlated between sites (r > 0......Objectives. To investigate associations between muscle strength and pain sensitivity among healthy volunteers and associations between different pain sensitivity measures. Methods. Twenty-eight healthy volunteers (21 females) participated. Pressure pain thresholds (PPTs) were obtained from 1...

  18. Patellofemoral pain syndrome: electromyography in a frequency domain analysis

    Science.gov (United States)

    Catelli, D. S.; Kuriki, H. U.; Polito, L. F.; Azevedo, F. M.; Negrão Filho, R. F.; Alves, N.

    2011-09-01

    The Patellofemoral Pain Syndrome (PFPS), has a multifactorial etiology and affects approximately 7 to 15% of the population, mostly women, youth, adults and active persons. PFPS causes anterior or retropatelar pain that is exacerbated during functional motor gestures, such as up and down stairs or spending long periods of time sitting, squatting or kneeling. As the diagnostic evaluation of this syndrome is still indirect, different mechanisms and methodologies try to make a classification that distinguishes patients with PFPS in relation to asymptomatic. Thereby, the purpose of this investigation was to determine the characteristics of the electromyographic (EMG) signal in the frequency domain of the vastus medialis oblique (VMO) and vastus lateralis (VL) in patients with PFPS, during the ascent of stairs. 33 young women (22 control group and 11 PFPS group), were evaluated by EMG during ascent of stairs. The VMO mean power frequency (MPF) and the VL frequency 95% (F95) were lower in symptomatic individuals. This may be related to the difference in muscle recruitment strategy exerted by each muscle in the PFPS group compared to the control group.

  19. Effect of squatting velocity on hip muscle latency in women with patellofemoral pain syndrome.

    Science.gov (United States)

    Orozco-Chavez, Ignacio; Mendez-Rebolledo, Guillermo

    2018-03-01

    [Purpose] Neuromuscular activity has been evaluated in patellofemoral pain syndrome but movement velocity has not been considered. The aim was to determine differences in onset latency of hip and knee muscles between individuals with and without patellofemoral pain syndrome during a single leg squat, and whether any differences are dependent on movement velocity. [Subjects and Methods] Twenty-four females with patellofemoral pain syndrome and 24 healthy females participated. Onset latency of gluteus maximus, anterior and posterior gluteus medius, rectus femoris, vastus medialis, vastus lateralis and biceps femoris during a single leg squat at high and low velocity were evaluated. [Results] There was an interaction between velocity and diagnosis for posterior gluteus medius. Healthy subjects showed a later posterior gluteus medius onset latency at low velocity than high velocity; and also later than patellofemoral pain syndrome subjects at low velocity and high velocity. [Conclusion] Patellofemoral pain syndrome subjects presented an altered latency of posterior gluteus medius during a single leg squat and did not generate adaptations to velocity variation, while healthy subjects presented an earlier onset latency in response to velocity increase.

  20. Sit to stand in elderly fallers vs non-fallers: new insights from force platform and electromyography data.

    Science.gov (United States)

    Chorin, Frédéric; Cornu, Christophe; Beaune, Bruno; Frère, Julien; Rahmani, Abderrahmane

    2016-10-01

    The sit-to-stand movement requires balance control and coordination between the trunk and lower limbs. For these reasons, it is commonly used in clinics for evaluating lower limb muscle function in the elderly. The aim of the present study was to point out re levant biomechanical and neurophysiological sit-to-stand parameters allowing comparison between elderly fallers and non-fallers. Ten elderly fallers and thirty non-fallers performed sit-to-stand movements. Sit-to-stand mechanical (maximal and mean force, impulse) and temporal parameters were measured in the vertical and anteroposterior axes using force platforms. Activity of rectus femoris, vastus lateralis, and gastrocnemius lateralis muscles was bilaterally recorded by surface electromyography. Time to realize sit-to-stand movements was significantly longer in elderly fallers compared to non-fallers (p movement are the most relevant parameters to differentiate fallers and non-fallers. Moreover, these factors highlight different strategies to rise from a chair between faller and non-faller group, suggesting that fallers would constantly adjust their control balance during the sit-to-stand movement.

  1. Pneumatic Muscles Actuated Lower-Limb Orthosis Model Verification with Actual Human Muscle Activation Patterns

    Directory of Open Access Journals (Sweden)

    Dzahir M.A.M

    2017-01-01

    Full Text Available A review study was conducted on existing lower-limb orthosis systems for rehabilitation which implemented pneumatic muscle type of actuators with the aim to clarify the current and on-going research in this field. The implementation of pneumatic artificial muscle will play an important role for the development of the advanced robotic system. In this research a derivation model for the antagonistic mono- and bi-articular muscles using pneumatic artificial muscles of a lower limb orthosis will be verified with actual human’s muscle activities models. A healthy and young male 29 years old subject with height 174cm and weight 68kg was used as a test subject. Two mono-articular muscles Vastus Medialis (VM and Vastus Lateralis (VL were selected to verify the mono-articular muscle models and muscle synergy between anterior muscles. Two biarticular muscles Rectus Femoris (RF and Bicep Femoris (BF were selected to verify the bi-articular muscle models and muscle co-contraction between anterior-posterior muscles. The test was carried out on a treadmill with a speed of 4.0 km/h, which approximately around 1.25 m/s for completing one cycle of walking motion. The data was collected for about one minute on a treadmill and 20 complete cycles of walking motion were successfully recorded. For the evaluations, the mathematical model obtained from the derivation and the actual human muscle activation patterns obtained using the surface electromyography (sEMG system were compared and analysed. The results shown that, high correlation values ranging from 0.83 up to 0.93 were obtained in between the derivation model and the actual human muscle’s model for both mono- and biarticular muscles. As a conclusion, based on the verification with the sEMG muscle activities data and its correlation values, the proposed derivation models of the antagonistic mono- and bi-articular muscles were suitable to simulate and controls the pneumatic muscles actuated lower limb

  2. The influence of acute resistance exercise on cyclooxygenase-1 and -2 activity and protein levels in human skeletal muscle.

    Science.gov (United States)

    Carroll, Chad C; O'Connor, Devin T; Steinmeyer, Robert; Del Mundo, Jonathon D; McMullan, David R; Whitt, Jamie A; Ramos, Jahir E; Gonzales, Rayna J

    2013-07-01

    This study evaluated the activity and content of cyclooxygenase (COX)-1 and -2 in response to acute resistance exercise (RE) in human skeletal muscle. Previous work suggests that COX-1, but not COX-2, is the primary COX isoform elevated with resistance exercise in human skeletal muscle. COX activity, however, has not been assessed after resistance exercise in humans. It was hypothesized that RE would increase COX-1 but not COX-2 activity. Muscle biopsies were taken from the vastus lateralis of nine young men (25 ± 1 yr) at baseline (preexercise), 4, and 24 h after a single bout of knee extensor RE (three sets of 10 repetitions at 70% of maximum). Tissue lysate was assayed for COX-1 and COX-2 activity. COX-1 and COX-2 protein levels were measured via Western blot analysis. COX-1 activity increased at 4 h (P 0.05) with acute RE. In contrast, COX-2 protein levels were nearly 3-fold greater (P > 0.05) at 4 h and 5-fold greater (P = 0.06) at 24 h, compared with preexercise. In conclusion, COX-1 activity increases transiently with exercise independent of COX-1 protein levels. In contrast, both COX-2 activity and protein levels were elevated with exercise, and this elevation persisted to at least 24 h after RE.

  3. Shifts in the relationship between motor unit recruitment thresholds versus derecruitment thresholds during fatigue.

    Science.gov (United States)

    Stock, Matt S; Mota, Jacob A

    2017-12-01

    Muscle fatigue is associated with diminished twitch force amplitude. We examined changes in the motor unit recruitment versus derecruitment threshold relationship during fatigue. Nine men (mean age = 26 years) performed repeated isometric contractions at 50% maximal voluntary contraction (MVC) knee extensor force until exhaustion. Surface electromyographic signals were detected from the vastus lateralis, and were decomposed into their constituent motor unit action potential trains. Motor unit recruitment and derecruitment thresholds and firing rates at recruitment and derecruitment were evaluated at the beginning, middle, and end of the protocol. On average, 15 motor units were studied per contraction. For the initial contraction, three subjects showed greater recruitment thresholds than derecruitment thresholds for all motor units. Five subjects showed greater recruitment thresholds than derecruitment thresholds for only low-threshold motor units at the beginning, with a mean cross-over of 31.6% MVC. As the muscle fatigued, many motor units were derecruited at progressively higher forces. In turn, decreased slopes and increased y-intercepts were observed. These shifts were complemented by increased firing rates at derecruitment relative to recruitment. As the vastus lateralis fatigued, the central nervous system's compensatory adjustments resulted in a shift of the regression line of the recruitment versus derecruitment threshold relationship. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  4. An Examination of Muscle Activation and Power Characteristics While Performing the Deadlift Exercise With Straight and Hexagonal Barbells.

    Science.gov (United States)

    Camara, Kevin D; Coburn, Jared W; Dunnick, Dustin D; Brown, Lee E; Galpin, Andrew J; Costa, Pablo B

    2016-05-01

    The deadlift exercise is commonly performed to develop strength and power, and to train the lower-body and erector spinae muscle groups. However, little is known about the acute training effects of a hexagonal barbell vs. a straight barbell when performing deadlifts. Therefore, the purpose of this study was to examine the hexagonal barbell in comparison with the straight barbell by analyzing electromyography (EMG) from the vastus lateralis, biceps femoris, and erector spinae, as well as peak force, peak power, and peak velocity using a force plate. Twenty men with deadlifting experience volunteered to participate in the study. All participants completed a 1 repetition maximum (1RM) test with each barbell on 2 separate occasions. Three repetitions at 65 and 85% 1RM were performed with each barbell on a third visit. The results revealed that there was no significant difference for 1RM values between the straight and hexagonal barbells (mean ± SD in kg = 181.4 ± 27.3 vs. 181.1 ± 27.6, respectively) (p > 0.05). Significantly greater normalized EMG values were found from the vastus lateralis for both the concentric (1.199 ± 0.22) and eccentric (0.879 ± 0.31) phases of the hexagonal-barbell deadlift than those of the straight-barbell deadlift (0.968 ± 0.22 and 0.559 ± 1.26), whereas the straight-barbell deadlift led to significantly greater EMG values from the bicep femoris during the concentric phase (0.835 ± 0.19) and the erector spinae (0.753 ± 0.28) during the eccentric phase than the corresponding values for the hexagonal-barbell deadlift (0.723 ± 0.20 and 0.614 ± 0.21) (p ≤ 0.05). In addition, the hexagonal-barbell deadlift demonstrated significantly greater peak force (2,553.20 ± 371.52 N), peak power (1,871.15 ± 451.61 W), and peak velocity (0.805 ± 0.165) values than those of the straight-barbell deadlift (2,509.90 ± 364.95 N, 1,639.70 ± 361.94 W, and 0.725 ± 0.138 m·s, respectively) (p ≤ 0.05). These results suggest that the barbells led

  5. Effect of segmental, localized lower limb cooling on dynamic balance.

    Science.gov (United States)

    Montgomery, Roger E; Hartley, Geoffrey L; Tyler, Christopher J; Cheung, Stephen S

    2015-01-01

    This study aimed to determine the effect of cooling progressively greater portions of the lower extremities on dynamic balance and neuromuscular activation. Ten healthy males (22.8 ± 3.4 yr, 76.5 ± 9.1 kg) performed one room air temperature control (22.4°C ± 0.8°C) and three trials of cold water immersion at 12°C (lateral malleolus, ankle; lateral femoral epicondyle, knee; anterior superior iliac spine, hip) for 10 min before performing a unipedal balance test (Star Excursion Balance Test (SEBT)) with their dominant limb. Muscle activation of the vastus lateralis, biceps femoris, tibialis anterior, and lateral gastrocnemius was measured with surface EMG during the SEBT. Core temperature remained euthermic throughout all trials. Gastrocnemius temperature decreased from control (30.4°C ± 0.5°C) with knee (23.7°C ± 1.7°C) and hip immersion (22.4°C ± 1.0°C), whereas vastus lateralis temperature decreased from control (33.7°C ± 1.7°C) with hip immersion (27.3°C ± 2.0°C) (P water immersion influenced mean anterior and posterior reach distance on the SEBT in a dose-dependent fashion. Compared with those in control, mean anterior and posterior SEBT reach distances were not decreased with ankle (-1.38% and -0.74%, respectively) and knee immersion (-2.48% and -2.74%), whereas hip immersion significantly reduced SEBT by 4.73% and 4.05% (P lower extremities were cooled, with only the lateral gastrocnemius during the anterior SEBT approaching a decrease (P = 0.059). Cooling larger portions of the lower extremities progressively affect dynamic balance, and thermal protection strategies should focus on maintaining temperature in the large muscle mass of the thigh.

  6. Detection of carriers and genetic counseling in duchenne muscular dystrophy by ribosomal protein synthesis.

    Science.gov (United States)

    Ionasescu, V; Zellweger, H; Burmeister, L

    1976-11-01

    The in vitro protein synthesis by polyribosomes extracted from biopsied muscle (vastus lateralis) was studied in 47 known carriers, 87 possible carriers and in 60 normal females. A significant increase in specific activity of monomeric ribosomes, total polyribosomes and collagen synthesis was found in 46 (97.8 per cent) known carriers and 47 (54 per cent) possible carriers of Duchenne muscular dytrophy. The latter showed an increase in ribosomal protein synthesis in 10 (52.6 per cent) of 19 mothers of isolated cases, 31 (53.3 per cent) of 58 sisters, and 6 (60 per cent) of other female relatives. Serum creatine phosphokinase was increased in 30 (63.8 per cent) of 47 known carriers.

  7. Sex Determination and Polyploid Gigantism in the Dwarf Surfclam (Mulinia Lateralis Say)

    Science.gov (United States)

    Guo, X.; Allen-Jr., S. K.

    1994-01-01

    Mulinia lateralis, the dwarf surfclam, is a suitable model for bivalve genetics because it is hardy and has a short generation time. In this study, gynogenetic and triploid. M. lateralis were successfully induced. For gynogenesis, eggs were fertilized with sperm irradiated with ultraviolet light and subsequently treated with cytochalasin B to block the release of the second polar body (PB2). Triploidy was induced by blocking PB2 in normally fertilized eggs. The survival of gynogenetic diploids was very low, only 0.7% to 8 days post-fertilization (PF), compared with 15.2% in the triploid groups and 27.5% in the normal diploid control. Larvae in all groups metamorphosed at 8-10 days PF, and there was no significant post-larval mortality. At sexual maturation (2-3 months PF), all gynogenetic diploids were female, and there was no significant difference (P > 0.05) in sex ratio between diploids and triploids. These results suggested that the dwarf surfclam may have an XX-female, XY-male sex determination with Y-domination. Compared with diploids, triploids had a relative fecundity of 59% for females and 80% for males. Eggs produced by triploid females were 53% larger (P 0.33) different from normal diploid females, suggesting that inbreeding depression was minimal in meiosis II gynogens. Triploid clams were significantly larger (P gigantism due to the increased cell volume and a lack of cell-number compensation. PMID:7896101

  8. CHANGES IN QUADRICEPS MUSCLE ACTIVITY DURING SUSTAINED RECREATIONAL ALPINE SKIING

    Directory of Open Access Journals (Sweden)

    Josef Kröll

    2011-03-01

    Full Text Available During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing and the last two (POSTskiing runs was measured from the vastus lateralis (VL and rectus femoris (RF using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs

  9. Experimental quadriceps muscle pain impairs knee joint control during walking

    DEFF Research Database (Denmark)

    Henriksen, Marius; Alkjaer, Tine; Lund, Hans

    2007-01-01

    Pain is a cardinal symptom in musculoskeletal diseases involving the knee joint, and aberrant movement patterns and motor control strategies are often present in these patients. However, the underlying neuromuscular mechanisms linking pain to movement and motor control are unclear. To investigate...... the functional significance of muscle pain on knee joint control during walking, three-dimensional gait analyses were performed before, during, and after experimentally induced muscle pain by means of intramuscular injections of hypertonic saline (5.8%) into vastus medialis (VM) muscle of 20 healthy subjects....... Isotonic saline (0.9%) was used as control. Surface electromyography (EMG) recordings of VM, vastus lateralis (VL), biceps femoris, and semitendinosus muscles were synchronized with the gait analyses. During experimental muscle pain, the loading response phase peak knee extensor moments were attenuated...

  10. The effect of running versus cycling high-intensity intermittent exercise on local tissue oxygenation and perceived enjoyment in 18–30-year-old sedentary men

    Science.gov (United States)

    Solomon, Colin

    2018-01-01

    Background High-intensity interval training (HIIT) has been proposed as a time-efficient exercise format to improve exercise adherence, thereby targeting the chronic disease burden associated with sedentary behaviour. Exercise mode (cycling, running), if self-selected, will likely affect the physiological and enjoyment responses to HIIT in sedentary individuals. Differences in physiological and enjoyment responses, associated with the mode of exercise, could potentially influence the uptake and continued adherence to HIIT. It was hypothesised that in young sedentary men, local and systemic oxygen utilisation and enjoyment would be higher during a session of running HIIT, compared to a session of cycling HIIT. Methods A total of 12 sedentary men (mean ± SD; age 24 ± 3 years) completed three exercise sessions: a maximal incremental exercise test on a treadmill (MAX) followed by two experiment conditions, (1) free-paced cycling HIIT on a bicycle ergometer (HIITCYC) and (2) constant-paced running HIIT on a treadmill ergometer (HIITRUN). Deoxygenated haemoglobin (HHb) in the gastrocnemius (GN), the left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, oxygen consumption (VO2), heart rate (HR), ratings of perceived exertion (RPE) and physical activity enjoyment (PACES) were measured during HIITCYC and HIITRUN. Results There was a higher HHb in the LVL (p = 0.001) and RVL (p = 0.002) sites and a higher VO2 (p = 0.017) and HR (p HIIT produces higher levels of physiological stress when compared to constant-paced running HIIT. Participants perceived running HIIT to be more enjoyable than cycling HIIT. These findings have implications for selection of mode of HIIT for physical stress, exercise enjoyment and compliance.

  11. The effect of running versus cycling high-intensity intermittent exercise on local tissue oxygenation and perceived enjoyment in 18-30-year-old sedentary men.

    Science.gov (United States)

    Kriel, Yuri; Askew, Christopher D; Solomon, Colin

    2018-01-01

    High-intensity interval training (HIIT) has been proposed as a time-efficient exercise format to improve exercise adherence, thereby targeting the chronic disease burden associated with sedentary behaviour. Exercise mode (cycling, running), if self-selected, will likely affect the physiological and enjoyment responses to HIIT in sedentary individuals. Differences in physiological and enjoyment responses, associated with the mode of exercise, could potentially influence the uptake and continued adherence to HIIT. It was hypothesised that in young sedentary men, local and systemic oxygen utilisation and enjoyment would be higher during a session of running HIIT, compared to a session of cycling HIIT. A total of 12 sedentary men (mean ± SD; age 24 ± 3 years) completed three exercise sessions: a maximal incremental exercise test on a treadmill (MAX) followed by two experiment conditions, (1) free-paced cycling HIIT on a bicycle ergometer (HIITCYC) and (2) constant-paced running HIIT on a treadmill ergometer (HIITRUN). Deoxygenated haemoglobin (HHb) in the gastrocnemius (GN), the left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, oxygen consumption (VO 2 ), heart rate (HR), ratings of perceived exertion (RPE) and physical activity enjoyment (PACES) were measured during HIITCYC and HIITRUN. There was a higher HHb in the LVL ( p = 0.001) and RVL ( p = 0.002) sites and a higher VO 2 ( p = 0.017) and HR ( p HIIT produces higher levels of physiological stress when compared to constant-paced running HIIT. Participants perceived running HIIT to be more enjoyable than cycling HIIT. These findings have implications for selection of mode of HIIT for physical stress, exercise enjoyment and compliance.

  12. Assessing phototoxicity of petroleum using the bivalve Mulinia lateralis and the mysid Mysidopsis bahia

    International Nuclear Information System (INIS)

    Pelletier, M.; Champlin, D.; Burgess, R.; Ho, K.; Kuhn-Hines, A.

    1995-01-01

    One of the major inputs of PAHs in the marine environment is petroleum products. A large and often catastrophic source of petroleum is an oil spill, which releases concentrated quantities of PAHs into the water column. Intermediate molecular weight compounds remain in the water column for a relatively extended length of time. These compounds include phototoxic PAHs such as anthracene, fluoranthene, pyrene, and their substituted derivatives. Assessments of the environmental impact of marine oil spills have not included phototoxicity tests using pelagic larvae of benthic invertebrates. In this study, the photoreactive toxicity of individual PAHs, including anthracene, pyrene, and fluoranthene, were determined using the bivalve, Mulinia lateralis and the mysid, Mysidopsis bahia. Ultraviolet light exposures increased toxicity relative to fluorescent light for both species but a particularly dramatic response was seen using M. lateralis embryos. This species was relatively insensitive when exposed under fluorescent lights, but exhibited up to a 4,000 fold increase in toxicity under ultraviolet lights. Exposures with different types of petroleum (e.g., fuel oil number-sign 2 and crude oil) under fluorescent and ultraviolet light will demonstrate the utility of this bivalve and mysid for assessing oil spill-related acute and sublethal toxicity in the marine environment

  13. Modiolarca lateralis (Pteryomorphia: Mytilidae: bivalve associated to six species of ascidians from Bocas del Toro, Panama

    Directory of Open Access Journals (Sweden)

    Juan I Cañete

    2013-11-01

    Full Text Available We describe the presence of the bivalve Modiolarca lateralis (Say, 1822 in six tropical ascidians Ascidia curvata, A. sydneiensis, A. panamensis, A. interrupta, Herdmania pallida and Polycarpa spongiabilis collected at depths of 1-3 m on coral reefs, mangrove roots and dock supports in Almirante Bay, Bocas del Toro, Panama (9°18'N, 82°13'W during June-July 2011. Bivalve prevalence varied between 9-30% across species, but was mainly associated with A. panamensis, P. spongiabilis and A. interrupta. Prevalence seems to be influenced by tunic thickness rather than by the ascidian size. Bivalves varied in size (0.6-11 mm shell length, with the smallest individual found in A. sydneiensis. There were only one or two bivalves per ascidians, although a maximum of 18 was found in one A. panamensis. M. lateralis seems to behave similarly to its temperate counterparts: it has a variety of hosts, occurs mainly in the anterior region of the ascidians, and has a variable abundance per host.

  14. Three dimensional reconstruction of the human skeletal muscle mitochondrial network as a tool to assess mitochondrial content and structural organization

    DEFF Research Database (Denmark)

    Dahl, Rannvá; Larsen, Steen; Dohlmann, Tine L

    2015-01-01

    a method to visualize mitochondrial networks in high resolution and assess mitochondrial volume. Methods: Confocal fluorescence microscopy imaging of mitochondrial network stains in human vastus lateralis single muscle fibers and, focused ion beam scanning electron microscopy (FIB/SEM) imaging, combined...... mitochondrial dynamics in response to life-style interventions and/or in certain pathologies. Our results question the classification of mitochondria into subsarcolemmal and intermyofibrillar pools, since they are physically interconnected. This article is protected by copyright. All rights reserved....

  15. Association between statin-associated myopathy and skeletal muscle damage.

    OpenAIRE

    Mohaupt Markus G; Karas Richard H; Babiychuk Eduard B; Sanchez-Freire Verónica; Monastyrskaya Katia; Iyer Lakshmanan; Hoppeler Hans; Breil Fabio; Draeger Annette

    2009-01-01

    BACKGROUND Many patients taking statins often complain of muscle pain and weakness. The extent to which muscle pain reflects muscle injury is unknown. METHODS We obtained biopsy samples from the vastus lateralis muscle of 83 patients. Of the 44 patients with clinically diagnosed statin associated myopathy 29 were currently taking a statin and 15 had discontinued statin therapy before the biopsy (minimal duration of discontinuation 3 weeks). We also included 19 patients who were taking stat...

  16. Passive leg movement enhances interstitial VEGF protein, endothelial cell proliferation, and eNOS mRNA content in human skeletal muscle

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Rufener, Nora; Nielsen, Jens J

    2008-01-01

    .05) in blood flow without a significant enhancement in oxygen uptake. Muscle interstitial fluid was sampled with microdialysis technique and analyzed for vascular endothelial growth factor (VEGF) protein and for the effect on endothelial cell proliferation. Biopsies obtained from the musculus vastus lateralis...... to cultured endothelial cells revealed that dialysate obtained during leg movement induced a 3.2-fold higher proliferation rate (P level fourfold above resting levels. VEGF mRNA and MMP-2 mRNA levels were...

  17. The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate intensity exercise in human skeletal muscle

    DEFF Research Database (Denmark)

    Vigelsø, Andreas; Gram, Martin; Dybboe, Rie

    2016-01-01

    in older than in young men, and while young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity, protein content of adipose triglyceride lipase (ATGL), acetyl-CoA carboxylase 2, AMP-activated......; 23 ± 1 years) and older (n = 15; 68 ± 1 years) men, while the contralateral leg served as control. After immobilization, the participants performed two-legged isolated knee-extensor exercise at 20 ± 1 Watt (∼50% Wattmax ) for 45 min with catheters inserted in the brachial artery and both femoral...... veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (RQ) did not differ between groups or legs. Leg fatty acid (FA) uptake was greater...

  18. Biomechanical and neuromuscular adaptations during the landing phase of a stepping-down task in patients with early or established knee osteoarthritis.

    Science.gov (United States)

    Sanchez-Ramirez, Diana C; Malfait, Bart; Baert, Isabel; van der Leeden, Marike; van Dieën, Jaap; Lems, Willem F; Dekker, Joost; Luyten, Frank P; Verschueren, Sabine

    2016-06-01

    To compare the knee joint kinematics, kinetics and EMG activity patterns during a stepping-down task in patients with knee osteoarthritis (OA) with control subjects. 33 women with knee OA (early OA, n=14; established OA n=19) and 14 female control subjects performed a stepping-down task from a 20cm step. Knee joint kinematics, kinetics and EMG activity were recorded on the stepping-down leg during the loading phase. During the stepping-down task patients with established knee OA showed greater normalized medial hamstrings activity (p=0.034) and greater vastus lateralis-medial hamstrings co-contraction (p=0.012) than controls. Greater vastus medialis-medial hamstrings co-contraction was found in patients with established OA compared to control subjects (p=0.040) and to patients with early OA (p=0.023). Self-reported knee instability was reported in 7% and 32% of the patients with early and established OA, respectively. The greater EMG co-activity found in established OA might suggest a less efficient use of knee muscles or an attempt to compensate for greater knee laxity usually present in patients with established OA. In the early stage of the disease, the biomechanical and neuromuscular control of stepping-down is not altered compared to healthy controls. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Muscles Activity in the elderly with Balance Impairments in walking under Dual tasks

    Directory of Open Access Journals (Sweden)

    Elaheh Azadian

    2016-09-01

    Full Text Available Objectives: Each step during gait requires different attention demands that will affect muscles activity. The study of changes in the timing and intensity of the muscles activity in walking with dual task has received less attention from researchers. The purpose of this study was to evaluate changes in electromyography patterns of gait with cognitive dual tasks in balance impaired elderly. Methods: Thirty older adults were recruited for this study. People were selected through berg balance test. Subjects walked 12-meters in two conditions, normal walking and walking with a cognitive dual task. Spatial-temporal kinematic parameters were recorded through the motion analysis and muscles activities were recorded through electromyography system. The data obtained was analyzed using repeated measures ANOVA at a significant level of p< 0.05.  Results: The results showed that walking under dual tasks would decrease gait speed and increase stride time and stance time. Also muscle activity in Tibialis anterior and Vastus lateralis in stance-phase would decrease significantly in dual tasks as compared with single task (p< 0.05, but timing of muscle activity would not change in dual task conditions.  Conclusions: Based on the results, it can be argued that walking under a dual task can change spatial-temporal parameters and muscle activity in gait pattern in the elderly with balance impairment. One explanation could be that the decreased control of the central nervous system on muscle activity in stance phase due to the performing of a dual task.

  20. Início da atividade elétrica dos músculos estabilizadores da patela em indivíduos com SDPF Onset of electrical activity of patellar stabilizer muscles in subjects with patellofemoral pain

    Directory of Open Access Journals (Sweden)

    Débora Bevilaqua-Grossi

    2009-01-01

    Full Text Available OBJETIVO: Avaliar a porcentagem de disparo inicial (PDI dos músculos estabilizadores da patela durante exercícios de contração isométrica voluntária máxima (CIVM em indivíduos com e sem sinais da síndrome da dor patelofemural (SDPF nos exercícios de cadeia cinética aberta (CCA e fechada (CCF. MÉTODO: Foram avaliadas 10 mulheres sem queixa de dor anterior no joelho e 12 mulheres com sinais de SDPF durante a CIM em CCA e CCF com o joelho posicionado a 90º de flexão do joelho. O início da atividade eletromiográfica dos músculos vasto medial obliquo (VMO, vasto lateral obliquo (VLO e vasto lateral longo (VLL foi identificada por meio de um algoritmo no programa Myosystem Br 1. A análise estatística empregada foi o teste Qui-Quadrado e o teste t de student, ambos os teste com nível de significância de 5%. RESULTADOS: Os músculos VMO e VLO apresentaram uma maior PDI em relação ao músculo VLL durante os exercícios em CCA para ambos os grupo e para o grupo SDPF em CCF. Não foi observado diferença entre os grupos. CONCLUSÃO: Pode-se sugerir que tanto os exercícios em CCA quanto em CCF, parecem beneficiar o sincronismo na musculatura estabilizadora da patela, podendo ser indicado nos programas de tratamento fisioterapêutico.OBJECTIVE: To asses the onset (% of patella stabilizer muscles during maximal isometric contraction exercises (MIC in individuals with and without signs of patellofemoral pain syndrome (PFPS in open (OKC and closed (CKC kinetic chain exercises. METHOD: Assessments were carried out on 22 women; ten with no complains of anterior knee pain, and 12 with PFPS signs during MIC in OKC and CKC with the knee flexed at 90º. The onset of the electromyographic activity of the vastus mediallis obliquus (VMO, vastus lateralis obliquus (VLO and vastus lateralis longus (VLL was identified by means of an algorithm in the Myosystem Br 1 software. The statistical analysis used was Chi-Square test and student's t test

  1. Vasoactive enzymes and blood flow responses to passive and active exercise in peripheral arterial disease

    DEFF Research Database (Denmark)

    Walker, Meegan A.; Høier, Birgitte; Walker, Philip J.

    2016-01-01

    Background: Peripheral arterial disease (PAD) is characterised by impaired leg blood flow, which contributes to claudication and reduced exercise capacity. This study investigated to what extent vasoactive enzymes might contribute to altered blood flow in PAD (Fontaine stage II). Methods: We...... compared femoral artery blood flow during reactive hyperaemia, leg-extension exercise and passive leg movement, and determined the level of vasoactive enzymes in skeletal muscle samples from the vastus lateralis in PAD (n = 10, 68.5 ± 6.5 years) and healthy controls (CON, n = 9, 62.1 ± 12.3 years). Leg...... than CON (1.04 ± 0.19 vs 0.50 ± 0.06 AU, P = 0.02), with no differences for other enzymes. Leg blood flow during exercise was correlated with prostacyclin synthase (P = 0.001). Conclusion: Elevated NADPH oxidase indicates that oxidative stress may be a primary cause of low nitric oxide availability...

  2. Phosphorylation of human skeletal muscle myosin

    International Nuclear Information System (INIS)

    Houston, M.E.; Lingley, M.D.; Stuart, D.S.; Hoffman-Goetz, L.

    1986-01-01

    Phosphorylation of the P-light chains (phosphorylatable light chains) in human skeletal muscle myosin was studied in vitro and in vivo under resting an d contracted conditions. biopsy samples from rested vastus lateralis muscle of male and female subjects were incubated in oxygenated physiological solution at 30 0 C. Samples frozen following a quiescent period showed the presence of only unphosphorylated P-light chains designated LC2f (light chain two of fast myosin) CL2s and LC2s'(light chains two of slow myosin). Treatment with caffeine (10 mM) or direct electrical stimulation resulted in the appearance of three additional bands which were identified as the phosphorylated forms of the P-light chains i.e. LC2f-P, LC2s-P and LC2s'-P. The presence of phosphate was confirmed by prior incubation with ( 30 P) orthophosphate. Muscle samples rapidly frozen from resting vastus lateralis muscle revealed the presence of unphosphorylated and phosphorylated P-light chains in approximately equal ratios. Muscle samples rapidly frozen following a maximal 10 second isometric contraction showed virtually only phosphorylated fast and slow P-light chains. These results reveal that the P-light chains in human fast and slow myosin may be rapidly phosphorylated, but the basal level of phosphorylation in rested human muscle considerably exceeds that observed in animal muscles studied in vitro or in situ

  3. The recovery of repeated-sprint exercise is associated with PCr resynthesis, while muscle pH and EMG amplitude remain depressed.

    Directory of Open Access Journals (Sweden)

    Alberto Mendez-Villanueva

    Full Text Available The physiological equivalents of power output maintenance and recovery during repeated-sprint exercise (RSE remain to be fully elucidated. In an attempt to improve our understanding of the determinants of RSE performance we therefore aimed to determine its recovery following exhaustive exercise (which affected intramuscular and neural factors concomitantly with those of intramuscular concentrations of adenosine triphosphate [ATP], phosphocreatine [PCr] and pH values and electromyography (EMG activity (a proxy for net motor unit activity changes. Eight young men performed 10, 6-s all-out sprints on a cycle ergometer, interspersed with 30 s of recovery, followed, after 6 min of passive recovery, by five 6-s sprints, again interspersed by 30 s of passive recovery. Biopsies of the vastus lateralis were obtained at rest, immediately after the first 10 sprints and after 6 min of recovery. EMG activity of the vastus lateralis was obtained from surface electrodes throughout exercise. Total work (TW, [ATP], [PCr], pH and EMG amplitude decreased significantly throughout the first ten sprints (P<0.05. After 6 min of recovery, TW during sprint 11 recovered to 86.3±7.7% of sprint 1. ATP and PCr were resynthesized to 92.6±6.0% and 85.3±10.3% of the resting value, respectively, but muscle pH and EMG amplitude remained depressed. PCr resynthesis was correlated with TW done in sprint 11 (r = 0.79, P<0.05 and TW done during sprints 11 to 15 (r = 0.67, P<0.05. There was a ∼2-fold greater decrease in the TW/EMG ratio in the last five sprints (sprint 11 to 15 than in the first five sprints (sprint 1 to 5 resulting in a disproportionate decrease in mechanical power (i.e., TW in relation to EMG. Thus, we conclude that the inability to produce power output during repeated sprints is mostly mediated by intramuscular fatigue signals probably related with the control of PCr metabolism.

  4. Knee Muscular Control During Jump Landing in Multidirections.

    Science.gov (United States)

    Sinsurin, Komsak; Vachalathiti, Roongtiwa; Jalayondeja, Wattana; Limroongreungrat, Weerawat

    2016-06-01

    Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direction jump landing. Eighteen male athletes performed the jump-landing test in four directions: forward (0°), 30° diagonal, 60° diagonal, and lateral (90°). Muscles tested were vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), and biceps femoris (BF). A Vicon(TM) 612 workstation collected the kinematic data. An electromyography was synchronized with the Vicon(TM) Motion system to quantify dynamic muscle function. Repeated measure ANOVA was used to analyze the data. Jump-landing direction significantly influenced (P jump landing. A higher risk of knee injury might occur during lateral jump landing than forward and diagonal directions. Athletes should have more practice in jump landing in lateral direction to avoid injury. Landing technique with high knee flexion in multi-directions should be taught to jumpers for knee injury prevention.

  5. Dynamic knee stability and ballistic knee movement after ACL reconstruction: an application on instep soccer kick.

    Science.gov (United States)

    Cordeiro, Nuno; Cortes, Nelson; Fernandes, Orlando; Diniz, Ana; Pezarat-Correia, Pedro

    2015-04-01

    The instep soccer kick is a pre-programmed ballistic movement with a typical agonist-antagonist coordination pattern. The coordination pattern of the kick can provide insight into deficient neuromuscular control. The purpose of this study was to investigate knee kinematics and hamstrings/quadriceps coordination pattern during the knee ballistic extension phase of the instep kick in soccer players after anterior cruciate ligament reconstruction (ACL reconstruction). Seventeen players from the Portuguese Soccer League participated in this study. Eight ACL-reconstructed athletes (experimental group) and 9 healthy individuals (control group) performed three instep kicks. Knee kinematics (flexion and extension angles at football contact and maximum velocity instants) were calculated during the kicks. Rectus femoris (RF), vastus lateralis, vastus medialis, biceps femoralis, and semitendinosus muscle activations were quantified during the knee extension phase. The ACL-reconstructed group had significantly lower knee extension angle (-1.2 ± 1.6, p ballistic control movement pattern between normal and ACL-reconstructed subjects. Performing open kinetic chain exercises using ballistic movements can be beneficial when recovering from ACL reconstruction. The exercises should focus on achieving multi-joint coordination and full knee extension (range of motion). III.

  6. Change in skeletal muscle stiffness after running competition is dependent on both running distance and recovery time: a pilot study.

    Science.gov (United States)

    Sadeghi, Seyedali; Newman, Cassidy; Cortes, Daniel H

    2018-01-01

    Long-distance running competitions impose a large amount of mechanical loading and strain leading to muscle edema and delayed onset muscle soreness (DOMS). Damage to various muscle fibers, metabolic impairments and fatigue have been linked to explain how DOMS impairs muscle function. Disruptions of muscle fiber during DOMS exacerbated by exercise have been shown to change muscle mechanical properties. The objective of this study is to quantify changes in mechanical properties of different muscles in the thigh and lower leg as function of running distance and time after competition. A custom implementation of Focused Comb-Push Ultrasound Shear Elastography (F-CUSE) method was used to evaluate shear modulus in runners before and after a race. Twenty-two healthy individuals (age: 23 ± 5 years) were recruited using convenience sampling and split into three race categories: short distance (nine subjects, 3-5 miles), middle distance (10 subjects, 10-13 miles), and long distance (three subjects, 26+ miles). Shear Wave Elastography (SWE) measurements were taken on both legs of each subject on the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), soleus, lateral gastrocnemius (LG), medial gastrocnemius (MG), biceps femoris (BF) and semitendinosus (ST) muscles. For statistical analyses, a linear mixed model was used, with recovery time and running distance as fixed variables, while shear modulus was used as the dependent variable. Recovery time had a significant effect on the soleus ( p  = 0.05), while running distance had considerable effect on the biceps femoris ( p  = 0.02), vastus lateralis ( p  trend from before competition to immediately after competition. The preliminary results suggest that SWE could potentially be used to quantify changes of muscle mechanical properties as a way for measuring recovery procedures for runners.

  7. Can increases in capillarization explain the early adaptations in metabolic regulation in human muscle to short-term training?

    Science.gov (United States)

    Green, Howard J; Burnett, Margaret; Kollias, Helen; Ouyang, Jing; Smith, Ian; Tupling, Susan

    2012-05-01

    To investigate the hypothesis that increases in fibre capillary density would precede increases in oxidative potential following training onset, tissue was extracted from the vastus lateralis prior to (0 days) and following 3 and 6 consecutive days of submaximal cycle exercise (2 h·day(-1)). Participants were untrained males (age = 21.4 ± 0.58 years; peak oxygen consumption = 46.2 ± 1.6 mL·kg(-1)·min(-1); mean ± standard error (SE)). Tissue was assessed for succinic dehydrogenase activity (SDH) by microphotometry and indices of capillarization based on histochemically assessed area and capillary counts (CC) in specific fibre types. Three days of training (n = 13) resulted in a generalized decrease (p metabolic alterations that also result.

  8. Centronuclear myopathy in a Border collie dog.

    Science.gov (United States)

    Eminaga, S; Cherubini, G B; Shelton, G D

    2012-10-01

    A two-year old, male entire Border collie was presented with a one-year history of exercise-induced collapsing on the pelvic limbs. Physical examination revealed generalised muscle atrophy. Neurological examination supported a generalised neuromuscular disorder. Electromyography revealed spontaneous electrical activity in almost all muscles. Unfixed and formaldehyde-fixed biopsy samples were collected from the triceps brachii, longissimus and vastus lateralis muscles. Histopathological, histochemical and ultrastructural examinations of biopsy specimens were consistent with either centronuclear or myotubular myopathy. The dog clinically improved with supportive treatment with L-carnitine, co-enzyme Q10 and vitamin B compound. To the authors' knowledge, this is the first report of centronuclear/myotubular myopathy in a Border collie. © 2012 British Small Animal Veterinary Association.

  9. Muscle reflexes during gait elicited by electrical stimulation of the posterior cruciate ligament in humans

    DEFF Research Database (Denmark)

    Fischer-Rasmussen, T; Krogsgaard, M R; Jensen, D B

    2002-01-01

    over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 Hz; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing......We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh and calf muscle during gait. The study group comprised eight young men without any history of injury to the knee joints. Multistranded teflon-insulated stainless...... steel wires were inserted into the PCL guided by sonography and in four subjects also into the fat pad of the knee. The PCL was electrically stimulated during gait on a treadmill at heel strike and 100 ms after heel strike. Electromyographic signals were recorded with bipolar surface electrodes placed...

  10. Effects of warm-up on vertical jump performance and muscle electrical activity using half-squats at low and moderate intensity.

    Science.gov (United States)

    Sotiropoulos, Konstantinos; Smilios, Ilias; Christou, Marios; Barzouka, Karolina; Spaias, Angelos; Douda, Helen; Tokmakidis, Savvas P

    2010-01-01

    The purpose of this study was to determine the effects of a specific warm-up using half-squats at low and moderate intensity on vertical jump performance and electromyographic activity of the thigh muscles. The subjects were 26 men who were divided into a low intensity group (LIG; n = 13) and a moderate intensity group (MIG; n = 13). The LIG performed a specific warm-up protocol that included the explosive execution of half-squats with loads 25 and 35% of the one repetition maximum (1RM) and the MIG with loads 45 and 65% of the 1RM. The two groups performed a countermovement jump (CMJ) before and three minutes after the specific warm-up protocols. During the concentric phase of the CMJ a linear encoder connected to an A/D converter interfaced to a PC with a software for data acquisition and analysis allowed the calculation of average mechanical power. The electromyographic (EMG) activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) were recorded during the concentric phase of the jumps. The average quadriceps (Qc) activity (mean value of the VL, VM and RF) was also calculated. A two way ANOVA (protocols X time) with repeated measures on the second factor was used to analyze the data. Following the specific warm-up procedure both groups improved (p ≤ 0.05) CMJ performance and mechanical power by 3.5% and 6.3%, respectively, with no differences observed between the two groups. EMG activity of the Qc and VL increased (p ≤ 0.05) for both groups by 5.9% and 8.5%, respectively. It is concluded that the use of a specific warm-up that includes half-squats, performed explosively with low to moderate intensity, improves CMJ performance. This may be due to increased muscle activation as evaluated by the surface EMG. Key pointsThe inclusion of two sets of explosively performed half squats with low to moderate loads in the warm up procedure elicited an acute performance en-hancement.The performance was enhanced regardless of the load used in

  11. Effect of Postactivation Potentiation Induced by Elastic Resistance on Kinematics and Performance in a Roundhouse Kick of Trained Martial Arts Practitioners.

    Science.gov (United States)

    Aandahl, Håkon S; Von Heimburg, Erna; Van den Tillaar, Roland

    2018-04-01

    Aandahl, HS, Von Heimburg, E, and Van den Tillaar, R. Effect of postactivation potentiation induced by elastic resistance on kinematics and performance in a roundhouse kick of trained martial arts practitioners. J Strength Cond Res 32(4): 990-996, 2018-The aim of this study was to examine whether kicking with elastic resistance during warm-up could initiate postactivation potentiation (PAP), and thereby positively influence kinematics and performance on subsequent explosive roundhouse kicking. Five women and 11 men (n = 16) with a background in kickboxing (n = 10) or taekwondo (n = 6) performed 2 warm-up strategies with 3 subsequent test kicks 5-8 minutes after a PAP-inducing exercise. Kicking performance, defined as roundhouse kicking velocity with the foot, was measured using 3D motion capture (500 Hz) with a 15 marker lower-body 3D model. In addition, electromyography of the prime movers-vastus lateralis, vastus medialis, and rectus femoris muscles-was measured to confirm the presence of PAP. Kicking velocity of the foot increased by 3.3% after performing a warming-up strategy including kicking with elastic resistance (p = 0.009, η = 0.32). Increases were also recorded in muscle activity in vastus medialis (35.2%, p = 0.05, η = 0.18) and rectus femoris (43.9%, p = 0.04, η = 0.20). These findings indicate that performing a warm-up strategy including kicking with elastic resistance can have a positive effect on kicking performance in a roundhouse kick.

