De Blaiser, C; De Ridder, R; Willems, T; Danneels, L; Vanden Bossche, L; Palmans, T; Roosen, P
The aims of this study were to research the amplitude and median frequency characteristics of selected abdominal, back, and hip muscles of healthy subjects during a prone bridging endurance test, based on surface electromyography (sEMG), (a) to determine if the prone bridging test is a valid field test to measure abdominal muscle fatigue, and (b) to evaluate if the current method of administrating the prone bridging test is reliable. Thirty healthy subjects participated in this experiment. The sEMG activity of seven abdominal, back, and hip muscles was bilaterally measured. Normalized median frequencies were computed from the EMG power spectra. The prone bridging tests were repeated on separate days to evaluate inter and intratester reliability. Significant differences in normalized median frequency slope (NMF slope ) values between several abdominal, back, and hip muscles could be demonstrated. Moderate-to-high correlation coefficients were shown between NMF slope values and endurance time. Multiple backward linear regression revealed that the test endurance time could only be significantly predicted by the NMF slope of the rectus abdominis. Statistical analysis showed excellent reliability (ICC=0.87-0.89). The findings of this study support the validity and reliability of the prone bridging test for evaluating abdominal muscle fatigue. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.
Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.
Helmi, Muhammad Hazimin Bin; Ping, Chew Sue; Ishak, Nur Elliza Binti; Saad, Mohd Alimi Bin Mohd; Mokhtar, Anis Shahida Niza Binti
Muscle fatigue is condition of muscle decline in ability after undergoing any physical activity. Observation of the muscle condition of an athlete during training is crucial to prevent or minimize injury and able to achieve optimum performance in actual competition. The aim of this project is to develop a muscle monitoring system to detect muscle fatigue in swimming athlete. This device is capable to measure muscle stress level of the swimmer and at the same time provide indication of muscle fatigue level to trainer. Electromyography signal was recorded from the muscle movement while practicing the front crawl stroke repetitively. The time domain data was processed to frequency spectra in order to study the effect of muscle fatigue. The results show that the recorded EMG signal is able to sense muscle fatigue.
Ørtenblad, Niels; Westerblad, Håkan; Nielsen, Joachim
Studies performed at the beginning of the last century revealed the importance of carbohydrate as a fuel during exercise, and the importance of muscle glycogen on performance has subsequently been confirmed in numerous studies. However, the link between glycogen depletion and impaired muscle...... function during fatigue is not well understood and a direct cause-and-effect relationship between glycogen and muscle function remains to be established. The use of electron microscopy has revealed that glycogen is not homogeneously distributed in skeletal muscle fibres, but rather localized in distinct...... pools. Furthermore, each glycogen granule has its own metabolic machinery with glycolytic enzymes and regulating proteins. One pool of such glycogenolytic complexes is localized within the myofibrils in close contact with key proteins involved in the excitation-contraction coupling and Ca2+ release from...
Knaflitz, Marco; Molinari, Filippo
The analysis of the surface myoelectric signal recorded while a muscle is performing a sustained contraction is a valuable tool for assessing the progression of localized fatigue. It is well known that the modifications of the spectral content of the myoelectric signal are mainly related to changes in the interstitial fluid pH, which, in turn, affect the membrane excitability of the active muscle fibers. This paper describes the effects of muscle fatigue on the surface myoelectric signal recorded from three thigh and leg muscles during biking, on a population consisting of 22 young healthy volunteers. The purpose of this study was to obtain normative data relative to an exercise protocol mild enough to be applicable, in the future, to pathological subjects as well. Each subject was asked to exercise 30 min on a cycloergometer at a constant velocity and against a constant torque. While subjects were biking, the surface myoelectric signal was recorded from the rectus femoris, the biceps femoris, and the gastrocnemius muscles. In this study, we considered two different aspects of muscle fatigue: first, the localized muscle fatigue as shown by the decrement of the instantaneous frequency of the myoelectric signal during the exercise; second, the modifications of the muscle ON-OFF timing, which could be explained as a strategy for increasing endurance by modifying the role of different muscles during the exercise. The first aspect was studied by obtaining the spectral characteristics of the signals by means of bilinear time-frequency transforms and by applying an original estimator of the instantaneous frequency of stochastic processes based on cross time-frequency transforms. Our results demonstrated that none of the subjects showed significant signs of localized muscle fatigue, since the decrement of the instantaneous frequency during the exercise was always lower than 5% of its initial value. Muscle ON-OFF timing was obtained by applying to the raw myoelectric signal
Jensen, K K; Kjaer, M; Jorgensen, L N
PURPOSE: Although ventral incisional hernia (VIH) repair in patients is often evaluated in terms of hernia recurrence rate and health-related quality of life, there is no clear consensus regarding optimal operative treatment based on these parameters. It was proposed that health-related quality...... of life depends largely on abdominal muscle function (AMF), and the present review thus evaluates to what extent AMF is influenced by VIH and surgical repair. METHODS: The PubMed and EMBASE databases were searched for articles following a systematic strategy for inclusion. RESULTS: A total of seven...... studies described AMF in relation to VIH. Five studies examined AMF using objective isokinetic dynamometers to determine muscle strength, and two studies examined AMF by clinical examination-based muscle tests. CONCLUSION: Both equipment-related and functional muscle tests exist for use in patients...
Full Text Available Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.
Powers, Scott K.; Lynch, Gordon S.; Murphy, Kate T.; Reid, Michael B.; Zijdewind, Inge
Numerous health problems including acute critical illness, cancer, diseases associated with chronic inflammation, and neurological disorders often result in skeletal muscle weakness and fatigue. Disease-related muscle atrophy and fatigue is an important clinical problem because acquired skeletal
Absent abdominal muscles, cryptorchidism, and hydroureteronephrosis are known to occur in the prune belly syndrome (PBS). We present a male with absent abdominal muscles, severe neurologic damage, with global developmental delay, hydroureteronephrosis, and cryptorchidism. The patient also had arthrogryposis ...
Yang, Zhao Feng; Kumar, Dinesh Kant; Arjunan, Sridhar Poosapadi
Mechanomyogram is the recording of the acoustic activity associated with the muscle contraction. While discovered nearly a decade ago with the intention of providing an alternate to the surface electromyogram, it has not yet been investigated thoroughly and there are no current applications associated with MMG. This paper reports an experimental study of MMG against force of contraction and muscle fatigue during cyclic contraction. The results indicate that there is a relationship between the intensity of the MMG recording and force of contraction. A change in the intensity of MMG is also observed with the onset of muscle fatigue. However, the inter-subject variation is very large. The results also indicate that the spectrum of the MMG is very inconsistent and not a useful feature of the signal.
Prinsen, Hetty; van Dijk, Johannes P; Zwarts, Machiel J; Leer, Jan Willem H; Bleijenberg, Gijs; van Laarhoven, Hanneke W M
Postcancer fatigue is a frequently occurring problem, impairing quality of life. Little is known about (neuro)physiological factors determining postcancer fatigue. It may be hypothesized that postcancer fatigue is characterized by low peripheral muscle fatigue and high central muscle fatigue. The aims of this study were to examine whether central and peripheral muscle fatigue differ between fatigued and non-fatigued cancer survivors and to examine the effect of cognitive behavioral therapy (CBT) on peripheral and central muscle fatigue of fatigued cancer survivors in a randomized controlled trial. Sixteen fatigued patients in the intervention group (CBT) and eight fatigued patients in the waiting list group were successfully assessed at baseline and six months later. Baseline measurements of 20 fatigued patients were compared with 20 non-fatigued patients. A twitch interpolation technique and surface electromyography were applied, respectively, during sustained contraction of the biceps brachii muscle. Muscle fiber conduction velocity (MFCV) and central activation failure (CAF) were not significantly different between fatigued and non-fatigued patients. Change scores of MFCV and CAF were not significantly different between patients in the CBT and waiting list groups. Patients in the CBT group reported a significantly larger decrease in fatigue scores than patients in the waiting list group. Postcancer fatigue is neither characterized by abnormally high central muscle fatigue nor by low peripheral muscle fatigue. These findings suggest a difference in the underlying physiological mechanism of postcancer fatigue vs. other fatigue syndromes. Copyright © 2015 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.