  12. Knee flexion with quadriceps cocontraction: A new therapeutic exercise for the early stage of ACL rehabilitation.

    Science.gov (United States)

    Biscarini, Andrea; Contemori, Samuele; Busti, Daniele; Botti, Fabio M; Pettorossi, Vito E

    2016-12-08

    Quadriceps strengthening exercises designed for the early phase of anterior cruciate ligament (ACL) rehabilitation should limit the anterior tibial translation developed by quadriceps contraction near full knee extension, in order to avoid excessive strain on the healing tissue. We hypothesize that knee-flexion exercises with simultaneous voluntary contraction of quadriceps (voluntary quadriceps cocontraction) can yield considerable levels of quadriceps activation while preventing the tibia from translating forward relative to the femur. Electromyographic activity in quadriceps and hamstring muscles was measured in 20 healthy males during isometric knee-flexion exercises executed near full knee extension with maximal voluntary effort of quadriceps cocontraction and external resistance (R) ranging from 0% to 60% of the 1-repetition maximum (1RM). Biomechanical modeling was applied to derive the shear (anterior/posterior) tibiofemoral force developed in each exercise condition. Isometric knee-flexion exercises with small external resistance (R=10% 1RM) and maximal voluntary effort of quadriceps cocontraction yielded a net posterior (ACL-unloading) tibial pull (P=0.005) and levels of activation of 32%, 50%, and 45% of maximum voluntary isometric contraction, for the rectus femoris, vastus medialis, and vastus lateralis, respectively. This exercise might potentially rank as one of the most appropriate quadriceps strengthening interventions in the early phase of ACL rehabilitation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Biomechanical analysis of knee and trunk in badminton players with and without knee pain during backhand diagonal lunges.

    Science.gov (United States)

    Lin, Cheng-Feng; Hua, Shiang-Hua; Huang, Ming-Tung; Lee, Hsing-Hsan; Liao, Jen-Chieh

    2015-01-01

    The contribution of core neuromuscular control to the dynamic stability of badminton players with and without knee pain during backhand lunges has not been investigated. Accordingly, this study compared the kinematics of the lower extremity, the trunk movement, the muscle activation and the balance performance of knee-injured and knee-uninjured badminton players when performing backhand stroke diagonal lunges. Seventeen participants with chronic knee pain (injured group) and 17 healthy participants (control group) randomly performed two diagonal backhand lunges in the forward and backward directions, respectively. This study showed that the injured group had lower frontal and horizontal motions of the knee joint, a smaller hip-shoulder separation angle and a reduced trunk tilt angle. In addition, the injured group exhibited a greater left paraspinal muscle activity, while the control group demonstrated a greater activation of the vastus lateralis, vastus medialis and medial gastrocnemius muscle groups. Finally, the injured group showed a smaller distance between centre of mass (COM) and centre of pressure, and a lower peak COM velocity when performing the backhand backward lunge tasks. In conclusion, the injured group used reduced knee and trunk motions to complete the backhand lunge tasks. Furthermore, the paraspinal muscles contributed to the lunge performance of the individuals with knee pain, whereas the knee extensors and ankle plantar flexor played a greater role for those without knee pain.

  14. Análise do tempo de resposta reflexa dos músculos estabilizadores patelares em indivíduos com síndrome da dor patelofemural Analysis of the reflex response time of the patellar stabilizer muscles in individuals with patellofemoral pain syndrome

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    D Bevilaqua-Grossi

    2008-02-01

    Full Text Available OBJETIVO: Avaliar o tempo de resposta reflexa (TRR dos músculos vasto medial oblíquo (VMO, vasto lateral oblíquo (VLO e vasto lateral longo (VLL em indivíduos clinicamente saudáveis e portadores de síndrome da dor patelofemural (SDPF. MÉTODOS: Foram avaliadas 12 mulheres clinicamente saudáveis e 12 mulheres com SDPF. Os registros eletromiográficos foram obtidos por eletrodos ativos simples conectados a um eletromiógrafo, acionados por um sensor externo fixado sobre a porção média do ligamento da patela a partir de sua percussão. A análise do TRR foi realizada por meio da medida do tempo zero ao pico da resposta elétrica dos músculos VMO, VLO e VLL, em segundos, para ambos os grupos. A análise estatística empregada foi o teste de análise de variância (ANOVA, pOBJECTIVE: To investigate the reflex response time (RRT of the vastus medialis obliquus (VMO, vastus lateralis obliquus (VLO and vastus lateralis longus (VLL muscles in clinically healthy individuals and subjects with patellofemoral pain syndrome (PPS. METHODS: Twelve clinically health women and twelve women with PPS were evaluated. Electromyography (EMG records were obtained using active electrodes connected to an electromyograph that was activated by an external sensor attached to the medial portion of the patella ligament, by means of percussion. The RRT was analyzed by measuring the time, in seconds, between zero and peak electrical response of the VMO, VLO and VLL muscles, for both groups. The statistical analysis consisted of analysis of variance (ANOVA, p< 0.05 and the Tukey post-hoc test (p< 0.05 to compare the response between muscles, and Student's t test (p< 0.05 to compare the response between groups. RESULTS: Both groups presented lower RRT for the VMO muscle than for the VLO and VLL muscles. However, no significant difference was seen between the VLO and VLL muscles. There was no significant difference in RRT between the groups. CONCLUSIONS: According to

  15. Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Produce the Same Activity?

    Science.gov (United States)

    Looney, David P; Kraemer, William J; Joseph, Michael F; Comstock, Brett A; Denegar, Craig R; Flanagan, Shawn D; Newton, Robert U; Szivak, Tunde K; DuPont, William H; Hooper, David R; Häkkinen, Keijo; Maresh, Carl M

    2016-03-01

    This investigation examined peak motor unit activity during sets that differed in resistance (50, 70, or 90% 1 repetition maximum [1RM]). Ten resistance-trained men (age, 23 ± 3 years; height, 187 ± 7 cm; body mass, 91.5 ± 6.9 kg; squat 1RM, 141 ± 28 kg) were assessed by electromyography (EMG) on the vastus lateralis and vastus medialis muscles in a randomized within-subject experiment consisting of 2 test visits: a drop-set day and a single-set day using only the 50% of 1RM intensity performed to failure. At the start of each day, subjects performed 2 submaximal repetition sets (50% 1RM × 10 repetitions and 70% 1RM × 7 repetitions). On the drop-set day, subjects performed 3 consecutive maximal repetition sets at 90%, 70%, and 50% 1RM to failure with no rest periods in between. On the single-set day, subjects performed a maximal repetition set at 50% 1RM to failure. Overall, the maximal repetition sets to failure at 50% and 70% 1RM resulted in higher peak EMG amplitude than during submaximal repetition sets with the same resistance. However, peak EMG amplitude was significantly (p ≤ 0.05) greater in the maximal 90% 1RM set than all other sets performed. When sets were performed to failure, ratings of perceived exertion (CR-10) did not differ over the intensity range of loads and suggests that perception is not capable of accurately detecting the actual amount of motor unit activation. The results of this investigation indicate that using higher external resistance is a more effective means of increasing motor unit activity than increasing the number of repetitions performed with lighter weights even when the end point is muscular failure. Accordingly, previous recommendations for the use of heavier loads during resistance training programs to stimulate the maximal development of strength and hypertrophy are further supported.

  16. The lower body muscle activation of intermediate to experienced kayakers when navigating white water.

    Science.gov (United States)

    Murtagh, Misha; Brooks, Darrell; Sinclair, Jonathan; Atkins, Stephen

    2016-11-01

    In white-water kayaking, the legs play a vital part in turning, stabilising and bracing actions. To date, there has been no reported information on neuromuscular activation of the legs in an authentic white-water environment. The aim of the current study was to identify lower body muscle activation, using 'in-boat' electromyography (EMG), whilst navigating a white-water run. Ten experienced male kayakers (age 31.5 ± 12.5 yr, intermediate to advanced experience) completed three successful runs of an international standard white-water course (grade 3 rapids), targeting right and left sides of the course, in a zigzag formation. Surface EMG (sEMG) outputs were generated, bilaterally, for the rectus femoris (RF), vastus lateralis, biceps femoris and gastrocnemius, expressed as a percentage of a dynamic maximal voluntary contraction (dMVC). Only RF showed significantly higher activation than any muscle on the left side of the body, and only on the left side of the course (P = .004; ETA(2) = 0.56). Other results showed no significant difference between muscle activation in the right and left legs during each run, nor when assessed at either the right or left side of the course (P > .05). These findings indicate that contralateral symmetry in lower limb muscle activation is evident during white-water kayaking. This symmetry may provide a stable base to allow more asymmetrical upper body and trunk movements to be fully optimised. Lower body symmetry development should be considered useful in targeted training programmes for white-water kayakers.

  17. Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training.

    Science.gov (United States)

    Paulsen, G; Hamarsland, H; Cumming, K T; Johansen, R E; Hulmi, J J; Børsheim, E; Wiig, H; Garthe, I; Raastad, T

    2014-12-15

    This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day(-1) and 235 mg day(-1), respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

  18. Gait characteristics in women's safety shoes.

    Science.gov (United States)

    Goto, Kanako; Abe, Kaoru

    2017-11-01

    Although workers in Japan are required to wear safety footwear, there is concern about occupational accidents that occur when wearing safety shoes. This study aimed to analyze the effect of wearing hardsoled safety shoes on both spatiotemporal gait characteristics and the muscle activity in the lower extremities. Seventeen young women participated in this study. A 5-m gait trial and a surface electromyography trial were conducted while the women walked in either safety shoes or sports shoes. Paired t-tests were performed to analyze the differences in gait characteristics when walking in the two different pairs of shoes. Walking in safety shoes was associated with a significant increase in vastus lateralis, biceps femoris and tibialis anterior activity. This increased muscle activity in the lower extremities is likely compensating for the lower flexibility of the safety shoes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Frequency band analysis of muscle activation during cycling to exhaustion

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    Fernando Diefenthaeler

    2012-04-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p243 Lower limb muscles activation was assessed during cycling to exhaustion using frequency band analysis. Nine cyclists were evaluated in two days. On the first day, cyclists performed a maximal incremental cycling exercise to measure peak power output, which was used on the second day to define the workload for a constant load time to exhaustion cycling exercise (maximal aerobic power output from day 1. Muscle activation of vastus lateralis (VL, long head of biceps femoris (BF, lateral head of gastrocnemius (GL, and tibialis anterior (TA from the right lower limb was recorded during the time to exhaustion cycling exercise. A series of nine band-pass Butterworth digital filters was used to analyze muscle activity amplitude for each band. The overall amplitude of activation and the high and low frequency components were defined to assess the magnitude of fatigue effects on muscle activity via effect sizes. The profile of the overall muscle activation during the test was analyzed using a second order polynomial, and the variability of the overall bands was analyzed by the coefficient of variation for each muscle in each instant of the test. Substantial reduction in the high frequency components of VL and BF activation was observed. The overall and low frequency bands presented trivial to small changes for all muscles. High relationship between the second order polynomial fitting and muscle activity was found (R2 > 0.89 for all muscles. High variability (~25% was found for muscle activation at the four instants of the fatigue test. Changes in the spectral properties of the EMG signal were only substantial when extreme changes in fatigue state were induced.

  20. Electrical stimulation counteracts muscle atrophy associated with aging in humans

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    Helmut Kern

    2013-07-01

    Full Text Available Functional and structural muscle decline is a major problem during aging. Our goal was to improve in old subjects quadriceps m. force and mobility functional performances (stair test, chair rise test, timed up and go test with neuromuscular electrical stimulation (9 weeks, 2-3times/week, 20-30 minutes per session. Furthermore we performed histological and biological molecular analyses of vastus lateralis m. biopsies. Our findings demonstrate that electrical stimulation significantly improved mobility functional performancies and muscle histological characteristics and molecular markers.

  1. Desaturation of skeletal muscle structural and depot lipids in obese individuals during a very-low-calorie diet intervention

    DEFF Research Database (Denmark)

    Haugaard, Steen B; Vaag, Allan; Høy, Carl-Erik

    2007-01-01

    would decrease saturated fatty acids (FAs) and increase long-chain polyunsaturated FAs (LCPUFAs) in muscular structural lipids, as such changes have been associated with improved insulin sensitivity. RESEARCH METHODS AND PROCEDURES: Skeletal muscle biopsies (vastus lateralis) were obtained from 13 obese...... during the VLCD. DISCUSSION: Desaturation of both muscle cell membrane phospholipid and IMTG was significant but modest during a VLCD in obese subjects. Further research must delineate whether such changes in skeletal muscle structural and depot lipid composition themselves are enough to promote...

  2. Desaturation of skeletal muscle structural and depot lipids in obese individuals during a very-low-calorie diet intervention

    DEFF Research Database (Denmark)

    Haugaard, S.B.; Vaag, A.; Høy, Carl-Erik

    2007-01-01

    would decrease saturated fatty acids (FAs) and increase long-chain polyunsaturated FAs (LCPUFAs) in muscular structural lipids, as such changes have been associated with improved insulin sensitivity. Research Methods and Procedures: Skeletal muscle biopsies (vastus lateralis) were obtained from 13 obese....... Discussion: Desaturation of both muscle cell membrane phospholipid and IMTG was significant but modest during a VLCD in obese subjects. Further research must delineate whether such changes in skeletal muscle structural and depot lipid composition themselves are enough to promote the observed improvements...

  3. Reinnervation of Vastus lateralis is increased significantly in seniors (70-years old with a lifelong history of high-level exercise

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    Simone Mosole

    2013-12-01

    Full Text Available It has long been recognized that histological changes observed in aging muscle suggest that denervation contributes to muscle deterioration and that disuse accelerates the process while running activity, sustained for decades, protects against age-related loss of motor units. Here we show at the histological level that lifelong increased physical activity promotes reinnervation of muscle fibers. In muscle biopsies from 70-year old men with a lifelong history of high-level physical activity, we observed a considerable increase in fiber-type groupings (almost exclusively of the slow type in comparison to sedentary seniors, revealing a large population of reinnervated muscle fibers in the sportsmen. Slow-type transformation by reinnervation in senior sportsmen seems to be a clinically relevant mechanism: the muscle biopsies fluctuate from those with scarce fiber-type transformation and groupings to almost fully transformed muscle, going through a process in which isolated fibers co-expressing fast and slow MHCs seems to fill the gaps. Taken together, our results suggest that, beyond the direct effects of aging on the muscle fibers, changes occurring in skeletal muscle tissue appear to be largely, although not solely, a result of sparse denervation. Our data suggest that lifelong exercise allows the body to adapt to the consequences of the age-related denervation and to preserve muscle structure and function by saving otherwise lost muscle fibers through recruitment to different, mainly slow, motor units. These beneficial effects on motoneurons and, subsequently on muscle fibers, serve to maintain size, structure and function of muscle fibers, delaying the functional decline and loss of independence that are commonly seen in late aging.

  4. Diferentes tempos de eletroestimulação neuromuscular (eenm de média frequência (kotz em cães Different times of neuromuscular electrical stimulation medium frequency (kotz in dogs

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    Charles Pelizzari

    2011-09-01

    Full Text Available O objetivo desta pesquisa foi empregar a estimulação elétrica neuromuscular (EENM de média frequência no músculo quadríceps femoral de cães com atrofia muscular induzida, avaliar o ganho de massa muscular e comparar a EENM sob diferentes tempos de tratamento. Foram utilizados oito cães, pesando entre 15 e 25kg e distribuídos aleatoriamente em dois grupos denominados de GI (30minutos e GII (60minutos. Para a indução da atrofia muscular, a articulação do joelho direito foi imobilizada por 30 dias por transfixação percutânea tipo II. Após a retirada do aparelho de imobilização, foi realizada a EENM nos cães dos grupos GI e GII três vezes por semana, com intervalo mínimo de 48 horas entre cada sessão, pelo período de 60 dias. Foram mensuradas a perimetria da coxa, goniometria dos joelhos, atividade da enzima creatina-quinase (CK e morfometria das fibras musculares do vasto lateral em cortes transversais colhido mediante a biópsia muscular. Não houve diferença quanto aos valores da perimetria da coxa e atividade da enzima CK. A goniometria revelou significância (PThe aim of this study was to use medium frequency Neuromuscular Electrical Stimulation (NMES in femoral quadriceps muscle of dogs with induced muscular atrophy to evaluate the occurrence of mass gain in these muscles and to compare NMES in different periods of treatment. Eight dogs, weighing between 15 and 25kg, were randomly placed in two groups: GI (NMES for 30min, GII, (NMES for 60min. For the muscular atrophy induction, the right knee was immobilized for 30 days by the percutaneous transfixation type II method. NMES was carried out in the dogs of which groups, three times a week, in between 48h each session, in a period of 60 days. The parameters measured were: thigh perimetry, knee goniometry, creatine kinase (CK enzyme activity and morphometry of the muscular fibers in transversal cuts of the vastus lateralis muscle, collected through a muscular biopsy

  5. Extracting time-frequency feature of single-channel vastus medialis EMG signals for knee exercise pattern recognition.

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    Yi Zhang

    Full Text Available The EMG signal indicates the electrophysiological response to daily living of activities, particularly to lower-limb knee exercises. Literature reports have shown numerous benefits of the Wavelet analysis in EMG feature extraction for pattern recognition. However, its application to typical knee exercises when using only a single EMG channel is limited. In this study, three types of knee exercises, i.e., flexion of the leg up (standing, hip extension from a sitting position (sitting and gait (walking are investigated from 14 healthy untrained subjects, while EMG signals from the muscle group of vastus medialis and the goniometer on the knee joint of the detected leg are synchronously monitored and recorded. Four types of lower-limb motions including standing, sitting, stance phase of walking, and swing phase of walking, are segmented. The Wavelet Transform (WT based Singular Value Decomposition (SVD approach is proposed for the classification of four lower-limb motions using a single-channel EMG signal from the muscle group of vastus medialis. Based on lower-limb motions from all subjects, the combination of five-level wavelet decomposition and SVD is used to comprise the feature vector. The Support Vector Machine (SVM is then configured to build a multiple-subject classifier for which the subject independent accuracy will be given across all subjects for the classification of four types of lower-limb motions. In order to effectively indicate the classification performance, EMG features from time-domain (e.g., Mean Absolute Value (MAV, Root-Mean-Square (RMS, integrated EMG (iEMG, Zero Crossing (ZC and frequency-domain (e.g., Mean Frequency (MNF and Median Frequency (MDF are also used to classify lower-limb motions. The five-fold cross validation is performed and it repeats fifty times in order to acquire the robust subject independent accuracy. Results show that the proposed WT-based SVD approach has the classification accuracy of 91.85%±0

  6. Hypoxia Aggravates Inactivity-Related Muscle Wasting

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    Tadej Debevec

    2018-05-01

    Full Text Available Poor musculoskeletal state is commonly observed in numerous clinical populations such as chronic obstructive pulmonary disease (COPD and heart failure patients. It, however, remains unresolved whether systemic hypoxemia, typically associated with such clinical conditions, directly contributes to muscle deterioration. We aimed to experimentally elucidate the effects of systemic environmental hypoxia upon inactivity-related muscle wasting. For this purpose, fourteen healthy, male participants underwent three 21-day long interventions in a randomized, cross-over designed manner: (i bed rest in normoxia (NBR; PiO2 = 133.1 ± 0.3 mmHg, (ii bed rest in normobaric hypoxia (HBR; PiO2 = 90.0 ± 0.4 mmHg and ambulatory confinement in normobaric hypoxia (HAmb; PiO2 = 90.0 ± 0.4 mmHg. Peripheral quantitative computed tomography and vastus lateralis muscle biopsies were performed before and after the interventions to obtain thigh and calf muscle cross-sectional areas and muscle fiber phenotype changes, respectively. A significant reduction of thigh muscle size following NBR (-6.9%, SE 0.8%; P < 0.001 was further aggravated following HBR (-9.7%, SE 1.2%; P = 0.027. Bed rest-induced muscle wasting in the calf was, by contrast, not exacerbated by hypoxic conditions (P = 0.47. Reductions in both thigh (-2.7%, SE 1.1%, P = 0.017 and calf (-3.3%, SE 0.7%, P < 0.001 muscle size were noted following HAmb. A significant and comparable increase in type 2× fiber percentage of the vastus lateralis muscle was noted following both bed rest interventions (NBR = +3.1%, SE 2.6%, HBR = +3.9%, SE 2.7%, P < 0.05. Collectively, these data indicate that hypoxia can exacerbate inactivity-related muscle wasting in healthy active participants and moreover suggest that the combination of both, hypoxemia and lack of activity, as seen in COPD patients, might be particularly harmful for muscle tissue.

  7. Motor Unit Interpulse Intervals During High Force Contractions.

    Science.gov (United States)

    Stock, Matt S; Thompson, Brennan J

    2016-01-01

    We examined the means, medians, and variability for motor-unit interpulse intervals (IPIs) during voluntary, high force contractions. Eight men (mean age = 22 years) attempted to perform isometric contractions at 90% of their maximal voluntary contraction force while bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis and vastus medialis muscles. Surface EMG signal decomposition was used to determine the recruitment thresholds and IPIs of motor units that demonstrated accuracy levels ≥ 96.0%. Motor units with high recruitment thresholds demonstrated longer mean IPIs, but the coefficients of variation were similar across all recruitment thresholds. Polynomial regression analyses indicated that for both muscles, the relationship between the means and standard deviations of the IPIs was linear. The majority of IPI histograms were positively skewed. Although low-threshold motor units were associated with shorter IPIs, the variability among motor units with differing recruitment thresholds was comparable.

  8. Adjustments of muscle capillarity but not mitochondrial protein with skiing in the elderly

    DEFF Research Database (Denmark)

    van Ginkel, S; Amami, M; Dela, F

    2015-01-01

    Downhill skiing in the elderly increases maximal oxygen uptake (VO2max) and carbohydrate handling, and produces muscle hypertrophy. We hypothesized that adjustments of the cellular components of aerobic glucose combustion in knee extensor muscle, and cardiovascular adjustments, would increase...... lateralis muscle were analyzed for capillary density and expression of respiratory chain markers (NDUFA9, SDHA, UQCRC1, ATP5A1) and the glucose transporter GLUT4. Statistical significance was assessed with a repeated analysis of variance and Fisher's post-hoc test at a P value of 5%. VO2max increased...... selectively with ski training (+7 ± 2%). Capillary density (+11 ± 5%) and capillary-to-fiber ratio (12 ± 5%), but not the concentration of metabolic proteins, in vastus lateralis were increased after skiing. Cardiovascular parameters did not change. Fold changes in VO2max and capillary-to-fiber ratio were...

  9. Ultrasound investigation of vastus medialis oblique muscle architecture: an in vivo study.

    Science.gov (United States)

    Engelina, S; Antonios, T; Robertson, C J; Killingback, A; Adds, P J

    2014-10-01

    There is thought to be a link between vastus medialis oblique (VMO) architecture and patellofemoral pain syndrome (PFPS). Historical data are largely derived from older populations, whereas PFPS commonly affects younger populations. The aim of this study was to gather data on VMO architecture in young asymptomatic adults, to provide baseline values for comparison with symptomatic sufferers. VMO maximum fiber angle and insertion ratio were measured with ultrasound. The insertion ratio represents the proportion (%) of the patella which has the muscle fibers attaching to its medial border. Eighty knees from 40 healthy young subjects (18 males, 22 females, and age 20-30) were assessed. Individual Tegner scores were recorded to assess participants' level of physical activity. Results were compared with data in the literature for PFPS sufferers and normal older individuals. Mean fiber angle and insertion ratio were 56.6° and 57.8%, respectively. There was no significant difference between age groups. The insertion ratio was higher among females (61.2% F:53.6% M). There was some evidence of increased fiber angle and decreased insertion ratio with increased Tegner score. There was some overlap in fiber angle between healthy knees in this study and values reported elsewhere for pathological knees. VMO fiber angle and insertion ratio are not age-related. The overlap in fiber angle values between healthy and pathological knees suggests that the cause of PFPS is multifactorial. An individual's VMO architecture may be affected by their physical activity level, which could have important implications for PFPS. © 2014 Wiley Periodicals, Inc.

  10. A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury.

    Science.gov (United States)

    Husted, Rasmus S; Bencke, Jesper; Andersen, Lars L; Myklebust, Grethe; Kallemose, Thomas; Lauridsen, Hanne B; Hölmich, Per; Aagaard, Per; Zebis, Mette K

    2016-06-01

    Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests. Sixty-two adolescent female elite football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored during three standardized screening tests - i.e. one-legged horizontal hop (OLH), drop vertical jump (DJ) and sidecutting (SC). Neuromuscular pre-activity was measured in the time interval 10ms prior to initial contact on a force plate. For neuromuscular hamstring muscle pre-activity, correlation analysis (Spearman correlation coefficient) showed low-to-moderate correlations between SC and 1) DJ (rs=0.34-0.36, Phamstring pre-activity share some common variance during the examined tests. However, a lack of strong correlation suggests that we cannot generalize one risk factor during one test to another test. The present data demonstrate that one-legged horizontal hop and drop vertical jump testing that are commonly used in the clinical setting does not resemble the specific neuromuscular activity patterns known to exist during sidecutting, a well known high risk movement for non-contact ACL injury. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Effect of Feedback Corrective Exercise on Knee Valgus and Electromyographic Activity of Lower Limb Muscles in Single Leg Squat

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    Negar Koorosh-fard

    2015-07-01

    Full Text Available Objective: The aim of this study was assessing the effect of feedback correcting exercise in front of mirror during running on frontal plane knee and pelvic kinematic and electromyography activity of some lower extremity muscles in single leg squat (SLS. Materials & Methods: This study was quasi experimental. 23 active female subjects participated in two experimental and control groups with mean age (21.86± 2.43 years .experimental group contains subjects with knee valgus and pelvic drop angle more than a mean plus one standard deviation of the population in functional SLS. Muscular activity (RMS of gluteus maximus, Gluteus medius, rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus, angle of knee valgus and pelvic drop were register in end of SLS Pre and post of 8 training sessions. Comparing Variable has done with independent t statistical test between 2 groups and pair sample t test within each groups with significant level of 0.05. Results: Statistical analysis Before training showed no significant differences in pelvic drop between two groups (P&ge0.05, but knee valgus angle was significantly more than control group (P&le0.05. In spit that most muscle activities (% MVC except biceps femoris (P&le0.05, were greater in experimental group, no significant difference (P&ge0.05 has seen in two groups. Comparing pre and post test has showed no significant difference in knee valgus of experimental group, however it decreased around 2 degrees and although %MVC decreased in all muscles, just rectuse femoris has shown significant difference (P&le0.05. No significant difference has seen in control group in all variables (P&ge0.05. Conclusion: Findings showed poor neuromuscular control in experimental group which improved to some extent after training because lower muscle activity and energy consumption in specific movement with similar kinematic indicate improvement of motor control or cause learning. It seems that

  12. Leg and trunk muscle coordination and postural sway during increasingly difficult standing balance tasks in young and older adults.

    Science.gov (United States)

    Donath, Lars; Kurz, Eduard; Roth, Ralf; Zahner, Lukas; Faude, Oliver

    2016-09-01

    Ageing impairs body balance and increases older adults' fall risk. Balance training can improve intrinsic fall risk factors. However, age comparisons of muscle activity responses during balance tasks are lacking. This study investigated relative muscle activity, muscle coordination and postural sway during various recommended static balance training tasks. Muscle activity (%MVC), amplitude ratios (AR) and co-activity (CAI) were determined during standing tasks for 30s (1: double limb stance on a foam surface, eyes open; 2: double limb stance on firm ground, eyes closed; 3: double limb stance, feet in step position on a foam surface, eyes open; 4: double limb stance, feet in step position on firm ground, eyes closed; 5: single limb stance on firm ground, eyes open) in 20 healthy young adults (24±2 y) and 20 older adults (73±6 y). Surface electromyography (SEMG) was applied (SENIAM guidelines) to ankle (tibialis anterior, soleus, medial gastrocnemius, peroneus longus) and thigh (vastus lateralis, vastus medialis, biceps femoris, semitendinosus) muscles (non-dominant leg). Electrodes over trunk (multifidus and internal oblique) muscles were applied bilaterally. Two- to six-fold higher levels of relative muscle activity were found in older adults for ankle (0.0002adults for the trunk (0.001older adults for the ankle (0.009Older adults had higher electrophysiological costs for all stance conditions. Muscle coordination showed inverse activity patterns at the ankle and trunk. Optimal balance and strength training programs should take into account age-specific alterations in muscle activity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. A comparison of muscle stiffness and musculoarticular stiffness of the knee joint in young athletic males and females.

    Science.gov (United States)

    Wang, Dan; De Vito, Giuseppe; Ditroilo, Massimiliano; Fong, Daniel T P; Delahunt, Eamonn

    2015-06-01

    The objective of this study was to investigate the gender-specific differences in peak torque (PT), muscle stiffness (MS) and musculoarticular stiffness (MAS) of the knee joints in a young active population. Twenty-two male and twenty-two female recreational athletes participated. PT of the knee joint extensor musculature was assessed on an isokinetic dynamometer, MS of the vastus lateralis (VL) muscle was measured in both relaxed and contracted conditions, and knee joint MAS was quantified using the free oscillation technique. Significant gender differences were observed for all dependent variables. Females demonstrated less normalized PT (mean difference (MD)=0.4Nm/kg, p=0.005, η(2)=0.17), relaxed MS (MD=94.2N/m, pjoint injury incidence and prevalence in females when compared to males. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Effect of lifelong football training on the expression of muscle molecular markers involved in healthy longevity

    DEFF Research Database (Denmark)

    Mancini, A; Vitucci, D; Labruna, G

    2017-01-01

    PURPOSE: We investigated whether lifelong football training affects the expression of healthy longevity-related muscle molecular markers. METHODS: Biopsies were collected from the vastus lateralis muscle of 10 lifelong football-trained men (68.2 ± 3.0 years) and of 10 active untrained healthy men...... the expression of key markers involved in muscle oxidative metabolism, and in the DNA repair and senescence suppression pathways, thus providing the molecular basis for healthy longevity....... (66.7 ± 1.3 years). Gene and protein expression was measured by RTqPCR on RNA and by western blotting on protein extracts from muscle biopsies, respectively. RESULTS: The expression of AMPKα1/α2, NAMPT, TFAM and PGC1α, which are markers of oxidative metabolism, and MyHC β isoform expression was higher...

  15. Differential glucose metabolism in mice and humans affected by McArdle disease

    DEFF Research Database (Denmark)

    Krag, Thomas O; Pinós, Tomàs; Nielsen, Tue L

    2016-01-01

    McArdle disease (muscle glycogenosis type V) is a disease caused by myophosphorylase deficiency leading to "blocked" glycogen breakdown. A significant but varying glycogen accumulation in especially distal hind limb muscles of mice affected by McArdle disease has recently been demonstrated......, which could lead to lower glycogen accumulation. In comparison, tibialis anterior, extensor digitorum longus, and soleus had massive glycogen accumulation, but few, if any, changes or adaptations in glucose metabolism compared with wild-type mice. The findings suggest plasticity in glycogen metabolism....... In this study, we investigated how myophosphorylase deficiency affects glucose metabolism in hind limb muscle of 20-wk-old McArdle mice and vastus lateralis muscles from patients with McArdle disease. Western blot analysis and activity assay demonstrated that glycogen synthase was inhibited in glycolytic muscle...

  16. Effects of exercise training on regulation of skeletal muscle glucose metabolism in elderly men

    DEFF Research Database (Denmark)

    Biensø, Rasmus Sjørup; Olesen, Jesper; Gliemann, Lasse

    2015-01-01

    glucose tolerance test (OGTT) and a muscle biopsy was obtained from the vastus lateralis before and 45 minutes into the OGTT. Blood samples were collected before and up to 120 minutes after glucose intake. RESULTS: Exercise training increased Hexokinase II, GLUT4, Akt2, glycogen synthase (GS), pyruvate......) phosphorylation was increased after exercise training. In the trained state, the PDHa activity was reduced following glucose intake and without changes in phosphorylation level of PDH-E1α. CONCLUSIONS: The present results suggest that exercise training improves glucose regulation in elderly subjects by enhancing......BACKGROUND: The aim was to investigate the molecular mechanisms behind exercise training-induced improvements in glucose regulation in aged subjects. METHODS: Twelve elderly male subjects completed 8 weeks of exercise training. Before and after the training period, the subjects completed an oral...

  17. The Influence of Ambulatory Aid on Lower-Extremity Muscle Activation During Gait.

    Science.gov (United States)

    Sanders, Michael; Bowden, Anton E; Baker, Spencer; Jensen, Ryan; Nichols, McKenzie; Seeley, Matthew K

    2018-05-10

    Foot and ankle injuries are common and often require a nonweight-bearing period of immobilization for the involved leg. This nonweight-bearing period usually results in muscle atrophy for the involved leg. There is a dearth of objective data describing muscle activation for different ambulatory aids that are used during the aforementioned nonweight-bearing period. To compare activation amplitudes for 4 leg muscles during (1) able-bodied gait and (2) ambulation involving 3 different ambulatory aids that can be used during the acute phase of foot and ankle injury care. Within-subject, repeated measures. University biomechanics laboratory. Sixteen able-bodied individuals (7 females and 9 males). Each participant performed able-bodied gait and ambulation using 3 different ambulatory aids (traditional axillary crutches, knee scooter, and a novel lower-leg prosthesis). Muscle activation amplitude quantified via mean surface electromyography amplitude throughout the stance phase of ambulation. Numerous statistical differences (P < .05) existed for muscle activation amplitude between the 4 observed muscles, 3 ambulatory aids, and able-bodied gait. For the involved leg, comparing the 3 ambulatory aids: (1) knee scooter ambulation resulted in the greatest vastus lateralis activation, (2) ambulation using the novel prosthesis and traditional crutches resulted in greater biceps femoris activation than knee scooter ambulation, and (3) ambulation using the novel prosthesis resulted in the greatest gastrocnemius activation (P < .05). Generally speaking, muscle activation amplitudes were most similar to able-bodied gait when subjects were ambulating using the knee scooter or novel prosthesis. Type of ambulatory aid influences muscle activation amplitude. Traditional axillary crutches appear to be less likely to mitigate muscle atrophy during the nonweighting, immobilization period that often follows foot or ankle injuries. Researchers and clinicians should consider

  18. Free Vastus Intermedius Muscle Flap: A Successful Alternative for Complex Reconstruction of the Neurocranium in Preoperated Patients.

    Science.gov (United States)

    Horn, Dominik; Freudlsperger, Christian; Berger, Moritz; Freier, Kolja; Ristow, Oliver; Hoffmann, Jürgen; Sakowitz, Oliver; Engel, Michael

    2017-07-01

    The reconstruction of large cranial and scalp defects is a surgical and esthetic challenge. Single autologous tissue transfer can be insufficient due to the defect size and the anatomic complexity of the recipient site. Alloplastic patient-specific preformed implants can be used to recover hard tissue defects of the neurocranium. Nevertheless, for long-term success adequate soft tissue support is required. In this brief clinical study, the authors describe calvarian reconstruction in a 33-year-old patient with wound healing disorder after an initial resection of ependymoma. The patient suffered from osteonecrosis and wound breakdown in the fronto-parietal region. An alloplastic polymethylmethacrylate implant for hard tissue support was manufactured based on 3-dimensional visualization of a computed tomography scan. After the resection of remaining pathologic bone from earlier surgical procedures, the alloplastic implant was inserted to achieve functional coverage of the brain. Due to anatomic variation of donor site vessels during anterolateral thigh flap preparation, the authors performed a vastus intermedius free flap as a new muscular flap for craniofacial reconstruction. The authors achieved excellent functional and esthetic results. The muscular vastus intermedius free flap in combination with a split skin graft proves to be a new alternative to the anterolateral thigh flap for soft tissue reconstruction of the neurocranium.

  19. Neuromuscular coordination deficit persists 12 months after ACL reconstruction but can be modulated by 6 weeks of kettlebell training

    DEFF Research Database (Denmark)

    Zebis, Mette K.; Andersen, Christoffer H.; Bencke, Jesper

    2017-01-01

    The aim of the present single-case study was to investigate the effect of 6 weeks' kettlebell training on the neuromuscular risk profile for ACL injury in a high-risk athlete returning to sport after ACL reconstruction. A female elite soccer player (age 21 years) with no previous history of ACL...... for semitendinosus and elevated EMG preactivity for vastus lateralis. Subsequently, the 6-week kettlebell training increased semitendinosus muscle preactivity during sidecutting by 38 percentage points to a level equivalent to a neuromuscular low-risk profile. An ACL rehabilitated female athlete with a high...

  20. Diet and exercise reduce low-grade inflammation and macrophage infiltration in adipose tissue but not in skeletal muscle in severely obese subjects

    DEFF Research Database (Denmark)

    Bruun, Jens M; Helge, Jørn W; Richelsen, Bjørn

    2006-01-01

    Obesity is associated with low-grade inflammation, insulin resistance, type 2 diabetes, and cardiovascular disease. This study investigated the effect of a 15-wk lifestyle intervention (hypocaloric diet and daily exercise) on inflammatory markers in plasma, adipose tissue (AT), and skeletal muscle...... (SM) in 27 severely obese subjects (mean body mass index: 45.8 kg/m2). Plasma samples, subcutaneous abdominal AT biopsies, and vastus lateralis SM biopsies were obtained before and after the intervention and analyzed by ELISA and RT-PCR. The intervention reduced body weight (P

  1. Skeletal muscle glycogen content and particle size of distinct subcellular localizations in the recovery period after a high-level soccer match

    DEFF Research Database (Denmark)

    Nielsen, Joachim; Krustrup, Peter; Nybo, Lars

    2012-01-01

    Whole muscle glycogen levels remain low for a prolonged period following a soccer match. The present study was conducted to investigate how this relates to glycogen content and particle size in distinct subcellular localizations. Seven high-level male soccer players had a vastus lateralis muscle...... biopsy collected immediately after and 24, 48, 72 and 120 h after a competitive soccer match. Transmission electron microscopy was used to estimate the subcellular distribution of glycogen and individual particle size. During the first day of recovery, glycogen content increased by ~60% in all...

  2. Impaired formation of vasodilators in peripheral tissue in essential hypertension is normalized by exercise training

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Jensen, Lasse Gliemann; Thaning, Pia

    2012-01-01

    OBJECTIVES:: This study examined vascular function and the adenosine system in skeletal muscle of patients diagnosed with essential hypertension (n¿=¿10) and of normotensive (n¿=¿11) patients, before and after aerobic training. METHODS:: Before and after 8 weeks of aerobic training, the patients...... biopsies were obtained from muscle vastus lateralis. RESULTS:: Before training, leg vascular conductance in response to arterial adenosine infusion was similar in the hypertensive and normotensive groups and the individual vascular response was positively correlated to that of both acetylcholine infusion...

  3. Energy metabolism during repeated sets of leg press exercise leading to failure or not

    DEFF Research Database (Denmark)

    Gorostiaga, Esteban M; Navarro-Amézqueta, Ion; Calbet, José A L

    2012-01-01

    This investigation examined the influence of the number of repetitions per set on power output and muscle metabolism during leg press exercise. Six trained men (age 34 ± 6 yr) randomly performed either 5 sets of 10 repetitions (10REP), or 10 sets of 5 repetitions (5REP) of bilateral leg press...... exercise, with the same initial load and rest intervals between sets. Muscle biopsies (vastus lateralis) were taken before the first set, and after the first and the final sets. Compared with 5REP, 10REP resulted in a markedly greater decrease (P...

  4. Effect of tapering after a period of high-volume sprint interval training on running performance and muscular adaptations in moderately trained runners

    DEFF Research Database (Denmark)

    Skovgaard, Casper; Almquist, Nicki Winfield; Kvorning, Thue

    2018-01-01

    The effect of tapering following a period of high-volume sprint interval training (SIT) and a basic volume of aerobic training on performance and muscle adaptations in moderately trained runners was examined. Eleven (8 males, 3 females) runners (maximum oxygen uptake (VO2-max): 56.8±2.9 mL·min(-1...... running test at 90% of vVO2-max to exhaustion (RRT). In addition, a biopsy from m. vastus lateralis was obtained at rest. Performance during RRT was better (P... at 60% of vVO2-max was lower (P

  5. Ativação muscular estabilizadora da patela e do quadril durante exercícios de agachamento em indivíduos saudáveis Muscular activity of patella and hip stabilizers of healthy subjects during squat exercises

    Directory of Open Access Journals (Sweden)

    Lilian R. Felício

    2011-06-01

    muscles is relevant for physical therapy treatments. OBJECTIVE: To compare the electromyographic activity of patella and pelvic stabilizers during traditional squat and squat associated with isometric hip adduction or abduction in subjects without AKP. METHODS: Electromyography signals were captured using double-differential electrodes at the vastus medialis obliquus (VMO, vastus lateralis obliquus (VLO, vastus lateralis longus (VLL and gluteus medium (GMed in 15 healthy and sedentary women during squats exercises: traditional and associated with hip adduction and hip abduction with load of 25% of body weight. Linear mixed models with significance level of 5% were used for data analysis. RESULTS: Squat associated with hip adduction and abduction produced electromyographic activity of GMed of 0.47 (0.2 and 0.59 (0.22 respectively, while conventional squat produced an electromyiographic activity of 0.33 (0.27. The higher VMO activity was 0.59 (0.27 during the isometric contraction in the squat associated with hip adduction. The higher VLO activity was 0.60 (0.32 during isometric contraction in the squat associated with hip abduction. CONCLUSION: Squat exercise associated with hip adduction increased VMO muscle activity as well as the activity of GMed activity.

  6. [Effects of steaming and baking on content of alkaloids in Aconite Lateralis Radix (Fuzi)].

    Science.gov (United States)

    Yang, Chang-lin; Huang, Zhi-fang; Zhang, Yi-han; Liu, Yu-hong; Liu, Yun-huan; Chen, Yan; Yi, Jin-hai

    2014-12-01

    To study the effect of steaming and baking process on contents of alkaloids in Aconite Lateralis Radix (Fuzi), 13 alkaloids were analyzed by UPLC-MS/MS equipped with ESI ion source in MRM mode. In steaming process, the contents of diester-diterpenoid alkaloids decreased rapidly, the contents of monoester-diterpenoid alkaloids firstly increased, reached the peak at 40 min, and then deceased gradually. The contents of aconine alkaloids (mesaconine, aconine and hypaconine) increased all the time during processing, while the contents of fuziline, songorine, karacoline, salsolionl were stable or slightly decreased. In baking process, dynamic variations of alkaloids were different from that in the steaming process. Diester-diterpenoid alkaloids were degraded slightly slower than in steaming process. Monoester-diterpenoid alkaloids, aconine alkaloids and the total alkaloids had been destroyed at different degrees, their contents were significantly lower than the ones in steaming Fuzi at the same processing time. This experiment revealed the dynamic variations of alkaloids in the course of steaming and baking. Two processing methods which can both effectively remove the toxic ingredients and retain the active ingredients are simple and controllable, and are valuable for popularization and application.

  7. Localization and expression of molt-inhibiting hormone and nitric oxide synthase in the central nervous system of the green shore crab, Carcinus maenas, and the blackback land crab, Gecarcinus lateralis.