Linek, Pawel; Saulicz, Edward; Wolny, Tomasz; Myśliwiec, Andrzej; Kokosz, Mirosław
Lateral abdominal wall muscles in children and adolescents have not been characterised to date. In the present report, we examined the reliability of the ultrasound measurement and thickness of the oblique external muscle (OE), oblique internal muscle (OI) and transverse abdominal muscle (TrA) at rest and during abdominal drawing-in manoeuvre (ADIM) on both sides of the body in healthy adolescents. We also determined possible differences between boys and girls and defined any factors-such as body mass, height and BMI-that may affect the thickness of the abdominal muscles. B-mode ultrasound was used to assess OE, OI and TrA on both sides of the body in the supine position. Ultrasound measurements at rest and during ADIM were reliable in this age group (ICC3,3 > 0.92). OI was always the thickest and TrA the thinnest muscle on both sides of the body. In this group, an identical pattern of the contribution of the individual muscles to the structure of the lateral abdominal wall (OI > OE > TrA) was observed. At rest and during ADIM, no statistically significant side-to-side differences were demonstrated in either gender. The body mass constitutes between 30% and <50% of the thickness differences in all muscles under examination at rest and during ADIM. The structure of lateral abdominal wall in adolescents is similar to that of adults. During ADIM, the abdominal muscles in adolescents react similarly to those in adults. This study provided extensive information regarding the structure of the lateral abdominal wall in healthy adolescents. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bandak, Elisabeth; Amris, Kirstine; Bliddal, Henning
To investigate relationships between perceived and objectively measured muscle fatigue during exhausting muscle contractions in women with fibromyalgia (FM) compared with healthy controls (HC).......To investigate relationships between perceived and objectively measured muscle fatigue during exhausting muscle contractions in women with fibromyalgia (FM) compared with healthy controls (HC)....
Huysmans, M.A.; Hoozemans, M.J.M.; van der Beek, A.J.; de Looze, M.P.; van Dieen, J.H.
It has been suggested that fatigue affects proprioception and consequently movement accuracy, the effects of which may be counteracted by increased muscle activity. To determine the effects of fatigue on tracking performance and muscle activity in the M. extensor carpi radialis (ECR), 11 female
Full Text Available The aim of our work was to identify gradient of the muscle fatigue of some muscle groups, among children with chronic juvenile arthritis, which are restricted in function by existing limitation in range of motions. Four patients in age of 9,5, with mentioned diagnosis were examined. Healthy subjects, with same ages were control group. Manuel muscle test, range of motion test and EMG examination were performed. Results shown significance difference in degree of muscle fatigue among observed patients, which explain decrease of muscle efficiency and must be taken when intensity of kinesitherapic treatment has to be done. It is concluded that structural changes on locomotory system induce secondary hypertrophy or atrophy of the muscle system and increase of muscle fatigue when activity of certain muscles is performed.
Soo, Yewguan; Sugi, Masao; Nishino, Masataka; Yokoi, Hiroshi; Arai, Tamio; Kato, Ryu; Nakamura, Tatsuhiro; Ota, Jun
Muscle fatigue is commonly associated with the musculoskeletal disorder problem. Previously, various techniques were proposed to index the muscle fatigue from electromyography signal. However, quantitative measurement is still difficult to achieve. This study aimed at proposing a method to estimate the degree of muscle fatigue quantitatively. A fatigue model was first constructed using handgrip dynamometer by conducting a series of static contraction tasks. Then the degree muscle fatigue can be estimated from electromyography signal with reasonable accuracy. The error of the estimated muscle fatigue was less than 10% MVC and no significant difference was found between the estimated value and the one measured using force sensor. Although the results were promising, there were still some limitations that need to be overcome in future study.
Eveland, Edward S; Pellettiere, Joseph A
.... Changes in neck muscle strength were identified along with EMG evidence of fatigue. When flights occurred on an almost daily basis over 4 days, the force imparted to the neck was reduced each day...
Thomsen, M.; Thomsen, M.; Veltink, Petrus H.
In acute experiments the sciatic nerve of the rat is electrically stimulated to induce fatigue in the medial Gastrocnemius muscle. Fatigue tests are carried out using intermittent stimulation of different compartments (sequential) or a single compartment (synchronous) of the sciatic nerve. The
Ali, SK; Tokhi, MO
Human muscle fatigue is identified as one of the causes to musculuskeletal disorder (MSD). The objective of this paper is to investigate the effect of an exoskeleton in dealing with muscle fatigue in a virtual environment. The focus of this work is, for the exoskeleton to provide support as needed by human joint. A (Proportional, Integration and Derivative) controller is used for both human and exoskeleton. Simmechanics and Simulink are used to evaluate the performance of the exoskeleton. Exp...
Full Text Available Sit-to-stand (STS tests measure the ability to get up from a chair, reproducing an important component of daily living activity. As this functional task is essential for human independence, STS performance has been studied in the past decades using several methods, including electromyography. The aim of this study was to measure muscular activity and fatigue during different repetitions and speeds of STS tasks using surface electromyography in lower-limb and trunk muscles. This cross-sectional study recruited 30 healthy young adults. Average muscle activation, percentage of maximum voluntary contraction, muscle involvement in motion and fatigue were measured using surface electrodes placed on the medial gastrocnemius (MG, biceps femoris (BF, vastus medialis of the quadriceps (QM, the abdominal rectus (AR, erector spinae (ES, rectus femoris (RF, soleus (SO and the tibialis anterior (TA. Five-repetition STS, 10-repetition STS and 30-second STS variants were performed. MG, BF, QM, ES and RF muscles showed differences in muscle activation, while QM, AR and ES muscles showed significant differences in MVC percentage. Also, significant differences in fatigue were found in QM muscle between different STS tests. There was no statistically significant fatigue in the BF, MG and SO muscles of the leg although there appeared to be a trend of increasing fatigue. These results could be useful in describing the functional movements of the STS test used in rehabilitation programs, notwithstanding that they were measured in healthy young subjects.
Roldán-Jiménez, Cristina; Bennett, Paul; Cuesta-Vargas, Antonio I
Sit-to-stand (STS) tests measure the ability to get up from a chair, reproducing an important component of daily living activity. As this functional task is essential for human independence, STS performance has been studied in the past decades using several methods, including electromyography. The aim of this study was to measure muscular activity and fatigue during different repetitions and speeds of STS tasks using surface electromyography in lower-limb and trunk muscles. This cross-sectional study recruited 30 healthy young adults. Average muscle activation, percentage of maximum voluntary contraction, muscle involvement in motion and fatigue were measured using surface electrodes placed on the medial gastrocnemius (MG), biceps femoris (BF), vastus medialis of the quadriceps (QM), the abdominal rectus (AR), erector spinae (ES), rectus femoris (RF), soleus (SO) and the tibialis anterior (TA). Five-repetition STS, 10-repetition STS and 30-second STS variants were performed. MG, BF, QM, ES and RF muscles showed differences in muscle activation, while QM, AR and ES muscles showed significant differences in MVC percentage. Also, significant differences in fatigue were found in QM muscle between different STS tests. There was no statistically significant fatigue in the BF, MG and SO muscles of the leg although there appeared to be a trend of increasing fatigue. These results could be useful in describing the functional movements of the STS test used in rehabilitation programs, notwithstanding that they were measured in healthy young subjects.