    Science.gov (United States)

    Pitts, Natalie L; Mykles, Donald L

    2017-01-01

    In decapod crustaceans, molting is controlled by the pulsatile release of molt-inhibiting hormone (MIH) from neurosecretory cells in the X-organ/sinus gland (XO/SG) complex in the eyestalk ganglia (ESG). A drop in MIH release triggers molting by activating the molting gland or Y-organ (YO). Post-transcriptional mechanisms ultimately control MIH levels in the hemolymph. Neurotransmitter-mediated electrical activity controls Ca 2+ -dependent vesicular release of MIH from the SG axon terminals, which may be modulated by nitric oxide (NO). In green shore crab, Carcinus maenas, nitric oxide synthase (NOS) protein and NO are present in the SG. Moreover, C. maenas are refractory to eyestalk ablation (ESA), suggesting other regions of the nervous system secrete sufficient amounts of MIH to prevent molting. By contrast, ESA induces molting in the blackback land crab, Gecarcinus lateralis. Double-label immunofluorescence microscopy and quantitative polymerase chain reaction were used to localize and quantify MIH and NOS proteins and transcripts, respectively, in the ESG, brain, and thoracic ganglion (TG) of C. maenas and G. lateralis. In ESG, MIH- and NOS-immunopositive cells were closely associated in the SG of both species; confocal microscopy showed that NOS was localized in cells adjacent to MIH-positive axon terminals. In brain, MIH-positive cells were located in a small number of cells in the olfactory lobe; no NOS immunofluorescence was detected. In TG, MIH and NOS were localized in cell clusters between the segmental nerves. In G. lateralis, Gl-MIH and Gl-crustacean hyperglycemic hormone (CHH) mRNA levels were ~10 5 -fold higher in ESG than in brain or TG of intermolt animals, indicating that the ESG is the primary source of these neuropeptides. Gl-NOS and Gl-elongation factor (EF2) mRNA levels were also higher in the ESG. Molt stage had little or no effect on CHH, NOS, NOS-interacting protein (NOS-IP), membrane Guanylyl Cyclase-II (GC-II), and NO-independent GC

  8. Comparing electro- and mechano-myographic muscle activation patterns in self-paced pediatric gait.

    Science.gov (United States)

    Plewa, Katherine; Samadani, Ali; Chau, Tom

    2017-10-01

    Electromyography (EMG) is the standard modality for measuring muscle activity. However, the convenience and availability of low-cost accelerometer-based wearables makes mechanomyography (MMG) an increasingly attractive alternative modality for clinical applications. Literature to date has demonstrated a strong association between EMG and MMG temporal alignment in isometric and isokinetic contractions. However, the EMG-MMG relationship has not been studied in gait. In this study, the concurrence of EMG- and MMG-detected contractions in the tibialis anterior, lateral gastrocnemius, vastus lateralis, and biceps femoris muscles were investigated in children during self-paced gait. Furthermore, the distribution of signal power over the gait cycle was statistically compared between EMG-MMG modalities. With EMG as the reference, muscular contractions were detected based on MMG with balanced accuracies between 88 and 94% for all muscles except the gastrocnemius. MMG signal power differed from that of EMG during certain phases of the gait cycle in all muscles except the biceps femoris. These timing and power distribution differences between the two modalities may in part be related to muscle fascicle length changes that are unique to muscle motion during gait. Our findings suggest that the relationship between EMG and MMG appears to be more complex during gait than in isometric and isokinetic contractions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A Soft-Inflatable Exosuit for Knee Rehabilitation: Assisting Swing Phase During Walking

    Directory of Open Access Journals (Sweden)

    Saivimal Sridar

    2018-05-01

    Full Text Available In this paper, we present a soft-inflatable exosuit to assist knee extension during gait training for stroke rehabilitation. The soft exosuit is designed to provide 25% of the knee moment required during the swing phase of the gait cycle and is integrated with inertial measurement units (IMUs and smart shoe insole sensors to improve gait phase detection and controller design. The stiffness of the knee joint during level walking is computed using inverse dynamics. The soft-inflatable actuators, with an I cross-section, are mechanically characterized at varying angles to enable generation of the required stiffness outputs. A linear relation between the inflatable actuator stiffness and internal pressure as a function of the knee angle is obtained, and a two-layer stiffness controller is implemented to assist the knee joint by providing appropriate stiffness during the swing phase. Finally, to evaluate the ability of the exosuit to assist in swing motion, surface-electromyography (sEMG sensors are placed on the three muscle groups of the quadriceps and two groups of the hamstrings, on three healthy participants. A reduction in muscle activity of the rectus femoris, vastus lateralis, and vastus medialis is observed, which demonstrates feasibility of operation and potential future usage of the soft inflatable exosuit by impaired users.

  10. Evaluation of Central and Peripheral Fatigue in the Quadriceps Using Fractal Dimension and Conduction Velocity in Young Females

    Science.gov (United States)

    Beretta-Piccoli, Matteo; D’Antona, Giuseppe; Barbero, Marco; Fisher, Beth; Dieli-Conwright, Christina M.; Clijsen, Ron; Cescon, Corrado

    2015-01-01

    Purpose Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD) and conduction velocity (CV) as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans. Methods A total of 29 recreationally active women (mean age±standard deviation: 24±4 years) and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years) performed two knee extensions: (1) at 20% maximal voluntary contraction (MVC) for 30 s, and (2) at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays. Results Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, pfatiguing task. Conclusions Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions. PMID:25880369

  11. Quantifying disease activity in fatty-infiltrated skeletal muscle by IDEAL-CPMG in Duchenne muscular dystrophy.

    Science.gov (United States)

    Mankodi, Ami; Bishop, Courtney A; Auh, Sungyoung; Newbould, Rexford D; Fischbeck, Kenneth H; Janiczek, Robert L

    2016-10-01

    The purpose of this study was to explore the use of iterative decomposition of water and fat with echo asymmetry and least-squares estimation Carr-Purcell-Meiboom-Gill (IDEAL-CPMG) to simultaneously measure skeletal muscle apparent fat fraction and water T 2 (T 2,w ) in patients with Duchenne muscular dystrophy (DMD). In twenty healthy volunteer boys and thirteen subjects with DMD, thigh muscle apparent fat fraction was measured by Dixon and IDEAL-CPMG, with the IDEAL-CPMG also providing T 2,w as a measure of muscle inflammatory activity. A subset of subjects with DMD was followed up during a 48-week clinical study. The study was in compliance with the Patient Privacy Act and approved by the Institutional Review Board. Apparent fat fraction in the thigh muscles of subjects with DMD was significantly increased compared to healthy volunteer boys (p Muscle T 2,w measured by IDEAL-CPMG was independent of changes in apparent fat fraction. Muscle T 2,w was higher in the biceps femoris and vastus lateralis muscles of subjects with DMD (p muscles and six-minute walk distance (6MWD) in subjects with DMD. IDEAL-CPMG allowed independent and simultaneous quantification of skeletal muscle fatty degeneration and disease activity in DMD. IDEAL-CPMG apparent fat fraction and T 2,w may be useful as biomarkers in clinical trials of DMD as the technique disentangles two competing biological processes. Published by Elsevier B.V.

  12. Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans.

    Science.gov (United States)

    Petrie, Michael A; Kimball, Amy L; McHenry, Colleen L; Suneja, Manish; Yen, Chu-Ling; Sharma, Arpit; Shields, Richard K

    2016-01-01

    Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat) and mechanical stress (vibration) on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction. The purpose of this study is to examine whether active mechanical stress (muscle contraction), passive mechanical stress (vibration), or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair. Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI) participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus) to analyze mRNA gene expression. We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold), PGC-1α (5.46 fold), and ABRA (5.98 fold); and repressed MSTN (0.56 fold). Heat stress repressed PGC-1α (0.74 fold change; p muscle contraction. Vibration induced FOXK2 (p muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell development, growth, and repair.

  13. Spatial distribution of motor units recruited during electrical stimulation of the quadriceps muscle versus the femoral nerve.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Maffiuletti, Nicola A; Place, Nicolas

    2013-11-01

    In this study we investigated differences in the spatial recruitment of motor units (MUs) in the quadriceps when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using over-the-quadriceps and femoral nerve stimulation of gradually increasing intensity from 22 young, healthy subjects. Spatial recruitment was investigated using recruitment curves of M-waves recorded from the vastus medialis (VM) and vastus lateralis (VL) and of twitches recorded from the quadriceps. At maximal stimulation intensity (Imax), no differences were found between nerve and over-the-quadriceps stimulation. At submaximal intensities, VL M-wave amplitude was higher for over-the-quadriceps stimulation at 40% Imax, and peak twitch force was greater for nerve stimulation at 60% and 80% Imax. For the VM, MU spatial recruitment during nerve and over-the-quadriceps stimulation of increasing intensity occurred in a similar manner, whereas significant differences were observed for the VL. Copyright © 2013 Wiley Periodicals, Inc.

  14. Effects of fatigue on motor unit firing rate versus recruitment threshold relationships.

    Science.gov (United States)

    Stock, Matt S; Beck, Travis W; Defreitas, Jason M

    2012-01-01

    The purpose of this study was to examine the influence of fatigue on the average firing rate versus recruitment threshold relationships for the vastus lateralis (VL) and vastus medialis. Nineteen subjects performed ten maximum voluntary contractions of the dominant leg extensors. Before and after this fatiguing protocol, the subjects performed a trapezoid isometric muscle action of the leg extensors, and bipolar surface electromyographic signals were detected from both muscles. These signals were then decomposed into individual motor unit action potential trains. For each subject and muscle, the relationship between average firing rate and recruitment threshold was examined using linear regression analyses. For the VL, the linear slope coefficients and y-intercepts for these relationships increased and decreased, respectively, after fatigue. For both muscles, many of the motor units decreased their firing rates. With fatigue, recruitment of higher threshold motor units resulted in an increase in slope for the VL. Copyright © 2011 Wiley Periodicals, Inc.

  15. Specific adaptations of neuromuscular control and knee joint stiffness following sensorimotor training.

    Science.gov (United States)

    Gruber, M; Bruhn, S; Gollhofer, A

    2006-08-01

    The aim of this study was to examine how fixations of the ankle joint during sensorimotor training (SMT) influence adaptations in mechanical stiffness and neuromuscular control of the knee joint. Sixty-three healthy subjects were randomly assigned to three training groups that differed in their degree of ankle joint fixation, which was either barefooted, with an ankle brace or with a ski boot. Mechanical knee joint stiffness and reflex control of m. vastus medialis, m. vastus lateralis, m. biceps femoris, and m. semitendinosus were tested during force controlled anterior tibial displacements. This force was applied as both a fast and a slow stimulus. After the training period the group that trained barefooted showed an increase in mechanical stiffness of the knee joint from 79 +/- 21 (Mean +/- SD) N/mm to 110 +/- 38 N/mm (p boots was able to improve knee joint stiffness from 67 +/- 26 N/mm to 96 +/- 47 N/mm (p knee joint injuries.

  16. Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques.

    Directory of Open Access Journals (Sweden)

    Takahito Suzuki

    Full Text Available Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10-100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG, lateral gastrocnemius (LG, and soleus muscles and quantified using the average rectified value (ARV. At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r2 > 0.65. The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006. Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively. These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis.

  17. Avaliação eletromiográfica e ressonância magnética do joelho de indivíduos com síndrome da dor femoropatelar Electromyographic and magnetic resonance imaging evaluations of individuals with patellofemoral pain syndrome

    Directory of Open Access Journals (Sweden)

    Alessandra C. S. Ribeiro

    2010-06-01

    Full Text Available OBJETIVOS: Analisar a atividade elétrica (EMG dos músculos vasto medial oblíquo (VMO, vasto lateral longo (VLL e vasto lateral oblíquo (VLO de indivíduos com síndrome da dor femoropatelar (SDFP durante contração isométrica voluntária máxima (CIVM de extensão da perna com o joelho a 30(0, a dor por meio da Escala Visual Analógica (EVA e o posicionamento da patela por meio da ressonância magnética nuclear por imagem (RMNI. MÉTODOS: Avaliaram-se 12 mulheres com SDFP e 12 clinicamente normais, que realizaram cinco CIVM de extensão da perna no ângulo de 30(0 para análise da EMG. Avaliou-se o ângulo do sulco (AS, ângulo de congruência (AC, ângulo de inclinação patelar (AIP e deslocamento patelar (DP pela RMNI. Utilizaram-se testes estatísticos: ANOVA, análise de variância de medidas repetidas para EMG; o teste Mann-Whitney U para análise da RMNI; o teste de correlação de Pearson (r entre EMG e RMNI e análise de variância one-way para avaliação da dor (pOBJECTIVES: To analyze the electrical activity of the vastus medialis obliquus (VMO, vastus lateralis longus (VLL and vastus lateralis obliquus (VLO muscles of individuals with patellofemoral pain syndrome (PFPS during maximum voluntary isometric contraction (MVIC of lower leg extension with the knee at 30°; to assess pain using a visual analogue scale (VAS; and to assess patellar positioning using magnetic resonance imaging (MRI. METHODS: Twelve women with PFPS and 12 clinically normal women were evaluated. They performed five MVICs of lower leg extension at 30° for electromyographic (EMG analysis. Using MRI, the sulcus angle (SA, congruence angle (CA, patellar tilt angle (PTA and patellar displacement (PD were obtained. The following statistical tests were used: analysis of variance (ANOVA for repeated measurements to assess EMGs; Mann-Whitney U test to analyze MRIs; Pearson's (r correlation test between EMGs and MRIs; and one-way ANOVA to evaluate pain (p<0

  18. Role of pathophysiology of patellofemoral instability in the treatment of spontaneous medial patellofemoral subluxation: a case report

    Directory of Open Access Journals (Sweden)

    Doğruyol Dağhan

    2010-05-01

    Full Text Available Abstract Introduction Medial patellar subluxation is usually seen after lateral retinacular release. Spontaneous medial subluxation of the patella is a very rare condition. There are few reports in the literature on the pathophysiology of iatrogenic medial patellar subluxation. To our knowledge, there are no reports of the pathophysiology of non-iatrogenic medial patellar subluxation in the English literature. In this study we present a case of spontaneous medial patellar instability that is more prominent in extension during weight bearing. We also try to define the treatment protocol based on pathophsiology. Case presentation We report the case of a 21-year-old Turkish man with spontaneous medial patellar instability. He had suffered right knee pain, clicking and popping sensation in the affected knee for three months prior to presentation. Clinical examination demonstrated medial patellar subluxation that is more prominent in extension during the weight bearing phase of gait and while standing. Increased medial tilt was observed when the patella was stressed medially. Conventional anterior to posterior, lateral and Merchant radiographs did not reveal any abnormalities. After three months of physical therapy, our patient was still suffering from right knee pain which disturbed his gait pattern. Throughout the surgery, medial patellar translation was tested following the imbrication of lateral structures. He still had a medial patellar translation that was more than 50% of his patellar width. Patellotibial ligament augmentation using an iliotibial band flap was added. When examined after surgery, the alignment of the patella was effectively corrected. Conclusions Chronic imbalance between the strengths of vastus lateralis and vastus medialis results in secondary changes in passive ligamentous structures and causes additional instability. Physical therapy modalities that aim to strengthen the vastus lateralis might be sufficient for the

  19. Change in skeletal muscle stiffness after running competition is dependent on both running distance and recovery time: a pilot study

    Directory of Open Access Journals (Sweden)

    Seyedali Sadeghi

    2018-03-01

    Full Text Available Long-distance running competitions impose a large amount of mechanical loading and strain leading to muscle edema and delayed onset muscle soreness (DOMS. Damage to various muscle fibers, metabolic impairments and fatigue have been linked to explain how DOMS impairs muscle function. Disruptions of muscle fiber during DOMS exacerbated by exercise have been shown to change muscle mechanical properties. The objective of this study is to quantify changes in mechanical properties of different muscles in the thigh and lower leg as function of running distance and time after competition. A custom implementation of Focused Comb-Push Ultrasound Shear Elastography (F-CUSE method was used to evaluate shear modulus in runners before and after a race. Twenty-two healthy individuals (age: 23 ± 5 years were recruited using convenience sampling and split into three race categories: short distance (nine subjects, 3–5 miles, middle distance (10 subjects, 10–13 miles, and long distance (three subjects, 26+ miles. Shear Wave Elastography (SWE measurements were taken on both legs of each subject on the rectus femoris (RF, vastus lateralis (VL, vastus medialis (VM, soleus, lateral gastrocnemius (LG, medial gastrocnemius (MG, biceps femoris (BF and semitendinosus (ST muscles. For statistical analyses, a linear mixed model was used, with recovery time and running distance as fixed variables, while shear modulus was used as the dependent variable. Recovery time had a significant effect on the soleus (p = 0.05, while running distance had considerable effect on the biceps femoris (p = 0.02, vastus lateralis (p < 0.01 and semitendinosus muscles (p = 0.02. Sixty-seven percent of muscles exhibited a decreasing stiffness trend from before competition to immediately after competition. The preliminary results suggest that SWE could potentially be used to quantify changes of muscle mechanical properties as a way for measuring recovery procedures for runners.

  20. Amino acid sequence and biological characterization of BlatPLA₂, a non-toxic acidic phospholipase A₂ from the venom of the arboreal snake Bothriechis lateralis from Costa Rica.

    Science.gov (United States)

    Van der Laat, Marco; Fernández, Julián; Durban, Jordi; Villalobos, Eva; Camacho, Erika; Calvete, Juan J; Lomonte, Bruno

    2013-10-01

    Bothriechis is considered a monophyletic, basal genus of arboreal Neotropical pitvipers distributed across Middle America. The four species found in Costa Rica (B. lateralis, B. schlegeli, B. nigroviridis, B. supraciliaris) differ in their venom proteomic profiles, suggesting that different Bothriechis taxa have evolved diverse trophic strategies. In this study, we isolated a phospholipase A₂ (PLA₂) from B. lateralis venom, aiming at increasing our knowledge on the structural and functional characteristics of group II acidic PLA₂s, whose toxic actions are generally more restricted than those displayed by basic PLA₂s. The new acidic enzyme, BlatPLA₂, occurs as a monomer of 13,917 Da, in contrast to many basic group II PLA₂s which associate into dimers and often display myotoxicity and/or neurotoxicity. Its amino acid sequence of 122 residues predicts an isoelectric point of 4.7, and displays significant differences with previously characterized acidic PLA₂s, with which it shows a maximum sequence identity of 78%. BlatPLA₂ is catalytically active but appears to be devoid of major toxic activities, lacking intravenous or intracerebroventricular lethality, myotoxicity, in vitro anticoagulant activity, and platelet aggregation or inhibition effects. Phylogenetic relationships with similar group II enzymes suggest that BlatPLA₂ may represent a basal sequence to other acidic PLA₂s. Due to the metabolic cost of venom protein synthesis, the presence of a relatively abundant (9%) but non-toxic component is somewhat puzzling. Nevertheless, we hypothesize that BlatPLA₂ could have a role in the pre-digestion of prey, possibly having retained characteristics of ancestral PLA₂s without evolving towards potent toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Corticosteroïdinjecties, fysiotherapie of een afwachtend beleid voor patiënten met een epicondylitis lateralis? Een gerandomiseerd onderzoek in de eerste lijn.

    NARCIS (Netherlands)

    Smidt, N.; Windt, D. van der; Assendelft, P.; Devillé, W.; Bouter, L.

    2004-01-01

    Doel: Vergelijking van de effecten van corticosteroïdinjecties, fysiotherapie en een afwachtend beleid voor een epicondylitis lateralis. Methoden: Patiëntenselectie vond plaats in 65 deelnemende huisartsenpraktijken. De belangrijkste insluitcriteria waren: minimaal 6 weken pijn aan de laterale zijde

  2. Ambient echolalia in a patient with germinoma around the bilateral ventriculus lateralis: a case report.

    Science.gov (United States)

    Suzuki, Tadashi; Itoh, Shouichi; Arai, Noritoshi; Kouno, Masako; Noguchi, Makoto; Takatsu, Masami; Takeda, Katsuhiko

    2012-01-01

    Ambient echolalia is a rare condition with few reported cases. We report the case of a 20-year-old man with a germinoma around the bilateral ventriculus lateralis who exhibited ambient echolalia. Clinical features included instinctive grasp reaction and compulsive manipulation of tools in his right hand. Speech or mental deterioration has been cited as a cause of ambient echolalia, but neither dementia nor aphasia was present. We propose that ambient echolalia in our case could be interpreted as a disinhibition of pre-existing essentially intact motor subroutines due to damage of the medial frontal lobe.

  3. Song convergence in multiple urban populations of silvereyes (Zosterops lateralis).

    Science.gov (United States)

    Potvin, Dominique A; Parris, Kirsten M

    2012-08-01

    Recent studies have revealed differences between urban and rural vocalizations of numerous bird species. These differences include frequency shifts, amplitude shifts, altered song speed, and selective meme use. If particular memes sung by urban populations are adapted to the urban soundscape, "urban-typical" calls, memes, or repertoires should be consistently used in multiple urban populations of the same species, regardless of geographic location. We tested whether songs or contact calls of silvereyes (Zosterops lateralis) might be subject to such convergent cultural evolution by comparing syllable repertoires of geographically dispersed urban and rural population pairs throughout southeastern Australia. Despite frequency and tempo differences between urban and rural calls, call repertoires were similar between habitat types. However, certain song syllables were used more frequently by birds from urban than rural populations. Partial redundancy analysis revealed that both geographic location and habitat characteristics were important predictors of syllable repertoire composition. These findings suggest convergent cultural evolution: urban populations modify both song and call syllables from their local repertoire in response to noise.

  4. Skeletal muscle plasticity with marathon training in novice runners.

    Science.gov (United States)

    Luden, N; Hayes, E; Minchev, K; Louis, E; Raue, U; Conley, T; Trappe, S

    2012-10-01

    The purpose of this study was to investigate leg muscle adaptation in runners preparing for their first marathon. Soleus and vastus lateralis (VL) biopsies were obtained from six recreational runners (23 ± 1 years, 61 ± 3 kg) before (T1), after 13 weeks of run training (T2), and after 3 weeks of taper and marathon (T3). Single muscle fiber size, contractile function (strength, speed, and power) and oxidative enzyme activity [citrate synthase (CS)] were measured at all three time points, and fiber type distribution was determined before and after the 16-week intervention. Training increased VO(2max) ∼9% (Pmarathon training elicits very specific skeletal muscle adaptations that likely support the ability to perform 42.2 km of continuous running - further strengthening the existing body of evidence for skeletal muscle specificity. © 2011 John Wiley & Sons A/S.

  5. High Intensity Exercise in Multiple Sclerosis

    DEFF Research Database (Denmark)

    Wens, Inez; Dalgas, Ulrik; Vandenabeele, Frank

    2015-01-01

    Introduction Low-to-moderate intensity exercise improves muscle contractile properties and endurance capacity in multiple sclerosis (MS). The impact of high intensity exercise remains unknown. Methods Thirty-four MS patients were randomized into a sedentary control group (SED, n = 11) and 2...... exercise groups that performed 12 weeks of a high intensity interval (HITR, n = 12) or high intensity continuous cardiovascular training (HCTR, n = 11), both in combination with resistance training. M.vastus lateralis fiber cross sectional area (CSA) and proportion, knee-flexor/extensor strength, body...... composition, maximal endurance capacity and self-reported physical activity levels were assessed before and after 12 weeks. Results Compared to SED, 12 weeks of high intensity exercise increased mean fiber CSA (HITR: +21±7%, HCTR: +23±5%). Furthermore, fiber type I CSA increased in HCTR (+29±6%), whereas type...

  6. The GLUT4 density in slow fibres is not increased in athletes. How does training increase the GLUT4 pool originating from slow fibres?

    DEFF Research Database (Denmark)

    Gaster, M; Franch, J; Beck-Nielsen, H

    2001-01-01

    % of the fraction in the control group. Thus, GLUT4 originating from slow-twitch fibres was increased by 30% (Pincreases slow-twitch fibre GLUT4 expression by means of an elevated slow-twitch fibre mass in human skeletal muscle.......The influence of training on GLUT4 expression in slow- and fast-twitch skeletal muscle fibres was studied in male endurance-trained athletes and control subjects. The trained state was ensured by elevated maximal oxygen uptake (29%), as well as citrate synthase (60%) and 3-hydroxy......-acyl-CoA dehydrogenase (38%) activities in muscle biopsy samples of the vastus lateralis. GLUT4 densities in slow- and fast-twitch fibres were measured by the use of a newly developed, sensitive method combining immunohistochemistry with morphometry, and no effect of training was found. GLUT4 density was higher in slow...

  7. Ski jumping boots limit effective take-off in ski jumping.

    Science.gov (United States)

    Virmavirta, M; Komi, P V

    2001-12-01

    In this study, we measured the vertical and horizontal take-off forces, plantar pressures and activation patterns of four muscles (vastus lateralis, gluteus maximus, tibialis anterior, gastrocnemius) in 10 ski jumpers in simulated laboratory conditions when wearing either training shoes or ski jumping boots. We found significant differences in vertical (P boots condition resulted in a smaller displacement in the final position of the following joint angles: ankle angle (P knee angle (P boots condition, significantly more pressure was recorded under the heel (P knee and hip extensors when wearing jumping boots. We conclude that the stiffness of the structure of the jumping boots may result in a forward shift of pressure, thus limiting the effective vertical force. To avoid this pressure shift, the pattern of movement of simulated take-offs should be carefully controlled, particularly when wearing training shoes.

  8. Gait transition and oxygen consumption in swimming striped surfperch Embiotoca lateralis Agassiz

    DEFF Research Database (Denmark)

    Cannas, M.; Schaefer, J.; Domenici, P.

    2006-01-01

    A flow-through respirometer and swim tunnel was used to estimate the gait transition speed (Up-c) of striped surfperch Embiotoca lateralis, a labriform swimmer, and to investigate metabolic costs associated with gait transition. The Up-c was defined as the lowest speed at which fish decrease...... the use of pectoral fins significantly. While the tail was first recruited for manoeuvring at relatively low swimming speeds, the use of the tail at these low speeds [as low as 0·75 body (fork) lengths s-1, LF s-1) was rare (..., either in addition to pectoral fins or during burst-and-coast mode. Oxygen consumption increased exponentially with swimming speeds up to gait transition, and then levelled off. Similarly, cost of transport (CT) decreased with increasing speed, and then levelled off near Up-c. When speeds =Up...

  9. The creation of a measurable contusion injury in skeletal muscle

    Directory of Open Access Journals (Sweden)

    Margaret N. Deane

    2014-08-01

    Full Text Available The effect that compressed air massage (CAM has on skeletal muscle has been ascertained by the morphological and morphometric evaluation of healthy vervet monkey and rabbit skeletal muscle. How CAM may influence the process of healing following a contusion injury is not known. To determine how CAM or other physiotherapeutic modalities may influence healing, it is necessary to create a minor injury that is both reproducible and quantifiable at the termination of a pre-determined healing period. An earlier study described changes in the morphology of skeletal muscle following a reproducible contusion injury. This study extended that work in that it attempted to quantify the ‘severity’ of such an injury. A 201 g, elongated oval-shaped weight was dropped seven times through a 1 m tube onto the left vastus lateralis muscle of four New Zealand white rabbits. Biopsies were obtained 6 days after injury from the left healing juxta-bone and sub-dermal muscle and uninjured (control right vastus lateralis of each animal. The tissue was fixed in formal saline, embedded in wax, cut and stained with haematoxylin and phosphotungstic haematoxylin. The muscle was examined by light microscopy and quantification of the severity of injury made using a modified, ‘in-house’ morphological index and by the comparative morphometric measurement of the cross-sectioned epimysium and myofibres in injured and control muscle. The results showed that a single contusion causes multiple, quantifiable degrees of injury from skin to bone – observations of particular importance to others wishing to investigate contusion injury in human or animal models.

  10. The effect of three different (-135°C whole body cryotherapy exposure durations on elite rugby league players.

    Directory of Open Access Journals (Sweden)

    James Selfe

    Full Text Available BACKGROUND: Whole body cryotherapy (WBC is the therapeutic application of extreme cold air for a short duration. Minimal evidence is available for determining optimal exposure time. PURPOSE: To explore whether the length of WBC exposure induces differential changes in inflammatory markers, tissue oxygenation, skin and core temperature, thermal sensation and comfort. METHOD: This study was a randomised cross over design with participants acting as their own control. Fourteen male professional first team super league rugby players were exposed to 1, 2, and 3 minutes of WBC at -135°C. Testing took place the day after a competitive league fixture, each exposure separated by seven days. RESULTS: No significant changes were found in the inflammatory cytokine interleukin six. Significant reductions (p<0.05 in deoxyhaemoglobin for gastrocnemius and vastus lateralis were found. In vastus lateralis significant reductions (p<0.05 in oxyhaemoglobin and tissue oxygenation index (p<0.05 were demonstrated. Significant reductions (p<0.05 in skin temperature were recorded. No significant changes were recorded in core temperature. Significant reductions (p<0.05 in thermal sensation and comfort were recorded. CONCLUSION: Three brief exposures to WBC separated by 1 week are not sufficient to induce physiological changes in IL-6 or core temperature. There are however significant changes in tissue oxyhaemoglobin, deoxyhaemoglobin, tissue oxygenation index, skin temperature and thermal sensation. We conclude that a 2 minute WBC exposure was the optimum exposure length at temperatures of -135°C and could be applied as the basis for future studies.

  11. Innervation zone of the vastus medialis muscle: position and effect on surface EMG variables

    International Nuclear Information System (INIS)

    Gallina, A; Merletti, R; Gazzoni, M

    2013-01-01

    The aim of this study was to investigate the position of the innervation zone (IZ) of the vastus medialis (VM) and its effect on the electromyographic (EMG) amplitude and mean frequency estimates. Eighteen healthy subjects performed maximal isometric knee extensions at three knee angles. Surface EMG signals were collected by using a 16 × 8 electrode grid placed on the VM muscle. The position of the IZ was estimated through visual analysis, and traditional bipolar signals were obtained from channels over and away from it; amplitude and mean frequency values were extracted and compared using an analysis of variance (ANOVA) with repeated measures. The IZ is shaped as a line running from the proximal–lateral to the distal–medial aspect of the VM muscle. The presence of an IZ under the electrodes lowered the EMG amplitude (P < 0.001, F = 58.11) and increased the EMG mean frequency (P < 0.001, F = 26.47); variations of these parameters due to the knee flexion angle were less frequently observed in EMG signals collected over than away from the IZ. Electrodes placed ‘over the belly of the VM muscle’ are likely to collect EMG signals influenced by the presence of the IZ, thus hindering the detection of changes in muscle activity. (paper)

  12. Influence of lower body pressure support on the walking patterns of healthy children and adults.

    Science.gov (United States)

    Kurz, Max J; Deffeyes, Joan E; Arpin, David J; Karst, Gregory M; Stuberg, Wayne A

    2012-11-01

    The purpose of this investigation was to evaluate the effect of a lower body positive pressure support system on the joint kinematics and activity of the lower extremity antigravity musculature of adults and children during walking. Adults (age = 25 ± 4 years) and children (age = 13 ± 2 years) walked at a preferred speed and a speed that was based on the Froude number, while 0-80% of their body weight was supported. Electrogoniometers were used to monitor knee and ankle joint kinematics. Surface electromyography was used to quantify the magnitude of the vastus lateralis and gastrocnemius muscle activity. There were three key findings: (1) The lower extremity joint angles and activity of the lower extremity antigravity muscles of children did not differ from those of adults. (2) The magnitude of the changes in the lower extremity joint motion and antigravity muscle activity was dependent upon an interaction between body weight support and walking speed. (3) Lower body positive pressure support resulted in reduced activation of the antigravity musculature, and reduced range of motion of the knee and ankle joints.

  13. Influence of Skeletal Muscle Carnosine Content on Fatigue during Repeated Resistance Exercise in Recreationally Active Women

    Science.gov (United States)

    Varanoske, Alyssa N.; Hoffman, Jay R.; Church, David D.; Baker, Kayla M.; Dodd, Sarah J.; Coker, Nicholas A.; Oliveira, Leonardo P.; Dawson, Virgil L.; Stout, Jeffrey R.

    2017-01-01

    Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine. PMID:28880219

  14. Human muscle fibre type-specific regulation of AMPK and downstream targets by exercise

    DEFF Research Database (Denmark)

    Kristensen, Dorte Enggaard; Albers, Peter Hjorth; Prats, Clara

    2015-01-01

    are expressed in a fibre type-dependent manner and that fibre type-specific activation of AMPK and downstream targets is dependent on exercise intensity. Pools of type I and II fibres were prepared from biopsies of m. vastus lateralis from healthy men before and after two exercise trials; A) continuous cycling......AMP-activated protein kinase (AMPK) is a regulator of energy homeostasis during exercise. Studies suggest muscle fibre type-specific AMPK expression. However, fibre type-specific regulation of AMPK and downstream targets during exercise has not been proven. We hypothesized that AMPK subunits...... (CON) 30 min at 69 ± 1% VO2peak or B) interval cycling (INT) 30 min with 6 × 1.5 min high-intense bouts peaking at 95 ± 2% VO2peak . In type I vs. II fibres a higher β1 AMPK (+215%) and lower γ3 AMPK expression (-71%) was found. α1 , α2 , β2 and γ1 AMPK expression was similar between fibre types...

  15. IL-1 receptor antagonism and muscle gene expression in patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Berchtold, L. A.; Larsen, C. M.; Vaag, A.

    2009-01-01

    ). To investigate the effects of IL-1Ra in insulin-sensitive tissue, gene expression levels in skeletal muscle from type 2 diabetic patients treated with IL-1Ra were analysed. Methods. Gene expression profiles in vastus lateralis muscle biopsies from five obese patients (BMI>27) were determined before and after 13......RT-PCR, were significantly altered when comparing the number of transcripts before and after treatment for each individual. Conclusion. Treatment with IL-1Ra did not significantly affect gene expression levels in skeletal muscle in this limited and selected sample of obese patients with type 2 diabetes. Larger...

  16. The effect of intensive insulin therapy on the insulin-regulatable glucose transporter (GLUT4) expression in skeletal muscle in type 1 diabetes

    DEFF Research Database (Denmark)

    Andersen, P H; Vestergaard, H; Lund, S

    1993-01-01

    h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble.......54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients....

  17. Maximal voluntary contraction force, SR function and glycogen resynthesis during the first 72 h after a high-level competitive soccer game

    DEFF Research Database (Denmark)

    Krustrup, Peter; Ørtenblad, Niels; Nielsen, Joachim

    2011-01-01

    The aim of this study was to examine maximal voluntary knee-extensor contraction force (MVC force), sarcoplasmic reticulum (SR) function and muscle glycogen levels in the days after a high-level soccer game when players ingested an optimised diet. Seven high-level male soccer players had a vastus...... lateralis muscle biopsy and a blood sample collected in a control situation and at 0, 24, 48 and 72 h after a competitive soccer game. MVC force, SR function, muscle glycogen, muscle soreness and plasma myoglobin were measured. MVC force sustained over 1 s was 11 and 10% lower (P ...

  18. Efeito da rotação do quadril na síndrome da dor femoropatelar Effect of hip rotation on patellofemoral pain syndrome

    Directory of Open Access Journals (Sweden)

    K Gramani-Say

    2006-01-01

    Full Text Available Objetivo: A proposta desse trabalho foi investigar o efeito da rotação do quadril na atividade elétrica dos músculos Vasto Medial Oblíquo (VMO, Vasto Lateral Oblíquo (VLO e Vasto Lateral Longo (VLL no agachamento a 45º de flexão do joelho associado à posição neutra, rotação lateral a 45º e rotação medial a 15 e 30º de quadril. Materiais e Método: Foram avaliadas 27 mulheres, sendo 15 mulheres normais do grupo Controle (21,1±2,1 anos e 12 portadoras de Síndrome da Dor Femoropatelar (SDFP (21,0±2,3 anos. A atividade elétrica do músculo quadríceps foi captada por eletrodos ativos diferenciais simples de superfície, eletromiógrafo de 8 canais e programa Aqdados 7.2.6. Os dados foram normalizados pela porcentagem da média do agachamento a 75º com o quadril em posição neutra RMS (µV. A análise estatística utilizada foi a ANOVA two way com medidas repetidas e Turkey post hoc (pObjective: The purpose of this study was to evaluate the effect of hip rotation on the electrical activity of the Vastus Medialis Obliquus (VMO, Vastus Lateralis Obliquus (VLO and Vastus Lateralis Longus (VLL muscles when squatting with 45º knee flexion, in association with the neutral position, 45º lateral rotation and 15 and 30º medial hip rotation. Method: 27 women were evaluated: 15 healthy women as a control group (21.1 ± 2.1 years and 12 subjects with patellofemoral pain syndrome (PFPS (21.0 ± 2.3 years. The electrical activity of the quadriceps muscle was detected using simple active differential surface electrodes, an eight-channel electromyography system and the Aqdados 7.2.6 software. The data were normalized by the mean squatting percentage at 75º with the hip in the neutral position RMS (µV. Two-way ANOVA with repeated measurements followed by the Tukey post hoc test (p<0.05 was used for statistical analysis. Results: The results revealed interaction between groups and muscles (p=0.00, independent of hip position (p=0.39, and

  19. Skeletal muscle lipid quantification in lean and diabetic subjects using in vivo proton MR spectroscopy

    Directory of Open Access Journals (Sweden)

    Sunil K Valaparla

    2014-03-01

    Full Text Available Purpose: To quantify and compare the intramyocellular (IMCL, extramyocellular (EMCL lipids and total fat fraction in human vastus lateralis muscle between lean and type 2 diabetic (T2DM subjects using long echo time (TE STEAM proton MR spectroscopy (1H-MRS. Methods: 1H-MRS using single voxel (15 × 15 × 15 mm3 stimulated acquisition mode (STEAM was performed in right vastus lateralis m. on 10 lean controls (age: 28.3 ± 3.94 yo, BMI: 24.25 ± 3.20 kg/m2 and 7 type 2 diabetic (age: 54.28 ± 6.42 yo, BMI: 31.34 ± 3.13 kg/m2 subjects with Siemens 3T MRI and a four-channel flex coil. Unsuppressed water spectra (NSA = 16 with TR/TE = 3000/30 ms, TM = 10 ms BW = 2000 Hz, and water-suppressed spectra (NSA = 128 with TR/TE = 3000/270 ms, TM = 10 ms, fixed water suppression BW = 50 Hz were acquired. Spectral intensity ratios of IMCL-CH2, EMCL-CH2 and total lipid (IMCL + EMCL with unsuppressed water signal (W were converted into absolute concentrations expressed in mmol/kg. Fat fraction (100 × F/(W+F was also calculated, where F includes the signal intensities of IMCL and EMCL methylene (CH2n, peaks only.Results: Comparison of IMCL (controls: 11.70 ± 6.7, T2DM: 21.74 ± 10.2, p < 0.01, EMCL (controls: 22.89 ± 18.42, T2DM: 77.21 ± 33.4, p < 0.001 and total lipid (64.35 mmol/kg less in controls, p < 0.001 showed statistical significance using two-tailed student’s t-test. Mean fat fraction (% exhibited considerable inter-individual variability for controls (3.14 ± 2.09; range: 1.34 – 7.04 and T2DM (9.34 ± 2.88; range: 4.15 – 13.67 and deemed significant (p < 0.05. Conclusion: Single voxel STEAM 1H-MRS at long TE provides a robust non-invasive method for characterizing lipids within localized muscle regions, with well-resolved IMCL/EMCL peak separation. Regional lipid estimate and fat fraction in vastus lateralis muscle is significantly different in T2DM compared to normal lean controls.------------------------------Cite this article as

  20. Influence of variable resistance loading on subsequent free weight maximal back squat performance.

    Science.gov (United States)

    Mina, Minas A; Blazevich, Anthony J; Giakas, Giannis; Kay, Anthony D

    2014-10-01

    The purpose of the study was to determine the potentiating effects of variable resistance (VR) exercise during a warm-up on subsequent free-weight resistance (FWR) maximal squat performance. In the first session, 16 recreationally active men (age = 26.0 ± 7.8 years; height = 1.7 ± 0.2 m; mass = 82.6 ± 12.7 kg) were familiarized with the experimental protocols and tested for 1 repetition maximum (1RM) squat lift. The subjects then visited the laboratory on 2 further occasions under either control or experimental conditions. During these conditions, 2 sets of 3 repetitions of either FWR (control) or VR (experimental) squat lifts at 85% of 1RM were performed; during the experimental condition, 35% of the load was generated from band tension. After a 5-minute rest, 1RM, 3D knee joint kinematics, and vastus medialis, vastus lateralis, rectus femoris, and semitendinosus electromyogram (EMG) signals were recorded simultaneously. No subject increased 1RM after FWR, however, 13 of 16 (81%) subjects increased 1RM after VR (mean = 7.7%; p 0.05) or EMG amplitudes (mean = 5.9%; p > 0.05) occurred. Preconditioning using VR significantly increased 1RM without detectable changes in knee extensor muscle activity or knee flexion angle, although eccentric and concentric velocities were reduced. Thus, VR seems to potentiate the neuromuscular system to enhance subsequent maximal lifting performance. Athletes could thus use VR during warm-up routines to maximize squat performance.

  1. Clinical and Functional Outcomes following Primary Repair versus Reconstruction of the Medial Patellofemoral Ligament for Recurrent Patellar Instability

    Directory of Open Access Journals (Sweden)

    Marc Tompkins

    2014-01-01

    Full Text Available Background. The purpose of this study was to compare outcomes of medial patellofemoral ligament (MPFL repair or reconstruction. Methods. Fourteen knees that underwent MPFL repair and nine (F5, M4 knees that underwent reconstruction at our institution were evaluated for objective and subjective outcomes. The mean age at operation was 20.1 years for repair and 19.8 years for reconstruction. All patients had a minimum of 2 years of follow-up (range: 24–75 months. Patient subjective outcomes were obtained using the International Knee Documentation Committee (IKDC and Kujala patellofemoral subjective evaluations, as well as Visual Analog (VAS and Tegner Activity Scales. Bilateral isometric quadriceps strength and vastus medialis obliquus (VMO and vastus lateralis (VL surface EMG were measured during maximal isometric quadriceps contractions at 30° and 60° of flexion. Results. There were no redislocations in either group. There was no difference in IKDC (P=0.16, Kujala (P=0.43, Tegner (P=0.12, or VAS (P=0.05 scores at follow-up. There were no differences between repair and reconstruction in torque generation of the involved side at 30° (P=0.96 and 60° (P=0.99. In addition, there was no side to side difference in torque generation or surface EMG activation of VL or VMO. Conclusions. There were minimal differences found between patients undergoing MPFL repair and MPFL reconstruction for the objective and subjective evaluations in this study.

  2. The Angiotensin Converting Enzyme Insertion/Deletion Polymorphism Modifies Exercise-Induced Muscle Metabolism.

    Directory of Open Access Journals (Sweden)

    David Vaughan

    Full Text Available A silencer region (I-allele within intron 16 of the gene for the regulator of vascular perfusion, angiotensin-converting enzyme (ACE, is implicated in phenotypic variation of aerobic fitness and the development of type II diabetes. We hypothesised that the reportedly lower aerobic performance in non-carriers compared to carriers of the ACE I-allele, i.e. ACE-DD vs. ACE-ID/ACE-II genotype, is associated with alterations in activity-induced glucose metabolism and capillarisation in exercise muscle.Fifty-three, not-specifically trained Caucasian men carried out a one-legged bout of cycling exercise to exhaustion and/or participated in a marathon, the aim being to identify and validate genotype effects on exercise metabolism. Respiratory exchange ratio (RER, serum glucose and lipid concentration, glycogen, and metabolite content in vastus lateralis muscle based on ultra-performance lipid chromatography-mass spectrometry (UPLC-MS, were assessed before and after the cycling exercise in thirty-three participants. Serum metabolites were measured in forty subjects that completed the marathon. Genotype effects were assessed post-hoc.Cycling exercise reduced muscle glycogen concentration and this tended to be affected by the ACE I-allele (p = 0.09. The ACE-DD genotype showed a lower maximal RER and a selective increase in serum glucose concentration after exercise compared to ACE-ID and ACE-II genotypes (+24% vs. +2% and -3%, respectively. Major metabolites of mitochondrial metabolism (i.e. phosphoenol pyruvate, nicotinamide adenine dinucleotide phosphate, L-Aspartic acid, glutathione were selectively affected in vastus lateralis muscle by exercise in the ACE-DD genotype. Capillary-to-fibre ratio was 24%-lower in the ACE-DD genotype. Individuals with the ACE-DD genotype demonstrated an abnormal increase in serum glucose to 7.7 mM after the marathon.The observations imply a genetically modulated role for ACE in control of glucose import and oxidation in

  3. Dose-response effect of photobiomodulation therapy on neuromuscular economy during submaximal running.

    Science.gov (United States)

    Dellagrana, Rodolfo André; Rossato, Mateus; Sakugawa, Raphael Luiz; Lazzari, Caetano Decian; Baroni, Bruno Manfredini; Diefenthaeler, Fernando

    2018-02-01

    The purpose of this study was to verify the photobiomodulation therapy (PBMT) effects with different doses on neuromuscular economy during submaximal running tests. Eighteen male recreational runners participate in a randomized, double-blind, and placebo-controlled trial, which each participant was submitted to the same testing protocol in five conditions: control, placebo, and PBMT with doses of 15, 30, and 60 J per site (14 sites in each lower limb). The submaximal running was performed at 8 and 9 km h -1 during 5 min for each velocity. Muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), and gastrocnemius lateralis (GL) was collected during the last minute of each running test. The root mean square (RMS) was normalized by maximal isometric voluntary contraction (MIVC) performed a priori in an isokinetic dynamometer. The RMS sum of all muscles (RMS LEG ) was considered as main neuromuscular economy parameter. PBMT with doses of 15, 30, and 60 J per site [33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm)] or placebo applications occurred before running tests. For the statistical analysis, the effect size was calculated. Moreover, a qualitative inference was used to determine the magnitude of differences between groups. Peak torque and RMS during MIVCs showed small effect sizes. According to magnitude-based inference, PBMT with dose of 15 J per site showed possibly and likely beneficial effects on neuromuscular economy during running at 8 and 9 km h -1 , respectively. On other hand, PBMT with doses of 30 and 60 J per site showed possible beneficial effects only during running at 9 km h -1 . We concluded that PBMT improve neuromuscular economy and the best PBMT dose was 15 J per site (total dose of 420 J).