Brunetti, Orazio; Della Torre, Giovannella; Lucchi, Maria Luisa; Chiocchetti, Roberto; Bortolami, Ruggero; Pettorossi, Vito Enrico
The influence of muscle fatigue on the jaw-closing muscle spindle activity has been investigated by analyzing: (1) the field potentials evoked in the trigeminal motor nucleus (Vmot) by trigeminal mesencephalic nucleus (Vmes) stimulation, (2) the orthodromic and antidromic responses evoked in the Vmes by stimulation of the peripheral and central axons of the muscle proprioceptive afferents, and (3) the extracellular unitary discharge of masseter muscle spindles recorded in the Vmes. The masseter muscle was fatigued by prolonged tetanic masseter nerve electrical stimulation. Pre- and postsynaptic components of the potentials evoked in the Vmot showed a significant reduction in amplitude following muscle fatigue. Orthodromic and antidromic potentials recorded in the Vmes also showed a similar amplitude decrease. Furthermore, muscle fatigue caused a decrease of the discharge frequency of masseter muscle spindle afferents in most of the examined units. The inhibition of the potential amplitude and discharge frequency was strictly correlated with the extent of muscle fatigue and was mediated by the group III and IV afferent muscle fibers activated by fatigue. In fact, the inhibitory effect was abolished by capsaicin injection in the masseter muscle that provokes selective degeneration of small afferent muscle fibers containing neurokinins. We concluded that fatigue signals originating from the muscle and traveling through capsaicin-sensitive fibers are able to diminish the proprioceptive input by a central presynaptic influence. In the second part of the study, we examined the central projection of the masseter small afferents sensitive to capsaicin at the electron-microscopic level. Fiber degeneration was induced by injecting capsaicin into the masseter muscle. Degenerating terminals were found on the soma and stem process in Vmes and on the dendritic tree of neurons in Vmot. This suggests that small muscle afferents may influence the muscle spindle activity through
Norren, van K.; Helvoort, van A.; Argiles, J.M.; Tuijl, van S.; Arts, K.; Gorselink, M.; Laviano, A.; Kegler, D.; Haagsman, H.P.; Beek, E.M.
Chemotherapy-induced fatigue is a multidimensional symptom. Oxidative stress has been proposed as a working mechanism for anthracycline-induced cardiotoxicity. In this study, doxorubicin (DOX) was tested on skeletal muscle function. Doxorubicin induced impaired ex vivo skeletal muscle relaxation
Naik, Ganesh R; Kumar, Dinesh K; Yadav, Vivek; Wheeler, Katherine; Arjunan, Sridhar
Spectral compression of surface electromyogram (sEMG) is associated with onset of localized muscle fatigue. The spectral compression has been explained based on motor unit synchronization theory. According to this theory, motor units are pseudo randomly excited during muscle contraction, and with the onset of muscle fatigue the recruitment pattern changes such that motor unit firings become more synchronized. While this is widely accepted, there is little experimental proof of this phenomenon. This paper has used source dependence measures developed in research related to independent component analysis (ICA) to test this theory.
Okubo, Yu; Kaneoka, Koji; Shiina, Itsuo; Tatsumura, Masaki; Miyakawa, Shumpei
Experimental laboratory study. To measure the activation patterns (onset and magnitude) of the abdominal muscles during a standing long jump using wire and surface electromyography. Activation patterns of the abdominal muscles, especially the deep muscles such as the transversus abdominis (TrA), have yet to be examined during full-body movements such as jumping. Thirteen healthy men participated. Wire electrodes were inserted into the TrA with the guidance of ultrasonography, and surface electrodes were attached to the skin overlying the rectus abdominis (RA) and external oblique (EO). Electromyographic signals and video images were recorded while each subject performed a standing long jump. The jump task was divided into 3 phases: preparation, push-off, and float. For each muscle, activation onset relative to the onset of the RA and normalized muscle activation levels (percent maximum voluntary contraction) were analyzed during each phase. Comparisons between muscles and phases were assessed using 2-way analyses of variance. The onset times of the TrA and EO relative to the onset of the RA were -0.13 ? 0.17 seconds and -0.02 ? 0.07 seconds, respectively. Onset of TrA activation was earlier than that of the EO. The activation levels of all 3 muscles were significantly greater during the push-off phase than during the preparation and float phases. Consistent with previously published trunk-perturbation studies in healthy persons, the TrA was activated prior to the RA and EO. Additionally, the highest muscle activation levels were observed during the push-off phase.
Full Text Available Seseorang yang memiliki kebiasaan melakukan aktivitas pasif seperti duduk lama saat bekerja dapat meningkatkan resiko terjadinya muscle power imbalance pada otot-otot penyangga tubuh yang pada akhirnya mudah mengalami nyeri pada punggung bagian bawah, sehinga bila melakukan aktifitas atau pekerjaan yang melebihi kapasitas fisik yang dimiliki, akan mudah mengalami kelelahan dan bila dipaksakan dapat terjadi cedera, seperti terjadinya spasme atau kram pada otot perut. Peningkatan kekuatan otot perut, salah satunya dapat dicapai dengan latihan Pilates yang memiliki keunggulan memiliki fokus latihan yang bertujuan menguatkan otot-otot core stability diantaranya adalah otot perut. Tujuan: Untuk mengetahui pengaruh latihan Pilates terhadap peningkatan kekuatan otot perut. Subyek Penelitian Sebanyak 34 terdiri dari ibu-ibu rumah tangga dengan rentang usia antara 30–50 tahun. Metode Penelitian: Eksperimen dengan rancangan one group pre-post test with control dengan kriteria inklusi dan ekslusi. Bentuk latihan pilates yang dipilih adalah khusus gerakan yang ditujukan untuk latihan otot-otot perut sebanyak 16 gerakan, program latihan diberikan selama 2 bulan, dengan durasi selama 45 menit/sesi latihan, 2 kali/minggu. Pengukuran kekuatan otot perut menggunakan curl up test. Analisis Statistik: Uji beda pre-post test dengan Wilcoxon Test, didapatkan p=0,000 (p<0.05 dan uji beda pre-pre test dan post-post test dengan Mann-whitney U Test kedua kelompok p=0,849(p<0.05 dan post-post test kedua kelompok p=0,007 (p<0.05. Kesimpulan: Latihan Pilates berpengaruh terhadap peningkatan kekuatan otot perut.
Kawabata, Y; Senda, M; Oka, T; Yagata, Y; Takahara, Y; Nagashima, H; Inoue, H
In order to examine fatigue of the knee flexor and extensor muscles and to investigate the characteristics of muscular fatigue in different sports, a Cybex machine was used to measure muscle fatigue and recovery during isokinetic knee flexion and extension. Eighteen baseball players, 12 soccer players and 13 marathon runners were studied. Each subject was tested in the sitting position and made to perform 50 consecutive right knee bends and stretches at maximum strength. This was done 3 times with an interval of 10 min between each series. The peak torque to body weight ratio and the fatigue rate were determined in each case. In all subjects, the peak torque to body weight ratio was higher for extensors than flexors. Over the 3 trials, the fatigue rate of extensors showed little change, while that of flexors had a tendency to increase. In each subject, knee extensors showed a high fatigue rate but a quick recovery, while knee flexors showed a low fatigue rate but a slow recovery. As the marathon runners had the smallest fatigue rates for both flexors and extensors, we concluded that marathon runners had more stamina than baseball players and soccer players.
Full Text Available Roland Staud,1 Taylor Kizer,1 Michael E Robinson2 1Department of Medicine, College of Medicine, 2Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA Objective: Patients with chronic fatigue syndrome (CFS complain of long-lasting fatigue and pain which are not relieved by rest and worsened by physical exertion. Previous research has implicated metaboreceptors of muscles to play an important role for chronic fatigue and pain. Therefore, we hypothesized that blocking impulse input from deep tissues with intramuscular lidocaine injections would improve not only the pain but also fatigue of CFS patients. Methods: In a double-blind, placebo-controlled study, 58 CFS patients received 20 mL of 1% lidocaine (200 mg or normal saline once into both trapezius and gluteal muscles. Study outcomes included clinical fatigue and pain, depression, and anxiety. In addition, mechanical and heat hyperalgesia were assessed and serum levels of lidocaine were obtained after the injections. Results: Fatigue ratings of CFS patients decreased significantly more after lidocaine compared to saline injections (p = 0.03. In contrast, muscle injections reduced pain, depression, and anxiety (p < 0.001, but these changes were not statistically different between lidocaine and saline (p > 0.05. Lidocaine injections increased mechanical pain thresholds of CFS patients (p = 0.04 but did not affect their heat hyperalgesia. Importantly, mood changes or lidocaine serum levels did not significantly predict fatigue reductions. Conclusion: These results demonstrate that lidocaine injections reduce clinical fatigue of CFS patients significantly more than placebo, suggesting an important role of peripheral tissues for chronic fatigue. Future investigations will be necessary to evaluate the clinical benefits of such interventions. Keywords: muscle injections, lidocaine, metaboreceptor, chronic fatigue
Full Text Available Abstract Background A high rate of post-infectious fatigue and abdominal symptoms two years after a waterborne outbreak of giardiasis in Bergen, Norway in 2004 has previously been reported. The aim of this report was to identify risk factors associated with such manifestations. Methods All laboratory confirmed cases of giardiasis (n = 1262 during the outbreak in Bergen in 2004 received a postal questionnaire two years after. Degree of post-infectious abdominal symptoms and fatigue, as well as previous abdominal problems, was recorded. In the statistical analyses number of treatment courses, treatment refractory infection, delayed education and sick leave were used as indices of protracted and severe Giardia infection. Age, gender, previous abdominal problems and symptoms during infection were also analysed as possible risk factors. Simple and multiple ordinal logistic regression models were used for the analyses. Results The response rate was 81% (1017/1262, 64% were women and median age was 31 years (range 3-93, compared to 61% women and 30 years (range 2-93 among all 1262 cases. Factors in multiple regression analysis significantly associated with abdominal symptoms two years after infection were: More than one treatment course, treatment refractory infection, delayed education, bloating and female gender. Abdominal problems prior to Giardia infection were not associated with post-infectious abdominal symptoms. More than one treatment course, delayed education, sick leave more than 2 weeks, and malaise at the time of infection, were significantly associated with fatigue in the multiple regression analysis, as were increasing age and previous abdominal problems. Conclusion Protracted and severe giardiasis seemed to be a risk factor for post-infectious fatigue and abdominal symptoms two years after clearing the Giardia infection.
Han, Hyonyoung; Jo, Sungho; Kim, Jung
This paper proposes the feasibility of a stiffness measurement for muscle contraction force estimation under muscle fatigue conditions. Bioelectric signals have been widely studied for the estimation of the contraction force for physical human-robot interactions, but the correlation between the biosignal and actual motion is decreased under fatigue conditions. Muscle stiffness could be a useful contraction force estimator under fatigue conditions because it measures the same physical quantity as the muscle contraction that generates the force. Electromyography (EMG), mechanomyography (MMG), and a piezoelectric resonance-based active muscle stiffness sensor were used to analyze the biceps brachii under isometric muscle fatigue conditions with reference force sensors at the end of the joint. Compared to EMG and MMG, the change in the stiffness signal was smaller (p fatigue condition changed fatigue conditions. This result indicates that the muscle stiffness signal is less sensitive to muscle fatigue than other biosignals. This investigation provides insights into methods of monitoring and compensating for muscle fatigue.
Full Text Available Objective: To determine the correlations between muscle mass, muscle strength, physical performance, and muscle fatigue resistance in community-dwelling elderly people in order to elucidate factors which contribute to elderly’s performance of daily activities. Methods: A cross-sectional study was conducted on community-dwelling elderly in Bandung from September to December 2014. One hundred and thirty elderly, 60 years old or above, were evaluated using bioelectrical impedance analysis to measure muscle mass; grip strength to measure muscle strength and muscle fatigue resistance; habitual gait speed to measure physical performance; and Global Physical Activity Questionnaire (GPAQ to assess physical activity. Results: There were significant positive correlations between muscle mass (r=0,27, p=0,0019, muscle strength (r=0,26, p=0,0024, and physical performance (r=0,32, p=0,0002 with muscle fatigue resistance. Physical performance has the highest correlation based on multiple regression test (p=0,0025. In association with muscle mass, the physical activity showed a significant positive correlation (r=0,42, p=0,0000. Sarcopenia was identified in 19 (14.61% of 130 subjects. Conclusions: It is suggested that muscle mass, muscle strength, and physical performance influence muscle fatigue resistance.
Full Text Available Twitch potentiation and fatigue in skeletal muscle are two conditions in which force production is affected by the stimulation history. Twitch potentiation is the increase in the twitch active force observed after a tetanic contraction or during and following low-frequency stimulation. There is evidence that the mechanism responsible for potentiation is phosphorylation of the regulatory light chains of myosin, a Ca2+-dependent process. Fatigue is the force decrease observed after a period of repeated muscle stimulation. Fatigue has also been associated with a Ca2+-related mechanism: decreased peak Ca2+ concentration in the myoplasm is observed during fatigue. This decrease is probably due to an inhibition of Ca2+ release from the sarcoplasmic reticulum. Although potentiation and fatigue have opposing effects on force production in skeletal muscle, these two presumed mechanisms can coexist. When peak myoplasmic Ca2+ concentration is depressed, but myosin light chains are relatively phosphorylated, the force response can be attenuated, not different, or enhanced, relative to previous values. In circumstances where there is interaction between potentiation and fatigue, care must be taken in interpreting the contractile responses.
Zhou, Qianxiang; Chen, Yuhong; Ma, Chao; Zheng, Xiaohui
Fatigue is believed to be a major contributory factor to occupational injuries in machine operators. The development of accurate and usable techniques to measure operator fatigue is therefore important. In this study, we used a novel method based on surface electromyography (sEMG) of the biceps brachii and the Borg scale to evaluate local muscle fatigue in the upper limb after isometric muscle action. Thirteen young males performed isometric actions with the upper limb at different force levels. sEMG activities of the biceps brachii were recorded during the actions. Borg scales were used to evaluate the subjective sensation of local fatigue of the biceps brachii after the actions. sEMG activities were analyzed using the one-third band octave method, and an equation to determine the degree of fatigue was derived based on the relationship between the variable and the Borg scale. The results showed that the relationship could be expressed by a conic curve, and could be used to evaluate muscle fatigue during machine operation.
Klaver-Król, Ewa G; Rasker, Johannes J; Henriquez, Nizare R; Verheijen, Wilma G; Zwarts, Machiel J
Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. sEMG was performed on the biceps brachii muscle of 13 women with FM and 14 matched healthy controls during prolonged dynamic exercises, unloaded, and loaded up to 20% of maximum voluntary contraction. The sEMG parameters were: muscle fiber conduction velocity (CV); skewness of motor unit potential (peak) velocities; peak frequency (PF) (number of peaks per second); and average rectified voltage (ARV). There was significantly higher CV in the FM group. Although the FM group performed the tests equally well, their electromyographic fatigue was significantly less expressed compared with controls (in CV, PF, and ARV). In the patients with FM, we clearly showed functional abnormalities of the muscle membrane, which led to high conduction velocity and resistance to fatigue in electromyography. Copyright © 2012 Wiley Periodicals, Inc.
Vissing, John; Haller, Ronald G
, which may be important for maintaining muscle membrane excitability by decreasing chloride permeability, (2) loss of the osmotic effect related to lactate accumulation, which may account for absence of the normal increase in water content of exercised muscle, and thus promote higher than normal...... concentrations of extracellular potassium in exercising muscle and (3) exaggerated accumulation of ADP during exercise that may inhibit sodium-potassium and calcium-ATPases. Disorders of muscle glycogenolysis and glycolysis reveal the crucial role of these metabolic processes for supplying both anaerobic...
Jensen, Lauren; Dancisak, Michael; Korndorffer, James
A localized, intermittent muscle-cooling protocol was implemented to determine cooling garment efficacy in reducing upper extremity muscular fatigue and tremor in novice ( n = 10) and experienced surgeons ( n = 9). Subjects wore a muscle-cooling garment while performing multiple trials of a forearm exercise and paired suturing task to induce muscular fatigue and exercise-induced tremor. A reduction in tremor amplitude and an extension in time to fatigue were expected with muscle...
Paulo H. Marchetti
Full Text Available In order to understand the potential selective activation of the rectus abdominis muscle, we conducted two experiments. In the first, subjects performed two controlled isometric exercises: the curl up (supine trunk raise and the leg raise (supine bent leg raise at low intensity (in which only a few motor units are recruited. In the second experiment, subjects performed the same exercises, but they were required to maintain a certain force level in order to induce fatigue. We recorded the electromyographic (EMG activities of the lower and upper portions of the rectus abdominis muscle during the exercises and used spatial-temporal and frequency analyses to describe muscle activation patterns. At low-intensity contractions, the ratio between the EMG intensities of the upper and lower portions during the curl up exercise was significantly larger than during the leg raise exercise (p = 0.02. A cross-correlation analysis indicated that the signals of the abdominal portions were related to each other and this relation did not differ between the tasks (p = 0.12. In the fatiguing condition, fatigue for the upper portion was higher than for the lower portion during the curl up exercise (p = 0.008. We conclude that different exercises evoked, to a certain degree, individualized activation of each part of the rectus abdominis muscle, but different portions of the rectus abdominis muscle contributed to the same task, acting like a functional unit. These results corroborate the relevance of varying exercise to modify activation patterns of the rectus abdominis muscle
Mänty, Minna; Ekmann, Anette; Thinggaard, Mikael
needs to be considered when interpreting the results. Accordingly, participants without fatigue had significantly higher chances of being alive and having muscle strength above gender-specific median at first (RR 1.32, 95 % CI 1.07-1.58), second (RR 1.51, 1.06-1.96) and third (RR 1.39, 1...