  4. The Metabolic Response of Skeletal Muscle to Endurance Exercise Is Modified by the ACE-I/D Gene Polymorphism and Training State

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    Paola Valdivieso

    2017-12-01

    Full Text Available The insertion/deletion polymorphism in the gene for the regulator of vascular tone, angiotensin-converting enzyme (ACE, is the prototype of a genetic influence on physical fitness and this involves an influence on capillary supply lines and dependent aerobic metabolism in skeletal muscle. The respective interaction of ACE-I/D genotype and training status on local metabolic and angiogenic reactions in exercised muscle is not known. Toward this end we characterized the metabolomic and angiogenic response in knee extensor muscle, m. vastus lateralis, in 18 untrained and 34 endurance-trained (physically active, V˙O2max > 50 mL min−1 kg−1 white British men to an exhaustive bout of one-legged cycling exercise. We hypothesized that training status and ACE-I/D genotype affect supply-related muscle characteristics of exercise performance in correspondence to ACE expression and angiotensin 2 levels. ACE-I/D genotype and training status developed an interaction effect on the cross-sectional area (CSA of m. vastus lateralis and mean CSA of slow type fibers, which correlated with peak power output (r ≥ 0.44. Genotype × training interactions in muscle also resolved for exercise-induced alterations of 22 metabolites, 8 lipids, glycogen concentration (p = 0.016, ACE transcript levels (p = 0.037, and by trend for the pro-angiogenic factor tenascin-C post exercise (p = 0.064. Capillary density (p = 0.001, capillary-to-fiber ratio (p = 0.010, systolic blood pressure (p = 0.014, and exercise-induced alterations in the pro-angiogenic protein VEGF (p = 0.043 depended on the ACE-I/D genotype alone. Our observations indicate that variability in aerobic performance in the studied subjects was in part reflected by an ACE-I/D-genotype-modulated metabolic phenotype of a major locomotor muscle. Repeated endurance exercise appeared to override this genetic influence in skeletal muscle by altering the ACE-related metabolic response and molecular aspects of the

  5. The Metabolic Response of Skeletal Muscle to Endurance Exercise Is Modified by the ACE-I/D Gene Polymorphism and Training State.

    Science.gov (United States)

    Valdivieso, Paola; Vaughan, David; Laczko, Endre; Brogioli, Michael; Waldron, Sarah; Rittweger, Jörn; Flück, Martin

    2017-01-01

    The insertion/deletion polymorphism in the gene for the regulator of vascular tone, angiotensin-converting enzyme (ACE), is the prototype of a genetic influence on physical fitness and this involves an influence on capillary supply lines and dependent aerobic metabolism in skeletal muscle. The respective interaction of ACE-I/D genotype and training status on local metabolic and angiogenic reactions in exercised muscle is not known. Toward this end we characterized the metabolomic and angiogenic response in knee extensor muscle, m. vastus lateralis , in 18 untrained and 34 endurance-trained (physically active, [Formula: see text]O2max > 50 mL min -1 kg -1 ) white British men to an exhaustive bout of one-legged cycling exercise. We hypothesized that training status and ACE-I/D genotype affect supply-related muscle characteristics of exercise performance in correspondence to ACE expression and angiotensin 2 levels. ACE-I/D genotype and training status developed an interaction effect on the cross-sectional area (CSA) of m. vastus lateralis and mean CSA of slow type fibers, which correlated with peak power output ( r ≥ 0.44). Genotype × training interactions in muscle also resolved for exercise-induced alterations of 22 metabolites, 8 lipids, glycogen concentration ( p = 0.016), ACE transcript levels ( p = 0.037), and by trend for the pro-angiogenic factor tenascin-C post exercise ( p = 0.064). Capillary density ( p = 0.001), capillary-to-fiber ratio ( p = 0.010), systolic blood pressure ( p = 0.014), and exercise-induced alterations in the pro-angiogenic protein VEGF ( p = 0.043) depended on the ACE-I/D genotype alone. Our observations indicate that variability in aerobic performance in the studied subjects was in part reflected by an ACE-I/D-genotype-modulated metabolic phenotype of a major locomotor muscle. Repeated endurance exercise appeared to override this genetic influence in skeletal muscle by altering the ACE-related metabolic response and molecular aspects

  6. Frequency band analysis of muscle activation during cycling to exhaustion.DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p243

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Vaz

    2012-05-01

    Full Text Available Lower limb muscles activation was assessed during cycling to exhaustion using frequency band analysis. Nine cyclists were evaluated in two days. On the first day, cyclists performed a maximal incremental cycling exercise to measure peak power output, which was used on the second day to define the workload for a constant load time to exhaustion cycling exercise (maximal aerobic power output from day 1. Muscle activation of vastus lateralis (VL, long head of biceps femoris (BF, lateral head of gastrocnemius (GL, and tibialis anterior (TA from the right lower limb was recorded during the time to exhaustion cycling exercise. A series of nine band-pass Butterworth digital filters was used to analyze muscle activity amplitude for each band. The overall amplitude of activation and the high and low frequency components were defined to assess the magnitude of fatigue effects on muscle activity via effect sizes. The profile of the overall muscle activation during the test was analyzed using a second order polynomial, and the variability of the overall bands was analyzed by the coefficient of variation for each muscle in each instant of the test. Substantial reduction in the high frequency components of VL and BF activation was observed. The overall and low frequency bands presented trivial to small changes for all muscles. High relationship between the second order polynomial fitting and muscle activity was found (R2 > 0.89 for all muscles. High variability (~25% was found for muscle activation at the four instants of the fatigue test. Changes in the spectral properties of the EMG signal were only substantial when extreme changes in fatigue state were induced.

  7. Aging Reduces the Activation of the mTORC1 Pathway after Resistance Exercise and Protein Intake in Human Skeletal Muscle: Potential Role of REDD1 and Impaired Anabolic Sensitivity.

    Science.gov (United States)

    Francaux, Marc; Demeulder, Bénédicte; Naslain, Damien; Fortin, Raphael; Lutz, Olivier; Caty, Gilles; Deldicque, Louise

    2016-01-15

    This study was designed to better understand the molecular mechanisms involved in the anabolic resistance observed in elderly people. Nine young (22 ± 0.1 years) and 10 older (69 ± 1.7 years) volunteers performed a one-leg extension exercise consisting of 10 × 10 repetitions at 70% of their 3-RM, immediately after which they ingested 30 g of whey protein. Muscle biopsies were taken from the vastus lateralis at rest in the fasted state and 30 min after protein ingestion in the non-exercised (Pro) and exercised (Pro+ex) legs. Plasma insulin levels were determined at the same time points. No age difference was measured in fasting insulin levels but the older subjects had a 50% higher concentration than the young subjects in the fed state (p young subjects. After Pro+ex, REDD1 expression tended to be higher (p = 0.087) in the older group while AMPK phosphorylation was not modified by any condition. In conclusion, we show that the activation of the mTORC1 pathway is reduced in skeletal muscle of older subjects after resistance exercise and protein ingestion compared with young subjects, which could be partially due to an increased expression of REDD1 and an impaired anabolic sensitivity.

  8. Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

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    Huang Stephanie

    2012-08-01

    Full Text Available Abstract Background Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user’s nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. Methods We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step inter-subject variability of these profiles by calculating variance-to-signal ratios. Results We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. Conclusion Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee’s nervous system.

  9. Normal mitochondrial function and increased fat oxidation capacity in leg and arm muscles in obese humans

    DEFF Research Database (Denmark)

    Ara, I; Larsen, S; Stallknecht, Bente Merete

    2011-01-01

    was that fat oxidation during exercise might be differentially preserved in leg and arm muscles after weight loss.Methods:Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsy samples were obtained from musculus...... deltoideus (m. deltoideus) and m. vastus lateralis muscles. Fibre-type composition, enzyme activity and O(2) flux capacity of saponin-permeabilized muscle fibres were measured, the latter by high-resolution respirometry.Results:During the graded exercise tests, peak fat oxidation during leg cycling...... and the relative workload at which it occurred (FatMax) were higher in PO and O than in C. During arm cranking, peak fat oxidation was higher in O than in C, and FatMax was higher in O than in PO and C. Similar fibre-type composition was found between groups. Plasma adiponectin was higher in PO than in C and O...

  10. Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle

    DEFF Research Database (Denmark)

    Jørgensen, Stine Ringholm; Biensø, Rasmus S; Kiilerich, Kristian

    2011-01-01

    Background: The aim was to test the hypothesis that one week of bed rest will reduce mitochondrial number and expression and activity of oxidative proteins in human skeletal muscle, but that exercise-induced intracellular signaling as well as mRNA and microRNA (miR) responses are maintained after......-legged knee extensor exercise performed before and after bed rest. Results: Maximal oxygen uptake decreased 5% and exercise endurance decreased non-significantly 25% by bed rest. Bed rest reduced skeletal muscle mitochondrial DNA/nuclear DNA content 15%, hexokinase II and sirtuin 1 protein content ~45%, 3...... bed rest. Research Design and Methods: Twelve young, healthy, male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies taken before and after bed rest. In addition, muscle biopsies were obtained from 6 of the subjects prior to, immediately after and 3h after 45 min one...

  11. Training affects muscle phospholipid fatty acid composition in humans

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Wu, B J; Willer, Mette

    2001-01-01

    on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk......, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P fatty acids...... was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P

  12. [Metabonomics on toxicity reduction of Glycyrrhizae Radix et Rhizoma for Aconiti Lateralis Radix Preparata in Sini Tang].

    Science.gov (United States)

    Li, Ying; Fu, Chao-Mei; Peng, Wei; Li, Bo; Fu, Shu; Zhang, Hui-Min

    2016-04-01

    To analyze the endogenous metabolite changes in rat plasma after intervention by Sini Tang and Sini Tang without Glycyrrhizae Radix et Rhizoma based on GC-MS metabonomics technology, and study the toxicity reduction effect of Glycyrrhizae Radix et Rhizoma in Sini Tang on Aconiti Lateralis Radix Preparata. Eighteen SD rats were randomly divided into normal group, Sini Tang group and Sini Tang without Glycyrrhizae Radix et Rhizoma group on average. The rats in Sini Tang group and Sini Tang without Glycyrrhizae Radix et Rhizoma group were treated respectively with physic liquor by intragastric administration at the dose of 0.02 mL•g ⁻¹ (equivalent to 0.8 g•mL ⁻¹ crude drugs) once a day for 7 days. The rats in normal group were given with equal volume of saline solution. The plasma samples were collected from each rat 0.5 h after the last administration for GC-MS detection. The data was used for multivariate statistical analysis to obtain 14 potential metabolic markers(13 of them were identified). Then their relative content and metabolic pathways were analyzed. Compared with Sini Tang without Glycyrrhizae Radix et Rhizoma group, seven metabolic markers of were reduced in Sini Tang group. Analysis on physiological functions of these potential metabolic markers showed that the Glycyrrhizae Radix et Rhizoma in Sini Tang could reduce the toxicity of Aconiti Lateralis Radix Preparata by adjusting the glycolysis, lipid metabolism, citrate cycle and some amino acids metabolism. Copyright© by the Chinese Pharmaceutical Association.

  13. Kinematics and energetic benefits of schooling in the labriform fish, striped surfperch Embiotoca lateralis

    DEFF Research Database (Denmark)

    Johansen, J. L.; Vaknin, R.; Steffensen, John Fleng

    2010-01-01

    Schooling can provide fish with a number of behavioural and ecological advantages, including increased food supply and reduced predator risk. Previous work suggests that fish swimming using body and caudal fin locomotion may also experience energetic advantages when trailing behind neighbours......, based on correlations between swimming speeds and pectoral fin beat frequency and between swimming speeds and oxygen consumption of solitary fish. In addition, leading individuals in a school were estimated to have higher oxygen consumption than solitary individuals swimming at the same speed, based....... However, little is known about the potential energetic advantages associated with schooling in fish that swim using their pectoral fins. Using the striped surfperch Embiotoca lateralis, a labriform fish that swims routinely with its pectoral fins, we found that pectoral fin beat frequencies were...

  14. Muscle fibre type composition and body composition in hammer throwers.

    Science.gov (United States)

    Terzis, Gerasimos; Spengos, Konstantinos; Kavouras, Stavros; Manta, Panagiota; Georgiadis, Giorgos

    2010-01-01

    Aim of the present study was to describe the muscle fibre type composition and body composition of well-trained hammer throwers. Six experienced hammer throwers underwent the following measurements: one repetition maximum in squat, snatch, and clean, standing broad jump, backward overhead shot throw and the hammer throw. Dual x-ray absorptiometry was used for body composition analysis. Fibre type composition and cross sectional area was determined in muscle biopsy samples of the right vastus lateralis. Eight physical education students served as a control group. One repetition maximum in squat, snatch and clean for the hammer throwers was 245 ± 21, 132 ± 13 and 165 ± 12kg, respectively. Lean body mass was higher in hammer throwers (85.9 ± 3. 9kg vs. 62.7 ± 5.1kg (p hammer throwers and 51 ± 8% in the control group (p Hammer throwers had significantly larger type IIA fibres (7703 ± 1171 vs. 5676 ± 1270μm(2), p Hammer throwing performance correlated significantly with lean body mass (r = 0.81, p hammer throwers have larger lean body mass and larger muscular areas occupied by type II fibres, compared with relatively untrained subjects. Moreover, it seems that the enlarged muscle mass of the hammer throwers contributes significantly to the hammer throwing performance. Key pointsWell-trained hammer throwers had increased lean body mass, higher type IIA muscle fibres cross sectional areas, as well as higher bone mineral density, compared to controls.Increased lean body mass was closely related with hammer throwing performance.The relative high percentage of type IIX muscle fibres in vastus lateralis in hammer throwers warrants further investigation.

  15. Changes in Muscle Architecture, Explosive Ability, and Track and Field Throwing Performance Throughout a Competitive Season and After a Taper.

    Science.gov (United States)

    Bazyler, Caleb D; Mizuguchi, Satoshi; Harrison, Alex P; Sato, Kimitake; Kavanaugh, Ashley A; DeWeese, Brad H; Stone, Michael H

    2017-10-01

    The purpose of this study was to examine the effects of an overreach and taper on measures of muscle architecture, jumping, and throwing performance in Division I collegiate throwers preparing for conference championships. Six collegiate track and field throwers (3 hammer, 2 discus, 1 javelin) trained for 12 weeks using a block-periodization model culminating with a 1-week overreach followed by a 3-week taper (ORT). Session rating of perceived exertion training load (RPETL) and strength training volume-load times bar displacement (VLd) were recorded weekly. Athletes were tested pre-ORT and post-ORT on measures of vastus lateralis architecture, unloaded and loaded squat and countermovement jump performance, underhand and overhead throwing performance, and competition throwing performance. There was a statistical reduction in weight training VLd/session (d = 1.21, p ≤ 0.05) and RPETL/session (d = 0.9, p ≤ 0.05) between the in-season and ORT training phases. Five of 6 athletes improved overhead throw and competition throwing performance after the ORT (d = 0.50, p ≤ 0.05). Vastus lateralis muscle thickness statistically increased after the in-season training phase (d = 0.28, p ≤ 0.05) but did not change after the ORT. Unloaded countermovement jump peak force and relative peak power improved significantly after the ORT (d = 0.59, p ≤ 0.05, d = 0.31, p ≤ 0.05, respectively). These findings demonstrate that an overreaching week followed by a 3-week taper is an effective means of improving explosive ability and throwing performance in collegiate track and field throwers despite the absence of detectable changes in muscle architecture.

  16. Skeletal muscle magnetic resonance biomarkers correlate with function and sentinel events in Duchenne muscular dystrophy.

    Science.gov (United States)

    Barnard, Alison M; Willcocks, Rebecca J; Finanger, Erika L; Daniels, Michael J; Triplett, William T; Rooney, William D; Lott, Donovan J; Forbes, Sean C; Wang, Dah-Jyuu; Senesac, Claudia R; Harrington, Ann T; Finkel, Richard S; Russman, Barry S; Byrne, Barry J; Tennekoon, Gihan I; Walter, Glenn A; Sweeney, H Lee; Vandenborne, Krista

    2018-01-01

    To provide evidence for quantitative magnetic resonance (qMR) biomarkers in Duchenne muscular dystrophy by investigating the relationship between qMR measures of lower extremity muscle pathology and functional endpoints in a large ambulatory cohort using a multicenter study design. MR spectroscopy and quantitative imaging were implemented to measure intramuscular fat fraction and the transverse magnetization relaxation time constant (T2) in lower extremity muscles of 136 participants with Duchenne muscular dystrophy. Measures were collected at 554 visits over 48 months at one of three imaging sites. Fat fraction was measured in the soleus and vastus lateralis using MR spectroscopy, while T2 was assessed using MRI in eight lower extremity muscles. Ambulatory function was measured using the 10m walk/run, climb four stairs, supine to stand, and six minute walk tests. Significant correlations were found between all qMR and functional measures. Vastus lateralis qMR measures correlated most strongly to functional endpoints (|ρ| = 0.68-0.78), although measures in other rapidly progressing muscles including the biceps femoris (|ρ| = 0.63-0.73) and peroneals (|ρ| = 0.59-0.72) also showed strong correlations. Quantitative MR biomarkers were excellent indicators of loss of functional ability and correlated with qualitative measures of function. A VL FF of 0.40 was an approximate lower threshold of muscle pathology associated with loss of ambulation. Lower extremity qMR biomarkers have a robust relationship to clinically meaningful measures of ambulatory function in Duchenne muscular dystrophy. These results provide strong supporting evidence for qMR biomarkers and set the stage for their potential use as surrogate outcomes in clinical trials.

  17. Supersonic Shear Imaging Elastography in Skeletal Muscles: Relationship Between In Vivo and Synthetic Fiber Angles and Shear Modulus.

    Science.gov (United States)

    Lima, Kelly; Rouffaud, Remi; Pereira, Wagner; Oliveira, Liliam F

    2018-04-30

    To verify a relationship between the pennation angle of synthetic fibers and muscle fibers with the shear modulus (μ) generated by Supersonic shear imaging (SSI) elastography and to compare the anisotropy of synthetic and in vivo pennate muscle fibers in the x 2 -x 3 plane (probe perpendicular to water surface or skin). First, the probe of Aixplorer ultrasound scanner (v.9, Supersonic Imagine, Aix-en-Provence, France) was placed in 2 positions (parallel [aligned] and transverse to the fibers) to test the anisotropy in the x 2 -x 3 plane. Subsequently, it was inclined (x 1 -x 3 plane) in relation to the fibers, forming 3 angles (18.25 °, 21.55 °, 36.86 °) for synthetic fibers and one (approximately 0 °) for muscle fibers. On the x 2 -x 3 plane, μ values of the synthetic and vastus lateralis fibers were significantly lower (P < .0001) at the transverse probe position than the longitudinal one. In the x 1 -x 3 plane, the μ values were significantly reduced (P < .0001) with the probe angle increasing, only for the synthetic fibers (approximately 0.90 kPa for each degree of pennation angle). The pennation angle was not related to the μ values generated by SSI elastography for the in vivo lateral head of the gastrocnemius and vastus lateralis muscles. However, a μ reduction with an angle increase in the synthetic fibers was observed. These findings contribute to increasing the applicability of SSI in distinct muscle architecture at normal or pathologic conditions. © 2018 by the American Institute of Ultrasound in Medicine.

  18. Nearly complete mitogenome of hairy sawfly, Corynis lateralis (Brullé, 1832) (Hymenoptera: Cimbicidae): rearrangements in the IQM and ARNS1EF gene clusters.

    Science.gov (United States)

    Doğan, Özgül; Korkmaz, E Mahir

    2017-10-01

    The Cimbicidae is a small family of the primitive and relatively less diverse suborder Symphyta (Hymenoptera). Here, nearly complete mitochondrial genome (mitogenome) of hairy sawfly, Corynis lateralis (Hymenoptera: Cimbicidae) was sequenced using next generation sequencing and comparatively analysed with the mitogenome of Trichiosoma anthracinum. The sequenced length of C. lateralis mitogenome was 14,899 bp with an A+T content of 80.60%. All protein coding genes (PCGs) are initiated by ATN codons and all are terminated with TAR or T- stop codon. All tRNA genes preferred usual anticodons. Compared with the inferred insect ancestral mitogenome, two tRNA rearrangements were observed in the IQM and ARNS1EF gene clusters, representing a new event not previously reported in Symphyta. An illicit priming of replication and/or intra/inter-mitochondrial recombination and TDRL seem to be responsible mechanisms for the rearrangement events in these gene clusters. Phylogenetic analyses confirmed the position of Corynis within Cimbicidae and recovered a relationship of Tenthredinoidea + (Cephoidea + Orussoidea) in Symphyta.

  19. Perawatan Ulang Saluran Akar Insisivus Lateralis Kiri Maksila dengan Medikamen Kalsium Hidroksida-Chlorhexidine

    Directory of Open Access Journals (Sweden)

    Ni Gusti Ayu Ariani

    2013-06-01

    Full Text Available Banyak faktor yang menyebabkan kegagalan terapi endodontik antara lain pembersihan dan membentuk saluran akar yang tidak sempurna dan obturasi tidak hermetis sehingga menyebabkan kurangnya kemampuan untuk menghilangkan mikroorganisme yang ada. Saluran akar yang terinfeksi membutuhkan suatu medikamen untuk menunjang keberhasilan dalam perawatan saluran akar.Kalsium hidroksida merupakan salah satu bahan medikamen yang efektif karena memiliki sifat antibakteri dengan spektrum luas, pH tinggi, biokompatibilitas baik, mampu menetralkan endotoksin bakteri, memiliki sifat toksik yang paling rendah, serta menstimulasi pembentukan jaringan keras. Tujuan laporan kasus untuk menunjukan keberhasilan perawatan ulang saluran akar gigi insisivus lateralis kiri maksila dengan lesi periapikal menggunakan medikamen kalsium hidroksida- chlorhexidine. Pasien wanita umur 53 tahun, gigi insisivus lateralis kiri maksila dengan lesi periapikal.Radiografi tampak obturasi kurang hermetis dan radiolusen daerah periapikal. Perawatan ulang saluran akar,diikuti pemasangan pasak fiber frefabricated dan restorasi porselin fuse metal.Keseimpulan setelah evaluasi setelah enam bulan pasca perawatan ulang saluran akar, radiografi menunjukan radiolusen mengecil dan gigi dapat berfungsi dengan normal. Re-Treatment of Root Canal of Maxillary Left Lateral Incisor with Calcium Hydroxide-Chlorhexidine Medicament. There are many factors that cause failure of endodontic therapy. For instances, incomplete cleaning and shaping of root canal and inadequate obturation that results in difficulty to remove the microorganisms. Infected root canal requires a medicament for the success of the root canal treatment. Calcium hydroxide is one of the effective ingredients as medicament because it has broad spectrum antibacterial properties, high pH, good biocompatibility, and it is able to neutralize bacterial endotoxins, decrease tissue toxicity, and stimulate the formation of hard tissue. The purpose

  20. Expression of extracellular matrix components and related growth factors in human tendon and muscle after acute exercise

    DEFF Research Database (Denmark)

    Heinemeier, K M; Bjerrum, S S; Schjerling, P

    2013-01-01

    Acute kicking exercise induces collagen synthesis in both tendon and muscle in humans, but it is not known if this relates to increased collagen transcription and if other matrix genes are regulated. Young men performed 1 h of one-leg kicking at 67% of max workload. Biopsies were taken from...... the patellar tendon and vastus lateralis muscle of each leg at 2 (n = 10), 6 (n = 11), or 26 h (n = 10) after exercise. Levels of messenger ribonucleic acid mRNA for collagens, noncollagenous matrix proteins, and growth factors were measured with real-time reverse transcription polymerase chain reaction...

  1. A decline in PABPN1 induces progressive muscle weakness in oculopharyngeal muscle dystrophy and in muscle aging

    DEFF Research Database (Denmark)

    Anvar, Seyed Yahya; Raz, Yotam; Verway, Nisha

    2013-01-01

    Oculopharyngeal muscular dystrophy (OPMD) is caused by trinucleotide repeat expansion mutations in Poly(A) binding protein 1 (PABPN1). PABPN1 is a regulator of mRNA stability and is ubiquitously expressed. Here we investigated how symptoms in OPMD initiate only at midlife and why a subset...... of skeletal muscles is predominantly affected. Genome-wide RNA expression profiles from Vastus lateralis muscles human carriers of expanded-PABPN1 at pre-symptomatic and symptomatic stages were compared with healthy controls. Major expression changes were found to be associated with age rather than...... with expression of expanded-PABPN1, instead transcriptomes of OPMD and elderly muscles were significantly similar (P...

  2. Enhanced fatty acid oxidation and FATP4 protein expression after endurance exercise training in human skeletal muscle

    DEFF Research Database (Denmark)

    Jeppesen, Jacob; Jordy, Andreas B; Sjøberg, Kim A

    2012-01-01

    ; however, it is not known whether this involves up-regulation of FATP1 and FATP4 protein. Therefore, the aim of this project was to investigate FATP1 and FATP4 protein expression in the vastus lateralis muscle from healthy human individuals and to what extent FATP1 and FATP4 protein expression were......FATP1 and FATP4 appear to be important for the cellular uptake and handling of long chain fatty acids (LCFA). These findings were obtained from loss- or gain of function models. However, reports on FATP1 and FATP4 in human skeletal muscle are limited. Aerobic training enhances lipid oxidation...

  3. Effects of long-term football training on the expression profile of genes involved in muscle oxidative metabolism

    DEFF Research Database (Denmark)

    Alfieri, A; Martone, D; Randers, Morten Bredsgaard

    2015-01-01

    and a muscle biopsy from the vastus lateralis were collected at T0 (pre intervention) and at T1 (post intervention). Gene expression was measured by RTqPCR on RNA extracted from muscle biopsies. The expression levels of the genes principally involved in energy metabolism (PPARγ, adiponectin, AMPKα1/α2, TFAM...... to improve the expression of muscle molecular biomarkers that are correlated to oxidative metabolism in healthy males....... are directly or indirectly involved in the glucose and lipid oxidative metabolism. Multiple linear regression analysis revealed that fat percentage was independently associated with NAMPT, PPARγ and adiponectin expression. In conclusion, long-term recreational football training could be a useful tool...

  4. Effect of formoterol, a long-acting β2-adrenergic agonist, on muscle strength and power output, metabolism and fatigue during maximal sprinting in men

    DEFF Research Database (Denmark)

    Kalsen, Anders; Hostrup, Morten; Backer, Vibeke

    2016-01-01

    The aim was to investigate the effect of the long-acting β2-adrenergic agonist formoterol on muscle strength and power output, muscle metabolism and phosphorylation of CaMKII Thr(287) and FXYD1 during maximal sprinting. In a double-blind crossover study, thirteen males (VO2max: 45.0±0.2 (mean±SE) m......L min(-1) kg(-1)) performed a 30-s cycle ergometer sprint after inhalation of either 54 µg formoterol (FOR) or placebo (PLA). Before and after the sprint, muscle biopsies were collected from vastus lateralis and maximal voluntary contraction (MVC) and contractile properties of quadriceps were measured...

  5. MODERN TAKE-OFF POWER DIAGNOSTICS

    Directory of Open Access Journals (Sweden)

    Milan Čoh

    2008-08-01

    Full Text Available Take-off power is one of the main biomotor abilities for predicting the results of many sport disciplines. It plays a particularly important role in motor situations when the take-off power is combined with the velocity of movement. The core aim of this study was to establish and analyse the fundamental kinematic, dynamic and electromyographic parameters which generate the results of selected take-off power tests. The experimental procedure involved two elite female triple jumpers. According to Bosco’s protocol the following tests were selected: squat jump, countermovement jump and drop jump – 25 cm. The following were analysed: jump height, take-off time, flight time, take-off velocity, maximum take-off force, angle velocity of the ankle, knee and hip joints, force impulse and duration of the eccentric and concen ric phases of take-off. The 3D-kinematic analysis of jumps was based on a system of nine SMART-e 600 video-cameras (BTS Bioengineering, with a 60 Hz frequency and a 768 x 576 pixel resolution. The kinematic parameters were processed using the BTS SMART Suite programme. Dynamic parameters were established by means of two separate force-plat forms, namely Kistler, Type 9286A. The analysis of the electromyographic activity (EMG of the following muscles: m. erector spinae, m. gluteus maximus, m. rectus femoris, m. vastus medialis, m. vastus lateralis, m. biceps femoris, m. tibialis anterior and m. gastrocnemius medialis was made using a 16-channel electromyograph (BTS Pocket EMG, MYOLAB. The research showed that the jump height (h as a criterion of explosive power was generated by: the velocity of take-off, flight time, force impulse in the concentric phase and optimal knee joint angle. The analysis of the EMG activation in vertical jumps showed the proximaldistal principle of muscle activation. In the first phase of the take-off action, the trunk extensors (m. erector spinae and hip extensors (m. gluteus maximus are activated. In the

  6. Effects of muscle composition and architecture on specific strength in obese older women.

    Science.gov (United States)

    Rastelli, F; Capodaglio, P; Orgiu, S; Santovito, C; Caramenti, M; Cadioli, M; Falini, A; Rizzo, G; Lafortuna, C L

    2015-10-01

    What is the central question of this study? Do obesity-specific factors affect skeletal muscle performance in older individuals? What is the main finding and its importance? Older obese women have a larger quadriceps femoris size but develop lower tension per unit of skeletal muscle than their normal-weight counterparts. Muscle impairment and excess body mass are very common among older people. Given that the effect of obesity on strength production has scarcely been studied in older individuals, we analysed functional and structural characteristics of quadriceps femoris (QF) in obese (OB) and normal-weight (NW) older women with comparable habitual physical activity. In five OB (body mass index 36.8 ± 1.9 kg m(-2), age 72.4 ± 2.3 years) and six NW well-functioning older women (body mass index 24.3 ± 1.8 kg m(-2), age 72.7 ± 1.9 years), peak knee-extension torque (KET) was measured in isometric (90 deg knee flexion) and isokinetic conditions (240, 180, 120 and 60 deg s(-1)). Mid-thigh QF cross-sectional area (CSA) and muscle tissue fat content (MF%) were determined with magnetic resonance imaging (Dixon sequence). Muscle fascicle length and pennation angle (PA) were assessed with ultrasonography for each muscle belly of the QF (vastus lateralis, vastus intermedius, rectus femoris and vastus intermedius). Despite similar values of KET, CSA was 17.0% larger in OB than in NW women (P Muscle composition and architecture seem to be important determinants of KET/CSA in elderly women. In fact, owing to the effect of obesity overload, OB women have a larger QF size than NW women, but unfavourable muscle composition and architecture. The higher MF% and steeper PA observed in OB women are associated with reduced levels of muscle specific strength. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

  7. Muscular co-contraction during walking and landing from a jump: comparison between genders and influence of activity level.

    Science.gov (United States)

    da Fonseca, Sergio Teixeira; Vaz, Daniela Virgínia; de Aquino, Cecília Ferreira; Brício, Rachel Soares

    2006-06-01

    Women have higher rates of knee ligament injury than men. Co-contraction of knee muscles is proposed to be an important mechanism to protect the joint from injuries. Females have lower co-contraction levels when compared to males. Exploratory, cross-sectional design. Thirty-six men and women equally divided into four groups according to gender and activity level (sedentary and athletic) were compared in relation to vastus lateralis and biceps femoris co-contraction before heel strike during level walking and before floor contact during landing from a jump. Muscular co-contraction was assessed by surface electromyography. Correlations between co-contraction and ligament laxity, extensor and flexor work, and flexion/extension torque ratio were also analyzed. No differences between genders were found in the studied situations (p0.381). During walking, co-contraction was greater in sedentary women compared to athletic women (p=0.002). A moderate inverse correlation was found between co-contraction during walking and women extensor (r=-0.613; p=0.007) and flexor (r=-0.575; p=0.012) work. During landing from a jump, no variables correlated to co-contraction in any of the groups tested (r0.477; p0.061). Co-contraction levels were not different between genders. Results suggest that women compensate strength deficits by means of increasing activation levels, possibly to generate adequate joint stiffness to meet stabilization demands. However, this is not evident in a more stressful activity like landing from a jump. This study contributes to a better understanding of the factors related to joint protection in females, who are at a greater risk of ligament injuries.

  8. Voluntary drive-dependent changes in vastus lateralis motor unit firing rates during a sustained isometric contraction at 50% of maximum knee extension force.

    NARCIS (Netherlands)

    de Ruiter, C.J.; Elzinga, M.J.; Verdijk, PW; van Mechelen, W.; de Haan, A.

    2004-01-01

    The purpose of the present study was to relate the expected inter-subject variability in voluntary drive of the knee extensor muscles during a sustained isometric contraction to the changes in firing rates of single motor units. Voluntary activation, as established with super-imposed electrical

  9. Effects of powdered Montmorency tart cherry supplementation on an acute bout of intense lower body strength exercise in resistance trained males.

    Science.gov (United States)

    Levers, Kyle; Dalton, Ryan; Galvan, Elfego; Goodenough, Chelsea; O'Connor, Abigail; Simbo, Sunday; Barringer, Nicholas; Mertens-Talcott, Susanne U; Rasmussen, Christopher; Greenwood, Mike; Riechman, Steven; Crouse, Stephen; Kreider, Richard B

    2015-01-01

    The purpose of this study was to examine whether short-term ingestion of a powdered tart cherry supplement prior to and following intense resistance-exercise attenuates muscle soreness and recovery strength loss, while reducing markers of muscle damage, inflammation, and oxidative stress. Twenty-three healthy, resistance-trained men (20.9 ± 2.6 yr, 14.2 ± 5.4% body fat, 63.9 ± 8.6 kg FFM) were matched based on relative maximal back squat strength, age, body weight, and fat free mass. Subjects were randomly assigned to ingest, in a double blind manner, capsules containing a placebo (P, n = 12) or powdered tart cherries [CherryPURE(®)] (TC, n = 11). Participants supplemented one time daily (480 mg/d) for 10-d including day of exercise up to 48-h post-exercise. Subjects performed ten sets of ten repetitions at 70% of a 1-RM back squat exercise. Fasting blood samples, isokinetic MVCs, and quadriceps muscle soreness ratings were taken pre-lift, 60-min, 24-h, and 48-h post-lift and analyzed by MANOVA with repeated measures. Muscle soreness perception in the vastus medialis (¼) (p = 0.10) and the vastus lateralis (¼) (p = 0.024) was lower in TC over time compared to P. Compared to pre-lift, TC vastus medialis (¼) soreness was significantly attenuated up to 48-h post-lift with vastus lateralis (¼) soreness significantly lower at 24-h post-lift compared to P. TC changes in serum creatinine (p = 0.03, delta p = 0.024) and total protein (p = 0.018, delta p = 0.006) were lower over time and smaller from pre-lift levels over time compared to P Significant TC group reductions from pre-lift levels were found for AST and creatinine 48-h post-lift, bilirubin and ALT 60-min and 48-h post-lift. No significant supplementation effects were observed for serum inflammatory or anti-inflammatory markers. None of the free radical production, lipid peroxidation, or antioxidant capacity markers (NT, TBARS, TAS, SOD) demonstrated significant changes with supplementation. Changes in TC

  10. PRE-ACTIVITY MODULATION OF LOWER EXTREMITY MUSCLES WITHIN DIFFERENT TYPES AND HEIGHTS OF DEEP JUMP

    Directory of Open Access Journals (Sweden)

    Vladimir Mrdakovic

    2008-06-01

    Full Text Available The purpose of this study was to determine modulation of pre- activity related to different types and heights of deep jump. Sixteen male soccer players without experience in deep jumps training (the national competition; 15.0 ± 0.5yrs; weight 61.9 ± 6.1kg; height 1.77 ± 0.07m, who participated in the study, performed three types of deep jump (bounce landing, counter landing, and bounce drop jump from three different heights (40cm, 60cm, and 80cm. Surface EMG device (1000Hz was used to estimate muscle activity (maximal amplitude of EMG - AmaxEMG; integral EMG signal - iEMG of five muscles (mm.gastrocnemii, m.soleus, m.tibialis anterior, m.vastus lateralis within 150ms before touchdown. All the muscles, except m. gastrocnemius medialis, showed systematic increase in pre-activity when platform height was raised. For most of the lower extremity muscles, the most significant differences were between values of pre-activity obtained for 40 cm and 80 cm platforms. While the amount of muscle pre-activity in deep jumps from the heights above and beneath the optimal one did not differ significantly from that generated in deep jumps from the optimal drop height of 60 cm, the patterns of muscle pre-activity obtained for the heights above the optimal one did differ from those obtained for the optimal drop height. That suggests that deep jumps from the heights above the optimal one do not seem to be an adequate exercise for adjusting muscle activity for the impact. Muscle pre-activity in bounce drop jumps differed significantly from that in counter landing and bounce landing respectively, which should indicate that a higher amount of pre-activity generated during bounce drop jumps was used for performing take-offs. As this study included the subjects who were not familiar with deep jumps training, the prospective studies should reveal the results of athletes with previous experience

  11. Partial body weight support treadmill training speed influences paretic and non-paretic leg muscle activation, stride characteristics, and ratings of perceived exertion during acute stroke rehabilitation.

    Science.gov (United States)

    Burnfield, Judith M; Buster, Thad W; Goldman, Amy J; Corbridge, Laura M; Harper-Hanigan, Kellee

    2016-06-01

    Intensive task-specific training is promoted as one approach for facilitating neural plastic brain changes and associated motor behavior gains following neurologic injury. Partial body weight support treadmill training (PBWSTT), is one task-specific approach frequently used to improve walking during the acute period of stroke recovery (training parameters and physiologic demands during this early recovery phase. To examine the impact of four walking speeds on stride characteristics, lower extremity muscle demands (both paretic and non-paretic), Borg ratings of perceived exertion (RPE), and blood pressure. A prospective, repeated measures design was used. Ten inpatients post unilateral stroke participated. Following three familiarization sessions, participants engaged in PBWSTT at four predetermined speeds (0.5, 1.0, 1.5 and 2.0mph) while bilateral electromyographic and stride characteristic data were recorded. RPE was evaluated immediately following each trial. Stride length, cadence, and paretic single limb support increased with faster walking speeds (p⩽0.001), while non-paretic single limb support remained nearly constant. Faster walking resulted in greater peak and mean muscle activation in the paretic medial hamstrings, vastus lateralis and medial gastrocnemius, and non-paretic medial gastrocnemius (p⩽0.001). RPE also was greatest at the fastest compared to two slowest speeds (ptraining at the slowest speeds. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Euroopal tuleb leida vastus Vene Monroe-doktriinile / Lennart Meri ; intervjueerinud Olaf Ihlan, Andreas Lorentz

    Index Scriptorium Estoniae

    Meri, Lennart, 1929-2006

    1993-01-01

    Eesti Vabariigi president L. Meri Baltikumist ja suurvene šovinismist. Intervjuu ajakirjale "Der Spiegel", nr. 44, 1. nov. 1993, lk. 200, 202-203, 206, pealkiri: "Dann wird Europa verbluten" : Estlands Präsident Lennart Meri über das Baltikum und den grossrussischen Chauvinismus. Ilmunud ka: Õhtuleht, 8. nov., lk. 5, pealkiri: "Siis voolab Euroopas veri" : Eesti president Lennart Meri Baltikumist ja suurvene šovinismist ; Rahva Hääl, 9. nov., lk., 3 ; Eesti Rada (Köln, 1993) nr. 6, lk. 3, pealkiri: President Lennart Meri intervjuu "Spiegelile" / refereerinud ja tsiteerinud J. P ; Eesti Päevaleht (Stockholm), 24. nov., lk. 2 : ill., pealkiri: President Lennart Meri : "Venemaa laiendab oma huvisfääri" ; Vaba Eestlane (Toronto), 9. dets., lk. 3, 11, pealkiri: "Euroopal tuleb leida vastus Vene - Monroe doktriinile" ; Meie Kodu, 15. dets., lk. 6, pealkiri: Eesti Vabariigi President Lennart Meri Baltikumist ja suurvene šovinismist

  13. Reliability of maximal mitochondrial oxidative phosphorylation in permeabilized fibers from the vastus lateralis employing high-resolution respirometry

    DEFF Research Database (Denmark)

    Cardinale, Daniele A; Gejl, Kasper D; Ørtenblad, Niels

    2018-01-01

    The purpose was to assess the impact of various factors on methodological errors associated with measurement of maximal oxidative phosphorylation (OXPHOS) in human skeletal muscle determined by high-resolution respirometry in saponin-permeabilized fibers. Biopsies were collected from 25 men...

  14. Neuromechanical evidence of improved neuromuscular control around knee joint in volleyball players.

    Science.gov (United States)

    Masci, Ilaria; Vannozzi, Giuseppe; Gizzi, Leonardo; Bellotti, Pasquale; Felici, Francesco

    2010-02-01

    The aim of the present work was to verify that skilled volleyball players present specific adaptations in both neuromuscular control and movement biomechanics, showing an improved neuromuscular control around the knee joint than in non-jumper athletes. Seven male volleyball players and seven male non-jumper athletes were recruited for this study. The following tests were performed in a random order: single countermovement jump (CMJ), single squat jump. At the end of the series, subjects performed a repetitive CMJ test. Electromyographic signals were recorded from vastus lateralis and biceps femoris muscles on both sides. Ground reaction forces and moments were measured with a force plate. Volleyball athletes performed better in all tests and were more resistant to fatigue than non-jumper athletes. Furthermore, volleyball athletes showed a reduced co-activation of knee flexor/extensor muscles. The present results seem to stand for a neural adaptation of the motor control scheme to training.

  15. IMP metabolism in human skeletal muscle after exhaustive exercise

    DEFF Research Database (Denmark)

    Tullson, P. C.; Bangsbo, Jens; Hellsten, Ylva

    1995-01-01

    This study addressed whether AMP deaminase (AMPD)myosin binding occurs with deamination during intense exercise in humans and the extent of purine loss from muscle during the initial minutes of recovery. Male subjects performed cycle exercise (265 +/- 2 W for 4.39 +/- 0.04 min) to stimulate muscle...... inosine 5'-monophosphate (IMP) formation. After exercise, blood flow to one leg was occluded. Muscle biopsies (vastus lateralis) were taken before and 3.6 +/- 0.2 min after exercise from the occluded leg and 0.7 +/- 0.0, 1.1 +/- 0.0, and 2.9 +/- 0.1 min postexercise in the nonoccluded leg. Exercise...... activated AMPD; at exhaustion IMP was 3.5 +/- 0.4 mmol/kg dry muscle. Before exercise, 16.0 +/- 1.6% of AMPD cosedimented with the myosin fraction; the extent of AMPD:myosin binding was unchanged by exercise. Inosine content increased about threefold during exercise and twofold more during recovery; by 2...

  16. Effect of muscle acidity on muscle metabolism and fatigue during intense exercise in man

    DEFF Research Database (Denmark)

    Bangsbo, Jens; Madsen, K.; Kiens, Bente

    1996-01-01

    1. The aim of this study was to examine the effect of muscle pH on muscle metabolism and development of fatigue during intense exercise. 2. Seven subjects performed intense exhaustive leg exercise on two occasions: with and without preceding intense intermittent arm exercise leading to high...... or moderate (control) blood lactate concentrations (HL and C, respectively). Prior to and immediately after each exercise bout, a muscle biopsy was taken from m. vastus lateralis of the active leg. Leg blood flow was measured and femoral arterial and venous blood samples were collected before and frequently...... during the exhaustive exercises. 3. The duration of the exercise was shorter in HL than in C (3.46 +/- 0.28 vs. 4.67 +/- 0.55 min; means +/- S.E.M.; P muscle pH was the same in C and HL (7.17 vs. 7.10), but at the end of exercise muscle pH was lower in HL than in C (6.82 vs. 6...

  17. Insulin action in human thighs after one-legged immobilization

    DEFF Research Database (Denmark)

    Richter, Erik; Kiens, Bente; Mizuno, M.

    1989-01-01

    Insulin action was assessed in thighs of five healthy young males who had one knee immobilized for 7 days by a splint. The splint was not worn in bed. Subjects also used crutches to prevent weight bearing of the immobilized leg. Immobilization decreased the activity of citrate synthase and 3-OH......-acyl-CoA-dehydrogenase in the vastus lateralis muscle by 9 and 14%, respectively, and thigh volume by 5%. After 7 days of immobilization, a two-step euglycemic hyperinsulinemic clamp procedure combined with arterial and bilateral femoral venous catheterization was performed. Insulin action on glucose uptake and tyrosine release...... of the thighs at mean plasma insulin concentrations of 67 (clamp step I) and 447 microU/ml (clamp step II) was decreased by immobilization, whereas immobilization did not affect insulin action on thigh exchange of free fatty acids, glycerol, O2, or potassium. Before and during the clamp step I, lactate release...