Jensen, K K; Kjaer, M; Jorgensen, L N
Although ventral incisional hernia (VIH) repair in patients is often evaluated in terms of hernia recurrence rate and health-related quality of life, there is no clear consensus regarding optimal operative treatment based on these parameters. It was proposed that health-related quality of life depends largely on abdominal muscle function (AMF), and the present review thus evaluates to what extent AMF is influenced by VIH and surgical repair. The PubMed and EMBASE databases were searched for articles following a systematic strategy for inclusion. A total of seven studies described AMF in relation to VIH. Five studies examined AMF using objective isokinetic dynamometers to determine muscle strength, and two studies examined AMF by clinical examination-based muscle tests. Both equipment-related and functional muscle tests exist for use in patients with VIH, but very few studies have evaluated AMF in VIH. There are no randomized controlled studies to describe the impact of VIH repair on AMF, and no optimal surgical treatment in relation to AMF after VIH repair can be advocated for at this time.
Corben, Jeffrey S; Cerrone, Sara A; Soviero, Julie E; Kwiecien, Susan Y; Nicholas, Stephen J; McHugh, Malachy P
Monitoring pitch count is standard practice in minor league baseball but not in softball because of the perception that fast-pitch softball pitching is a less stressful motion. To examine muscle fatigue after fast-pitch softball performances to provide an assessment of performance demand. Descriptive laboratory study. Bilateral strength measurements (handheld dynamometer) were made on 19 female softball pitchers (mean age [±SD], 15.2 ± 1.2 years) before and after pitching a game (mean number of pitches, 99 ± 21; mean innings pitched, 5 ± 1). A total of 20 tests were performed on the dominant and nondominant sides: forearm (grip, wrist flexion/extension, pronation/supination, elbow flexion/extension), shoulder (flexion, abduction/adduction, external/internal rotation, empty can test), scapula (middle/lower trapezius, rhomboid), and hip (hip flexion/extension, abduction/adduction). Fatigue (percentage strength loss) was categorized based on bilateral versus unilateral presentation using paired t tests: bilateral symmetric (significant on dominant and nondominant and not different between sides), bilateral asymmetric (significant on dominant and nondominant but significantly greater on dominant), unilateral asymmetric (significant on dominant only and significantly greater than nondominant), or unilateral equivocal (significant on dominant only but not different from nondominant). Bilateral symmetric fatigue was evident for all hip (dominant, 19.3%; nondominant, 15.2%) and scapular tests (dominant, 19.2%; nondominant, 19.3%). In general, shoulder tests exhibited bilateral asymmetric fatigue (dominant, 16.9%; nondominant, 11.6%). Forearm tests were more variable, with bilateral symmetric fatigue in the elbow flexors (dominant, 22.5%; nondominant, 19.2%), and wrist flexors (dominant, 21.6%; nondominant, 19.0%), bilateral asymmetric fatigue in the supinators (dominant, 21.8%; nondominant, 15.5%), unilateral asymmetric fatigue in the elbow extensors (dominant, 22
Gregory C. Bogdanis
Full Text Available The aim of this review was to examine the mechanisms by which physical activity and inactivity modify muscle fatigue. It is well known that acute or chronic increases in physical activity result in structural, metabolic, hormonal, neural and molecular adaptations that increase the level of force or power that can be sustained by a muscle. These adaptations depend on the type, intensity and volume of the exercise stimulus, but recent studies have highlighted the role of high intensity, short duration exercise as a time-efficient method to achieve both anaerobic and aerobic/endurance type adaptations. The factors that determine the fatigue profile of a muscle during intense exercise include muscle fibre composition, neuromuscular characteristics high energy metabolite stores, buffering capacity, ionic regulation, capillarization and mitochondrial density. Muscle fiber type transformation during exercise training is usually towards the intermediate type IIA at the expense of both type I and type IIx myosin heavy chain isoforms. High intensity training results in increases of both glycolyic and oxidative enzymes, muscle capilarization, improved phosphocreatine resynthesis and regulation of K+, H+ and lactate ions. Decreases of the habitual activity level due to injury or sedentary lifestyle result in partial or even compete reversal of the adaptations due to previous training, manifested by reductions in fibre cross-sectional area, decreased oxidative capacity and capillarization. Complete immobilization due to injury results in markedly decreased force output and fatigue resistance. Muscle unloading reduces electromyographic activity and causes muscle atrophy and significant decreases in capillarization and oxidative enzymes activity. The last part of the review discusses the beneficial effects of intermittent high intensity exercise training in patients with different health conditions to demonstrate the powerful effect exercise on health and well
Martyn G. Morris
Full Text Available The aim of this study was to examine the relationship of a range of in-vivo whole muscle characteristics to determinants of endurance performance. Eleven healthy males completed a cycle ergometer step test to exhaustion for the determination of the lactate threshold, gross mechanical efficiency, peak power and VO2max. On two separate occasions, contractile and fatigue characteristics of the quadriceps femoris were collected using a specially designed isometric strength-testing chair. Muscle fatigue was then assessed by stimulating the muscle for 3 minutes. Force, rate of force development and rates of relaxation were calculated at the beginning and end of the 3 minute protocol and examined for reliability and in relation to lactate threshold, VO2max, gross mechanical efficiency and peak power. Muscle characteristics, rate of force development and relaxation rate were demonstrated to be reliable measures. Force drop off over the 3 minutes (fatigue index was related to lactate threshold (r = -0.72 p < 0.01 but not to VO2max. The rate of force development related to the peak power at the end of the cycle ergometer test (r = -0.75 p < 0.01. Rates of relaxation did not relate to any of the performance markers. We found in-vivo whole muscle characteristics, such as the fatigue index and rate of force development, relate to specific markers of peripheral, but not to central, fitness components. Our investigation suggests that muscle characteristics assessed in this way is reliable and could be feasibly utilised to further our understanding of the peripheral factors underpinning performance
Full Text Available The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD. Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97 participated in this study. Electromyographical (EMG recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany. Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF% revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P<0.0000. The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction.
Aim The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue. Methods Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To characterize muscle activity distribution, dispersion was used. During the fatigue task, EMG amplitude root mean square (RMS), median frequency and dispersion in x- and y-axis were compared before and after spinal creep. Results Important fatigue-related changes in EMG median frequency were observed during muscle fatigue. Median frequency values showed a significant main creep effect, with lower median frequency values on the left side under the creep condition (p≤0.0001). A significant main creep effect on RMS values was also observed as RMS values were higher after creep deformation on the right side (p = 0.014); a similar tendency, although not significant, was observed on the left side (p = 0.06). A significant creep effects for x-axis dispersion values was observed, with higher dispersion values following the deformation protocol on the left side (p≤0.001). Regarding y-axis dispersion values, a significant creep x fatigue interaction effect was observed on the left side (p = 0.016); a similar tendency, although not significant, was observed on the right side (p = 0.08). Conclusion Combined muscle fatigue and creep deformation of spinal tissues led to changes in muscle activity amplitude, frequency domain and distribution. PMID:26866911
Rastovic, Pejana; Gojanovic, Marija Definis; Berberovic, Marina; Pavlovic, Marko; Lesko, Josip; Galic, Gordan; Pandza, Maja
Whiplash-associated disorders (WAD) result from injury of neck structures that most often occur during traffic accidents as a result of rapid acceleration-deceleration. The dominant symptoms manifest in the musculoskeletal system and include increased fatigue. Because of the frequency of whiplash injuries, a simple, cheap and useful diagnostic tool is needed to differentiate whiplash injury from healthy patients or those faking symptoms. To determine muscle fatigue in patients with whiplash injury in six body positions. Analytical cross-sectional study. Emergency center, university hospital. We studied patients with whiplash injury from vehicular traffic accidents who presented to the emergency center within 6 hours of sustaining the injury. We determined whiplash injury grade according to the Quebec Task Force (QTF) classification and measured isometric muscle endurance in six different body positions. Control subjects for each patient were matched by age, gender and anthropomorphic characteristics. Cut-off values were determined to distinguish patients with whiplash injury from controls and for determination of injury grade . QTF grade, time to muscle fatigue in seconds. From September 2013 to September 2016, we enrolled 75 patients with whiplash injury and 75 matching control subjects. In all six positions, the patients with whiplash injury felt muscle fatigue faster than equivalent controls (P whiplash injury grade in all six positions (P whiplash injury and grade. The size of the sample was small. An objective parameter such as electromyography is needed to confirm isometric muscle fatigue.