  18. Effects of immobilization and aerobic training on proteins related to intramuscular substrate storage and metabolism in young and older men

    DEFF Research Database (Denmark)

    Vigelsø Hansen, Andreas; Gram, Martin; Wiuff, Caroline

    2016-01-01

    by aerobic training in young and older men. METHODS: 17 young (23 ± 1 years, 24 ± 1 kg m(-2), and 20 ± 2% body fat) and 15 older men (68 ± 1 years; 27 ± 1 kg m(-2), and 29 ± 2% body fat) underwent 2 weeks' one leg immobilization followed by 6 weeks' cycle training. Biopsies were obtained from m. vastus...... lateralis just before immobilization (at inclusion), after immobilization, and the after 6 weeks' training. The biopsies were analyzed for muscle substrates; muscle perilipin protein (PLIN), glycogen synthase (GS), synaptosomal-associated protein of 23 kDa (SNAP23) protein content, and muscle 3-hydroxyacyl...... GS (74%) protein compared to the older men. Immobilization decreased and training restored HAD activity, GS and SNAP23 protein content in young and older men. CONCLUSION: Evidence of age-related metabolic inflexibility is presented, seen as body fat and IMTG accumulation. The question arises...

  19. Influence of Synchronized Dead Point Elimination Crank on Cyclist Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Abdul Aziz Khadijah Akmal

    2016-01-01

    Full Text Available The aim of this study was to investigate the influence of newly proposed bicycle’s crank to crank angle setting on the Vastus Lateralis (VL and Bicep Femoris (BF muscle activity during cycling. Procedures of Conconi Test were used throughout the experiment for the data collection purpose. The muscles activities were recorded using surface electromyography and software LabChart7. The raw data were further processed in time (Root-Mean-Square, RMS and frequency (Mean Power Frequency, MPF domain. It was found that 0° crank to crank setting (similar to conventional crank to crank angle setting caused the prime mover VL (Normalized RMS = 0.119 to fatigue more than BF (Normalized RMS = 0.102. This setting is expected to decrease the cycling performance. In addition, −5° is the best crank to crank angle setting that causes least fatigue to both VL and BF. In short, to increase the cycling performance by avoiding the fatigue to the main muscles, −5° is the suggested as setting angle for the proposed crank design.

  20. Contrasting microsatellite diversity in the evolutionary lineages of Phytophthora lateralis.

    Science.gov (United States)

    Vettraino, AnnaMaria; Brasier, Clive M; Webber, Joan F; Hansen, Everett M; Green, Sarah; Robin, Cecile; Tomassini, Alessia; Bruni, Natalia; Vannini, Andrea

    2017-02-01

    Following recent discovery of Phytophthora lateralis on native Chamaecyparis obtusa in Taiwan, four phenotypically distinct lineages were discriminated: the Taiwan J (TWJ) and Taiwan K (TWK) in Taiwan, the Pacific Northwest (PNW) in North America and Europe and the UK in west Scotland. Across the four lineages, we analysed 88 isolates from multiple sites for microsatellite diversity. Twenty-one multilocus genotypes (MLGs) were resolved with high levels of diversity of the TWK and PNW lineages. No alleles were shared between the PNW and the Taiwanese lineages. TWK was heterozygous at three loci, whereas TWJ isolates were homozygous apart from one isolate, which exhibited a unique allele also present in the TWK lineage. PNW lineage was heterozygous at three loci. The evidence suggests its origin may be a yet unknown Asian source. North American and European PNW isolates shared all their alleles and also a dominant MLG, consistent with a previous proposal that this lineage is a recent introduction into Europe from North America. The UK lineage was monomorphic and homozygous at all loci. It shared its alleles with the PNW and the TWJ and TWK lineages, hence a possible origin in a recent hybridisation event between a Taiwan lineage and PNW cannot be ruled out. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  1. Evaluation of central and peripheral fatigue in the quadriceps using fractal dimension and conduction velocity in young females.

    Directory of Open Access Journals (Sweden)

    Matteo Beretta-Piccoli

    Full Text Available Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD and conduction velocity (CV as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans.A total of 29 recreationally active women (mean age±standard deviation: 24±4 years and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years performed two knee extensions: (1 at 20% maximal voluntary contraction (MVC for 30 s, and (2 at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays.Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01 was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task.Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions.

  2. Warm-Up Exercises May Not Be So Important for Enhancing Submaximal Running Performance.

    Science.gov (United States)

    Takizawa, Kazuki; Yamaguchi, Taichi; Shibata, Keisuke

    2018-05-01

    Takizawa, K, Yamaguchi, T, and Shibata, K. Warm-up exercises may not be so important for enhancing submaximal running performance. J Strength Cond Res 32(5): 1383-1390, 2018-The purpose of this study was to determine an appropriate warm-up intensity for enhancing performance in submaximal running at 90% vV[Combining Dot Above]O2max (it assumes 3,000-5,000 m in track events). Seven trained male university athletes took part in this study (age: 21.3 ± 2.1 years, height: 169.3 ± 4.7 cm, body mass: 58.4 ± 5.6 kg, V[Combining Dot Above]O2max: 73.33 ± 5.46 ml·kg·min). Each subject ran on a treadmill at 90% vV[Combining Dot Above]O2max until exhaustion after 1 of 4 warm-up treatments. The 4 warm-up treatments were no warm-up, 15 minutes running at 60% vV[Combining Dot Above]O2max, at 70% vV[Combining Dot Above]O2max, and at 80% vV[Combining Dot Above]O2max. The running performance was evaluated by time to exhaustion (TTE). V[Combining Dot Above]O2, and vastus lateralis muscle temperature were also measured. There were no significant differences in TTE among the warm-up exercises (p > 0.05). V[Combining Dot Above]O2 in no warm-up showed slower reaction than the other warm-up exercises. Regarding, the vastus lateralis muscle temperature immediately after warm-up, no warm-up was significantly (p warm-up exercises. Our results suggested that submaximal running performance was not affected by the presence or absence of a warm-up or by warm-up intensity, although physiological changes occurred.

  3. An ethanolic extract of Artemisia dracunculus L. regulates gene expression of ubiquitin-proteasome system enzymes in skeletal muscle: potential role in the treatment of sarcopenic obesity.

    Science.gov (United States)

    Kirk-Ballard, Heather; Kilroy, Gail; Day, Britton C; Wang, Zhong Q; Ribnicky, David M; Cefalu, William T; Floyd, Z Elizabeth

    2014-01-01

    Obesity is linked to insulin resistance, a primary component of metabolic syndrome and type 2 diabetes. The problem of obesity-related insulin resistance is compounded when age-related skeletal muscle loss, called sarcopenia, occurs with obesity. Skeletal muscle loss results from elevated levels of protein degradation and prevention of obesity-related sarcopenic muscle loss will depend on strategies that target pathways involved in protein degradation. An extract from Artemisia dracunculus, termed PMI 5011, improves insulin signaling and increases skeletal muscle myofiber size in a rodent model of obesity-related insulin resistance. The aim of this study was to examine the effect of PMI 5011 on the ubiquitin-proteasome system, a central regulator of muscle protein degradation. Gastrocnemius and vastus lateralis skeletal muscle was obtained from KK-A(y) obese diabetic mice fed a control or 1% (w/w) PMI 5011-supplemented diet. Regulation of genes encoding enzymes of the ubiquitin-proteasome system was determined using real-time quantitative reverse transcriptase polymerase chain reaction. Although MuRF-1 ubiquitin ligase gene expression is consistently down-regulated in skeletal muscle, atrogin-1, Fbxo40, and Traf6 expression is differentially regulated by PMI 5011. Genes encoding other enzymes of the ubiquitin-proteasome system ranging from ubiquitin to ubiquitin-specific proteases are also regulated by PMI 5011. Additionally, expression of the gene encoding the microtubule-associated protein-1 light chain 3 (LC3), a ubiquitin-like protein pivotal to autophagy-mediated protein degradation, is down-regulated by PMI 5011 in the vastus lateralis. PMI 5011 alters the gene expression of ubiquitin-proteasome system enzymes that are essential regulators of skeletal muscle mass. This suggests that PMI 5011 has therapeutic potential in the treatment of obesity-linked sarcopenia by regulating ubiquitin-proteasome-mediated protein degradation. Copyright © 2014 Elsevier Inc

  4. PRONOUNCED MUSCLE DEOXYGENATION DURING SUPRAMAXIMAL EXERCISE UNDER SIMULATED HYPOXIA IN SPRINT ATHLETES

    Directory of Open Access Journals (Sweden)

    Kazuo Oguri

    2008-12-01

    Full Text Available The purpose of this study was to determine whether acute hypoxia alters the deoxygenation level in vastus lateralis muscle during a 30 s Wingate test, and to compare the muscle deoxygenation level between sprint athletes and untrained men. Nine male track sprinters (athletic group, VO2max 62.5 ± 4.1 ml/kg/min and 9 healthy untrained men (untrained group, VO2max 49.9 ± 5.2 ml·kg-1·min-1 performed a 30 s Wingate test under simulated hypoxic (FIO2 = 0.164 and PIO2 = 114 mmHg and normoxic conditions. During the exercise, changes in oxygenated hemoglobin (OxyHb in the vastus lateralis were measured using near infrared continuous wave spectroscopy. Decline in OxyHb, that is muscle deoxygenation, was expressed as percent change from baseline. Percutaneous arterial oxygen saturation (SpO2, oxygen uptake (VO2, and ventilation (VE were measured continuously. In both groups, there was significantly greater muscle deoxygenation, lower SpO2, lower peakVO2, and higher peakVE during supramaximal exercise under hypoxia than under normoxia, but no differences in peak and mean power output during the exercise. Under hypoxia, the athletic group experienced significantly greater muscle deoxygenation, lower SpO2, greater decrement in peakVO2 and increment in peakVE during the exercise than the untrained group. When the athletic and untrained groups were pooled, the increment of muscle deoxygenation was strongly correlated with lowest SpO2 in the 30 s Wingate test under hypoxia. These results suggest that acute exposure to hypoxia causes a greater degree of peripheral muscle deoxygenation during supramaximal exercise, especially in sprint athletes, and this physiological response would be explained mainly by lower arterial oxygen saturation

  5. Microvascular Endothelial Dysfunction in Sedentary, Obese Humans is mediated by NADPH Oxidase; Influence of Exercise Training

    Science.gov (United States)

    La Favor, Justin D.; Dubis, Gabriel S.; Yan, Huimin; White, Joseph D.; Nelson, Margaret A.M.; Anderson, Ethan J.; Hickner, Robert C.

    2016-01-01

    Objective The objectives of this study were to determine the impact of in vivo reactive oxygen species (ROS) on microvascular endothelial function in obese human subjects and to determine the efficacy of an aerobic exercise intervention on alleviating obesity-associated dysfunctionality. Approach and Results Young, sedentary men and women were divided into lean (BMI 18–25; n=14), intermediate (BMI 28–32.5; n=13), and obese (BMI 33–40; n=15) groups. A novel microdialysis technique was utilized to detect elevated interstitial hydrogen peroxide (H2O2) and superoxide levels in the vastus lateralis of obese compared to both lean and intermediate subjects. Nutritive blood flow was monitored in the vastus lateralis via the microdialysis-ethanol technique. A decrement in acetylcholine-stimulated blood flow revealed impaired microvascular endothelial function in the obese subjects. Perfusion of apocynin, an NADPH oxidase (Nox) inhibitor, lowered (normalized) H2O2 and superoxide levels and reversed microvascular endothelial dysfunction in obese subjects. Following 8-weeks of exercise, H2O2 levels were decreased in the obese subjects and microvascular endothelial function in these subjects was restored to levels similar to lean subjects. Skeletal muscle protein expression of the Nox subunits p22phox, p47phox, and p67phox were increased in obese relative to lean subjects, where p22phox and p67phox expression was attenuated by exercise training in obese subjects. Conclusions This study implicates Nox as a source of excessive ROS production in skeletal muscle of obese individuals, and links excessive Nox derived ROS to microvascular endothelial dysfunction in obesity. Furthermore, aerobic exercise training proved to be an effective strategy for alleviating these maladies. PMID:27765769

  6. Laimre ja "mina" : Marco Laimre isiknäitus "Küsimused ja vastused" Rotermanni Soolalaos = Laimre and "me" : Marco Laimre solo exhibition "Questions and answers" at the Rotermann salt storage / Anders Härm

    Index Scriptorium Estoniae

    Härm, Anders, 1977-

    2009-01-01

    Marko Laimre unikaalsest ja isikupärasest maailmanägemise ning -käsitlemise viisist, tema raskesti defineeritavast ja irriteerivast loomingust ning isiknäitusest "Küsimused ja vastused" 2004. aastal

  7. Effects of concentric and repeated eccentric exercise on muscle damage and calpain-calpastatin gene expression in human skeletal muscle

    DEFF Research Database (Denmark)

    Vissing, K.; Overgaard, K.; Nedergaard, A.

    2008-01-01

    , and was compared to a control-group (n = 6). Muscle strength and soreness and plasma creatine kinase and myoglobin were measured before and during 7 days following exercise bouts. Muscle biopsies were collected from m. vastus lateralis of both legs prior to and at 3, 24 h and 7 days after exercise and quantified...... for muscle Ca2+-content and mRNA levels for calpain isoforms and calpastatin. Exercise reduced muscle strength and increased muscle soreness predominantly in the eccentric leg (P ... eccentric exercise bout (P muscle Ca2+-content did not differ between interventions. mRNA levels for calpain 2 and calpastatin were upregulated exclusively by eccentric exercise 24 h post-exercise (P

  8. Muscle specific microRNAs are regulated by endurance exercise in human skeletal muscle

    DEFF Research Database (Denmark)

    Nielsen, Søren; Scheele, Camilla; Yfanti, Christina

    2010-01-01

    Muscle specific miRNAs, myomiRs, have been shown to control muscle development in vitro and are differentially expressed at rest in diabetic skeletal muscle. Therefore, we investigated the expression of these myomiRs, including miR-1, miR-133a, miR-133b and miR-206 in muscle biopsies from vastus...... lateralis of healthy young males (n = 10) in relation to a hyperinsulinaemic–euglycaemic clamp as well as acute endurance exercise before and after 12 weeks of endurance training. The subjects increased their endurance capacity, VO2max (l min-1) by 17.4% (P improved insulin sensitivity by 19......, but their role in regulating human skeletal muscle adaptation remains unknown....

  9. Human and rodent muscle Na(+)-K(+)-ATPase in diabetes related to insulin, starvation, and training

    DEFF Research Database (Denmark)

    Schmidt, T A; Hasselbalch, S; Farrell, P A

    1994-01-01

    cerebral cortex Na(+)-K(+)-ATPase concentration as a result of diabetes, semistarvation, or insulin treatment. In human subjects, Na(+)-K(+)-ATPase concentration in vastus lateralis muscle biopsies was 17 and 22% greater (P dependent diabetes...... mellitus (n = 24) and insulin-dependent diabetes mellitus (n = 7) than in control subjects (n = 8). A positive linear correlation between muscle Na(+)-K(+)-ATPase and plasma insulin concentrations was observed (r = 0.50, P = 0.006; n = 29). Thus, insulin seems a regulator of muscle Na......(+)-K(+)-ATPase concentration, reduction of muscle Na(+)-K(+)-ATPase concentration with untreated diabetes bears similarities with undernourishment, and physical conditioning may ameliorate the muscle Na(+)-K(+)-ATPase concentration decrease induced by diabetes....

  10. Exercise training normalizes skeletal muscle vascular endothelial growth factor levels in patients with essential hypertension

    DEFF Research Database (Denmark)

    Hansen, Ane Håkansson; Nielsen, Jens Jung; Saltin, Bengt

    2010-01-01

    METHODS: Vascular endothelial growth factor (VEGF) protein and capillarization were determined in muscle vastus lateralis biopsy samples in individuals with essential hypertension (n = 10) and normotensive controls (n = 10). The hypertensive individuals performed exercise training for 16 weeks....... Muscle samples as well as muscle microdialysis fluid samples were obtained at rest, during and after an acute exercise bout, performed prior to and after the training period, for the determination of muscle VEGF levels, VEGF release, endothelial cell proliferative effect and capillarization. RESULTS......: Prior to training, the hypertensive individuals had 36% lower levels of VEGF protein and 22% lower capillary density in the muscle compared to controls. Training in the hypertensive group reduced (P

  11. ADAPTIVE CHANGES OF MYOSIN ISOFORMS IN RESPONSE TO LONG-TERM STRENGTH AND POWER TRAINING IN MIDDLE-AGED MEN

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    Raivo Puhke

    2006-06-01

    Full Text Available The purpose of the study was to examine the adaptive changes in myosin heavy chain (MHC and light chain (MLC isoforms in human vastus lateralis muscle caused by long-term strength and power training (54 weeks, approximately 3 times a week in untrained middle- aged men (16 in the training and 6 in the control group. Muscular MHC and MLC isoforms were determined by means of SDS-PAGE gel electrophoresis. During the training period, maximal anaerobic cycling power increased by 64 W (p < 0.001 and the maximal jumping height by 1.5 cm (p < 0. 05 in the training group, but no significant changes were found in the control group. However, the group by time effect was not significant. In the training group, the increase of the maximal jumping height correlated with the number of strength and power training sessions (r = 0.56; p < 0.05. The change of the proportion of MHC IIa isoform from 52.6 ± 12.2% to 59.4 ± 11.6% did not reach statistical significance (p = 0.070 for group by time; within training group p = 0.061 and neither did the change of the proportion of MHC IIx isoform from 18.1 ± 11.4% to 11.1 ± 9.1% (p = 0.104 for group by time; within training group p=0.032. The degree of change of MHC IIx isoform correlated with the amount of earlier recreational sports activity (r = 0.61; p < 0.05. In the training group, the changes of MLC1s isoform correlated negatively with the changes of MLC1f isoform (r = -0. 79; p < 0.05 as well as with the changes in maximal anaerobic cycling power (r = -0.81; p < 0.05, and positively with those of MHC I isoform (r = 0.81; p < 0.05. In conclusion, the long- term strength and power training ~3 times a week seemed to have only slight effects on fast MHC isoforms in the vastus lateralis muscle of untrained middle-aged men; the proportion of MHC IIa tended to increase and that of MHC IIx tended to decrease. No changes in MLC isoform profile could be shown

  12. Analysis of the Response Speed of Musculature of the Knee in Professional Male and Female Volleyball Players

    Directory of Open Access Journals (Sweden)

    D. Rodríguez-Ruiz

    2014-01-01

    Full Text Available The aim of this study was to evaluate the normalized response speed (Vrn of the knee musculature (flexor and extensor in high competitive level volleyball players using tensiomyography (TMG and to analyze the muscular response of the vastus medialis (VM, rectus femoris (RF, vastus lateralis (VL, and biceps femoris (BF in accordance with the specific position they play in their teams. One hundred and sixty-six players (83 women and 83 men were evaluated. They belonged to eight teams in the Spanish women’s superleague and eight in the Spanish men’s superleague. The use of Vrn allows avoiding possible sample imbalances due to anatomical and functional differences and demands. We found differences between Vrn in each of the muscles responsible for extension (VM, RF, and VL and flexion (BF regardless of the sex. Normalized response speed differences seem to be larger in setters, liberos and outside players compared to middle blockers and larger in males when compared to females. These results of Vrn might respond to the differences in the physical and technical demands of each specific position, showing an improved balance response of the knee extensor and flexor musculature in male professional volleyball players.

  13. Analysis of the Response Speed of Musculature of the Knee in Professional Male and Female Volleyball Players

    Science.gov (United States)

    Rodríguez-Ruiz, D.; Diez-Vega, I.; Rodríguez-Matoso, D.; Fernandez-del-Valle, M.; Sagastume, R.; Molina, J. J.

    2014-01-01

    The aim of this study was to evaluate the normalized response speed (Vrn) of the knee musculature (flexor and extensor) in high competitive level volleyball players using tensiomyography (TMG) and to analyze the muscular response of the vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), and biceps femoris (BF) in accordance with the specific position they play in their teams. One hundred and sixty-six players (83 women and 83 men) were evaluated. They belonged to eight teams in the Spanish women's superleague and eight in the Spanish men's superleague. The use of Vrn allows avoiding possible sample imbalances due to anatomical and functional differences and demands. We found differences between Vrn in each of the muscles responsible for extension (VM, RF, and VL) and flexion (BF) regardless of the sex. Normalized response speed differences seem to be larger in setters, liberos and outside players compared to middle blockers and larger in males when compared to females. These results of Vrn might respond to the differences in the physical and technical demands of each specific position, showing an improved balance response of the knee extensor and flexor musculature in male professional volleyball players. PMID:25003109

  14. A muscle ultrasound score in the diagnosis of amyotrophic lateral sclerosis.

    Science.gov (United States)

    Tsuji, Yukiko; Noto, Yu-Ichi; Shiga, Kensuke; Teramukai, Satoshi; Nakagawa, Masanori; Mizuno, Toshiki

    2017-06-01

    The aims of this study are to elucidate the frequencies and distribution of fasciculations using muscle ultrasound in patients with amyotrophic lateral sclerosis (ALS) and those with other conditions mimicking ALS, and subsequently to develop a novel fasciculation score for the diagnosis of ALS. Ultrasound of 21 muscles was performed to detect fasciculations in 36 consecutive patients suspected of having ALS. We developed a fasciculation ultrasound score that indicated the number of muscles with fasciculations in statistically selected muscles. A total of 525 muscles in 25 ALS patients and 231 in 11 non-ALS patients were analysed. Using relative operating characteristic and multivariate logistic regression analysis, we selected the trapezius, deltoid, biceps brachii, abductor pollicis brevis, abdominal, vastus lateralis, vastus medialis, biceps femoris, and gastrocnemius muscles for the fasciculation ultrasound score. The mean scores were higher in the ALS group than those in the non-ALS group (5.3±0.5vs. 0.3±0.7) (mean±SD); pdifferentiating ALS patients from non-ALS patients. The fasciculation ultrasound score can be a simple and useful diagnostic marker of ALS. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  15. A new approach to assess the spasticity in hamstrings muscles using mechanomyography antagonist muscular group.

    Science.gov (United States)

    Krueger, Eddy; Scheeren, Eduardo M; Nogueira-Neto, Guilherme N; Button, Vera Lúcia da S N; Nohama, Percy

    2012-01-01

    Several pathologies can cause muscle spasticity. Modified Ashworth scale (MAS) can rank spasticity, however its results depend on the physician subjective evaluation. This study aims to show a new approach to spasticity assessment by means of MMG analysis of hamstrings antagonist muscle group (quadriceps muscle). Four subjects participated in the study, divided into two groups regarding MAS (MAS0 and MAS1). MMG sensors were positioned over the muscle belly of rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) muscles. The range of movement was acquired with an electrogoniometer placed laterally to the knee. The system was based on a LabVIEW acquisition program and the MMG sensors were built with triaxial accelerometers. The subjects were submitted to stretching reflexes and the integral of the MMG (MMG(INT)) signal was calculated to analysis. The results showed that the MMG(INT) was greater to MAS1 than to MAS0 [muscle RF (p = 0.004), VL (p = 0.001) and VM (p = 0.007)]. The results showed that MMG was viable to detect a muscular tonus increase in antagonist muscular group (quadriceps femoris) of spinal cord injured volunteers.

  16. Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

    Science.gov (United States)

    Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

    2011-01-01

    During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

  17. The single nucleotide polymorphism Gly482Ser in the PGC-1α gene impairs exercise-induced slow-twitch muscle fibre transformation in humans.

    Directory of Open Access Journals (Sweden)

    Peter Steinbacher

    Full Text Available PGC-1α (peroxisome proliferator-activated receptor γ co-activator 1α is an important regulator of mitochondrial biogenesis and a master regulator of enzymes involved in oxidative phosphorylation. Recent evidence demonstrated that the Gly482Ser single nucleotide polymorphism (SNP in the PGC-1α gene affects insulin sensitivity, blood lipid metabolism and binding to myocyte enhancer factor 2 (MEF2. Individuals carrying this SNP were shown to have a reduced cardiorespiratory fitness and a higher risk to develop type 2 diabetes. Here, we investigated the responses of untrained men with the Gly482Ser SNP to a 10 week programme of endurance training (cycling, 3 x 60 min/week, heart rate at 70-90% VO2peak. Quantitative data from analysis of biopsies from vastus lateralis muscle revealed that the SNP group, in contrast to the control group, lacked a training-induced increase in content of slow contracting oxidative fibres. Capillary supply, mitochondrial density, mitochondrial enzyme activities and intramyocellular lipid content increased similarly in both groups. These results indicate that the impaired binding of MEF2 to PGC-1α in humans with this SNP impedes exercise-induced fast-to-slow muscle fibre transformation.

  18. The single nucleotide polymorphism Gly482Ser in the PGC-1α gene impairs exercise-induced slow-twitch muscle fibre transformation in humans.

    Science.gov (United States)

    Steinbacher, Peter; Feichtinger, René G; Kedenko, Lyudmyla; Kedenko, Igor; Reinhardt, Sandra; Schönauer, Anna-Lena; Leitner, Isabella; Sänger, Alexandra M; Stoiber, Walter; Kofler, Barbara; Förster, Holger; Paulweber, Bernhard; Ring-Dimitriou, Susanne

    2015-01-01

    PGC-1α (peroxisome proliferator-activated receptor γ co-activator 1α) is an important regulator of mitochondrial biogenesis and a master regulator of enzymes involved in oxidative phosphorylation. Recent evidence demonstrated that the Gly482Ser single nucleotide polymorphism (SNP) in the PGC-1α gene affects insulin sensitivity, blood lipid metabolism and binding to myocyte enhancer factor 2 (MEF2). Individuals carrying this SNP were shown to have a reduced cardiorespiratory fitness and a higher risk to develop type 2 diabetes. Here, we investigated the responses of untrained men with the Gly482Ser SNP to a 10 week programme of endurance training (cycling, 3 x 60 min/week, heart rate at 70-90% VO2peak). Quantitative data from analysis of biopsies from vastus lateralis muscle revealed that the SNP group, in contrast to the control group, lacked a training-induced increase in content of slow contracting oxidative fibres. Capillary supply, mitochondrial density, mitochondrial enzyme activities and intramyocellular lipid content increased similarly in both groups. These results indicate that the impaired binding of MEF2 to PGC-1α in humans with this SNP impedes exercise-induced fast-to-slow muscle fibre transformation.

  19. Efeitos da eletroestimulação do músculo vasto medial oblíquo em portadores de síndrome da dor patelofemoral: uma análise eletromiográfica Effects of electrical stimulation of vastus medialis obliquus muscle in patients with patellofemoral pain syndrome: an electromyographic analysis

    Directory of Open Access Journals (Sweden)

    Fabiana R. Garcia

    2010-12-01

    study. They performed the functional test of stair stepping to capture the electromyographic (EMG activity of the VMO and vastus lateralis (VL muscles, before and after a program of electrical stimulation of the VMO muscle. The electrical stimulation was performed three times per week for six weeks. For analysis between the VMO and VL muscles, we considered the variables: ratio of time of onset to peak of activation, ratio of the integrals of the signals (t-test for dependent samples, and difference between onsets of activation (Wilcoxon test, with significance level of p<0.05. RESULTS: The results only showed change in behavior in the EMG signal for the ratio of the integrals of the signals, indicating that changes occurred in the force-generating capacity of the muscle after the training. CONCLUSION: The use of electrical stimulation should be considered to complement the conservative therapeutic approach in patients with PFPS, and the analysis of the ratio of the integrals of the SEMG signals should be considered as an instrument of evaluation. Article registered in the Australian New Zealand Clinical Trials Registry (ANZCTR under number ACTRN 12609000079246.

  20. Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review

    Directory of Open Access Journals (Sweden)

    Jesper Bencke

    2018-05-01

    injury risk, reporting that low medial hamstring activation and high vastus lateralis activation prior to landing was associated with an elevated incidence of ACL-injury. A majority of studies were performed in adult female athletes. The striking paucity of studies in adolescent female athletes emphasizes the need for increased research activities to examine of lower limb muscle activity in relation to non-contact ACL injury in this high-risk athlete population.

  1. Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review.

    Science.gov (United States)

    Bencke, Jesper; Aagaard, Per; Zebis, Mette K

    2018-01-01

    , reporting that low medial hamstring activation and high vastus lateralis activation prior to landing was associated with an elevated incidence of ACL-injury. A majority of studies were performed in adult female athletes. The striking paucity of studies in adolescent female athletes emphasizes the need for increased research activities to examine of lower limb muscle activity in relation to non-contact ACL injury in this high-risk athlete population.

  2. Elevated expression of neuropeptide signaling genes in the eyestalk ganglia and Y-organ of Gecarcinus lateralis individuals that are refractory to molt induction.

    Science.gov (United States)

    Pitts, Natalie L; Schulz, Hanna M; Oatman, Stephanie R; Mykles, Donald L

    2017-12-01

    Molting is induced in decapod crustaceans via multiple leg autotomy (MLA) or eyestalk ablation (ESA). MLA removes five or more walking legs, which are regenerated and become functional appendages at ecdysis. ESA eliminates the primary source of molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH), which suppress the production of molting hormones (ecdysteroids) from the molting gland or Y-organ (YO). Both MLA and ESA are effective methods for molt induction in Gecarcinus lateralis. However, some G. lateralis individuals are refractory to MLA, as they fail to complete ecdysis by 12weeks post-MLA; these animals are in the "blocked" condition. Quantitative polymerase chain reaction was used to quantify mRNA levels of neuropeptide and mechanistic target of rapamycin (mTOR) signaling genes in YO, eyestalk ganglia (ESG), thoracic ganglion (TG), and brain of intact and blocked animals. Six of the seven neuropeptide signaling genes, three of four mTOR signaling genes, and Gl-elongation factor 2 (EF2) mRNA levels were significantly higher in the ESG of blocked animals. Gl-MIH and Gl-CHH mRNA levels were higher in the TG and brain of blocked animals and levels increased in both control and blocked animals in response to ESA. By contrast, mRNA levels of Gl-EF2 and five of the 10 MIH signaling pathway genes in the YO were two to four orders of magnitude higher in blocked animals compared to controls. These data suggest that increased MIH and CHH synthesis in the ESG contributes to the prevention of molt induction by MLA in blocked animals. The up-regulation of MIH signaling genes in the YO of blocked animals suggests that the YO is more sensitive to MIH produced in the ESG, as well as MIH produced in brain and TG of ESA animals. Both the up-regulation of MIH signaling genes in the YO and of Gl-MIH and Gl-CHH in the ESG, TG, and brain appear to contribute to some G. lateralis individuals being refractory to MLA and ESA. Copyright © 2017 Elsevier Inc. All

  3. The Gluteus Medius Vs. Thigh Muscles Strength Ratio and Their Relation to Electromyography Amplitude During a Farmer’s Walk Exercise

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    Stastny Petr

    2015-03-01

    Full Text Available The strength ratio between hamstrings and quadriceps (H/Q is associated with knee injuries as well as hip abductor muscle (HAB weakness. Sixteen resistance trained men (age, 32.5 ± 4.2 years performed 5 s maximal isometric contractions at 75° of knee flexion/extension and 15° of hip abduction on a dynamometer. After this isometric test they performed a Farmer´s walk exercise to find out if the muscle strength ratio predicted the electromyography amplitude expressed as a percentage of maximum voluntary isometric contraction (%MVIC. The carried load represented a moderate intensity of 75% of the exercise six repetitions maximum (6RM. Electromyography data from the vastus medialis (VM, vastus lateralis (VL, biceps femoris (BF and gluteus medius (Gmed on each leg were collected during the procedure. The groups selected were participants with H/Q ≥ 0.5, HQ < 0.5, HAB/H ≥ 1, HAB/H < 1, HAB/Q ≥ 0.5 and HAB/Q < 0.5. One way ANOVA showed that Gmed activity was significantly greater in the group with HAB/H < 1 (42 ± 14 %MVIC as compared to HAB/H ≥ 1 (26 ± 10 %MVIC and HAB/Q < 0.5 (47 ± 19 %MVIC compared to HAB/Q ≥ 0.5 (26 ± 12 %MVIC. The individuals with HAB/H < 1 were found to have greater activation of their Gmed during the Farmer’s walk exercise. Individuals with HAB/Q < 0.5 had greater activation of the Gmed. Gmed strength ratios predict the muscle involvement when a moderate amount of the external load is used. The Farmer’s walk is recommended as an exercise which can strengthen the gluteus medius, especially for individuals with a HAB/H ratio < 1 and HAB/Q < 0.5.

  4. An acoustic startle alters knee joint stiffness and neuromuscular control.

    Science.gov (United States)

    DeAngelis, A I; Needle, A R; Kaminski, T W; Royer, T R; Knight, C A; Swanik, C B

    2015-08-01

    Growing evidence suggests that the nervous system contributes to non-contact knee ligament injury, but limited evidence has measured the effect of extrinsic events on joint stability. Following unanticipated events, the startle reflex leads to universal stiffening of the limbs, but no studies have investigated how an acoustic startle influences knee stiffness and muscle activation during a dynamic knee perturbation. Thirty-six individuals were tested for knee stiffness and muscle activation of the quadriceps and hamstrings. Subjects were seated and instructed to resist a 40-degree knee flexion perturbation from a relaxed state. During some trials, an acoustic startle (50 ms, 1000 Hz, 100 dB) was applied 100 ms prior to the perturbation. Knee stiffness, muscle amplitude, and timing were quantified across time, muscle, and startle conditions. The acoustic startle increased short-range (no startle: 0.044 ± 0.011 N·m/deg/kg; average startle: 0.047 ± 0.01 N·m/deg/kg) and total knee stiffness (no startle: 0.036 ± 0.01 N·m/deg/kg; first startle 0.027 ± 0.02 N·m/deg/kg). Additionally, the startle contributed to decreased [vastus medialis (VM): 13.76 ± 33.6%; vastus lateralis (VL): 6.72 ± 37.4%] but earlier (VM: 0.133 ± 0.17 s; VL: 0.124 ± 0.17 s) activation of the quadriceps muscles. The results of this study indicate that the startle response can significantly disrupt knee stiffness regulation required to maintain joint stability. Further studies should explore the role of unanticipated events on unintentional injury. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Estimulação elétrica neuromuscular de média freqüência (russa em cães com atrofia muscular induzida Medium frequency neuromuscular electrical stimulation (russian in dogs with induced muscle atrophy

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    Charles Pelizzari

    2008-06-01

    interval of 48 hours between each session, during 60 days. The following parameters were measured: thigh perimeter, goniometry of the knee, creatine kinase (CK enzymes and morphometry of the muscular fibers in transversal cuts of the vastus lateralis muscle, collected through a muscular biopsy. EENM was utilized on the femoral quadriceps at a frequency of 2500 Hz, with pulse duration of 50%, and the time on/off was at a proportion of 1:2. There was no significant difference between the thigh perimeter and the activity of enzyme CK between groups I and II. As for the goniometry a significant increase (P<0,05 was observed among 0 and 30 days after the immobilization in group II. As for the morphometry of the fibers of the vastus lateralis, a significant increase (P<0,05 was observed in the transversal area of the treated group on the 90th day when compared with that observed at the time of immobilization and among the groups, group II presented a greater transversal area (P<0.05 on the 90th day. The medium frequency NMES brings about a hypertrophy of the vastus lateralis muscle in dogs after induced muscular atrophy.

  6. Physical activity modulates corticospinal excitability of the lower limb in young and old adults.

    Science.gov (United States)

    Hassanlouei, Hamidollah; Sundberg, Christopher W; Smith, Ashleigh E; Kuplic, Andrew; Hunter, Sandra K

    2017-08-01

    Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 ± 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 ± 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was used to elicit MEPs in the active vastus lateralis muscle (10% maximal voluntary contraction) with 5% increments in stimulator intensity until the maximum MEP amplitude. Stimulus-response curves of MEP amplitudes were fit with a four-parameter sigmoidal curve and the maximal slope calculated (slope max ). Habitual PA was assessed with tri-axial accelerometry and participants categorized into either those meeting the recommended PA guidelines for optimal health benefits (>10,000 steps/day, high-PA; n = 21) or those not meeting the guidelines ( 0.05), suggesting that habitual PA influenced the excitability of the corticospinal tract projecting to the lower limb similarly in both young and old adults. These findings provide evidence that achieving the recommended PA guidelines for optimal health may mediate its effects on the nervous system by decreasing corticospinal excitability. NEW & NOTEWORTHY Transcranial magnetic stimulation was used to determine whether achieving the recommended 10,000 steps/day for optimal health influenced the excitability of the corticospinal tract projecting to the knee extensor muscles. Irrespective of age and sex, individuals who achieved >10,000 steps/day had lower corticospinal excitability than those who performed Physical activity involving >10,000 steps/day may mediate its effects on the nervous system by decreasing

  7. Motor unit firing frequency of lower limb muscles during an incremental slide board skating test.

    Science.gov (United States)

    Piucco, Tatiane; Bini, Rodrigo; Sakaguchi, Masanori; Diefenthaeler, Fernando; Stefanyshyn, Darren

    2017-11-01

    This study investigated how the combination of workload and fatigue affected the frequency components of muscle activation and possible recruitment priority of motor units during skating to exhaustion. Ten male competitive speed skaters performed an incremental maximal test on a slide board. Activation of six muscles from the right leg was recorded throughout the test. A time-frequency analysis was performed to compute overall, high, and low frequency bands from the whole signal at 10, 40, 70, and 90% of total test time. Overall activation increased for all muscles throughout the test (p  0.80). There was an increase in low frequency (90 vs. 10%, p = 0.035, ES = 1.06) and a decrease in high frequency (90 vs. 10%, p = 0.009, ES = 1.38, and 90 vs. 40%, p = 0.025, ES = 1.12) components of gluteus maximus. Strong correlations were found between the maximal cadence and vastus lateralis, gluteus maximus and gluteus medius activation at the end of the test. In conclusion, the incremental skating test lead to an increase in activation of lower limb muscles, but only gluteus maximus was sensitive to changes in frequency components, probably caused by a pronounced fatigue.

  8. Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans.

    Directory of Open Access Journals (Sweden)

    Michael A Petrie

    Full Text Available Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat and mechanical stress (vibration on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction.The purpose of this study is to examine whether active mechanical stress (muscle contraction, passive mechanical stress (vibration, or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair.Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus to analyze mRNA gene expression.We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold, PGC-1α (5.46 fold, and ABRA (5.98 fold; and repressed MSTN (0.56 fold. Heat stress repressed PGC-1α (0.74 fold change; p < 0.05; while vibration induced FOXK2 (2.36 fold change; p < 0.05. Vibration similarly caused a down regulation of MSTN (0.74 fold change; p < 0.05, but to a lesser extent than active muscle contraction. Vibration induced FOXK2 (p < 0.05 while heat stress repressed PGC-1α (0.74 fold and ANKRD1 genes (0.51 fold; p < 0.05.These findings support a distinct gene regulation in response to heat stress, vibration, and muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell

  9. Myostatin in relation to physical activity and dysglycaemia and its effect on energy metabolism in human skeletal muscle cells.

    Science.gov (United States)

    Hjorth, M; Pourteymour, S; Görgens, S W; Langleite, T M; Lee, S; Holen, T; Gulseth, H L; Birkeland, K I; Jensen, J; Drevon, C A; Norheim, F

    2016-05-01

    Some health benefits of exercise may be explained by an altered secretion of myokines. Because previous focus has been on upregulated myokines, we screened for downregulated myokines and identified myostatin. We studied the expression of myostatin in relation to exercise and dysglycaemia in skeletal muscle, adipose tissue and plasma. We further examined some effects of myostatin on energy metabolism in primary human muscle cells and Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. Sedentary men with or without dysglycaemia underwent a 45-min acute bicycle test before and after 12 weeks of combined endurance and strength training. Blood samples and biopsies from m. vastus lateralis and adipose tissue were collected. Myostatin mRNA expression was reduced in skeletal muscle after acute as well as long-term exercise and was even further downregulated by acute exercise on top of 12-week training. Furthermore, the expression of myostatin at baseline correlated negatively with insulin sensitivity. Myostatin expression in the adipose tissue increased after 12 weeks of training and correlated positively with insulin sensitivity markers. In cultured muscle cells but not in SGBS cells, myostatin promoted an insulin-independent increase in glucose uptake. Furthermore, muscle cells incubated with myostatin had an enhanced rate of glucose oxidation and lactate production. Myostatin was differentially expressed in the muscle and adipose tissue in relation to physical activity and dysglycaemia. Recombinant myostatin increased the consumption of glucose in human skeletal muscle cells, suggesting a complex regulatory role of myostatin in skeletal muscle homeostasis. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  10. Mammalian target of rapamycin complex 1 activation is required for the stimulation of human skeletal muscle protein synthesis by essential amino acids.

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    Dickinson, Jared M; Fry, Christopher S; Drummond, Micah J; Gundermann, David M; Walker, Dillon K; Glynn, Erin L; Timmerman, Kyle L; Dhanani, Shaheen; Volpi, Elena; Rasmussen, Blake B

    2011-05-01

    The relationship between mammalian target of rapamycin complex 1 (mTORC1) signaling and muscle protein synthesis during instances of amino acid surplus in humans is based solely on correlational data. Therefore, the goal of this study was to use a mechanistic approach specifically designed to determine whether increased mTORC1 activation is requisite for the stimulation of muscle protein synthesis following L-essential amino acid (EAA) ingestion in humans. Examination of muscle protein synthesis and signaling were performed on vastus lateralis muscle biopsies obtained from 8 young (25 ± 2 y) individuals who were studied prior to and following ingestion of 10 g of EAA during 2 separate trials in a randomized, counterbalanced design. The trials were identical except during 1 trial, participants were administered a single oral dose of a potent mTORC1 inhibitor (rapamycin) prior to EAA ingestion. In response to EAA ingestion, an ~60% increase in muscle protein synthesis was observed during the control trial, concomitant with increased phosphorylation of mTOR (Ser(2448)), ribosomal S6 kinase 1 (Thr(389)), and eukaryotic initiation factor 4E binding protein 1 (Thr(37/46)). In contrast, prior administration of rapamycin completely blocked the increase in muscle protein synthesis and blocked or attenuated activation of mTORC1-signaling proteins. The inhibition of muscle protein synthesis and signaling was not due to differences in either extracellular or intracellular amino acid availability, because these variables were similar between trials. These data support a fundamental role for mTORC1 activation as a key regulator of human muscle protein synthesis in response to increased EAA availability. This information will be useful in the development of evidence-based nutritional therapies targeting mTORC1 to counteract muscle wasting associated with numerous clinical conditions.

  11. Free amino acid pools in muscle and hemolymph during the molt cycle of the land crab, Gecarcinus lateralis

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    Yamaoka, L.H.; Skinner, D.M.

    1976-01-01

    The total free amino acids in muscle water of the land crab, Gecarcinus lateralis, decrease almost 3-fold during the premolt period in comparison to the intermolt period (193 ..mu..M/g during intermolt and 67 ..mu..M/g during late premolt). This decrease is accounted for primarily by changes in the nonessential amino acids proline, glycine and alanine. At the same stage, several essential amino acids (lysine, methionine and tyrosine) increase 2- to 4-fold. Although free amino acid levels in hemolymph are lower and more variable than those in muscle, the same amino acids show similar molt-stage-related changes. The decreases in glycine and proline may be associated with the synthesis of the new exoskeleton and connective tissue during the premolt period.

  12. Rediscovery of Meristaspis lateralis (Kolenati) (Acari: Mesostigmata: Spinturnicidae) parasitizing the Egyptian fruit bat, Rousettus aegyptiacus (Geoffroy) (Mammalia: Chiroptera), with a key to mites of bats in Egypt.

    Science.gov (United States)

    Negm, Mohamed W; Fakeer, Mahmoud M

    2014-04-01

    Faunistic information about bat mites in Egypt is scarce. Collection records of parasitic mites, Meristaspis lateralis (Kolenati, 1856) (Mesostigmata: Spinturnicidae), are reported from the Egyptian fruit bat, Rousettus aegyptiacus (Geoffroy, 1810) (Mammalia: Chiroptera) in Assiut Governorate, Egypt. Seven species of bat mites are recognized from Egypt to date. A host-parasite checklist and an identification key to these species are presented.

  13. Muscle adaptations to plyometric vs. resistance training in untrained young men

    DEFF Research Database (Denmark)

    Vissing, Kristian; Brink, Mads; Lønbro, Simon

    2008-01-01

    The purpose of this study was to compare changes in muscle strength, power, and morphology induced by conventional strength training vs. plyometric training of equal time and effort requirements. Young, untrained men performed 12 weeks of progressive conventional resistance training (CRT, n = 8......) or plyometric training (PT, n = 7). Tests before and after training included one-repetition maximum (1 RM) incline leg press, 3 RM knee extension, and 1 RM knee flexion, countermovement jumping (CMJ), and ballistic incline leg press. Also, before and after training, magnetic resonance imaging scanning...... was performed for the thigh, and a muscle biopsy was sampled from the vastus lateralis muscle. Muscle strength increased by approximately 20-30% (1-3 RM tests) (p Plyometric training increased maximum CMJ height (10...

  14. Quadriceps exercise intolerance in patients with chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Gifford, Jayson R; Trinity, Joel D; Layec, Gwenael

    2015-01-01

    This study sought to determine if qualitative alterations in skeletal muscle mitochondrial respiration, associated with decreased mitochondrial efficiency, contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). Using permeabilized muscle fibers from.......05). Overall, this study indicates that COPD is associated with qualitative alterations in skeletal muscle mitochondria that affect the contribution of CI and CII-driven respiration, which potentially contributes to the exercise intolerance associated with this disease....... the vastus lateralis of 13 patients with COPD and 12 healthy controls, complex I (CI) and complex II (CII)-driven State 3 mitochondrial respiration were measured separately (State 3:CI and State 3:CII) and in combination (State 3:CI+CII). State 2 respiration was also measured. Exercise tolerance was assessed...

  15. Mitochondrial function in human skeletal muscle following high-altitude exposure

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    Jacobs, Robert A; Boushel, Robert; Wright-Paradis, Cynthia

    2013-01-01

    Studies regarding mitochondrial modifications in human skeletal muscle following acclimatization to high altitude are conflicting, and these inconsistencies may be due to the prevalence of representing mitochondrial function through static and isolated measurements of specific mitochondrial...... characteristics. The aim of this study, therefore, was to investigate mitochondrial function in response to high-altitude acclimatization through measurements of respiratory control in the vastus lateralis muscle. Skeletal muscle biopsies were obtained from 10 lowland natives prior to and again after a total of 9......-11 days of exposure to 4559 m. High-resolution respirometry was performed on the muscle samples to compare respiratory chain function and respiratory capacities. Respirometric analysis revealed that mitochondrial function was largely unaffected, because high-altitude exposure did not affect the capacity...

  16. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth

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    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon

    2014-01-01

    -specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose......Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type......) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P

  17. Increased subsarcolemmal lipids in type 2 diabetes: effect of training on localization of lipids, mitochondria, and glycogen in sedentary human skeletal muscle

    DEFF Research Database (Denmark)

    Nielsen, Joachim; Hey-Mogensen, Martin; Vind, Birgitte F

    2010-01-01

    The purpose of the study was to investigate the effect of aerobic training and type 2 diabetes on intramyocellular localization of lipids, mitochondria, and glycogen. Obese type 2 diabetic patients (n = 12) and matched obese controls (n = 12) participated in aerobic cycling training for 10 wk....... Endurance-trained athletes (n = 15) were included for comparison. Insulin action was determined by euglycemic-hyperinsulinemic clamp. Intramyocellular contents of lipids, mitochondria, and glycogen at different subcellular compartments were assessed by transmission electron microscopy in biopsies obtained...... from vastus lateralis muscle. Type 2 diabetic patients were more insulin resistant than obese controls and had threefold higher volume of subsarcolemmal (SS) lipids compared with obese controls and endurance-trained subjects. No difference was found in intermyofibrillar lipids. Importantly, following...

  18. Capillary growth, ultrastructure remodeling and exercise training in skeletal muscle of essential hypertensive patients

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    Gliemann, Lasse; Buess, Rahel; Nyberg, Michael Permin

    2015-01-01

    obtained from m. vastus lateralis in essential hypertensive patients (n=10) and normotensive controls (n=11) before and after 8 weeks of aerobic exercise training. Morphometry was performed after transmission electron microscopy and protein levels of several angioregulatory factors were determined. RESULTS......AIM: The aim was to elucidate whether essential hypertension is associated with altered capillary morphology and density and to what extend exercise training can normalize these parameters. METHODS: To investigate angiogenesis and capillary morphology in essential hypertension, muscle biopsies were...... of vascular endothelial growth factor (VEGF), VEGF receptor-2 and thrombospondin-1 were similar in normo- and hypertensive subjects but tissue inhibitor of matrix metalloproteinase was 69% lower in the hypertensive group. After training, angiogenesis was evident by 15% increased capillary-to-fiber ratio...

  19. Influence of pre-exercise muscle glycogen content on exercise-induced transcriptional regulation of metabolic genes

    DEFF Research Database (Denmark)

    Pilegaard, Henriette; Keller, Charlotte; Steensberg, Adam

    2002-01-01

    Transcription of metabolic genes is transiently induced during recovery from exercise in skeletal muscle of humans. To determine whether pre-exercise muscle glycogen content influences the magnitude and/or duration of this adaptive response, six male subjects performed one-legged cycling exercise...... to lower muscle glycogen content in one leg and then, the following day, completed 2.5 h low intensity two-legged cycling exercise. Nuclei and mRNA were isolated from biopsies obtained from the vastus lateralis muscle of the control and reduced glycogen (pre-exercise glycogen = 609 +/- 47 and 337 +/- 33...... mmol kg(-1) dry weight, respectively) legs before and after 0, 2 and 5 h of recovery. Exercise induced a significant (P glycogen leg only. Although PDK4...

  20. Myoeletric indices of fatigue adopting different rest intervals during leg press sets.

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    Miranda, Humberto; Maia, Marianna; de Oliveira, Carlos G; Farias, Déborah; da Silva, Jurandir B; Lima, Vicente P; Willardson, Jeffrey M; Paz, Gabriel A

    2018-01-01

    The purpose of this study was to examine the acute effect of different rest intervals between multiple sets of the 45° angled leg press exercise (LP45) on surface electromyographic (SEMG) spectral and amplitude indices of fatigue. Fifteen recreationally trained females performed three protocols in a randomized crossover design; each consisting of four sets of 10 repetitions with 1 (P1), 3 (P3), or 5 (P5) minute rest intervals between sets. Each set was performed with 70% of the LP45 ten-repetition maximum load. The SEMG data for biceps femoris (BF), vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles was then evaluated. The SEMG amplitude change in the time coefficient (CRMS) and spectral fatigue index (Cf5) indicated higher levels of fatigue for all muscles evaluated during the P3 protocol versus the P1 and P5 protocols (p ≤ 0.05), respectively. The RF and VL muscles showed greater fatigue levels by the second and third sets; whereas, greater fatigue was shown in the VM and BF muscles by the fourth set (p ≤ 0.05). A three-minute rest interval between sets might represent a neuromuscular window between a fatigue stated and fully recovered state in the context of neural activation. Moreover, a three minute rest interval between sets might allow for consistent recruitment of high threshold motor units over multiple sets, and thus promote a more effective stimulus for strength gains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Avaliação eletromiográfica dos músculos estabilizadores da patela durante exercício isométrico de agachamento em indivíduos com síndrome da dor femoropatelar Evaluacion eletromiográfica de los músculos estabilizadores patelares durante el ejercício isométrico de agachamiento en indivíduos con síndrome de dolor femoropatelar Electromyographic activity evaluation of the patella muscles during squat isometric exercise in individuals with patellofemoral pain syndrome

    Directory of Open Access Journals (Sweden)

    Débora Bevilaqua-Grossi

    2005-06-01

    Full Text Available O objetivo deste trabalho foi comparar a atividade elétrica dos músculos vasto medial oblíquo (VMO, vasto lateral longo (VLL e vasto lateral oblíquo (VLO durante os exercícios isométricos de agachamento wall slide a 45º (WS 45º e 60º (WS 60º de flexão do joelho. Foram avaliadas 15 mulheres clinicamente saudáveis e 15 mulheres com síndrome da dor femoropatelar (SDFP. Os registros eletromiográficos foram obtidos por eletrodos ativos simples conectados a um eletromiógrafo durante a contração isométrica voluntária máxima (CIVM do WS 45º e WS 60º. Os dados foram analisados pela média dos valores do root mean square (RMS do sinal eletromiográfico, normalizado pela média do RMS obtido no agachamento a 75º de flexão do joelho. A análise estatística empregada foi o teste ANOVA two way (p El objetivo de este trabajo fué el de comparar la actvividad eléctrica de los músculos vasto medial oblíqüo (VMO, vasto lateral longo (VLL y vasto lateral oblicuo (VLO durante los ejercicios isometricos de agachamiento wall slide a 45º (WS 45º e 60º (WS 60º de flexión de rodilla. Fueron evaluadas 15 mujeres clinicamente saludables con sindrome de dolor femoropatelar (SDFP. Los registros fueron obtenidos por electrodos activos simples conectados a un electromiografo durante la contraccion isometrica voluntaria máxima (CIVM de WS 45º y de WS 60º. Los datos fueron analizados por la media de los valores de Root Mean Square - RMS de señal eletromiográfica, normalizada por la media del RMS obtenido en el agachamiento a 75º de flexión de la rodilla. El análisis estatístico empleado fue el test ANOVA two way (p The objective of this study was to compare the electromyographic (EMG activity of vastus medialis obliquus (VMO, vastus lateralis longus (VLL and vastus lateralis oblíquus (VLO during wall slide squat isometric exercises at 45º (WS 45º and at 60º (WS 60º of knee flexion. Fifteen healthy control women and fifteen women

  2. Isometric and dynamic strength and neuromuscular attributes as predictors of vertical jump performance in 11- to 13-year-old male athletes.

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    McKinlay, Brandon John; Wallace, Phillip J; Dotan, Raffy; Long, Devon; Tokuno, Craig; Gabriel, David A; Falk, Bareket

    2017-09-01

    In explosive contractions, neural activation is a major factor in determining the rate of torque development, while the latter is an important determinant of jump performance. However, the contribution of neuromuscular activation and rate of torque development to jump performance in children and youth is unclear. The purpose of this study was to examine the relationships between the rate of neuromuscular activation, peak torque, rate of torque development, and jump performance in young male athletes. Forty-one 12.5 ± 0.5-year-old male soccer players completed explosive, unilateral isometric and dynamic (240°/s) knee extensions (Biodex System III), as well as countermovement-, squat-, and drop-jumps. Peak torque (pT), peak rate of torque development (pRTD), and rate of vastus lateralis activation (Q 30 ) during the isometric and dynamic contractions were examined in relation to attained jump heights. Isometric pT and pRTD were strongly correlated (r = 0.71) but not related to jump performance. Dynamic pT and pRTD, normalized to body mass, were significantly related to jump height in all 3 jumps (r = 0.38-0.66, p jump performance, while isometric contractions are not. These findings have implications in the choice of training and assessment methods for young athletes.

  3. Cycle Training Increased GLUT4 and Activation of mTOR in Fast Twitch Muscle Fibers

    Science.gov (United States)

    Stuart, Charles A.; Howell, Mary E.A.; Baker, Jonathan D.; Dykes, Rhesa J.; Duffourc, Michelle M.; Ramsey, Michael W.; Stone, Michael H.

    2009-01-01

    Purpose To determine if cycle training of sedentary subjects would increase the expression of the principle muscle glucose transporters, six volunteers completed six weeks of progressively increasing intensity stationary cycle cycling. Methods In vastus lateralis muscle biopsies, changes in expression of GLUT1, GLUT4, GLUT5, and GLUT12 were compared using quantitative immunoblots with specific protein standards. Regulatory pathway components were evaluated by immunoblots of muscle homogenates and immunohistochemistry of microscopic sections. Results GLUT1 was unchanged, GLUT4 increased 66%, GLUT12 increased 104%, and GLUT5 decreased 72%. A mitochondrial marker (cytochrome c) and regulators of mitochondrial biogenesis (PGC-1α and phospho-AMPK) were unchanged, but the muscle hypertrophy pathway component, phospho-mTOR increased 83% after the exercise program. In baseline biopsies, GLUT4 by immunohistochemical techniques was 37% greater in Type I (slow twitch, red) muscle fibers, but the exercise training increased GLUT4 expression in Type II (fast twitch, white) fibers by 50%, achieving parity with the Type I fibers. Baseline phospho-mTOR expression was 50% higher in Type II fibers and increased more in Type II fibers (62%) with training, but also increased in Type I fibers (34%). Conclusion Progressive intensity stationary cycle training of previously sedentary subjects increased muscle insulin-responsive glucose transporters (GLUT4 and GLUT12) and decreased the fructose transporter (GLUT5). The increase in GLUT4 occurred primarily in Type II muscle fibers and this coincided with activation of the mTOR muscle hypertrophy pathway. There was little impact on Type I fiber GLUT4 expression and no evidence of change in mitochondrial biogenesis. PMID:20010125

  4. Effects of Plyometric and Resistance Training on Muscle Strength, Explosiveness and Neuromuscular Function in Young Adolescent Soccer Players.

    Science.gov (United States)

    McKinlay, Brandon John; Wallace, Phillip; Dotan, Raffy; Long, Devon; Tokuno, Craig; Gabriel, David; Falk, Bareket

    2018-01-04

    This study examined the effect of 8-weeks of free-weight-resistance (RT) and plyometric (PLYO) training on maximal strength, explosiveness and jump performance compared with no added training (CON), in young male soccer players. Forty-one 11[FIGURE DASH]13-year-old soccer players were divided into three groups (RT, PLYO, CON). All participants completed isometric and dynamic (240°/s) knee extensions pre- and post-training. Peak torque (pT), peak rate of torque development (pRTD), electromechanical-delay (EMD), rate of muscle activation (Q50), m. vastus-lateralis thickness (VLT), and jump performance were examined. pT, pRTD and jump performance significantly improved in both training groups. Training resulted in significant (pplyometric training resulted in significant improvements in muscle strength and jump performance. Training resulted in similar muscle hypertrophy in the two training modes, with no clear differences in muscle performance. Plyometric training was more effective in improving jump performance, while free-weight resistance training was more advantageous in improving peak torque, where the stretch reflex was not involved.

  5. Kinetic and kinematic differences between squats performed with and without elastic bands.

    Science.gov (United States)

    Israetel, Michael A; McBride, Jeffrey M; Nuzzo, James L; Skinner, Jared W; Dayne, Andrea M

    2010-01-01

    The purpose of this investigation was to compare kinetic and kinematic variables between squats performed with and without elastic bands equalized for total work. Ten recreationally weight trained males completed 1 set of 5 squats without (Wht) and with (Band) elastic bands as resistance. Squats were completed while standing on a force platform with bar displacement measured using 2 potentiometers. Electromyography (EMG) was obtained from the vastus lateralis. Average force-time, velocity-time, power-time, and EMG-time graphs were generated and statistically analyzed for mean differences in values between the 2 conditions during the eccentric and concentric phases. The Band condition resulted in significantly higher forces in comparison to the Wht condition during the first 25% of the eccentric phase and the last 10% of the concentric phase (p squats equalized for total work with and without elastic bands significantly alter the force-time, power-time, velocity-time, and EMG-time curves associated with the movements. Specifically, elastic bands seem to increase force, power, and muscle activity during the early portions of the eccentric phase and latter portions of the concentric phase.

  6. A feasible, economical, and accurate analytical method for simultaneous determination of six alkaloid markers in Aconiti Lateralis Radix Praeparata from different manufacturing sources and processing ways.

    Science.gov (United States)

    Zhang, Yi-Bei; DA, Juan; Zhang, Jing-Xian; Li, Shang-Rong; Chen, Xin; Long, Hua-Li; Wang, Qiu-Rong; Cai, Lu-Ying; Yao, Shuai; Hou, Jin-Jun; Wu, Wan-Ying; Guo, De-An

    2017-04-01

    Aconiti Lateralis Radix Praeparata (Fuzi) is a commonly used traditional Chinese medicine in clinic for its potency in restoring yang and rescuing from collapse. Aconiti alkaloids, mainly including monoester-diterpenoidaconitines (MDAs) and diester-diterpenoidaconitines (DDAs), are considered to act as both bioactive and toxic constituents. In the present study, a feasible, economical, and accurate HPLC method for simultaneous determination of six alkaloid markers using the Single Standard for Determination of Multi-Components (SSDMC) method was developed and fully validated. Benzoylmesaconine was used as the unique reference standard. This method was proven as accurate (recovery varying between 97.5%-101.8%, RSD 0.999 9) over the concentration ranges, and subsequently applied to quantitative evaluation of 62 batches of samples, among which 45 batches were from good manufacturing practice (GMP) facilities and 17 batches from the drug market. The contents were then analyzed by principal component analysis (PCA) and homogeneity test. The present study provided valuable information for improving the quality standard of Aconiti Lateralis Radix Praeparata. The developed method also has the potential in analysis of other Aconitum species, such as Aconitum carmichaelii (prepared parent root) and Aconitum kusnezoffii (prepared root). Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  7. Determination of optimal whole body vibration amplitude and frequency parameters with plyometric exercise and its influence on closed-chain lower extremity acute power output and EMG activity in resistance trained males

    Science.gov (United States)

    Hughes, Nikki J.

    The optimal combination of Whole body vibration (WBV) amplitude and frequency has not been established. Purpose. To determine optimal combination of WBV amplitude and frequency that will enhance acute mean and peak power (MP and PP) output EMG activity in the lower extremity muscles. Methods. Resistance trained males (n = 13) completed the following testing sessions: On day 1, power spectrum testing of bilateral leg press (BLP) movement was performed on the OMNI. Days 2 and 3 consisted of WBV testing with either average (5.8 mm) or high (9.8 mm) amplitude combined with either 0 (sham control), 10, 20, 30, 40 and 50 Hz frequency. Bipolar surface electrodes were placed on the rectus femoris (RF), vastus lateralis (VL), bicep femoris (BF) and gastrocnemius (GA) muscles for EMG analysis. MP and PP output and EMG activity of the lower extremity were assessed pre-, post-WBV treatments and after sham-controls on the OMNI while participants performed one set of five repetitions of BLP at the optimal resistance determined on Day 1. Results. No significant differences were found between pre- and sham-control on MP and PP output and on EMG activity in RF, VL, BF and GA. Completely randomized one-way ANOVA with repeated measures demonstrated no significant interaction of WBV amplitude and frequency on MP and PP output and peak and mean EMGrms amplitude and EMG rms area under the curve. RF and VL EMGrms area under the curve significantly decreased (p plyometric exercise does not induce alterations in subsequent MP and PP output and EMGrms activity of the lower extremity. Future studies need to address the time of WBV exposure and magnitude of external loads that will maximize strength and/or power output.

  8. Recruitment order of quadriceps motor units: femoral nerve vs. direct quadriceps stimulation.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Place, Nicolas

    2013-12-01

    To investigate potential differences in the recruitment order of motor units (MUs) in the quadriceps femoris when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using femoral nerve stimulation and direct quadriceps stimulation of gradually increasing intensity from 20 young, healthy subjects. Recruitment order was investigated by analysing the time-to-peak twitch and the time interval from the stimulus artefact to the M-wave positive peak (M-wave latency) for the vastus medialis (VM) and vastus lateralis (VL) muscles. During femoral nerve stimulation, time-to-peak twitch and M-wave latency decreased consistently (P  0.05). For the VM muscle, M-wave latency decreased with increasing stimulation level for both femoral nerve and direct quadriceps stimulation, whereas, for the VL muscle, the variation of M-wave latency with stimulus intensity was different for the two stimulation geometries (P recruitment order during direct quadriceps stimulation was more complex, depending ultimately on the architecture of the peripheral nerve and its terminal branches below the stimulating electrodes for each muscle. For the VM, MUs were orderly recruited for both stimulation geometries, whereas, for the VL muscle, MUs were orderly recruited for femoral nerve stimulation, but followed no particular order for direct quadriceps stimulation.

  9. Modelling of Muscle Force Distributions During Barefoot and Shod Running

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    Sinclair Jonathan

    2015-09-01

    Full Text Available Research interest in barefoot running has expanded considerably in recent years, based around the notion that running without shoes is associated with a reduced incidence of chronic injuries. The aim of the current investigation was to examine the differences in the forces produced by different skeletal muscles during barefoot and shod running. Fifteen male participants ran at 4.0 m·s-1 (± 5%. Kinematics were measured using an eight camera motion analysis system alongside ground reaction force parameters. Differences in sagittal plane kinematics and muscle forces between footwear conditions were examined using repeated measures or Freidman’s ANOVA. The kinematic analysis showed that the shod condition was associated with significantly more hip flexion, whilst barefoot running was linked with significantly more flexion at the knee and plantarflexion at the ankle. The examination of muscle kinetics indicated that peak forces from Rectus femoris, Vastus medialis, Vastus lateralis, Tibialis anterior were significantly larger in the shod condition whereas Gastrocnemius forces were significantly larger during barefoot running. These observations provide further insight into the mechanical alterations that runners make when running without shoes. Such findings may also deliver important information to runners regarding their susceptibility to chronic injuries in different footwear conditions.

  10. Detecting fatigue thresholds from electromyographic signals: A systematic review on approaches and methodologies.

    Science.gov (United States)

    Ertl, Peter; Kruse, Annika; Tilp, Markus

    2016-10-01

    The aim of the current paper was to systematically review the relevant existing electromyographic threshold concepts within the literature. The electronic databases MEDLINE and SCOPUS were screened for papers published between January 1980 and April 2015 including the keywords: neuromuscular fatigue threshold, anaerobic threshold, electromyographic threshold, muscular fatigue, aerobic-anaerobictransition, ventilatory threshold, exercise testing, and cycle-ergometer. 32 articles were assessed with regard to their electromyographic methodologies, description of results, statistical analysis and test protocols. Only one article was of very good quality. 21 were of good quality and two articles were of very low quality. The review process revealed that: (i) there is consistent evidence of one or two non-linear increases of EMG that might reflect the additional recruitment of motor units (MU) or different fiber types during fatiguing cycle ergometer exercise, (ii) most studies reported no statistically significant difference between electromyographic and metabolic thresholds, (iii) one minute protocols with increments between 10 and 25W appear most appropriate to detect muscular threshold, (iv) threshold detection from the vastus medialis, vastus lateralis, and rectus femoris is recommended, and (v) there is a great variety in study protocols, measurement techniques, and data processing. Therefore, we recommend further research and standardization in the detection of EMGTs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Potential factors associated with knee pain in cyclists: a systematic review

    Directory of Open Access Journals (Sweden)

    Bini RR

    2018-05-01

    Full Text Available Rodrigo Rico Bini, Alice Flores Bini La Trobe Rural Health School, La Trobe University, Flora Hill Campus, Bendigo, VIC, Australia Abstract: The potential factors associated with overuse injuries and pain in cyclists that are supported by evidence remain unclear. Our study aimed at assessing, using a systematic search of the most updated evidence, the main factors related to overuse knee-related pain and/or injuries in cyclists. The search assessed any potential mechanism related to knee pain or injury that could be used in the clinical practice. Databases were searched (i.e., PubMed, Scopus, Web of Science, and EBSCO. Studies were included if they presented results from original studies. They had to include, preferably but not limited to, recreational and/or competitive cyclists with or without knee pain. Quality of articles was assessed. Eleven articles were deemed eligible for full text appraisal. Studies involved generally the assessment of biomechanical outcomes associated with knee pain in cyclists. Overall, studies showed that cyclists with knee pain present larger knee adduction and larger ankle dorsiflexion and differences in activation for hamstrings and quadriceps muscles. Unclear results were observed for knee moments and no differences were observed for knee flexion angle, tibiofemoral and patellofemoral forces. It is important to state that varied types of knee pain were mixed in most studies, with 2 focused on anterior-related pain. Cyclists with overuse-related pain or injuries on their knees presented an increased medial projection of their knees and an altered activation of the Vastus Medialis and Vastus Lateralis muscles. However, this limited evidence is based on retrospective studies comparing cyclists with and without pain, which limits the conclusion on how cyclists develop knee pain and what are the main options for treatment of knee pain. Keywords: injury, cycling, overuse, biomechanics

  12. Insulin resistance in non-obese subjects is associated with activation of the JNK pathway and impaired insulin signaling in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Umesh B Masharani

    2011-05-01

    Full Text Available The pathogenesis of insulin resistance in the absence of obesity is unknown. In obesity, multiple stress kinases have been identified that impair the insulin signaling pathway via serine phosphorylation of key second messenger proteins. These stress kinases are activated through various mechanisms related to lipid oversupply locally in insulin target tissues and in various adipose depots.To explore whether specific stress kinases that have been implicated in the insulin resistance of obesity are potentially contributing to insulin resistance in non-obese individuals, twenty healthy, non-obese, normoglycemic subjects identified as insulin sensitive or resistant were studied. Vastus lateralis muscle biopsies obtained during euglycemic, hyperinsulinemic clamp were evaluated for insulin signaling and for activation of stress kinase pathways. Total and regional adipose stores and intramyocellular lipids (IMCL were assessed by DXA, MRI and (1H-MRS. In muscle of resistant subjects, phosphorylation of JNK was increased (1.36±0.23 vs. 0.78±0.10 OD units, P<0.05, while there was no evidence for activation of p38 MAPK or IKKβ. IRS-1 serine phosphorylation was increased (1.30±0.09 vs. 0.22±0.03 OD units, P<0.005 while insulin-stimulated tyrosine phosphorylation decreased (10.97±0.95 vs. 0.89±0.50 OD units, P<0.005. IMCL levels were twice as high in insulin resistant subjects (3.26±0.48 vs. 1.58±0.35% H(2O peak, P<0.05, who also displayed increased total fat and abdominal fat when compared to insulin sensitive controls.This is the first report demonstrating that insulin resistance in non-obese, normoglycemic subjects is associated with activation of the JNK pathway related to increased IMCL and higher total body and abdominal adipose stores. While JNK activation is consistent with a primary impact of muscle lipid accumulation on metabolic stress, further work is necessary to determine the relative contributions of the various mediators of impaired

  13. EFFECTS OF FATIGUE ON FRONTAL PLANE KNEE MOTION, MUSCLE ACTIVITY, AND GROUND REACTION FORCES IN MEN AND WOMEN DURING LANDING

    Directory of Open Access Journals (Sweden)

    Michael P. Smith

    2009-09-01

    Full Text Available Women tear their Anterior Cruciate Ligament (ACL 2-8 times more frequently than men. Frontal plane knee motion can produce a pathological load in the ACL. During a state of fatigue the muscles surrounding the knee joint may lose the ability to protect the joint during sudden deceleration while landing. The purpose of this study was to investigate the effects of fatigue and gender on frontal plane knee motion, EMG amplitudes, and GRF magnitudes during drop- jump landing. Pretest-posttest comparison group design was used. Twenty-six volunteers (14 women; 12 Men; Mean ± standard deviation age = 24.5 ± 2.7 yrs; height = 1.73 ± 0.09 m; mass = 74.3 ± 11.8 kg participated in the study. Knee frontal plane ranges of motion and positions, ground reaction force peak magnitudes, and surface EMG RMS amplitudes from five lower extremity muscles (vastus medialis, vastus lateralis, medial hamstring, lateral hamstring, and lateral gastrocnemius were obtained during the landing phase of a drop-jump. MANOVA and ANOVA indicated that peak GRF significantly (p < 0.05; 2.50 ± 0.75 BW vs. 2.06 ± 0.93 BW decreased during fatigued landings. No other variables exhibited a fatigue main effect, although there was a significant (p < 0.05 fatigue by gender interaction for the frontal plane range of motion from initial contact to max knee flexion variable. Follow-up analyses failed to reveal significant gender differences at the different levels of fatigue for this variable. Additionally, no variables exhibited a significant gender main effect. Single subject analysis indicated that fatigue significantly altered frontal plane knee motion, peak GRF, and EMG in some subjects and the direction of differences varied by individual. Fatigue altered some aspects of landing performance in both men and women, but there were no gender differences. Additionally, both group and single subject analyses provided valuable but different information about factors representing

  14. The Combined Effects of Body Weight Support and Gait Speed on Gait Related Muscle Activity: A Comparison between Walking in the Lokomat Exoskeleton and Regular Treadmill Walking

    Science.gov (United States)

    Van Kammen, Klaske; Boonstra, Annemarijke; Reinders-Messelink, Heleen; den Otter, Rob

    2014-01-01

    Background For the development of specialized training protocols for robot assisted gait training, it is important to understand how the use of exoskeletons alters locomotor task demands, and how the nature and magnitude of these changes depend on training parameters. Therefore, the present study assessed the combined effects of gait speed and body weight support (BWS) on muscle activity, and compared these between treadmill walking and walking in the Lokomat exoskeleton. Methods Ten healthy participants walked on a treadmill and in the Lokomat, with varying levels of BWS (0% and 50% of the participants’ body weight) and gait speed (0.8, 1.8, and 2.8 km/h), while temporal step characteristics and muscle activity from Erector Spinae, Gluteus Medius, Vastus Lateralis, Biceps Femoris, Gastrocnemius Medialis, and Tibialis Anterior muscles were recorded. Results The temporal structure of the stepping pattern was altered when participants walked in the Lokomat or when BWS was provided (i.e. the relative duration of the double support phase was reduced, and the single support phase prolonged), but these differences normalized as gait speed increased. Alternations in muscle activity were characterized by complex interactions between walking conditions and training parameters: Differences between treadmill walking and walking in the exoskeleton were most prominent at low gait speeds, and speed effects were attenuated when BWS was provided. Conclusion Walking in the Lokomat exoskeleton without movement guidance alters the temporal step regulation and the neuromuscular control of walking, although the nature and magnitude of these effects depend on complex interactions with gait speed and BWS. If normative neuromuscular control of gait is targeted during training, it is recommended that very low speeds and high levels of BWS should be avoided when possible. PMID:25226302

  15. An optimized high-performance liquid chromatography (HPLC method for benzoylmesaconine determination in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots and its products

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    Xu Hongxi

    2008-05-01

    Full Text Available Abstract Background Benzoylmesaconine (BMA is the main Aconitum alkaloid in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots with potent pharmacological activities, such as analgesia and anti-inflammation. The present study developed a simple and reliable method using BMA as a marker compound for the quality control of processed aconite roots and their products. Methods After extraction, a high-performance liquid chromatography (HPLC determination of BMA was conducted on a RP-C18 column by gradient elution with acetonitrile and aqueous phase, containing 0.1% phosphoric acid adjusted with triethylamine to pH 3.0. Results A distinct peak profile was obtained and separation of BMA was achieved. Method validation showed that the relative standard deviations (RSDs of the precision of BMA in all intra-day and inter-day assays were less than 1.36%, and that the average recovery rate was 96.95%. Quantitative analysis of BMA showed that the content of BMA varied significantly in processed aconite roots and their products. Conclusion This HPLC method using BMA as a marker compound is applicable to the quality control of processed aconite roots and their products.

  16. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

    Science.gov (United States)

    Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

    2015-01-01

    Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

  17. Sprint acceleration mechanics: the major role of hamstrings in horizontal force production

    Directory of Open Access Journals (Sweden)

    Jean-Benoit eMORIN

    2015-12-01

    Full Text Available Recent literature supports the importance of horizontal ground reaction force (GRF production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG activity of the vastus lateralis, rectus femoris, biceps femoris and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024 between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.

  18. Impact of external pneumatic compression target inflation pressure on transcriptome-wide RNA expression in skeletal muscle.

    Science.gov (United States)

    Martin, Jeffrey S; Kephart, Wesley C; Haun, Cody T; McCloskey, Anna E; Shake, Joshua J; Mobley, Christopher B; Goodlett, Michael D; Kavazis, Andreas; Pascoe, David D; Zhang, Lee; Roberts, Michael D

    2016-11-01

    Next-generation RNA sequencing was employed to determine the acute and subchronic impact of peristaltic pulse external pneumatic compression (PEPC) of different target inflation pressures on global gene expression in human vastus lateralis skeletal muscle biopsy samples. Eighteen (N = 18) male participants were randomly assigned to one of the three groups: (1) sham (n = 6), 2) EPC at 30-40 mmHg (LP-EPC; n = 6), and 3) EPC at 70-80 mmHg (MP-EPC; n = 6). One hour treatment with sham/EPC occurred for seven consecutive days. Vastus lateralis skeletal muscle biopsies were performed at baseline (before first treatment; PRE), 1 h following the first treatment (POST1), and 24 h following the last (7th) treatment (POST2). Changes from PRE in gene expression were analyzed via paired comparisons within each group. Genes were filtered to include only those that had an RPKM ≥ 1.0, a fold-change of ≥1.5 and a paired t-test value of <0.01. For the sham condition, two genes at POST1 and one gene at POST2 were significantly altered. For the LP-EPC condition, nine genes were up-regulated and 0 genes were down-regulated at POST1 while 39 genes were up-regulated and one gene down-regulated at POST2. For the MP-EPC condition, two genes were significantly up-regulated and 21 genes were down-regulated at POST1 and 0 genes were altered at POST2. Both LP-EPC and MP-EPC acutely alter skeletal muscle gene expression, though only LP-EPC appeared to affect gene expression with subchronic application. Moreover, the transcriptome response to EPC demonstrated marked heterogeneity (i.e., genes and directionality) with different target inflation pressures. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  19. Experimental knee pain evoke spreading hyperalgesia and facilitated temporal summation of pain

    DEFF Research Database (Denmark)

    Jørgensen, Tanja Schjødt; Henriksen, Marius; Danneskiold-Samsøe, Bente

    2013-01-01

    OBJECTIVES: This study evaluated the deep-tissue pressure pain sensitivity and temporal summation of pain within and around healthy knees exposed to experimental pain. DESIGN: The study was designed as a randomized crossover trial, with each subject tested on 1 day. SETTING: All tests were carried...... occasions: baseline, immediately after the injection, and when pain had vanished. Assessments sites were located in the peripatellar region, vastus lateralis, and tibialis anterior muscles. RESULTS: The experimental knee pain model demonstrated 1) hyperalgesia to pressure stimulation on the infrapatellar...... fat pad during experimental pain, and 2) facilitated temporal summation of pressure pain at the infrapatellar fat pad and knee-related muscles. CONCLUSION: The increased sensitivity and temporal summation found in this study were exclusive to deep -tissue with no contralateral decreased pain...

  20. Alpha adrenergic receptor blockade increases capillarisation and fractional O2 extraction and lowers blood flow in contracting human skeletal muscle

    DEFF Research Database (Denmark)

    Mortensen, Stefan P; Egginton, Stuart; Madsen, Mads

    2017-01-01

    AIM: To investigate the effect of elevated basal shear stress on angiogenesis in humans, and the role of enhanced skeletal muscle capillarisation on blood flow and O2 extraction. METHODS: Limb haemodynamics and O2 extraction was measured at rest and during one-leg knee-extensor exercise (12 and 24W......) in 10 healthy untrained young men before and after 4 weeks treatment with an α1 receptor-antagonist (Terazosin, 1-2 mg day(-1) ). Corresponding biopsies were taken from the m. vastus lateralis. RESULTS: Resting leg blood flow was increased by 57% 6 hours following Terazosin treatment (P... basal capillary-to-fibre ratio was 1.69±0.08 and increased to 1.90±0.08 after treatment (Pblood flow and venous lactate levels lower (6-7%; P

  1. Prostaglandin synthesis can be inhibited locally by infusion of NSAIDS through microdialysis catheters in human skeletal muscle

    DEFF Research Database (Denmark)

    Mikkelsen, Ulla Ramer; Helmark, Ida Carøe; Kjaer, Michael

    2008-01-01

    of nonsteroidal anti-inflammatory drugs (NSAIDs). However, to study the local role of prostaglandins, the formation of prostaglandins within the tissue must be controlled. Microdialysis enables determination of local concentrations of water-soluble substances within the tissue. In the present study......, the microdialysis method was used to infuse NSAIDs locally into human skeletal muscles producing a local block of prostaglandin formation. In addition, the graded blockade at various distances from the infusion site within the muscle during rest, exercise and recovery was determined. Microdialysis was performed...... in thigh muscles (vastus lateralis muscle) in six healthy men. One of the microdialysis catheters was used to block prostaglandin synthesis by infusion of the NSAID indomethacin. Additional catheters were placed 1 and 4 cm away from the infusion and in the contralateral leg (working control). Following 2 h...

  2. Resistance training and testosterone levels in male patients with chronic kidney disease undergoing dialysis

    DEFF Research Database (Denmark)

    Molsted, Stig; Andersen, Jesper L.; Eidemak, Inge

    2014-01-01

    BACKGROUND: We investigated serum testosterone and insulin-like growth factor 1 (IGF-1) levels' associations with muscle fibre size and resistance training in male dialysis patients. METHODS: Male patients were included in a 16-week control period followed by 16 weeks of resistance training thrice...... weekly. Blood samples were obtained to analyse testosterone, luteinizing hormone (LH), IGF-1, and IGF-binding protein 3. Muscle fibres' size was analysed in biopsies from m. vastus lateralis. RESULTS: The patients' testosterone levels were within the normal range at baseline (n = 20) (19.5 (8......-9370) ng/mL versus 3244 (3020-3983), P muscle fibre size (n = 12) remained stable throughout the study. Age-adjusted IGF-1 was associated with type 1 and 2 fibre sizes (P testosterone values were normal due to markedly increased...

  3. Purinergic receptors expressed in human skeletal muscle fibres

    DEFF Research Database (Denmark)

    Bornø, A; Ploug, Thorkil; Bune, L T

    2012-01-01

    distribution of purinergic receptors in skeletal muscle fibres. We speculate that the intracellular localization of purinergic receptors may reflect a role in regulation of muscle metabolism; further studies are nevertheless needed to determine the function of the purinergic system in skeletal muscle cells.......Purinergic receptors are present in most tissues and thought to be involved in various signalling pathways, including neural signalling, cell metabolism and local regulation of the microcirculation in skeletal muscles. The present study aims to determine the distribution and intracellular content...... of purinergic receptors in skeletal muscle fibres in patients with type 2 diabetes and age-matched controls. Muscle biopsies from vastus lateralis were obtained from six type 2 diabetic patients and seven age-matched controls. Purinergic receptors were analysed using light and confocal microscopy...

  4. Effect of carrageenan addition on the yield and functional properties of charqui (Jerked Beef

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    Carlos Eduardo Rocha Garcia

    2013-04-01

    Full Text Available The objective of this work was to evaluate the application of carrageenan (CAR to improve the functional properties of the jerked beef (JF and to increase its processing yield. JB produced from Vastus lateralis with CAR (1.0% at 25ºC and NaCl (15.0% had approximately 15.0% higher moisture and a 32.0% higher processing yield in comparison to the control samples.JB-CAR presented shear force approximately 5.0 and 20% lower in the samples uncooked salted and desalted cooked, respectively, and sensorial acceptance above 80%. The results demonstrated the possibility of applying carrageenan to jerked beef in order to obtain an increase in the processing yield and a tender product while maintaining the sensorial quality and its intermediate-moisture meat product nature.

  5. Hormone-sensitive lipase serine phosphorylation and glycerol exchange across skeletal muscle in lean and obese subjects

    DEFF Research Database (Denmark)

    Jocken, Johan We; Roepstorff, Carsten; Goossens, Gijs H.

    2008-01-01

    from the vastus lateralis muscle before and during ISO to investigate hormone-sensitive lipase (HSL) protein expression and serine phosphorylation. Results: Baseline total glycerol release across the forearm was significantly blunted in obese compared with lean subjects (P=0.045). This was accompanied......Objective: Increased intramuscular triacylglycerol (IMTG) storage is a characteristic of the obese insulin resistant state. We aimed to investigate whether a blunted fasting or beta-adrenergically mediated lipolysis contributes to this increased IMTG storage in obesity. Research design and Methods......: Forearm skeletal muscle (SM) lipolysis was investigated in thirteen lean and ten obese men using [(2)H(5)]-glycerol combined with the measurement of arterio-venous differences before and during beta-adrenergic stimulation using the non-selective beta-agonist isoprenaline (ISO). Muscle biopsies were taken...

  6. MR imaging and ultrasonography findings of early myositis ossificans: a case report

    International Nuclear Information System (INIS)

    Lee, Kyung Ryeol; Park, So Young; Jin, Wook; Won, Kyu Yeoun

    2016-01-01

    Myositis ossificans (MO) is a benign soft tissue lesion with non-neoplastic heterotopic bone formation. MO in the intermediate and mature stages can be easily diagnosed if characteristic imaging findings such as a peripheral zonal pattern of ossification with variable thickness is observed. However, it is difficult to correctly diagnose early MO because it can mimic malignancy clinically, radiologically, and histopathologically. We report a case of early pseudosarcomatous phase of non-traumatic MO with atypical imaging findings. A 59-year-old woman presented with pain followed by a mass in the left thigh within a week. MR imaging and ultrasonography showed an intramuscular lesion with preserved muscle fascicles in the vastus lateralis muscle. Intralesional ossification or calcification was not seen on ultrasonography. A diagnosis of myositis ossificans was made by ultrasonographically guided biopsy. (orig.)

  7. MR imaging and ultrasonography findings of early myositis ossificans: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Ryeol [Jeju National University Hospital, Department of Radiology, Jeju-si, Jeju Special Self-Governing Province (Korea, Republic of); Park, So Young; Jin, Wook [Kyung Hee University Hospital at Gangdong, Department of Radiology, Seoul (Korea, Republic of); Won, Kyu Yeoun [Kyung Hee University Hospital at Gangdong, Department of Pathology, Seoul (Korea, Republic of)

    2016-10-15

    Myositis ossificans (MO) is a benign soft tissue lesion with non-neoplastic heterotopic bone formation. MO in the intermediate and mature stages can be easily diagnosed if characteristic imaging findings such as a peripheral zonal pattern of ossification with variable thickness is observed. However, it is difficult to correctly diagnose early MO because it can mimic malignancy clinically, radiologically, and histopathologically. We report a case of early pseudosarcomatous phase of non-traumatic MO with atypical imaging findings. A 59-year-old woman presented with pain followed by a mass in the left thigh within a week. MR imaging and ultrasonography showed an intramuscular lesion with preserved muscle fascicles in the vastus lateralis muscle. Intralesional ossification or calcification was not seen on ultrasonography. A diagnosis of myositis ossificans was made by ultrasonographically guided biopsy. (orig.)

  8. Improved glucose tolerance after high-load strength training in patients undergoing dialysis

    DEFF Research Database (Denmark)

    Mølsted, Stig; Harrison, Adrian Paul; Eidemak, Inge

    2013-01-01

    glucose tolerance (n = 9). Conclusion: The conducted strength training was associated with a significant improvement in glucose tolerance in patients with impaired glucose tolerance or type 2 diabetes undergoing dialysis. The effect was apparently not associated with muscle hypertrophy, whereas the muscle...... a week. Muscle fiber size, composition and capillary density were analyzed in biopsies obtained in the vastus lateralis muscle. Glucose tolerance and the insulin response were measured by a 2-hour oral glucose tolerance test. Results: All outcome measures remained unchanged during the control period....... After strength training the relative area of type 2X fibers was decreased. Muscle fiber size and capillary density remained unchanged. After the strength training, insulin concentrations were significantly lower in patients with impaired glucose tolerance or type 2 diabetes (n = 14) (fasting insulin...

  9. Effects of high-intensity physical training on muscle fiber characteristics in poststroke patients

    DEFF Research Database (Denmark)

    Andersen, Jesper Løvind; Jørgensen, Jørgen R.; Zeeman, Peter

    2017-01-01

    INTRODUCTION: Stroke is a leading cause of disability worldwide. High-intensity physical training can improve muscle strength and gait speed, but adaptive mechanisms at the muscle cellular level are largely unknown. METHODS: Outpatients with poststroke hemiparesis participated in a 3-month...... rehabilitation program combining high-intensity strength and body-weight supported treadmill-training. Biopsies sampled bilaterally from vastus lateralis muscles, before, after, and at 1-year follow-up after intervention, were analyzed for fiber size, type, and capillarization. RESULTS: At baseline, paretic...... lower limbs had smaller muscle fiber size and lower type I and IIA and higher type IIX percentages than nonparetic lower limbs. Paretic lower limbs had increased type IIA fibers after training. At follow-up, no difference between the lower limbs remained. CONCLUSIONS: Although high-intensity training...

  10. Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle

    DEFF Research Database (Denmark)

    Sahlin, Kent; Nielsen, Jens Steen; Mogensen, Martin

    2006-01-01

    Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2......+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus...... lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index...

  11. Improving Peripheral and Central Vascular Adjustments during Exercise through a Training Program in Adolescents with Obesity.

    Science.gov (United States)

    Julian, Valérie; Thivel, David; Pereira, Bruno; Costes, Frédéric; Richard, Ruddy; Duclos, Martine

    2016-01-01

    The effects of a training program (TP) on muscle microvascularization during exercise remained to be explored in adolescents with obesity. We hypothesized that a TP would lead to better microvascular adaptations to exercise in skeletal muscle. 15 inactive adolescents followed a 12-week TP where both peripheral (muscular microvascularization) and central (cardiac) adaptations to exercise (40 min exercise set at 70% V̇O2peak) were assessed before and after intervention. Microvascular adaptations were evaluated in the Musculus vastus lateralis with near-infrared spectroscopy, by measurement of muscular blood volume (IR-BV) and tissue oxygen saturation (IR-SO2). Central adaptations were evaluated using thoracic impedance. The TP favored lower BMI (p exercise in adolescents with obesity. © 2016 The Author(s) Published by S. Karger GmbH, Freiburg.