Szpala, Agnieszka; Rutkowska-Kucharska, Alicja; Drapala, Jaroslaw
The objective of the research was to assess the effect of a 4-week-long training program on selected parameters: electromechanical delay (EMD) and amplitude of electromyographic signal (EMG). Fourteen female students of the University School of Physical Education participated in the study. Torques and surface electromyography were evaluated under static conditions. Surface electrodes were glued to both sides of the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles. The 4-week-long program was aimed at strengthening the abdominal muscles and resulted in increased EMD during maximum torque production by flexors of the trunk, increased amplitudes of the signals of the erector spinae ( p = 0.005), and increased EMG amplitude asymmetry of the lower ( p = 0.013) and upper part ( p = 0.006) of the rectus abdominis muscle. In a training program composed of a large number of repetitions of strength exercises, in which the training person uses their own weight as the load (like in exercises such as curl-ups), the process of recruitment of motor units is similar to that found during fatiguing exercises and plyometric training.
Conclusion: Median frequency shift toward low values following fatigue in global and local paraspinal muscles was seen. However, median frequency values for the local stabilizer muscle were higher than median frequency values for the global muscles.
Demoulin Christophe; George, Florian; Matheve, Thomas; Jidovtseff, Boris; Vanderthommen, Marc
The Sorensen test has been extensively studied and is a rapid, simple, and reproducible evaluation of the trunk extensor muscles . It is often considered as a fatigue test because fatigue-related electromyographic (EMG) parameters change throughout the test ; however, only recently it has been confirmed that this test induces a decrease of trunk extensor force during a maximal voluntary contraction (MVC) , which best characterises muscle fatigue. The main aim of this stud...
Timmermans, Lucas; Deerenberg, Eva B; van Dijk, Sven M; Lamme, Bas; Koning, Anton H; Kleinrensink, Gert-Jan; Jeekel, Johannes; Lange, Johan F
Incisional hernia (IH) can be attributed to multiple factors. The presence of a parastomal hernia has shown to be a risk factor for IH after midline laparotomy. Our hypothesis is that this increased risk of IH may be caused by changes in biomechanical forces, such as midline shift to the contralateral side of the colostomy owing to decreased restraining forces at the site of the colostomy, and left abdominal rectus muscle (ARM) atrophy owing to intercostal nerve damage. Patients were selected if they underwent end-colostomy via open operation between 2004 and 2011. Patients were eligible if computed tomography (CT) had been performed postoperatively. If available, preoperative CTs were collected for case-control analyses. Midline shift was measured using V-scope application in the I-space, a CAVE-like virtual reality system. For the ARM atrophy hypothesis, measurements of ARM were performed at the level of colostomy, and 3 and 8 cm cranial and caudal of the colostomy. Postoperative CT were available for 77 patients; of these patients, 30 also had a preoperative CT. Median follow-up was 19 months. A mean shift to the right side was identified after preoperative and postoperative comparison; from -1.3 ± 4.6 to 2.1 ± 9.3 (P = .043). Furthermore, during rectus muscle measurements, a thinner left ARM was observed below the level of colostomy. Creation of a colostomy alters the abdominal wall. Atrophy of the left ARM was seen caudal to the level of the colostomy, and a midline shift to the right side was evident on CT. These changes may explain the increased rate of IH after colostomy creation. Copyright © 2014 Mosby, Inc. All rights reserved.
Fernando, Jeffry Bonar; Yoshioka, Mototaka; Ozawa, Jun
A new method to estimate muscle fatigue quantitatively from surface electromyography (EMG) is proposed. The ratio of mean frequency (MNF) to average rectified value (ARV) is used as the index of muscle fatigue, and muscle fatigue is detected when MNF/ARV falls below a pre-determined or pre-calculated baseline. MNF/ARV gives larger distinction between fatigued muscle and non-fatigued muscle. Experiment results show the effectiveness of our method in estimating muscle fatigue more correctly compared to conventional methods. An early evaluation based on the initial value of MNF/ARV and the subjective time when the subjects start feeling the fatigue also indicates the possibility of calculating baseline from the initial value of MNF/ARV.
Uchida, Kousuke; Nuruki, Atsuo; Tsujimura, Sei-Ichi; Tamari, Youzou; Yunokuchi, Kazutomo
The purpose of this study is to investigate the effect of magnetic stimulation for muscle fatigue. The six healthy subjects participated in the experiment with the repetition grasp using a hand dynamometer. The measurement of EMG (electromyography) and MMG (mechanomyography) is performed on the left forearm. All subjects performed MVC (maximum voluntary contraction), and repeated exercise in 80%MVC after the MVC measurement. The repetition task was entered when display muscular strength deteriorated. We used an EMG and MMG for the measurement of the muscle fatigue. Provided EMG and MMG waves were calculated integral calculus value (iEMG, and iMMG). The result of iEMG and iMMG were divided by muscular strength, because we calculate integral calculus value per the unit display muscular strength. The result of our study, we found recovery effect by the magnetic stimulation in voluntarily muscular strength and iEMG. However, we can not found in a figure of iMMG.
Monjo, F; Forestier, N
To investigate the effects of focal muscle fatigue induced by electromyostimulation (EMS) on Anticipatory Postural Adjustments (APAs) during arm flexions performed at maximal velocity. Fifteen healthy subjects performed self-paced arm flexions at maximal velocity before and after the completion of fatiguing electromyostimulation programs involving the medial and anterior deltoids and aiming to degrade movement peak acceleration. APA timing and magnitude were measured using surface electromyography. Following muscle fatigue, despite a lower mechanical disturbance evidenced by significant decreased peak accelerations (-12%, pcontrol trials (p>.11 for all analyses). The fatigue signals evoked by externally-generated contractions seem to be gated by the Central Nervous System and result in postural strategy changes which aim to increase the postural safety margin. EMS is widely used in rehabilitation and training programs for its neuromuscular function-related benefits. However and from a motor control viewpoint, the present results show that the use of EMS can lead to acute inaccuracies in predictive motor control. We propose that clinicians should investigate the chronic and global effects of EMS on motor control. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Della Torre, G; Brunetti, O; Pettorossi, V E
The role of muscle ischemia and fatigue in modulating the monosynaptic reflex was investigated in decerebrate and spinalized rats. Field potentials and fast motoneuron single units in the lateral gastrocnemious (LG) motor pool were evoked by dorsal root stimulation. Muscle ischemia was induced by occluding the LG vascular supply and muscle fatigue by prolonged tetanic electrical stimulation of the LG motor nerve. Under muscle ischemia the monosynaptic reflex was facilitated since the size of the early and late waves of the field potential and the excitability of the motoneuron units increased. This effect was abolished after L3-L6 dorsal rhizotomy, but it was unaffected after L3-L6 ventral rhizotomy. By contrast, the monosynaptic reflex was inhibited by muscle fatiguing stimulation, and this effect did not fully depend on the integrity of the dorsal root. However, when ischemia was combined with repetitive tetanic muscle stimulation the inhibitory effect of fatigue was significantly enhanced. Both the ischemia and fatigue effects were abolished by capsaicin injected into the LG muscle at a dose that blocked a large number of group III and IV muscle afferents. We concluded that muscle ischemia and fatigue activate different groups of muscle afferents that are both sensitive to capsaicin, but enter the spinal cord through different roots. They are responsible for opposite effects, when given separately: facilitation during ischemia and inhibition during fatigue; however, in combination, ischemia enhances the responsiveness of the afferent fibres to fatigue.