  12. Antagonistic Mono- and Bi-Articular Lower-Limb Muscle Activities’ Model Characterization at Different Speeds

    Directory of Open Access Journals (Sweden)

    Dzahir M.A.M

    2017-01-01

    Full Text Available Nowadays, medical rehabilitation system has become a requirement due to increment in national rehabilitation centres and medical hospitals. An assistive rehabilitation orthosis becomes essential and was used for rehabilitation therapy, condition monitoring, and physical strengthening. This study focused on the lower limb assistive rehabilitation orthosis development using pneumatic artificial muscle. To successfully control this orthosis system which consists of antagonistic mono- and biarticular muscle actuators, it is necessary to construct a reliable control algorithm. The suitable control scheme and strategy to manoeuvre this orthosis system similar to human musculoskeletal system have yet to be fully developed and established. Based on the review study, it is said that the co-contraction controls of anterior-posterior pneumatic muscles was able to improve the joint stiffness and stability of the orthosis as well as good manoeuvrability. Therefore, a characterization model of an antagonistic mono- and bi-articular muscles activities of human's lowerlimb during walking motion will be necessary. A healthy young male subject was used as test subject to obtain the sEMG muscle activities for antagonistic mono- and bi-articular muscles (i.e., Vastus Medialis-VM, Vastus Lateralis-VL, Rectus Femoris-RF, and Bicep Femoris-BF. The tests were carried out at different speeds of 2km/h, 3km/h, and 4km/h for one minute walking motion on a treadmill. Then, the patterns of the sEMG muscle activities were modelled and characterised using fifth order polynomial equation. Based on the results, it is shown that the anterior and posterior muscles were exhibited a muscle synergy in-between multiple anterior or posterior muscles and muscle co-contraction between anteriorposterior muscles in order to control the movements at the joints during walking motion. As conclusion, it is proven that the sEMG muscle activities of the antagonistic mono- and bi

  13. Estimulação elétrica neuromuscular em cães com atrofia muscular induzida Neuromuscular electric stimulation in dogs with induced muscle atrophy

    Directory of Open Access Journals (Sweden)

    C. Pelizzari

    2008-02-01

    following parameters were measured: thigh circumference, goniometry of the knee, clinical gait analysis, creatine kinase (CK and aspartate aminotransferase (AST enzymes, and morphometry of the muscular fibers in transversal cuts of the vastus lateralis muscle collected through muscular biopsy. The NMES was applied on the femoral quadriceps at a frequency of 50 Hz, with pulse duration of 300 milliseconds, and the on/off time was at a proportion of 1:2. Regarding the morphometry of the vastus lateralis fibers, a significant increase (P<0.05 in the transversal area of the treated group at 90 days was observed when compared with that identified at the time of immobilization. Thus, it can be concluded that low frequency NMES brings about hypertrophy of the vastus lateralis muscle in dogs after temporary rigid immobilization of the knee joint.

  14. Test-retest reliability of myofascial trigger point detection in hip and thigh areas.

    Science.gov (United States)

    Rozenfeld, E; Finestone, A S; Moran, U; Damri, E; Kalichman, L

    2017-10-01

    Myofascial trigger points (MTrP's) are a primary source of pain in patients with musculoskeletal disorders. Nevertheless, they are frequently underdiagnosed. Reliable MTrP palpation is the necessary for their diagnosis and treatment. The few studies that have looked for intra-tester reliability of MTrPs detection in upper body, provide preliminary evidence that MTrP palpation is reliable. Reliability tests for MTrP palpation on the lower limb have not yet been performed. To evaluate inter- and intra-tester reliability of MTrP recognition in hip and thigh muscles. Reliability study. 21 patients (15 males and 6 females, mean age 21.1 years) referred to the physical therapy clinic, 10 with knee or hip pain and 11 with pain in an upper limb, low back, shin or ankle. Two experienced physical therapists performed the examinations, blinded to the subjects' identity, medical condition and results of the previous MTrP evaluation. Each subject was evaluated four times, twice by each examiner in a random order. Dichotomous findings included a palpable taut band, tenderness, referred pain, and relevance of referred pain to patient's complaint. Based on these, diagnosis of latent MTrP's or active MTrP's was established. The evaluation was performed on both legs and included a total of 16 locations in the following muscles: rectus femoris (proximal), vastus medialis (middle and distal), vastus lateralis (middle and distal) and gluteus medius (anterior, posterior and distal). Inter- and intra-tester reliability (Cohen's kappa (κ)) values for single sites ranged from -0.25 to 0.77. Median intra-tester reliability was 0.45 and 0.46 for latent and active MTrP's, and median inter-tester reliability was 0.51 and 0.64 for latent and active MTrPs, respectively. The examination of the distal vastus medialis was most reliable for latent and active MTrP's (intra-tester k = 0.27-0.77, inter-tester k = 0.77 and intra-tester k = 0.53-0.72, inter-tester k = 0.72, correspondingly

  15. The Effect of Active versus Passive Recovery Periods during High Intensity Intermittent Exercise on Local Tissue Oxygenation in 18 - 30 Year Old Sedentary Men.

    Directory of Open Access Journals (Sweden)

    Yuri Kriel

    Full Text Available High intensity interval training (HIIT has been proposed as a time-efficient format of exercise to reduce the chronic disease burden associated with sedentary behaviour. Changes in oxygen utilisation at the local tissue level during an acute session of HIIT could be the primary stimulus for the health benefits associated with this format of exercise. The recovery periods of HIIT effect the physiological responses that occur during the session. It was hypothesised that in sedentary individuals, local and systemic oxygen utilisation would be higher during HIIT interspersed with active recovery periods, when compared to passive recovery periods.Twelve sedentary males (mean ± SD; age 23 ± 3 yr completed three conditions on a cycle ergometer: 1 HIIT with passive recovery periods between four bouts (HIITPASS 2 HIIT with active recovery periods between four bouts (HIITACT 3 HIITACT with four HIIT bouts replaced with passive periods (REC. Deoxygenated haemoglobin (HHb in the vastus lateralis (VL and gastrocnemius (GN muscles and the pre-frontal cortex (FH, oxygen consumption (VO2, power output and heart rate (HR were measured continuously during the three conditions.There was a significant increase in HHb at VL during bouts 2 (p = 0.017, 3 (p = 0.035 and 4 (p = 0.035 in HIITACT, compared to HIITPASS. Mean power output was significantly lower in HIITACT, compared to HIITPASS (p < 0.001. There was a significant main effect for site in both HIITPASS (p = 0.029 and HIITACT (p = 0.005. There were no significant differences in VO2 and HR between HIITPASS and HIITACT.The increase in HHb at VL and the lower mean power output during HIITACT could indicate that a higher level of deoxygenation contributes to decreased mechanical power in sedentary participants. The significant differences in HHb between sites indicates the specificity of oxygen utilisation.

  16. Increased oxidative stress and anaerobic energy release, but blunted Thr172-AMPKα phosphorylation, in response to sprint exercise in severe acute hypoxia in humans.

    Science.gov (United States)

    Morales-Alamo, David; Ponce-González, Jesús Gustavo; Guadalupe-Grau, Amelia; Rodríguez-García, Lorena; Santana, Alfredo; Cusso, Maria Roser; Guerrero, Mario; Guerra, Borja; Dorado, Cecilia; Calbet, José A L

    2012-09-01

    AMP-activated protein kinase (AMPK) is a major mediator of the exercise response and a molecular target to improve insulin sensitivity. To determine if the anaerobic component of the exercise response, which is exaggerated when sprint is performed in severe acute hypoxia, influences sprint exercise-elicited Thr(172)-AMPKα phosphorylation, 10 volunteers performed a single 30-s sprint (Wingate test) in normoxia and in severe acute hypoxia (inspired Po(2): 75 mmHg). Vastus lateralis muscle biopsies were obtained before and immediately after 30 and 120 min postsprint. Mean power output and O(2) consumption were 6% and 37%, respectively, lower in hypoxia than in normoxia. O(2) deficit and muscle lactate accumulation were greater in hypoxia than in normoxia. Carbonylated skeletal muscle and plasma proteins were increased after the sprint in hypoxia. Thr(172)-AMPKα phosphorylation was increased by 3.1-fold 30 min after the sprint in normoxia. This effect was prevented by hypoxia. The NAD(+)-to-NADH.H(+) ratio was reduced (by 24-fold) after the sprints, with a greater reduction in hypoxia than in normoxia (P exercise in human skeletal muscle is altered in severe acute hypoxia, which abrogated Thr(172)-AMPKα phosphorylation, likely due to lower LKB1 activation by SIRT1.

  17. Early Changes in Costameric and Mitochondrial Protein Expression with Unloading Are Muscle Specific

    Directory of Open Access Journals (Sweden)

    Martin Flück

    2014-01-01

    Full Text Available We hypothesised that load-sensitive expression of costameric proteins, which hold the sarcomere in place and position the mitochondria, contributes to the early adaptations of antigravity muscle to unloading and would depend on muscle fibre composition and chymotrypsin activity of the proteasome. Biopsies were obtained from vastus lateralis (VL and soleus (SOL muscles of eight men before and after 3 days of unilateral lower limb suspension (ULLS and subjected to fibre typing and measures for costameric (FAK and FRNK, mitochondrial (NDUFA9, SDHA, UQCRC1, UCP3, and ATP5A1, and MHCI protein and RNA content. Mean cross-sectional area (MCSA of types I and II muscle fibres in VL and type I fibres in SOL demonstrated a trend for a reduction after ULLS (0.05≤P<0.10. FAK phosphorylation at tyrosine 397 showed a 20% reduction in VL muscle (P=0.029. SOL muscle demonstrated a specific reduction in UCP3 content (-23%; P = 0.012. Muscle-specific effects of ULLS were identified for linear relationships between measured proteins, chymotrypsin activity and fibre MCSA. The molecular modifications in costamere turnover and energy homoeostasis identify that aspects of atrophy and fibre transformation are detectable at the protein level in weight-bearing muscles within 3 days of unloading.

  18. Early Changes in Costameric and Mitochondrial Protein Expression with Unloading Are Muscle Specific

    Science.gov (United States)

    Li, Ruowei; Linnehan, Richard M.; Castells, Josiane; Tesch, Per; Gustafsson, Thomas

    2014-01-01

    We hypothesised that load-sensitive expression of costameric proteins, which hold the sarcomere in place and position the mitochondria, contributes to the early adaptations of antigravity muscle to unloading and would depend on muscle fibre composition and chymotrypsin activity of the proteasome. Biopsies were obtained from vastus lateralis (VL) and soleus (SOL) muscles of eight men before and after 3 days of unilateral lower limb suspension (ULLS) and subjected to fibre typing and measures for costameric (FAK and FRNK), mitochondrial (NDUFA9, SDHA, UQCRC1, UCP3, and ATP5A1), and MHCI protein and RNA content. Mean cross-sectional area (MCSA) of types I and II muscle fibres in VL and type I fibres in SOL demonstrated a trend for a reduction after ULLS (0.05 ≤ P < 0.10). FAK phosphorylation at tyrosine 397 showed a 20% reduction in VL muscle (P = 0.029). SOL muscle demonstrated a specific reduction in UCP3 content (−23%; P = 0.012). Muscle-specific effects of ULLS were identified for linear relationships between measured proteins, chymotrypsin activity and fibre MCSA. The molecular modifications in costamere turnover and energy homoeostasis identify that aspects of atrophy and fibre transformation are detectable at the protein level in weight-bearing muscles within 3 days of unloading. PMID:25313365

  19. Mechanical response of knee muscles in high level bodyboarders during performance

    Directory of Open Access Journals (Sweden)

    Dario Rodríguez-Matoso

    2015-04-01

    Full Text Available INTRODUCTION: bodyboarding is a kind of surfing that has been growing very rapidly over the last decade and has now developed into one of the fastest growing water sports in the world. OBJECTIVES: evaluate the effects of fatigue on rectus femoris RF, vastus lateralis VL and vastus medialis VM and biceps femoris BF and semitendinosus ST during a high-level bodyboard competition using tensiomyography TMG. METHODS: subjects were 11 highly experienced years of practice: 15, SD=4.65 male bodyboarders age: 28.17, SD=2.89, body weight: 74.83, SD=6.13kg; height: 179.25, SD=3.93cm; BMI: 23.29, SD=1.81 participating in the final of the 2010 Spanish championship. RESULTS: the fatigue is especially evident due to a decrease in the values of relaxation time Tr and sustain time Ts caused by the specific characteristics of waves, how the waves evolve and the type of manoeuvre executed in competition due to the wave characteristics. The maximum radial displacement Dm value increased slightly in all muscles analysed and normalised response speed Vrn was stable, with a tendency to improve as athletes adapted to the type of physical effort and the environmental conditions of the competition. CONCLUSIONS: the study shows that the fatigue in the extensor and flexor muscles of the knee occurs in response to the demands of competition.

  20. Baseline Mechanical and Neuromuscular Profile of Knee Extensor and Flexor Muscles in Professional Soccer Players at the Start of the Pre-Season

    Directory of Open Access Journals (Sweden)

    García-García Oscar

    2017-08-01

    Full Text Available The aim of the study was to determine the mechanical and neuromuscular profile of knee extensor and flexor muscles in professional soccer players at the start of the pre-season, and to calculate percentages for symmetry, as well as examine differences according to the player’s positional role. The vastus medialis (VM, vastus lateralis (VL, rectus femoris (RF and biceps femoris (BF of 16 professional soccer players were evaluated by means of tensiomyography (TMG on the first day of the pre-season. A paired-samples t test (p < .05 was used to compare the dominant and non-dominant lower limb. One-way ANOVA was applied, with the positional role as an independent factor. No differences were observed between the dominant and non-dominant leg. The highest degree of symmetry corresponded to the VM (92.5 ± 2.7%, and the lowest to the BF (80.7 ± 10.9%. The positional role was associated with significant differences in some of the variables for the BF, RF and VM, although only the half-relaxation time in the BF and the time to sustain force in the VM differed across all the playing positions considered. TMG was shown to be a useful way of evaluating the neuromuscular characteristics of soccer players at the start of the pre-season, and of establishing baseline values for individual players.

  1. Baseline Mechanical and Neuromuscular Profile of Knee Extensor and Flexor Muscles in Professional Soccer Players at the Start of the Pre-Season.

    Science.gov (United States)

    García-García, Oscar; Serrano-Gómez, Virginia; Hernández-Mendo, Antonio; Morales-Sánchez, Verónica

    2017-09-01

    The aim of the study was to determine the mechanical and neuromuscular profile of knee extensor and flexor muscles in professional soccer players at the start of the pre-season, and to calculate percentages for symmetry, as well as examine differences according to the player's positional role. The vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) and biceps femoris (BF) of 16 professional soccer players were evaluated by means of tensiomyography (TMG) on the first day of the pre-season. A paired-samples t test (p < .05) was used to compare the dominant and non-dominant lower limb. One-way ANOVA was applied, with the positional role as an independent factor. No differences were observed between the dominant and non-dominant leg. The highest degree of symmetry corresponded to the VM (92.5 ± 2.7%), and the lowest to the BF (80.7 ± 10.9%). The positional role was associated with significant differences in some of the variables for the BF, RF and VM, although only the half-relaxation time in the BF and the time to sustain force in the VM differed across all the playing positions considered. TMG was shown to be a useful way of evaluating the neuromuscular characteristics of soccer players at the start of the pre-season, and of establishing baseline values for individual players.

  2. Quantitative magnetic resonance imaging in limb-girdle muscular dystrophy 2I: a multinational cross-sectional study.

    Directory of Open Access Journals (Sweden)

    Tracey A Willis

    Full Text Available We conducted a prospective multinational study of muscle pathology using magnetic resonance imaging (MRI in patients with limb-girdle muscular dystrophy 2I (LGMD2I. Thirty eight adult ambulant LGMD2I patients (19 male; 19 female with genetically identical mutations (c.826C>A in the fukutin-related protein (FKRP gene were recruited. In each patient, T1-weighted (T1w imaging was assessed by qualitative grading for 15 individual lower limb muscles and quantitative Dixon imaging was analysed on 14 individual lower limb muscles by region of interest analysis. We described the pattern and appearance of muscle pathology and gender differences, not previously reported for LGMD2I. Diffuse fat infiltration of the gastrocnemii muscles was demonstrated in females, whereas in males fat infiltration was more prominent in the medial than the lateral gastrocnemius (p = 0.05. In the anterior thigh of males, in contrast to females, median fat infiltration in the vastus medialis muscle (45.7% exceeded that in the vastus lateralis muscle (11.2% (p<0.005. MRI is non-invasive, objective and does not rely on patient effort compared to clinical and physical measures that are currently employed. We demonstrated (i that the quantitative Dixon technique is an objective quantitative marker of disease and (ii new observations of gender specific patterns of muscle involvement in LGMD2I.

  3. The order of exercise during concurrent training for rehabilitation does not alter acute genetic expression, mitochondrial enzyme activity or improvements in muscle function.

    Directory of Open Access Journals (Sweden)

    Lauren G MacNeil

    Full Text Available Concurrent exercise combines different modes of exercise (e.g., aerobic and resistance into one training protocol, providing stimuli meant to increase muscle strength, aerobic capacity and mass. As disuse is associated with decrements in strength, aerobic capacity and muscle size concurrent training is an attractive modality for rehabilitation. However, interference between the signaling pathways may result in preferential improvements for one of the exercise modes. We recruited 18 young adults (10 ♂, 8 ♀ to determine if order of exercise mode during concurrent training would differentially affect gene expression, protein content and measures of strength and aerobic capacity after 2 weeks of knee-brace induced disuse. Concurrent exercise sessions were performed 3x/week for 6 weeks at gradually increasing intensities either with endurance exercise preceding (END>RES or following (RES>END resistance exercise. Biopsies were collected from the vastus lateralis before, 3 h after the first exercise bout and 48 h after the end of training. Concurrent exercise altered the expression of genes involved in mitochondrial biogenesis (PGC-1α, PRC, PPARγ, hypertrophy (PGC-1α4, REDD2, Rheb and atrophy (MuRF-1, Runx1, increased electron transport chain complex protein content, citrate synthase and mitochondrial cytochrome c oxidase enzyme activity, muscle mass, maximum isometric strength and VO 2peak. However, the order in which exercise was completed (END>RES or RES>END only affected the protein content of mitochondrial complex II subunit. In conclusion, concurrent exercise training is an effective modality for the rehabilitation of the loss of skeletal muscle mass, maximum strength, and peak aerobic capacity resulting from disuse, regardless of the order in which the modes of exercise are performed.

  4. Local NSAID infusion does not affect protein synthesis and gene expression in human muscle after eccentric exercise

    DEFF Research Database (Denmark)

    Mikkelsen, U R; Schjerling, P; Helmark, Ida Carøe

    2010-01-01

    models, and inhibit the exercise-induced satellite cell proliferation and protein synthesis in humans. However, the cellular mechanisms eliciting these responses remain unknown. Eight healthy male volunteers performed 200 maximal eccentric contractions with each leg. To block prostaglandin synthesis...... locally in the skeletal muscle, indomethacin (NSAID) was infused for 7.5 h via microdialysis catheters into m. vastus lateralis of one leg. Protein synthesis was determined by the incorporation of 1,2-(13)C(2) leucine into muscle protein from 24 to 28 h post-exercise. Furthermore, mRNA expression...... of selected genes was measured in muscle biopsies (5 h and 8 days post-exercise) by real-time reverse transcriptase PCR. Myofibrillar and collagen protein synthesis were unaffected by the local NSAID infusion. Five hours post-exercise, the mRNA expression of cyclooxygenase-2 (COX2) was sixfold higher...

  5. Insulin Resistance and Increased Muscle Cytokine Levels in Patients With Mitochondrial Myopathy

    DEFF Research Database (Denmark)

    Rue, Nana; Vissing, John; Galbo, Henrik

    2014-01-01

    CONTEXT: Mitochondrial dysfunction has been proposed to cause insulin resistance and that might stimulate cytokine production. OBJECTIVE: The objective of the study was to elucidate the association between mitochondrial myopathy, insulin sensitivity, and cytokine levels in muscle. DESIGN......: The intervention included a 120-minute hyperinsulinemic, euglycemic clamp. Another morning, microdialysis of both vastus lateralis muscles for 4 hours, including one-legged, knee extension exercise for 30 minutes, was performed. MAIN OUTCOME MEASURES: Glucose infusion rate during 90-120 minutes of insulin infusion...... was measured. Cytokine concentrations in dialysate were also measured. RESULTS: Muscle strength, percentage fat mass, and creatine kinase in plasma did not differ between groups. The maximal oxygen uptake was 21 ± 3 (SE) (P) and 36 ± 3(C) mL/kg·min (2P insulin, C-peptide, and glucagon were higher...

  6. Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body.

    Science.gov (United States)

    van der Zwaard, Stephan; van der Laarse, Willem J; Weide, Guido; Bloemers, Frank W; Hofmijster, Mathijs J; Levels, Koen; Noordhof, Dionne A; de Koning, Jos J; de Ruiter, Cornelis J; Jaspers, Richard T

    2018-04-01

    Optimizing physical performance is a major goal in current physiology. However, basic understanding of combining high sprint and endurance performance is currently lacking. This study identifies critical determinants of combined sprint and endurance performance using multiple regression analyses of physiologic determinants at different biologic levels. Cyclists, including 6 international sprint, 8 team pursuit, and 14 road cyclists, completed a Wingate test and 15-km time trial to obtain sprint and endurance performance results, respectively. Performance was normalized to lean body mass 2/3 to eliminate the influence of body size. Performance determinants were obtained from whole-body oxygen consumption, blood sampling, knee-extensor maximal force, muscle oxygenation, whole-muscle morphology, and muscle fiber histochemistry of musculus vastus lateralis. Normalized sprint performance was explained by percentage of fast-type fibers and muscle volume ( R 2 = 0.65; P body.

  7. Interleukin-6 and vitamin D status during high-intensity resistance training in patients with chronic kidney disease

    DEFF Research Database (Denmark)

    Molsted, Stig; Eiken, Pia Agnete; Andersen, Jesper L.

    2014-01-01

    Background. The aim of this study was to investigate IL-6 and 25-hydroxyvitamin D (25-OH D) associations with muscle size and muscle function in dialysis patients. Methods. Patients were included in a 16-week control period followed by 16 weeks of high-intensity resistance training thrice weekly....... IL-6 and 25-OH D were analysed after an over-night fast. Muscle fibre size was analysed in biopsies from m. vastus lateralis. Muscle power was tested using a Leg Extensor Power Rig. Results. Patients (n = 36) with IL-6 ≥ 6.49 pg/ml (median) were older and had decreased muscle power and a reduced...... power increased by 20-23% (P Half of the patients were suffering from vitamin D deficiency, which was not associated with muscle power. IL-6 was unchanged by high...

  8. Early phase interference between low-intensity running and power training in moderately trained females

    DEFF Research Database (Denmark)

    Terzis, Gerasimos; Spengos, Kostas; Methenitis, Spyros

    2016-01-01

    PURPOSE: The aim of the study was to investigate the effects of low-intensity running performed immediately after lower-body power-training sessions on power development. METHODS: Twenty young females participated in 6 weeks, 3/week, of either lower body power training (PT) or lower body power...... training followed by 30 min of low-intensity running (PET) eliciting 60-70 % of maximal heart rate. The following were measured before and after the training period: counter-movement jump, isometric leg press force and rate of force development (RFD), half squat 1-RM, vastus lateralis fiber type...... performed after lower-body power training impairs the exercise-induced adaptation in stretch-shortening cycle jumping performance (vertical jump height, peak power), during the first 6 weeks of training, which may be partially linked to inhibited muscle fiber hypertrophy and muscle fiber conduction velocity....

  9. Ceramide content is higher in type I compared to type II fibers in obesity and type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Kristensen, Ditte Bech; Prats Gavalda, Clara; Larsen, Steen

    2012-01-01

    This study investigated fiber-type-specific muscle ceramide content in obese subjects and type 2 diabetes patients. Two substudies, one which compared type 2 diabetes patients to both lean- and obese BMI-matched subjects and the other study which compared lean body-matched post-obese, obese......, and control subjects, were performed. A fasting blood sample was obtained and plasma insulin and glucose determined. A muscle biopsy was obtained from deltoideus and vastus lateralis, and fiber-type ceramide content was determined by fluorescence immunohistochemistry. Insulin sensitivity estimated by Quicki...... index was higher in lean compared to type 2 diabetes patients and obese controls. Also in control and post-obese subjects, a higher insulin sensitivity was observed compared to obese subjects. Ceramide content was consistently higher in type I than in type II muscle fibers and higher in deltoideus than...

  10. Muscle-specific expression of hypoxia-inducible factor in human skeletal muscle

    DEFF Research Database (Denmark)

    Mounier, Rémi; Pedersen, Bente Klarlund; Plomgaard, Peter

    2010-01-01

    fibres that possess unique patterns of protein and gene expression, producing different capillarization and energy metabolism systems. In this work, we analysed HIF-1alpha mRNA and protein expression related to the fibre-type composition in untrained human skeletal muscle by obtaining muscle biopsies...... from triceps brachii (characterized by a high proportion of type II fibres), from soleus (characterized by a high proportion of type I fibres) and from vastus lateralis (characterized by an equal proportion of type I and II fibres). The hypothesis was that type I muscle fibres would have lower HIF-1......alpha protein level. Interestingly, none of the HIF-1alpha target genes, like the most studied angiogenic factor involved in muscle angiogenesis, vascular endothelial growth factor (VEGF), exhibited a muscle fibre-specific-related mRNA expression at rest in normoxia. However, soleus presented...

  11. Effect of exercise on insulin action in human skeletal muscle

    DEFF Research Database (Denmark)

    Richter, Erik; Mikines, K J; Galbo, Henrik

    1989-01-01

    The effect of 1 h of dynamic one-legged exercise on insulin action in human muscle was studied in 6 healthy young men. Four hours after one-legged knee extensions, a three-step sequential euglycemic hyperinsulinemic clamp combined with arterial and bilateral femoral vein catheterization...... was performed. Increased insulin action on glucose uptake was found in the exercised compared with the rested thigh at mean plasma insulin concentrations of 23, 40, and 410 microU/ml. Furthermore, prior contractions directed glucose uptake toward glycogen synthesis and increased insulin effects on thigh O2...... consumption and at some insulin concentrations on potassium exchange. In contrast, no change in insulin effects on limb exchange of free fatty acids, glycerol, alanine or tyrosine were found after exercise. Glycogen concentration in rested vastus lateralis muscle did not increase measurably during the clamp...

  12. Enhanced satellite cell proliferation with resistance training in elderly men and women

    DEFF Research Database (Denmark)

    Mackey, Abigail; Esmarck, B; Kadi, F

    2007-01-01

    In addition to the well-documented loss of muscle mass and strength associated with aging, there is evidence for the attenuating effects of aging on the number of satellite cells in human skeletal muscle. The aim of this study was to investigate the response of satellite cells in elderly men...... and women to 12 weeks of resistance training. Biopsies were collected from the m. vastus lateralis of 13 healthy elderly men and 16 healthy elderly women (mean age 76+/-SD 3 years) before and after the training period. Satellite cells were visualized by immunohistochemical staining of muscle cross.......15+/-0.06; mean+/-SD) and females (from 0.11+/-0.04 to 0.13+/-0.05). These results suggest that 12 weeks of resistance training is effective in enhancing the satellite cell pool in skeletal muscle in the elderly....

  13. Non-invasive assessment of muscle stiffness in patients with Duchenne muscular dystrophy.

    Science.gov (United States)

    Lacourpaille, Lilian; Hug, François; Guével, Arnaud; Péréon, Yann; Magot, Armelle; Hogrel, Jean-Yves; Nordez, Antoine

    2015-02-01

    Assessment of muscle mechanical properties may provide clinically valuable information for follow-up of patients with Duchenne muscular dystrophy (DMD) through the course of their disease. In this study we aimed to assess the effect of DMD on stiffness of relaxed muscles using elastography (supersonic shear imaging). Fourteen DMD patients and 13 control subjects were studied. Six muscles were measured at 2 muscle lengths (shortened and stretched): gastrocnemius medialis (GM); tibialis anterior (TA); vastus lateralis (VL); biceps brachii (BB); triceps brachii (TB); and abductor digiti minimi (ADM). Stiffness was significantly higher in DMD patients compared with controls for all the muscles (main effect for population, P muscle lengths) to large (d = 0.86 for BB/stretched). Supersonic shear imaging is a sensitive non-invasive technique to assess the increase in muscle stiffness associated with DMD. © 2014 Wiley Periodicals, Inc.

  14. Nitric oxide and prostaglandins influence local skeletal muscle blood flow during exercise in humans: coupling between local substrate uptake and blood flow

    DEFF Research Database (Denmark)

    Kalliokoski, Kari K; Langberg, Henning; Ryberg, Ann Kathrine

    2006-01-01

    -legged dynamic knee-extension exercise. Local blockade was produced by infusing nitro-L-arginine methyl ester and indomethacin directly in the muscle via a microdialysis catheter. Blood flow and glucose uptake were measured in the region of blockade and in two additional regions of vastus lateralis muscle 1......Synergic action of nitric oxide (NO) and prostaglandins (PG) in the regulation of muscle blood flow during exercise has been demonstrated. In the present study, we investigated whether these vasodilators also regulate local blood flow, flow heterogeneity, and glucose uptake within the exercising...... skeletal muscle. Skeletal muscle blood flow was measured in seven healthy young men using near-infrared spectroscopy and indocyanine green and muscle glucose uptake using positron emission tomography and 2-fluoro-2-deoxy-D-[(18)F]glucose without and with local blockade of NO and PG at rest and during one...

  15. Coordinated increase in skeletal muscle fiber area and expression of IGF-I with resistance exercise in elderly post-operative patients

    DEFF Research Database (Denmark)

    Suetta, Charlotte; Clemmensen, Christoffer; Andersen, Jesper L

    2010-01-01

    Hypertrophy of developing skeletal muscle involves stimulation by insulin-like growth factor-I (IGF-I), however, the role of IGF-I in adult muscle is less clarified. In the present study, the mRNA splice variants of IGF-I (IGF-IEa and MGF) and the changes in muscle fiber cross sectional area after...... and in addition induces marked increases in the expression of IGF-I splice variants, supporting the idea that IGF-I is involved in regulating muscle hypertrophy.......-operated-side served as a within subject control. Muscle biopsies were obtained from the vastus lateralis of both limbs at +2d post-operative (baseline), at 5weeks and 12weeks post-surgery to analyze for changes in type 1 and type 2 muscle fiber area. Changes in expression levels of IGF-I mRNA isoforms were determined...

  16. Changes in muscle size and MHC composition in response to resistance exercise with heavy and light loading intensity

    DEFF Research Database (Denmark)

    Holm, L.; Reitelseder, S.; Pedersen, T.G.

    2008-01-01

    resonance imaging, muscle biopsies were obtained bilaterally from vastus lateralis for determination of myosin heavy chain (MHC) composition, and maximal muscle strength was assessed by 1RM testing and in an isokinetic dynamometer at 60 degrees /s. Quadriceps muscle cross-sectional area increased (P ...Muscle mass accretion is accomplished by heavy-load resistance training. The effect of light-load resistance exercise has been far more sparsely investigated with regard to potential effect on muscle size and contractile strength. We applied a resistance exercise protocol in which the same...... individual trained one leg at 70% of one-repetition maximum (1RM) (heavy load, HL) while training the other leg at 15.5% 1RM (light load, LL). Eleven sedentary men (age 25 +/- 1 yr) trained for 12 wk at three times/week. Before and after the intervention muscle hypertrophy was determined by magnetic...

  17. Myogenic response of human skeletal muscle to 12 weeks of resistance training at light loading intensity

    DEFF Research Database (Denmark)

    Mackey, Abigail; Holm, L; Reitelseder, S

    2011-01-01

    There is strong evidence for enhanced numbers of satellite cells with heavy resistance training. The satellite cell response to very light muscle loading is, however, unknown. We, therefore, designed a 12-week training protocol where volunteers trained one leg with a high load (H) and the other leg...... with a light load (L). Twelve young healthy men [mean age 25 ± 3 standard deviation (SD) years] volunteered for the study. Muscle biopsies were collected from the m. vastus lateralis of both legs before and after the training period and satellite cells were visualized by CD56 immunohistochemistry....... A significant main effect of time was observed (P12 ± 0.03 to 0.15 ± 0.05, mean ± SD). The finding that 12 weeks of training skeletal muscle even with very light loads can induce an increase in the number of satellite...

  18. Oxidative stress and mitochondrial impairment can be separated from lipofuscin accumulation in aged human skeletal muscle

    DEFF Research Database (Denmark)

    Hütter, Eveline; Skovbro, Mette; Lener, Barbara

    2007-01-01

    According to the free radical theory of aging, reactive oxygen species (ROS) act as a driving force of the aging process, and it is generally believed that mitochondrial dysfunction is a major source of increased oxidative stress in tissues with high content of mitochondria, such as muscle or brain....... However, recent experiments in mouse models of premature aging have questioned the role of mitochondrial ROS production in premature aging. To address the role of mitochondrial impairment and ROS production for aging in human muscles, we have analyzed mitochondrial properties in muscle fibres isolated...... from the vastus lateralis of young and elderly donors. Mitochondrial respiratory functions were addressed by high-resolution respirometry, and ROS production was analyzed by in situ staining with the redox-sensitive dye dihydroethidium. We found that aged human skeletal muscles contain fully functional...

  19. Moderate Recovery Unnecessary to Sustain High Stroke Volume during Interval Training. A Brief Report

    Directory of Open Access Journals (Sweden)

    Jamie Stanley

    2014-06-01

    Full Text Available It has been suggested that the time spent at a high stroke volume (SV is important for improving maximal cardiac function. The aim of this study was to examine the effect of recovery intensity on cardiovascular parameters during a typical high-intensity interval training (HIIT session in fourteen well-trained cyclists. Oxygen consumption (VO2, heart rate (HR, SV, cardiac output (Qc, and oxygenation of vastus lateralis (TSI were measured during a HIIT (3×3-min work period, 2 min of recovery session on two occasions. VO2, HR and Qc were largely higher during moderate-intensity (60% compared with low-intensity (30% (VO2, effect size; ES = +2.6; HR, ES = +2.8; Qc, ES = +2.2 and passive (HR, ES = +2.2; Qc, ES = +1.7 recovery. By contrast, there was no clear difference in SV between the three recovery conditions, with the SV during the two active recovery periods not being substantially different than during exercise (60%, ES = −0.1; 30%, ES = −0.2. To conclude, moderate-intensity recovery may not be required to maintain a high SV during HIIT.

  20. Muscle utilization patterns vary by skill levels of the practitioners across specific yoga poses (asanas).

    Science.gov (United States)

    Ni, Meng; Mooney, Kiersten; Balachandran, Anoop; Richards, Luca; Harriell, Kysha; Signorile, Joseph F

    2014-08-01

    To compare muscle activation patterns in 14 dominant side muscles during different yoga poses across three skill levels. Mixed repeated-measures descriptive study. University neuromuscular research laboratory, Miami, US. A group of 36 yoga practitioners (9 M/27 F; mean ± SD, 31.6 ± 12.6 years) with at least 3 months yoga practice experience. Each of the 11 surya namaskar poses A and B was performed separately for 15s and the surface electromyography for 14 muscles were recorded. Normalized root mean square of the electromyographic signal (NrmsEMG) for 14 muscles (5 upper body, 4 trunk, 5 lower body). There were significant main effects of pose for all fourteen muscles except middle trapezius (p<.02) and of skill level for the vastus medialis; p=.027). A significant skill level × pose interaction existed for five muscles (pectoralis major sternal head, anterior deltoid, medial deltoid, upper rectus abdominis and gastrocnemius lateralis; p<.05). Post hoc analyses using Bonferroni comparisons indicated that different poses activated specific muscle groups; however, this varied by skill level. Our results indicate that different poses can produce specific muscle activation patterns which may vary due to practitioners' skill levels. This information can be used in designing rehabilitation and training programs and for cuing during yoga training. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Proliferation of Human Primary Myoblasts Is Associated with Altered Energy Metabolism in Dependence on Ageing In Vivo and In Vitro

    Directory of Open Access Journals (Sweden)

    Reedik Pääsuke

    2016-01-01

    Full Text Available Background. Ageing is associated with suppressed regenerative potential of muscle precursor cells due to decrease of satellite cells and suppressive intramuscular milieu on their activation, associated with ageing-related low-grade inflammation. The aim of the study was to characterize the function of oxidative phosphorylation (OXPHOS, glycolysis, adenylate kinase (AK, and creatine kinase (CK mediated systems in young and older individuals. Materials and Methods. Myoblasts were cultivated from biopsies taken by transcutaneous conchotomy from vastus lateralis muscle in young (20–29 yrs, n=7 and older (70–79 yrs, n=7 subjects. Energy metabolism was assessed in passages 2 to 6 by oxygraphy and enzyme analysis. Results. In myoblasts of young and older subjects the rate of OXPHOS decreased during proliferation from passages 2 to 6. The total activities of CK and AK decreased. Myoblasts of passage 2 cultivated from young muscle showed higher rate of OXPHOS and activities of CK and AK compared to myoblasts from older subjects while hexokinase and pyruvate kinase were not affected by ageing. Conclusions. Proliferation of myoblasts in vitro is associated with downregulation of OXPHOS and energy storage and transfer systems. Ageing in vivo exerts an impact on satellite cells which results in altered metabolic profile in favour of the prevalence of glycolytic pathways over mitochondrial OXPHOS of myoblasts.

  2. Mechanical and morphological properties of different muscle-tendon units in the lower extremity and running mechanics: effect of aging and physical activity.

    Science.gov (United States)

    Karamanidis, Kiros; Arampatzis, Adamantios

    2005-10-01

    The objectives of this work were (i) to investigate whether chronic endurance running is a sufficient stimulus to counteract the age-related changes in the mechanical and morphological properties of human triceps surae (TS) and quadriceps femoris (QF) muscle-tendon units (MTUs) by comparing runners and non-active subjects at different ages (young and old), (ii) to identify adaptational phenomena in running mechanics due to age-related changes in the mechanical and morphological properties of the TS and QF MTUs, and finally (iii) to examine whether chronic endurance-running exercise is associated with adaptational effects on running characteristics in old and young adults. The investigation was conducted on 30 old and 19 young adult males divided into two subgroups according to their running activity: endurance-runners vs non-active. To analyse the properties of the MTUs, all subjects performed isometric maximal voluntary (MVC) ankle plantarflexion and knee extension contractions at 11 different MTU lengths on a dynamometer. The activation of the TS and QF during MVC was estimated by surface electromyography. The gastrocnemius medialis and the vastus lateralis and their distal aponeuroses were visualized by ultrasonography at rest and during MVC, respectively. Ground reaction forces and kinematic data were recorded during running trials at 2.7 m s(-1). The TS and QF MTU capacities were reduced with aging (lower muscle strength and lower tendon stiffness). Runners and non-active subjects had similar MTU properties, suggesting that chronic endurance-running exercise does not counteract the age-related degeneration of the MTUs. Runners showed a higher mechanical advantage for the QF MTU while running (lower gear ratio) compared to non-active subjects, indicating a task-specific adaptation even at old age. Older adults reacted to the reduced capacities of their MTUs by increasing running safety (higher duty factor, lower flight time) and benefitting from a mechanical

  3. Neuromuscular adaptations associated with knee joint angle-specific force change.

    Science.gov (United States)

    Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

    2014-08-01

    Neuromuscular adaptations to joint angle-specific force increases after isometric training have not yet been fully elucidated. This study examined angle-specific neuromuscular adaptations in response to isometric knee extension training at short (SL, joint angle 38.1° ± 3.7°) versus long (LL, 87.5° ± 6.0°) muscle lengths. Sixteen men trained three times a week for 6 wk either at SL (n = 8) or LL (n = 8). Voluntary maximal isometric knee extensor (MVC) force, doublet twitch force, EMG amplitudes (EMG/Mmax), and voluntary activation during MVC force (VA%) were measured at eight knee joint angles (30°-100°) at weeks 0, 3, and 6. Muscle volume and cross-sectional area (CSA) were measured from magnetic resonance imaging scans, and fascicle length (Lf) was assessed using ultrasonography before and after training. Clear joint angle specificity of force increase was seen in SL but not in LL. The 13.4% ± 9.7% (P = 0.01) force increase around the training angle in SL was related to changes in vastus lateralis and vastus medialis EMG/Mmax around the training angle (r = 0.84-0.88, P < 0.05), without changes in the doublet twitch force-angle relation or muscle size. In LL, muscle volume and CSA increased and the changes in CSA at specific muscle regions were correlated with changes in MVC force. A 5.4% ± 4.9% (P = 0.001) increase in Lf found in both groups was not associated with angle-specific force changes. There were no angle-specific changes in VA%. The EMG/Mmax, although not VA%, results suggest that neural adaptations underpinned training-related changes at short quadriceps lengths, but hypertrophic changes predominated after training at long lengths. The findings of this study should contribute to the development of more effective and evidence-based rehabilitation and strength training protocols.

  4. Effects of a foot placement constraint on use of motor equivalence during human hopping.

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    Arick G Auyang

    Full Text Available Humans can robustly locomote over complex terrains even while simultaneously attending to other tasks such as accurate foot placement on the ground. We investigated whether subjects would exploit motor redundancy across the joints of the leg to stabilize overall limb kinematics when presented with a hopping task that constrained foot placement position. Subjects hopped in place on one leg (2.2 Hz while having to place their foot into one of three target sizes upon landing (0.250, 0.063, 0.010 m(2. As takeoff and landing angles are critical to this task performance, we hypothesized smaller target sizes would increase the need to stabilize (i.e., make more consistent the leg orientation through motor equivalent combinations of segment angles. As it was not critical to the targeting task, we hypothesized no changes for leg length stabilization across target size. With smaller target sizes, we saw total segment angle variance increase due to greater signal-dependent noise associated with an increased activation of leg extensor muscles (medial and lateral gastrocnemius, vastus medialis, vastus lateralis and rectus femoris. At smaller target sizes, more segment angle variance was aligned to kinematic deviations with the goal of maintaining leg orientation trajectory. We also observed a decrease in the variance structure for stabilizing leg length at the smallest target conditions. This trade-off effect is explained by the nearly orthogonal relationship between the two goal-equivalent manifolds for leg length vs. leg orientation stabilization. Our results suggest humans increasingly rely on kinematic redundancy in their legs to achieve robust, consistent locomotion when faced with novel conditions that constrain performance requirements. These principles may generalize to other human locomotor gaits and provide important insights into the control of the legs during human walking and running.

  5. TIME-OF-DAY EFFECTS ON EMG PARAMETERS DURING THE WINGATE TEST IN BOYS

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    Hichem Souissi

    2012-09-01

    Full Text Available In boys, muscle power and strength fluctuate with time-of-day with morning nadirs and afternoon maximum values. However, the exact underlying mechanisms of this daily variation are not studied yet. Thus, the purpose of this study was to examine the time-of-day effects on electromyographic (EMG parameters changes during a Wingate test in boys. Twenty-two boys performed a 30-s Wingate test (measurement of muscle power and fatigue at 07:00 and 17:00-h on separate days. Surface EMG activity was recorded in the Vastus lateralis, rectus femoris and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root-mean-square (RMS and mean-power-frequency (MPF were calculated. Neuromuscular efficiency (NME was estimated from the ratio of power to RMS. Muscle power (8.22 ± 0.92 vs. 8.75 ± 0.99 W·kg-1 for peak power and 6.96 ± 0. 72 vs. 7.31 ± 0.77 W·kg-1 for mean power, p < 0.001 and fatigue (30.27 ± 7.98 vs. 34.5 ± 10. 15 %, p < 0.05 during the Wingate test increased significantly from morning to evening. Likewise, MPF (102.14 ± 18.15 vs. 92.38 ± 12.39 Hz during the first 5-s, p < 0.001 and NME (4.78 ± 1.7 vs. 3.88 ± 0.79 W·mV-1 during the first 5-s, p < 0.001 were higher in the evening than the morning; but no significant time-of-day effect was noticed for RMS. Taken together, these results suggest that peripheral mechanisms are more likely the cause of the child's diurnal variations of muscle power and fatigue during the Wingate test

  6. Upper Limb Static-Stretching Protocol Decreases Maximal Concentric Jump Performance

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    Paulo H. Marchetti

    2014-12-01

    Full Text Available The purpose of the present study was to evaluate the acute effects of an upper limb static-stretching (SS protocol on the maximal concentric jump performance. We recruited 25 young healthy, male, resistance trained individuals (stretched group, n = 15 and control group, n = 10 in this study. The randomized between group experimental protocol consisted of a three trials of maximal concentric jump task, before and after a SS of the upper limb. Vertical ground reaction forces (vGRF and surface electromyography (sEMG of both gastrocnemius lateralis (GL and vastus lateralis (VL were acquired. An extensive SS was employed consisting of ten stretches of 30 seconds, with 15 seconds of rest, and 70-90% of the point of discomfort (POD. ANOVA (2x2 (group x condition was used for shoulder joint range of motion (ROM, vGRF and sEMG. A significant interaction for passive ROM of the shoulder joint revealed significant increases between pre- and post-SS protocol (p < 0.001. A significant interaction demonstrated decreased peak force and an increased peak propulsion duration between pre- and post-stretching only for stretch group (p = 0.021, and p = 0.024, respectively. There was a significant main effect between groups (stretch and control for peak force for control group (p = 0.045. Regarding sEMG variables, there were no significant differences between groups (control versus stretched or condition (pre-stretching versus post-stretching for the peak amplitude of RMS and IEMG for both muscles (VL and GL. In conclusion, an acute extensive SS can increase the shoulder ROM, and negatively affect both the propulsion duration and peak force of the maximal concentric jump, without providing significant changes in muscle activation.