Weber, Tobias; Ducos, Michel; Mulder, Edwin; Beijer, Åsa; Herrera, Frankyn; Zange, Jochen; Degens, Hans; Bloch, Wilhelm; Rittweger, Jörn
In the light of the dynamic nature of habitual plantar flexor activity, we utilized an incremental isokinetic exercise test (IIET) to assess the work-related power deficit (WoRPD) as a measure for exercise-induced muscle fatigue before and after prolonged calf muscle unloading and in relation to arterial blood flow and muscle perfusion. Eleven male subjects (31 ± 6 years) wore the HEPHAISTOS unloading orthosis unilaterally for 56 days. It allows habitual ambulation while greatly reducing plantar flexor activity and torque production. Endpoint measurements encompassed arterial blood flow, measured in the femoral artery using Doppler ultrasound, oxygenation of the soleus muscle assessed by near-infrared spectroscopy, lactate concentrations determined in capillary blood and muscle activity using soleus muscle surface electromyography. Furthermore, soleus muscle biopsies were taken to investigate morphological muscle changes. After the intervention, maximal isokinetic torque was reduced by 23·4 ± 8·2% (Pflow, tissue oxygenation, lactate concentrations and EMG median frequency kinematics during the exercise test were comparable before and after the intervention, whereas the increase of RMS in response to IIET was less following the intervention (P = 0·03). In conclusion, following submaximal isokinetic muscle work exercise-induced muscle fatigue is unaffected after prolonged local muscle unloading. The observation that arterial blood flow was maintained may underlie the unchanged fatigability. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.
Boonstra, T.W.; Daffertshofer, A.; van Ditshuizen, J.C.; van den Heuvel, M.R.C.; Hofman, C.; Willigenburg, N.W.; Beek, P.J.
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
Full Text Available This study aimed to investigate the effect of fatigue in shoulder external rotator muscles on position sense of shoulder abduction, internal rotation, and external rotation. The study included 10 healthy subjects. Shoulder position sense was measured before and after a fatigue task involving shoulder external rotator muscles. The fatigue task was performed using an isokinetic machine. To confirm the muscle fatigue, electromyography (EMG was recorded, and an integrated EMG and median power frequency (MDF during 3 sec performed target torque were calculated. After the fatigue task, the MDF of the infraspinatus muscle significantly decreased. This indicates that the infraspinatus muscle was involved in the fatigue task. In addition, the shoulder position sense of internal and external rotation significantly decreased after the fatigue task. These results suggest that the fatigue reduced the accuracy of sensory input from muscle spindles. However, no significant difference was observed in shoulder position sense of abduction before and after the fatigue task. This may be due to the fact that infraspinatus muscle did not act as prime movers in shoulder abduction. These results suggest that muscle fatigue decreased position sense during movements in which the affected muscles acted as prime movers.
Liu, Jian; Zou, Renling; Zhang, Dongheng; Xu, Xiulin; Hu, Xiufang
Exercise-induced muscle fatigue is a phenomenon that the maximum voluntary contraction force or power output of muscle is temporarily reduced due to muscular movement.If the fatigue is not treated properly,it will bring about a severe injury to the human body.With multi-channel collection of lower limb surface electromyography signals,this article analyzes the muscle fatigue by adoption of band spectrum entropy method which combined electromyographic signal spectral analysis and nonlinear dynamics.The experimental result indicated that with the increase of muscle fatigue,muscle signal spectrum began to move to low frequency,the energy concentrated,the system complexity came down,and the band spectrum entropy which reflected the complexity was also reduced.By monitoring the entropy,we can measure the degree of muscle fatigue,and provide an indicator to judge fatigue degree for the sports training and clinical rehabilitation training.
Zu, Xiaoqi; Zhou, Qianxiang; Li, Yun
All movements are driven by muscle contraction, and it is easy to cause muscle fatigue. Evaluation of muscle fatigue is a hot topic in the area of astronaut life support training and rehabilitation. If muscle gets into fatigue condition, it may reduce work efficiency and has an impact on psychological performance. Therefore it is necessary to develop an accurate and usable method on muscle fatigue evaluation of astronaut upper limb. In this study, we developed a method based on surface electromyography (sEMG) and subjective assessment (Borg scale) to evaluate local muscle fatigue. Fifteen healthy young male subjects participated in the experiment. They performed isometric muscle contractions of the upper limb. sEMG of the biceps brachii were recorded during the entire process of isotonic muscle contraction and Borg scales of muscle fatigue were collected in certain times. sEMG were divided into several parts, and then mean energy of each parts were calculated by the one-twelfth band octave method. Equations were derived based on the relationship between the mean energy of sEMG and Borg scale. The results showed that cubic curve could describe the degree of local muscle fatigue, and could be used to evaluate and monitor local muscle fatigue during the entire process.
Kimura, Mitsutoshi; Sato, Hirotaka; Ochi, Mamoru; Hosoya, Satoshi; Sadoyama, Tsugutake
The purpose of the present study was to investigate the development and recovery of muscle fatigue in the upper trapezius muscle by analyzing electromyographic signals. Six male subjects performed a simulated typewriting task for four 25-min sessions. During fatigue and the following rest periods, subjective fatigue and surface electromyography (EMG) from the trapezius muscle during isometric contraction at 30% maximum voluntary contraction (MVC) were periodically measured in the interval. We detected a significant decrease in muscle fiber conduction velocity (MFCV) (P = 0.008) and median frequency (MDF) (P = 0.026) as well as an increase in root mean square (RMS) (P = 0.039) and subjective fatigue (P = 0.0004) during the fatigue period. During the recovery period, subjective fatigue decreased drastically and significantly (P = 0.0004), however, the EMG parameters did not recover completely. Thus, physiological muscle fatigue in the trapezius developed in accordance with subjective muscle fatigue during typewriting. On the other hand, differences between the physiological and subjective parameters were found during recovery. Further studies should be necessary to reveal the discrepancy could be a major factor of a transition from temporal phenomena to serious chronic muscle fatigue and to identify the necessity of some guidelines to prevent VDT work-related chronic muscle fatigue in the trapezius.
Full Text Available The objective of this paper is to model a bipedal robot with springs like biarticular muscles and to study the positions effect of biarticular muscles on the walking fatigue of bipedal robots through the analysis of the works of the ground reaction force (GRF accumulated at joints and the analysis of the works done by biarticular muscles. We can define the walking fatigue in this paper by the fatigue of joints and muscles caused by the increment of the works accumulated at joints and the increment of the works done by biarticular muscles during the walk period of bipedal robots. It’s found from this study that the position of the muscle biceps femoris (BF has a strong impact on the fatigue of leg joints and the fatigue of the muscle itself during the walk period of bipedal robots.
Ianuzzo, C. David; And Others
Describes an experiment which demonstrates the association of particular metabolic biochemical changes and muscular fatigue. Highlights applications related to cellular energy metabolism, metabolic regulation, and muscle energetics. (ML)
Sitilertpisan, Patraporn; Pirunsan, Ubon; Puangmali, Aatit; Ratanapinunchai, Jonjin; Kiatwattanacharoen, Suchart; Neamin, Hudsaleark; Laskin, James J
To compare lateral abdominal muscle thickness between weightlifters and matched controls. A case control study design. University laboratory. 16 female Thai national weightlifters and 16 matched controls participated in this study. Ultrasound imaging with a 12-MHz linear array was used to measure the resting thickness of transversus abdominis (TrA), internal oblique (IO) and total thickness (Total) of lateral abdominal muscle (LAM) on the right side of abdominal wall. The absolute muscle thickness and the relative contribution of each muscle to the total thickness were determined. Weightlifters had significantly thicker absolute TrA and IO muscles than matched controls (p routine Olympic style weight training among female weightlifters appears to result in preferential hypertrophy or adaptation of the IO muscle. Copyright © 2011 Elsevier Ltd. All rights reserved.