  7. Aging Reduces the Activation of the mTORC1 Pathway after Resistance Exercise and Protein Intake in Human Skeletal Muscle: Potential Role of REDD1 and Impaired Anabolic Sensitivity

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    Marc Francaux

    2016-01-01

    Full Text Available This study was designed to better understand the molecular mechanisms involved in the anabolic resistance observed in elderly people. Nine young (22 ± 0.1 years and 10 older (69 ± 1.7 years volunteers performed a one-leg extension exercise consisting of 10 × 10 repetitions at 70% of their 3-RM, immediately after which they ingested 30 g of whey protein. Muscle biopsies were taken from the vastus lateralis at rest in the fasted state and 30 min after protein ingestion in the non-exercised (Pro and exercised (Pro+ex legs. Plasma insulin levels were determined at the same time points. No age difference was measured in fasting insulin levels but the older subjects had a 50% higher concentration than the young subjects in the fed state (p < 0.05. While no difference was observed in the fasted state, in response to exercise and protein ingestion, the phosphorylation state of PKB (p < 0.05 in Pro and Pro+ex and S6K1 (p = 0.059 in Pro; p = 0.066 in Pro+ex was lower in the older subjects compared with the young subjects. After Pro+ex, REDD1 expression tended to be higher (p = 0.087 in the older group while AMPK phosphorylation was not modified by any condition. In conclusion, we show that the activation of the mTORC1 pathway is reduced in skeletal muscle of older subjects after resistance exercise and protein ingestion compared with young subjects, which could be partially due to an increased expression of REDD1 and an impaired anabolic sensitivity.

  8. Cellular assessment of muscle in COPD: case studies of two males

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    Howard J Green

    2009-11-01

    Full Text Available Howard J Green1, Eric Bombardier1, Margaret E Burnett1, Christine L D’Arsigny2, Sobia Iqbal1, Katherine A Webb2, Jing Ouyang1, Denis E O’Donnell21Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; 2Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen’s University, Kingston, ON, CanadaAbstract: The objective of this paper is to provide an overview of the recent developments in muscle physiology and biochemistry in general, and with respect to chronic obstructive pulmonary disease (COPD specifically. As a way of illustration, we have presented data on the remodeling that occurs in vastus lateralis in two patients with COPD (COPD #1, forced expiratory volume in one second/forced vital capacity [FEV1/FVC] = 63%; COPD #2, FEV1/FVC = 41% exhibiting differences in muscle wasting as compared to healthy controls (CON;FEV1/FVC = 111 ± 2.2%, n = 4. Type I fibers percentages were lower in both COPD #1 (16.7 and COPD #2 (24.9 compared to CON (57.3 ± 5.2. Cross sectional area of the type I fibers of the patients ranged between 65%–68% of CON and for the type II subtypes (IIA, IIAX, IIX between 74% and 89% (COPD #1 and 17%–32% (COPD #2. A lower number of capillary contacts were observed for all fiber types in COPD #1 but not COPD #2. Lower concentrations of adenosine triphosphate (ATP (24%–26% and phosphocreatine (18%–20%, but not lactate occurred in COPD. In contrast to COPD #1, who displayed normal glucose transporter content, GLUT1 and GLUT4 were only 71% and 54%, respectively of CON in COPD #2. Lower monocarboxylate contents were found for MCT1 in both COPD #1 (63% and COPD #2 (41% and for MCT4 (78% in COPD #1. Maximal oxidative enzyme activities (Vmax for COPD #2 ranged between 37% (succinic dehydrogenase and 70% (cytochrome C oxidase of CON. For the cytosolic enzymes, Vmax ranged between 89% (hexokinase to 31% (pyruvate kinase of CON. Depressions were also observed in Vmax of the Na

  9. S-glutathionylation of troponin I (fast) increases contractile apparatus Ca2+ sensitivity in fast-twitch muscle fibres of rats and humans.

    Science.gov (United States)

    Mollica, J P; Dutka, T L; Merry, T L; Lamboley, C R; McConell, G K; McKenna, M J; Murphy, R M; Lamb, G D

    2012-03-15

    Oxidation can decrease or increase the Ca2+ sensitivity of the contractile apparatus in rodent fast-twitch (type II) skeletal muscle fibres, but the reactions and molecular targets involved are unknown. This study examined whether increased Ca2+ sensitivity is due to S-glutathionylation of particular cysteine residues. Skinned muscle fibres were directly activated in heavily buffered Ca2+ solutions to assess contractile apparatus Ca2+ sensitivity. Rat type II fibres were subjected to S-glutathionylation by successive treatments with 2,2′-dithiodipyridine (DTDP) and glutathione (GSH), and displayed a maximal increase in pCa50 (−log10 [Ca2+] at half-maximal force) of ∼0.24 pCa units, with little or no effect on maximum force or Hill coefficient. Partial similar effect was produced by exposure to oxidized gluthathione (GSSG, 10 mM) for 10 min at pH 7.1, and near-maximal effect by GSSG treatment at pH 8.5. None of these treatments significantly altered Ca2+ sensitivity in rat type I fibres. Western blotting showed that both the DTDP–GSH and GSSG–pH 8.5 treatments caused marked S-glutathionylation of the fast troponin I isoform (TnI(f)) present in type II fibres, but not of troponin C (TnC) or myosin light chain 2. Both the increased Ca2+ sensitivity and glutathionylation of TnI(f) were blocked by N-ethylmaleimide (NEM). S-nitrosoglutathione (GSNO) also increased Ca2+ sensitivity, but only in conditions where it caused S-glutathionylation of TnI(f). In human type II fibres from vastus lateralis muscle, DTDP–GSH treatment also caused similar increased Ca2+ sensitivity and S-glutathionylation of TnI(f). When the slow isoform of TnI in type I fibres of rat was partially substituted (∼30%) with TnI(f), DTDP–GSH treatment caused a significant increase in Ca2+ sensitivity (∼0.08 pCa units). TnIf in type II fibres from toad and chicken muscle lack Cys133 present in mammalian TnIf, and such fibres showed no change in Ca2+ sensitivity with DTDP–GSH nor any S

  10. Substrate availability and transcriptional regulation of metabolic genes in human skeletal muscle during recovery from exercise

    DEFF Research Database (Denmark)

    Pilegaard, Henriette; Osada, Takuya; Andersen, Lisbeth Tingsted

    2005-01-01

    before exercise and 2, 5, 8, and 24 hours after exercise. Muscle glycogen was restored to near resting levels within 5 hours in the HC trial, but remained depressed through 24 hours in the LC trial. During the 2- to 8-hour recovery period, leg glucose uptake was 5- to 15-fold higher with HC ingestion......In skeletal muscle of humans, transcription of several metabolic genes is transiently induced during recovery from exercise when no food is consumed. To determine the potential influence of substrate availability on the transcriptional regulation of metabolic genes during recovery from exercise, 9...... male subjects (aged 22-27) completed 75 minutes of cycling exercise at 75% V¿o2max on 2 occasions, consuming either a high-carbohydrate (HC) or low-carbohydrate (LC) diet during the subsequent 24 hours of recovery. Nuclei were isolated and tissue frozen from vastus lateralis muscle biopsies obtained...

  11. Fat utilization during exercise

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Watt, Peter W.; Richter, Erik

    2001-01-01

    1. This study was carried out to test the hypothesis that the greater fat oxidation observed during exercise after adaptation to a high-fat diet is due to an increased uptake of fat originating from the bloodstream. 2. Of 13 male untrained subjects, seven consumed a fat-rich diet (62 % fat, 21...... % carbohydrate) and six consumed a carbohydrate-rich diet (20 % fat, 65 % carbohydrate). After 7 weeks of training and diet, 60 min of bicycle exercise was performed at 68 +/- 1 % of maximum oxygen uptake. During exercise [1-(13)C]palmitate was infused, arterial and venous femoral blood samples were collected......, and blood flow was determined by the thermodilution technique. Muscle biopsy samples were taken from the vastus lateralis muscle before and after exercise. 3. During exercise, the respiratory exchange ratio was significantly lower in subjects consuming the fat-rich diet (0.86 +/- 0.01, mean +/- S.E.M.) than...

  12. No effect of menstrual cycle on myofibrillar and connective tissue protein synthesis in contracting skeletal muscle

    DEFF Research Database (Denmark)

    Miller, B.F.; Hansen, M.; Olesen, J.L.

    2006-01-01

    We tested the hypothesis that acute exercise would stimulate synthesis of myofibrillar protein and intramuscular collagen in women and that the phase of the menstrual cycle at which the exercise took place would influence the extent of the change. Fifteen young, healthy female subjects were studied...... in the follicular (FP, n=8) or the luteal phase (LP, n=7, n=1 out of phase) 24 h after an acute bout of one-legged exercise (60 min of kicking at 67% W(max)), samples being taken from the vastus lateralis in both the exercised and resting legs. Rates of synthesis of myofibrillar and muscle collagen proteins were...... measured by incorporation of [(13)C]leucine. Myofibrillar protein synthesis (means+/-SD; rest FP: 0.053+/-0.009%/h, LP: 0.055+/-0.013%/h) was increased at 24-h postexercise (FP: 0.131+/-0.018%/h, Psynthesis...

  13. Local NSAID infusion inhibits satellite cell proliferation in human skeletal muscle after eccentric exercise

    DEFF Research Database (Denmark)

    Mikkelsen, U R; Langberg, H; Helmark, I C

    2009-01-01

    Despite the widespread consumption of nonsteroidal anti-inflammatory drugs (NSAIDs), the influence of these drugs on muscle satellite cells is not fully understood. The aim of the present study was to investigate the effect of a local NSAID infusion on satellite cells after unaccustomed eccentric...... exercise in vivo in human skeletal muscle. Eight young healthy males performed 200 maximal eccentric contractions with each leg. An NSAID was infused via a microdialysis catheter into the vastus lateralis muscle of one leg (NSAID leg) before, during, and for 4.5 h after exercise, with the other leg working...... cells (CD68(+) or CD16(+) cells) was not significantly increased in either of the legs 8 days after exercise and was unaffected by the NSAID. The main finding in the present study was that the NSAID infusion for 7.5 h during the exercise day suppressed the exercise-induced increase in the number...

  14. Inefficient skeletal muscle oxidative function flanks impaired motor neuron recruitment in Amyotrophic Lateral Sclerosis during exercise.

    Science.gov (United States)

    Lanfranconi, F; Ferri, A; Corna, G; Bonazzi, R; Lunetta, C; Silani, V; Riva, N; Rigamonti, A; Maggiani, A; Ferrarese, C; Tremolizzo, L

    2017-06-07

    This study aimed to evaluate muscle oxidative function during exercise in amyotrophic lateral sclerosis patients (pALS) with non-invasive methods in order to assess if determinants of reduced exercise tolerance might match ALS clinical heterogeneity. 17 pALS, who were followed for 4 months, were compared with 13 healthy controls (CTRL). Exercise tolerance was assessed by an incremental exercise test on cycle ergometer measuring peak O 2 uptake ([Formula: see text]O 2peak ), vastus lateralis oxidative function by near infrared spectroscopy (NIRS) and breathing pattern ([Formula: see text]E peak ). pALS displayed: (1) 44% lower [Formula: see text]O 2peak vs. CTRL (p motor units recruitment, is a major determinant of pALS clinical heterogeneity and working capacity exercise tolerance. CPET and NIRS are useful tools for detecting early stages of oxidative deficiency in skeletal muscles, disclosing individual impairments in the O 2 transport and utilization chain.

  15. Asterixis in the leg induced by anterior cerebral artery infarction.

    Science.gov (United States)

    Sunwoo, Mun Kyung; Jang, Hyun-Soon; Roh, Sook Young; Yoo, Hyun Jung; Jeong, Eun Hye; Kim, Byung-Su; Choe, Yeo Reum; Lee, Ko-Eun

    2016-06-01

    Asterixis commonly occurs in a patient with metabolic encephalopathy, whereas focal brain lesions such as thalamus, cerebellum, or frontal area also cause focal or unilateral asterixis in the arms. We report a novel case of asterixis in the leg after unilateral anterior cerebral artery territory infarction. A 76-year-old man was admitted with sudden-onset mild right leg weakness and postural instability due to knee buckling. He was diagnosed with ischemic stroke in the left prefrontal area and cingulated gyrus by brain magnetic imaging. Needle electromyography of the right vastus lateralis muscle while standing showed intermittent periods of EMG silence, consistent with asterixis. There were no abnormal involuntary movements in the upper extremities. This case suggests that gait disturbance or postural instability after structural lesions in the prefrontal area may be directly related to asterixis in the leg, not in the arm associated with postural failure.

  16. Effect of 5 weeks horizontal bed rest on human muscle thickness and architecture of weight bearing and non-weight bearing muscles.

    Science.gov (United States)

    de Boer, Maarten D; Seynnes, Olivier R; di Prampero, Pietro E; Pisot, Rado; Mekjavić, Igor B; Biolo, Gianni; Narici, Marco V

    2008-09-01

    The aim of the present study was to investigate the changes in thickness, fascicle length (L (f)) and pennation angle (theta) of the antigravity gastrocnemius medialis (GM) and vastus lateralis (VL) muscles, and the non-antigravity tibialis anterior (TA) and biceps brachii (BB) muscles measured by ultrasonography in ten healthy males (aged 22.3 +/- 2.2 years) in response to 5 weeks of horizontal bed rest (BR). After BR, muscle thickness decreased by 12.2 +/- 8.8% (P antigravity muscles of the lower limbs, the GM deteriorated to a greater extent than the VL is possibly related to the differences in relative load that this muscle normally experiences during daily loading. The dissimilar response in antigravity and non-antigravity muscles to unloading likely reflects differences in loading under normal conditions. The significant structural alterations of the GM and VL muscles highlight the rapid remodelling of muscle architecture occurring with disuse.

  17. Aerobic exercise training induces skeletal muscle hypertrophy and age-dependent adaptations in myofiber function in young and older men

    Science.gov (United States)

    Konopka, Adam R.; Undem, Miranda K.; Hinkley, James M.; Minchev, Kiril; Kaminsky, Leonard A.; Trappe, Todd A.; Trappe, Scott

    2012-01-01

    To examine potential age-specific adaptations in skeletal muscle size and myofiber contractile physiology in response to aerobic exercise, seven young (YM; 20 ± 1 yr) and six older men (OM; 74 ± 3 yr) performed 12 wk of cycle ergometer training. Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of isolated slow [myosin heavy chain (MHC) I] and fast (MHC IIa) myofibers, MHC composition, and muscle protein concentration. Aerobic capacity was higher (P 0.05) with training. Training reduced (P aerobic capacity are similar between YM and OM, while adaptations in myofiber contractile function showed a general improvement in OM. Training-related increases in MHC I and MHC IIa peak power reveal that skeletal muscle of OM is responsive to aerobic exercise training and further support the use of aerobic exercise for improving cardiovascular and skeletal muscle health in older individuals. PMID:22984247

  18. Exercise & NSAID: Effect on muscle protein synthesis in knee osteoarthritis patients?

    DEFF Research Database (Denmark)

    Petersen, S.G.; Miller, Ben F; Hansen, M

    2011-01-01

    the contralateral leg remained rested. Twenty-four hours after exercise, we determined circulating concentrations of inflammatory parameters and measured FSR of myofibrillar and sarcoplasmic protein fractions of vastus lateralis muscle and patellar tendon collagen protein by the direct incorporation method using...... a flooding dose of 13C/12C-proline.RESULTS:Circulating levels of prostaglandin F2α were lower in the NSAID group compared with the placebo group (P effect of exercise on FSR in muscle myofibrillar (P = 0.003) and sarcoplasmic protein (P = 0.026) but not in tendon...... collagen protein (P = 0.52). No overall significant effect of the drug was seen on either of the tissue protein fractions (P > 0.05) or on the interaction between the drug and exercise on FSR in tendon collagen (P = 0.21), muscle myofibrillar (P = 0.68), or sarcoplasmic protein, FSR (P = 0.16).CONCLUSION...

  19. Low expression of IL-18 and IL-18 receptor in human skeletal muscle is associated with systemic and intramuscular lipid metabolism-Role of HIV lipodystrophy

    DEFF Research Database (Denmark)

    Lindegaard, Birgitte; Hvid, Thine; Wolsk Mygind, Helene

    2018-01-01

    receptor (R) expression would be altered in patients with HIV-lipodystrophy. DESIGN AND METHODS: Twenty-three HIV-infected patients with LD and 15 age-matched healthy controls were included in a cross-sectional study. Biopsies from the vastus lateralis muscle were obtained and IL-18 and IL-18R m......-18 mRNA is expressed in human skeletal muscle but a role for IL-18 in muscle has not been identified. Patients with HIV-infection and lipodystrophy (LD) are characterized by lipid and glucose disturbances and increased levels of circulating IL-18. We hypothesized that skeletal muscle IL-18 and IL-18......RNA expression were measured by real-time PCR and sphingolipids (ceramides, sphingosine, sphingosine-1-Phosphate, sphinganine) were measured by HPLC. Insulin resistance was assessed by HOMA and the insulin response during an OGTT. RESULTS: Patients with HIV-LD had a 60% and 54% lower level of muscular IL-18...

  20. High responders to resistance exercise training demonstrate differential regulation of skeletal muscle microRNA expression

    DEFF Research Database (Denmark)

    Davidsen, Peter K; Gallagher, Iain J; Hartman, Joseph W

    2011-01-01

    MicroRNAs (miRNA), small noncoding RNA molecules, may regulate protein synthesis, while resistance exercise training (RT) is an efficient strategy for stimulating muscle protein synthesis in vivo. However, RT increases muscle mass, with a very wide range of effectiveness in humans. We therefore...... determined the expression level of 21 abundant miRNAs to determine whether variation in these miRNAs was able to explain the variation in RT-induced gains in muscle mass. Vastus lateralis biopsies were obtained from the top and bottom ~20% of responders from 56 young men who undertook a 5 day/wk RT program...... for 12 wk. Training-induced muscle mass gain was determined by dual-energy X-ray absorptiometry, and fiber size was evaluated by histochemistry. The expression level of each miRNA was quantified using TaqMan-based quantitative PCR, with the analysis carried out in a blinded manner. Gene ontology...

  1. GLUT-4 content in plasma membrane of muscle from patients with non-insulin-dependent diabetes mellitus

    DEFF Research Database (Denmark)

    Lund, S; Vestergaard, H; Andersen, P H

    1993-01-01

    The abundance of GLUT-4 protein in both total crude membrane and plasma membrane fractions of vastus lateralis muscle from 13 obese non-insulin-dependent diabetes mellitus (NIDDM) patients and 14 healthy subjects were examined in the fasting state and after supraphysiological hyperinsulinemia....... In the basal state the immunoreactive mass of GLUT-4 protein both in the crude membrane preparation and in the plasma membrane fraction was similar in NIDDM patients and control subjects. Moreover, in vivo insulin exposure neither for 30 min nor for 4 h had any impact on the content of GLUT-4 protein in plasma...... membranes. With the use of the same methodology, antibody, and achieving the same degree of plasma membrane purification and recovery, we found, however, that intraperitoneal administration of insulin to 7-wk-old rats within 30 min increased the content of GLUT-4 protein more than twofold (P

  2. Human skeletal muscle ceramide content is not a major factor in muscle insulin sensitivity

    DEFF Research Database (Denmark)

    Skovbro, M; Baranowski, M; Skov-Jensen, C

    2008-01-01

    -hyperinsulinaemic clamp was performed for 120 and 90 min for step 1 and step 2, respectively. Muscle biopsies were obtained from vastus lateralis at baseline, and after steps 1 and 2. RESULTS: Glucose infusion rates increased in response to insulin infusion, and significant differences were present between groups (T2D......AIMS/HYPOTHESIS: In skeletal muscle, ceramides may be involved in the pathogenesis of insulin resistance through an attenuation of insulin signalling. This study investigated total skeletal muscle ceramide fatty acid content in participants exhibiting a wide range of insulin sensitivities. METHODS......: The middle-aged male participants (n=33) were matched for lean body mass and divided into four groups: type 2 diabetes (T2D, n=8), impaired glucose tolerance (IGT, n=9), healthy controls (CON, n=8) and endurance-trained (TR, n=8). A two step (28 and 80 mU m(-2) min(-1)) sequential euglycaemic...

  3. Changes in Lumbopelvic Movement and Muscle Recruitment Associated with Prolonged Deep Squatting: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Tim K. S. Lui

    2018-05-01

    Full Text Available This study examined the changes in spinal kinematics and muscle recruitment of the lumbopelvic region associated with prolonged squatting. Eight subjects with chronic nonspecific low back pain (LBP and eight asymptomatic subjects (AS performed squat-to-stand and reverse movements, before and immediately after 15 min deep-squatting. Within-group and between-group differences in lumbopelvic kinematics and electromyographic activity acquired in lumbar erector spinae (ES, gluteus maximus (GM, and vastus lateralis (VL were analyzed. During squat-to-stand after squatting, the LBP group showed slower then faster lumbar movement in the second and third quartiles, respectively. In the second quartile, the AS group moved with a significantly greater lumbar angle. However, significantly greater bilateral GM activity (+4–4.5% was found in the LBP group only. A more profound decrease in bilateral ES activity (−10% was also shown in the LBP group, yet this was nonsignificant compared to the AS group (−4%. In the third quartile, only the LBP group moved with a significantly greater lumbar angle, together with a significant increase in bilateral ES (+6–8% and GM muscle (+2–3% activity. The findings of the altered pattern of joint kinematics and recruitment of the key lumbopelvic muscles displayed in the LBP group inform on the possible mechanisms that may contribute to the increased risk of developing lumbar dysfunctions for people who work in prolonged squatting postures.

  4. Using Electromyography to Detect the Weightings of the Local Muscle Factors to the Increase of Perceived Exertion During Stepping Exercise

    Directory of Open Access Journals (Sweden)

    Miao-Ju Hsu

    2008-06-01

    Full Text Available Rate of perceived exertion (RPE is a clinically convenient indicator for monitoring exercise intensity in cardiopulmonary rehabilitation. It might not be sensitive enough for clinicians to determine the patients’ physiological status because its association with the cardiovascular system and local muscle factors is unknown. This study used the electromyographic sensor to detect the local muscle fatigue and stabilization of patella, and analyzed the relationship between various local muscle and cardiovascular factors and the increase of RPE during stepping exercise, a common exercise program provided in cardiopulmonary rehabilitation. Ten healthy adults (4 males and 6 females participated in this study. Each subject used their right bare foot to step up onto a 23-cm-high step at a constant speed until the RPE score reached 20. The RPE, heart rate (HR, and surface EMG of the rectus femoris (RF, vastus medialis, and vastus lateralis were recorded at 1-minute intervals during the stepping exercise. The generalized estimating equations (GEE analysis indicated that the increase in RPE significantly correlated with the increase in HR, and decrease in median frequency (MF of the EMG power spectrum of the RF. Experimental results suggest that the increase in RPE during stepping exercise was influenced by the cardiovascular status, localized muscle fatigue in the lower extremities. The weighting of the local muscle factors was more than half of the weighting of the cardiovascular factor.

  5. Neuroprotective effects of testosterone metabolites and dependency on receptor action on the morphology of somatic motoneurons following the death of neighboring motoneurons.

    Science.gov (United States)

    Cai, Yi; Chew, Cory; Muñoz, Fernando; Sengelaub, Dale R

    2017-06-01

    Partial depletion of spinal motoneuron populations induces dendritic atrophy in neighboring motoneurons, and treatment with testosterone is neuroprotective, attenuating induced dendritic atrophy. In this study we examined whether the protective effects of testosterone could be mediated via its androgenic or estrogenic metabolites. Furthermore, to assess whether these neuroprotective effects were mediated through steroid hormone receptors, we used receptor antagonists to attempt to prevent the neuroprotective effects of hormones after partial motoneuron depletion. Motoneurons innervating the vastus medialis muscles of adult male rats were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, some saporin-injected rats were treated with either dihydrotestosterone or estradiol, alone or in combination with their respective receptor antagonists, or left untreated. Four weeks later, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. Compared with intact normal animals, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons. Dendritic atrophy was attenuated with both dihydrotestosterone and estradiol treatment to a degree similar to that seen with testosterone, and attenuation of atrophy was prevented by receptor blockade. Together, these findings suggest that neuroprotective effects on motoneurons can be mediated by either androgenic or estrogenic hormones and require action via steroid hormone receptors, further supporting a role for hormones as neurotherapeutic agents in the injured nervous system. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 691-707, 2017. © 2016 Wiley Periodicals, Inc.

  6. Implementation of a portable electronic system for providing pain relief to patellofemoral pain syndrome patients

    Science.gov (United States)

    Chang Chien, Jia-Ren; Lin, Guo-Hong; Hsu, Ar-Tyan

    2011-10-01

    In this study, a portable electromyogram (EMG) system and a stimulator are developed for patellofemoral pain syndrome patients, with the objective of reducing the pain experienced by these patients; the patellar pain is caused by an imbalance between the vastus medialis obliquus (VMO) and the vastus lateralis (VL). The EMG measurement circuit and the electrical stimulation device proposed in this study are specifically designed for the VMO and the VL; they are capable of real-time waveform recording, possess analyzing functions, and can upload their measurement data to a computer for storage and analysis. The system can calculate and record the time difference between the EMGs of the VMO and the VL, as well as the signal strengths of both the EMGs. As soon as the system detects the generation of the EMG of the VL, it quickly calculates and processes the event and stimulates the VMO as feedback through electrical stimulation units, in order to induce its contraction. The system can adjust the signal strength, time length, and the sequence of the electrical stimulation, both manually and automatically. The output waveform of the electrical stimulation circuit is a dual-phase asymmetrical pulse waveform. The primary function of the electrical simulation circuit is to ensure that the muscles contract effectively. The performance of the device can be seen that the width of each pulse is 20-1000 μs, the frequency of each pulse is 10-100 Hz, and current strength is 10-60 mA.

  7. Diagnostic accuracy of the electromyography parameters associated with anterior knee pain in the diagnosis of patellofemoral pain syndrome.

    Science.gov (United States)

    Ferrari, Deisi; Kuriki, Heloyse Uliam; Silva, Cristiano Rocha; Alves, Neri; Mícolis de Azevedo, Fábio

    2014-08-01

    To assess the diagnostic accuracy of the surface electromyography (sEMG) parameters associated with referred anterior knee pain in diagnosing patellofemoral pain syndrome (PFPS). Sensitivity and specificity analysis. Physical rehabilitation center and laboratory of biomechanics and motor control. Pain-free subjects (n=29) and participants with PFPS (n=22) selected by convenience. Not applicable. The diagnostic accuracy was calculated for sEMG parameters' reliability, precision, and ability to differentiate participants with and without PFPS. The selected sEMG parameter associated with anterior knee pain was considered as an index test and was compared with the reference standard for the diagnosis of PFPS. Intraclass correlation coefficient, SEM, independent t tests, sensitivity, specificity, negative and positive likelihood ratios, and negative and positive predictive values were used for the statistical analysis. The medium-frequency band (B2) parameter was reliable (intraclass correlation coefficient=.80-.90), precise (SEM=2.71-3.87 normalized unit), and able to differentiate participants with and without PFPS (Ppain showed positive diagnostic accuracy values (specificity, .87; sensitivity, .70; negative likelihood ratio, .33; positive likelihood ratio, 5.63; negative predictive value, .72; and positive predictive value, .86). The results provide evidence to support the use of EMG signals (B2-frequency band of 45-96 Hz) of the vastus lateralis and vastus medialis muscles with referred anterior knee pain in the diagnosis of PFPS. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  8. Does external pneumatic compression treatment between bouts of overreaching resistance training sessions exert differential effects on molecular signaling and performance-related variables compared to passive recovery? An exploratory study.

    Science.gov (United States)

    Haun, Cody T; Roberts, Michael D; Romero, Matthew A; Osburn, Shelby C; Mobley, Christopher B; Anderson, Richard G; Goodlett, Michael D; Pascoe, David D; Martin, Jeffrey S

    2017-01-01

    We sought to compare the effects of external pneumatic compression (EPC) and sham when used concurrently with resistance training on performance-related outcomes and molecular measures related to recovery. Twenty (N = 20) resistance-trained male participants (aged 21.6±2.4 years) were randomized to balanced sham or EPC intervention groups. The protocol consisted of 3 consecutive days of heavy, voluminous back squat exercise followed by EPC/sham treatment (Days2-4) and 3 consecutive days of recovery (Days5-7) with EPC/sham only on Days5-6. On Day1 (PRE), and Days3-7, venipuncture, flexibility and pressure-to-pain threshold (PPT) measures were performed. Vastsus lateralis muscle tissue was biopsied at PRE, 1-h post-EPC/sham treatment on Day2 (POST1) and 24-h post-EPC/sham treatment on Day7 (POST2). Isokinetic peak torque was assessed at PRE and POST2. Peak isokinetic strength did not change from PRE to POST2 in either group. The PPT was significantly lower on Days3-6 with sham, indicating greater muscle soreness, though this was largely abolished in the EPC group. A significant decrease in flexibility with sham was observed on Day3 (+16.2±4.6% knee joint angle; P0.01). Vastus lateralis poly-ubiquitinated proteins significantly increased at the POST2 time point relative to PRE with sham (+66.6±24.6%; Pmuscle oxidative stress and proteolysis markers during recovery from heavy resistance exercise.

  9. Effects of prior short multiple-sprint exercises with different intersprint recoveries on the slow component of oxygen uptake during high-intensity exercise.

    Science.gov (United States)

    Lanzi, Stefano; Borrani, Fabio; Wolf, Martin; Gojanovic, Boris; Malatesta, Davide

    2012-12-01

    This study compares the effects of two short multiple-sprint exercise (MSE) (6 × 6 s) sessions with two different recovery durations (30 s or 180 s) on the slow component of oxygen uptake ([Formula: see text]O(2)) during subsequent high-intensity exercise. Ten male subjects performed a 6-min cycling test at 50% of the difference between the gas exchange threshold and [Formula: see text]O(2peak) (Δ50). Then, the subjects performed two MSEs of 6 × 6 s separated by two intersprint recoveries of 30 s (MSE(30)) and 180 s (MSE(180)), followed 10 min later by the Δ50 (Δ50(30) and Δ50(180), respectively). Electromyography (EMG) activities of the vastus medialis and lateralis were measured throughout each exercise bout. During MSE(30), muscle activity (root mean square) increased significantly (p ≤ 0.04), with a significant leftward-shifted median frequency of the power density spectrum (MDF; p ≤ 0.01), whereas MDF was significantly rightward-shifted during MSE(180) (p = 0.02). The mean [Formula: see text]O(2) value was significantly higher in MSE(30) than in MSE(180) (p motor units recruitment profile (i.e., change in the type of muscle fibers recruited) and (or) an improved muscle O(2) delivery during subsequent exercise.

  10. The influence of capillarization on satellite cell pool expansion and activation following exercise-induced muscle damage in healthy young men.

    Science.gov (United States)

    Nederveen, Joshua P; Joanisse, Sophie; Snijders, Tim; Thomas, Aaron C Q; Kumbhare, Dinesh; Parise, Gianni

    2018-03-15

    Skeletal muscle stem cells (satellite cells) play a crucial role in repair and remodelling of muscle in response to exercise. Satellite cells are in close spatial proximity to muscle capillaries and therefore may be influenced by them. In this study, we describe the activation and expansion of the satellite cell pool in response to eccentric contraction-induced muscle damage in individuals with significantly different levels of muscle capillarization. Individuals with greater capillarization and capacity for muscle perfusion demonstrated enhanced activation and/or expansion of the satellite cell pool allowing for an accelerated recovery of muscle function. These results provide insight into the critical relationship between muscle capillarization and satellite cells during skeletal muscle repair. Factors that determine the skeletal muscle satellite cell (SC) response remain incompletely understood. It is known, however, that SC activation status is closely related to the anatomical relationship between SCs and muscle capillaries. We investigated the impact of muscle fibre capillarization on the expansion and activation status of SCs following a muscle-damaging exercise protocol in healthy young men. Twenty-nine young men (21 ± 0.5 years) performed 300 unilateral eccentric contractions (180 deg s -1 ) of the knee extensors. Percutaneous muscle biopsies from the vastus lateralis and blood samples from the antecubital vein were taken prior to (Pre) exercise and at 6, 24, 72 and 96 h of post-exercise recovery. A comparison was made between subjects who had a relative low mixed muscle capillary-to-fibre perimeter exchange index (CFPE; Low group) and high mixed muscle CFPE index (High group) at baseline. Type I and type II muscle fibre size, myonuclear content, capillarization, and SC response were determined via immunohistochemistry. Overall, there was a significant correlation (r = 0.39; P < 0.05) between the expansion of SC content (change in total Pax7

  11. Gain modulation of the middle latency cutaneous reflex in patients with chronic joint instability after ankle sprain.

    Science.gov (United States)

    Futatsubashi, Genki; Sasada, Shusaku; Tazoe, Toshiki; Komiyama, Tomoyoshi

    2013-07-01

    To investigate the neural alteration of reflex pathways arising from cutaneous afferents in patients with chronic ankle instability. Cutaneous reflexes were elicited by applying non-noxious electrical stimulation to the sural nerve of subjects with chronic ankle instability (n=17) and control subjects (n=17) while sitting. Electromyographic (EMG) signals were recorded from each ankle and thigh muscle. The middle latency response (MLR; latency: 70-120 ms) component was analyzed. In the peroneus longus (PL) and vastus lateralis (VL) muscles, linear regression analyses between the magnitude of the inhibitory MLR and background EMG activity showed that, compared to the uninjured side and the control subjects, the gain of the suppressive MLR was increased in the injured side. This was also confirmed by the pooled data for both groups. The degree of MLR alteration was significantly correlated to that of chronic ankle instability in the PL. The excitability of middle latency cutaneous reflexes in the PL and VL is modulated in subjects with chronic ankle instability. Cutaneous reflexes may be potential tools to investigate the pathological state of the neural system that controls the lower limbs in subjects with chronic ankle instability. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Insulin resistance and increased muscle cytokine levels in patients with mitochondrial myopathy.

    Science.gov (United States)

    Rue, Nana; Vissing, John; Galbo, Henrik

    2014-10-01

    Mitochondrial dysfunction has been proposed to cause insulin resistance and that might stimulate cytokine production. The objective of the study was to elucidate the association between mitochondrial myopathy, insulin sensitivity, and cytokine levels in muscle. This was an experimental, controlled study in outpatients. Eight overnight-fasted patients (P) with various inherited mitochondrial myopathies and eight healthy subjects (C) matched for sex, age, weight, height, and physical activity participated in the study. The intervention included a 120-minute hyperinsulinemic, euglycemic clamp. Another morning, microdialysis of both vastus lateralis muscles for 4 hours, including one-legged, knee extension exercise for 30 minutes, was performed. Glucose infusion rate during 90-120 minutes of insulin infusion was measured. Cytokine concentrations in dialysate were also measured. Muscle strength, percentage fat mass, and creatine kinase in plasma did not differ between groups. The maximal oxygen uptake was 21 ± 3 (SE) (P) and 36 ± 3(C) mL/kg·min (2P fatty acids and glycerol at 120 minutes were higher in P vs C (2P myopathies, insulin sensitivity of muscle, adipose tissue, and pancreatic A cells is reduced, supporting that mitochondrial function influences insulin action. Furthermore, a local, low-grade inflammation of potential clinical importance exists in the muscle of these patients.

  13. Influence of priming exercise on pulmonary O2 uptake kinetics during transitions to high-intensity exercise from an elevated baseline.

    Science.gov (United States)

    DiMenna, Fred J; Wilkerson, Daryl P; Burnley, Mark; Jones, Andrew M

    2008-08-01

    It has been suggested that the slower O2 uptake (VO2) kinetics observed when exercise is initiated from an elevated baseline metabolic rate are linked to an impairment of muscle O2 delivery. We hypothesized that "priming" exercise would significantly reduce the phase II time constant (tau) during subsequent severe-intensity cycle exercise initiated from an elevated baseline metabolic rate. Seven healthy men completed exercise transitions to 70% of the difference between gas exchange threshold (GET) and peak VO2 from a moderate-intensity baseline (90% GET) on three occasions in each of the "unprimed" and "primed" conditions. Pulmonary gas exchange, heart rate, and the electromyogram of m. vastus lateralis were measured during all tests. The phase II VO2 kinetics were slower when severe exercise was initiated from a baseline of moderate exercise compared with unloaded pedaling (mean+/-SD tau, 42+/-15 vs. 33+/-8 s; P0.05). The amplitude of the VO2 slow component and the change in electromyogram from minutes 2 to 6 were both significantly reduced following priming exercise (VO2 slow component: from 0.47+/-0.09 to 0.27+/-0.13 l/min; change in integrated electromyogram between 2 and 6 min: from 51+/-35 to 26+/-43% of baseline; Pchanges in muscle fiber activation.

  14. Relationship between efficiency and pedal rate in cycling

    DEFF Research Database (Denmark)

    Hansen, E A; Sjøgaard, G

    2007-01-01

    Cycling was performed to test the following two hypotheses: (1) muscular efficiency is unrelated to pedal rate (61, 88, and 115 r.p.m.) for a group of subjects with a wide range of slow twitch (ST) fibers in spite of decreasing whole-body efficiency and (2) muscular efficiency correlates positively...... with % ST muscle fibers, and this correlation is more pronounced at low pedal rates than at high pedal rates. Whole-body gross efficiency decreased from 20-22% at 61 r.p.m. to 15-18% at 115 r.p.m. Mean muscular efficiency for all subjects (n=16) was approximately 26%, with delta efficiency being constant...... and muscular efficiency (taking internal power into account) slightly increasing with pedal rate. Muscular efficiency correlated positively (R(2)=0.25) with % ST fibers (21-97% ST in m. vastus lateralis) at 115 r.p.m. while not at 61 and 88 r.p.m. In conclusion, the decrease in whole-body gross efficiency...

  15. Histochemical and functional parameters in Nordic combination athletes.

    Science.gov (United States)

    Matolín, S; Vaverka, F; Lunák, J; Novák, J; Horák, V; Krejcí, P

    1994-01-01

    Bioptic samples from the vastus lateralis muscle were analyzed in a group of Czechoslovak representatives in the Nordic combination (ski-jumping and 15 km cross-country skiing). The distribution of individual muscle fibre types (FG, FOG and SO) was detected and correlated with values obtained by motor and functional performance tests. Histochemical analysis of the bioptic samples revealed a considerably heterogeneous distribution of muscle fibre types in the group studied. No typical profilation for this sport discipline was found. Weak correlation between the proportion of fast muscle fibres and explosive strength parameters was ascertained. The correlation between the proportion of slow muscle fibres and the capacity of O2 utilization (VO2max) was statistically significant. Strong correlation between the proportion of fast twitch fibres and relative maximal strength of knee extensors (N/kg) was disclosed. A non-linear relation between the area of fast twitch fibres and vigour of take-off was found.

  16. Skeletal muscle phosphatidylcholine fatty acids and insulin sensitivity in normal humans.

    Science.gov (United States)

    Clore, J N; Li, J; Gill, R; Gupta, S; Spencer, R; Azzam, A; Zuelzer, W; Rizzo, W B; Blackard, W G

    1998-10-01

    The fatty acid composition of skeletal muscle membrane phospholipids (PL) is known to influence insulin responsiveness in humans. However, the contribution of the major PL of the outer (phosphatidylcholine, PC) and inner (phosphatidylethanolamine, PE) layers of the sarcolemma to insulin sensitivity is not known. Fatty acid composition of PC and PE from biopsies of vastus lateralis from 27 normal men and women were correlated with insulin sensitivity determined by the hyperinsulinemic euglycemic clamp technique at insulin infusion rates of 0.4, 1.0, and 10.0 mU . kg-1 . min-1. Significant variation in the half-maximal insulin concentration (ED50) was observed in the normal volunteers (range 24.0-146.0 microU/ml), which correlated directly with fasting plasma insulin (r = 0.75, P insulin sensitivity was observed in PE (NS). These studies suggest that the fatty acid composition of PC may be of particular importance in the relationship between fatty acids and insulin sensitivity in normal humans.

  17. Skeletal muscle phosphatidylcholine and phosphatidylethanolamine respond to exercise and influence insulin sensitivity in men.

    Science.gov (United States)

    Lee, Sindre; Norheim, Frode; Gulseth, Hanne L; Langleite, Torgrim M; Aker, Andreas; Gundersen, Thomas E; Holen, Torgeir; Birkeland, Kåre I; Drevon, Christian A

    2018-04-25

    Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) composition in skeletal muscle have been linked to insulin sensitivity. We evaluated the relationships between skeletal muscle PC:PE, physical exercise and insulin sensitivity. We performed lipidomics and measured PC and PE in m. vastus lateralis biopsies obtained from 13 normoglycemic normal weight men and 13 dysglycemic overweight men at rest, immediately after 45 min of cycling at 70% maximum oxygen uptake, and 2 h post-exercise, before as well as after 12 weeks of combined endurance- and strength-exercise intervention. Insulin sensitivity was monitored by euglycemic-hyperinsulinemic clamp. RNA-sequencing was performed on biopsies, and mitochondria and lipid droplets were quantified on electron microscopic images. Exercise intervention for 12 w enhanced insulin sensitivity by 33%, skeletal muscle levels of PC by 21%, PE by 42%, and reduced PC:PE by 16%. One bicycle session reduced PC:PE by 5%. PC:PE correlated negatively with insulin sensitivity (β = -1.6, P insulin sensitivity.

  18. Impaired insulin-induced site-specific phosphorylation of TBC1 domain family, member 4 (TBC1D4) in skeletal muscle of type 2 diabetes patients is restored by endurance exercise-training

    DEFF Research Database (Denmark)

    Vind, B. F.; Pehmøller, Christian; Treebak, Jonas Thue

    2011-01-01

    AIMS/HYPOTHESIS: Insulin-mediated glucose disposal rates (R (d)) are reduced in type 2 diabetic patients, a process in which intrinsic signalling defects are thought to be involved. Phosphorylation of TBC1 domain family, member 4 (TBC1D4) is at present the most distal insulin receptor signalling...... event linked to glucose transport. In this study, we examined insulin action on site-specific phosphorylation of TBC1D4 and the effect of exercise training on insulin action and signalling to TBC1D4 in skeletal muscle from type 2 diabetic patients. METHODS: During a 3 h euglycaemic-hyperinsulinaemic (80...... mU min(-1) m(-2)) clamp, we obtained M. vastus lateralis biopsies from 13 obese type 2 diabetic and 13 obese, non-diabetic control individuals before and after 10 weeks of endurance exercise-training. RESULTS: Before training, reductions in insulin-stimulated R (d), together with impaired insulin...

  19. Myosin heavy-chain isoform distribution, fibre-type composition and fibre size in skeletal muscle of patients on haemodialysis

    DEFF Research Database (Denmark)

    Molsted, Stig; Eidemak, Inge; Sorensen, Helle Tauby

    2007-01-01

    of age-, gender- and BMI-matched untrained control subjects. The aerobic work capacity of the patients was also determined. Results. The MHC composition for I, IIA and IIX isoforms was found to be 35.3%±18.2%, 35.9%±7.1% and 28.9%±15.6%, respectively, findings supported by the ATPase histochemically...... determined fibre-type composition of the vastus lateralis muscle. The mean fibre area of type 1 and 2 fibres was 3283±873 and 3594±1483 µm2, respectively. The MHC composition and the size of the type 1 fibres of the patients on HD were significantly different from those of the control subjects. Conclusions....... The data demonstrate relatively fewer type 1 and consequently more type 2x fibres, with a corresponding change in MHC isoforms (MHC I and MHC IIX) in the skeletal muscle of patiens on HD. Several patients on HD were found to have type 1 (or relative percentage of MHC I) fibres. Such a low percentage...

  20. Low birthweight is associated with specific changes in muscle insulin-signalling protein expression

    DEFF Research Database (Denmark)

    Ozanne, SE; Jensen, CB; Tingey, KJ

    2005-01-01

    muscle in a human cohort and a rat model. METHODS: We recruited 20 young men with low birthweight (mean birthweight 2702+/-202 g) and 20 age-matched control subjects (mean birthweight 3801+/-99 g). Biopsies were obtained from the vastus lateralis muscle and protein expression of selected insulin......-signalling proteins was determined. Rats used for this study were male offspring born to dams fed a standard (20%) protein diet or a low (8%) protein diet during pregnancy and lactation. Protein expression was determined in soleus muscle from adult offspring. RESULTS: Low-birthweight subjects showed reduced muscle...... expression of protein kinase C (PKC)zeta, p85alpha, p110beta and GLUT4. PKCzeta, GLUT4 and p85 were also reduced in the muscle of rats fed a low-protein diet. Other proteins studied were unchanged in low-birthweight humans and in rats fed a low-protein diet when compared with control groups. CONCLUSIONS...