Søgaard, Karen; Gandevia, Simon C; Todd, Gabrielle
Subjects quickly fatigue when they perform maximal voluntary contractions (MVCs). Much of the loss of force is from processes within muscle (peripheral fatigue) but some occurs because voluntary activation of the muscle declines (central fatigue). The role of central fatigue during submaximal...... contractions is not clear. This study investigated whether central fatigue developed during prolonged low-force voluntary contractions. Subjects (n=9) held isometric elbow flexions of 15% MVC for 43 min. Voluntary activation was measured during brief MVCs every 3 min. During each MVC, transcranial magnetic...... several minutes while MVC torque only returned to approximately 85% baseline. The resting twitch showed no recovery. Thus, as well as fatigue in the muscle, the prolonged low-force contraction produced progressive central fatigue, and some of this impairment of the subjects' ability to drive the muscle...
Hu, Boyi; Ning, Xiaopeng
Lumbar muscle fatigue is a potential risk factor for the development of low back pain. In this study, we investigated the influence of lumbar extensor muscle fatigue on lumbar-pelvic coordination patterns during weightlifting. Each of the 15 male subjects performed five repetitions of weightlifting tasks both before and after a lumbar extensor muscle fatiguing protocol. Lumbar muscle electromyography was collected to assess fatigue. Trunk kinematics was recorded to calculate lumbar-pelvic continuous relative phase (CRP) and CRP variability. Results showed that fatigue significantly reduced the average lumbar-pelvic CRP value (from 0.33 to 0.29 rad) during weightlifting. The average CRP variability reduced from 0.17 to 0.15 rad, yet this change ws statistically not significant. Further analyses also discovered elevated spinal loading during weightlifting after the development of lumbar extensor muscle fatigue. Our results suggest that frequently experienced lumbar extensor muscle fatigue should be avoided in an occupational environment. Lumbar extensor muscle fatigue generates more in-phase lumbar-pelvic coordination patterns and elevated spinal loading during lifting. Such increase in spinal loading may indicate higher risk of back injury. Our results suggest that frequently experienced lumbar muscle fatigue should be avoided to reduce the risk of LBP.
Grassi, Bruno; Rossiter, Harry B; Zoladz, Jerzy A
During high-intensity submaximal exercise, muscle fatigue and decreased efficiency are intertwined closely, and each contributes to exercise intolerance. Fatigue and muscle inefficiency share common mechanisms, for example, decreased "metabolic stability," muscle metabolite accumulation, decreased free energy of adenosine triphosphate breakdown, limited O2 or substrate availability, increased glycolysis, pH disturbance, increased muscle temperature, reactive oxygen species production, and altered motor unit recruitment patterns.
Buller, N P; Jones, D; Poole-Wilson, P A
Skeletal muscle function was measured as force production and fatigue in both the quadriceps (a large locomotive muscle) and adductor pollicis (a small intrinsic hand muscle) in five healthy volunteers, five patients with mild chronic heart failure, and five patients with severe chronic heart failure. The quadriceps of patients with chronic heart failure had a reduced muscle cross sectional area, a reduced maximum isometric force production, and an increased tendency to fatigue. Isometric for...
Ha, Sung-min; Oh, Jae-seop; Jeon, In-cheol; Kwon, Oh-yun
To treat low-back pain, various spinal stability exercises are commonly used to improve trunk muscle function and strength. Because human movement for normal daily activity occurs in multi-dimensions, the importance of exercise in multi-dimensions or on unstable surfaces has been emphasized. Recently, a motorized rotating platform (MRP) for facilitating multi-dimensions dynamic movement was introduced for clinical use. However, the abdominal muscle activity with this device has not been reported. The purpose of this study was to compare the abdominal muscle activity (rectus abdominis, external and internal oblique muscles) during an active single-leg-hold (SLH) exercise on a floor (stable surface), foam roll, and motorized rotating platform (MRP). Thirteen healthy male subjects participated in this study. Using electromyography, the abdominal muscle activity was measured while the subjects performed SLH exercises on floor (stable surface), foam roll, and MRP. There were significant differences in the abdominal muscle activities among conditions (P.05) (Fig. 2). After the Bonferroni correction, however, no significant differences among conditions remained, except for differences in both side IO muscle activity between the floor and foam roll conditions (padjexercises on a foam roll and MRP is more effective increased activities of both side of RA and IO, and Rt. EO compared to floor condition. However, there were no significant differences in abdominal muscles activity in the multiple comparison between conditions (mean difference were smaller than the standard deviation in the abdominal muscle activities) (padj>0.017), except for differences in both side IO muscle activity between the floor (stable surface) and foam roll (padj<0.017) (effect size: 0.79/0.62 (non-supporting/supporting leg) for foam-roll versus floor). Copyright © 2014 Elsevier Ltd. All rights reserved.
Full Text Available Background: Surface electromyography (sEMG of muscles is a non-invasive tool that can be helpful in the assessment of muscle function and some motor control evaluations. A loss of force, known as muscle fatigue is accompanied by changes in muscle electrical activity. One of the most commonly used surface EMG parameters which reflects paraspinal muscle fatigue during different tasks and positions is median frequency. Although it is widely known that the electromyography power spectrum shifts to lower frequencies during fatiguing contraction, an opinion exists that the validity of spectral shifts in assessment of fatigue is questionable. Some researchers have examined whether other quantities derived from sEMG signals are better indicators for muscle fatigue. Following cyclic flexion/extension and consequence fatigue, variation in sEMG signals may be complex for study. The aim of this study was to determine which of the median frequency (MF or entropic (ENTR is more sensitive for measuring muscular fatigue in erector spinae muscles during cyclic flexion/extension. Methods: Surface electromyography of erector spine muscles was recorded in 25 healthy subjects during cyclic dynamic contractions. The experimental session consisted of two parts: measurement of Maximal Voluntary Contraction (MVC, and performing the fatigue test. All subjects performed rhythmic flexion/extension with 50% MVC loading against B-200 Isostation, about 4-6 minutes. The MF and ENTR of the muscle activities were computed to assess muscular fatigue. Results: Paired sample t-tests showed that MF and ENTR changes after fatigue test were significant (P<0.001. Percentage changes of both MF and ENTR were reduced, this reduction for ENTR was more than 40% (P<0.001. Conclusion: It seems that the changes of ENTR in muscle activities have the ability to measure muscular fatigue and is more sensitive in comparison to MF.
Darques, J L; Jammes, Y
Recordings of group IV afferent activity of tibialis anterior muscle were performed in paralysed rabbits during runs of electrically induced fatigue produced by direct muscle stimulation at a high (100 Hz, high-frequency fatigue HFF) or a low rate (10 Hz, low-frequency fatigue LFF). In addition to analysis of afferent nerve action potentials, muscle force and compound muscle action potentials (M waves) elicited by direct muscle stimulation with single shocks were recorded. Changes in M wave configuration were used as an index of the altered propagation of membrane potentials and the associated efflux of potassium from muscle fibers. The data show that increased group IV afferent activity occurred during LFF as well as HFF trials and developed parallel with force failure. Enhanced afferent activity was significantly higher during LFF (maximal delta f(impulses) = 249 +/- 35%) than HFF (147 +/- 45%). No correlation was obtained between the responses of group IV afferents to LFF or to pressure exerted on tibialis anterior muscle. On the other hand, decreased M wave amplitude was minimal with LFF while it was pronounced with HFF. Close correlations were found between fatigue-induced activation of group IV afferents and decreases in force or M wave amplitude, but their strength was significantly higher with LFF compared to HFF. Thus, electrically induced fatigue activates group IV muscle afferents with a prominent effect of low-frequency stimulation. The mechanism of muscle afferent stimulation does not seem to be due to the sole increase in extracellular potassium concentration, but also by the efflux of muscle metabolites, present during fatiguing contractions at low rate of stimulation.
Bosch, T.; Looze, M.P. de; Kingma, I.; Visser, B.; Dieën, J.H. van
The purpose of this study was to determine whether objective electromyographical manifestations of muscle fatigue develop in the upper trapezius muscle in two assembly tasks involving contractions of different low-intensity levels (8% and 12% MVC) and whether these indications of fatigue are
Bizid, Riadh; Margnes, Eric; François, Yrieix; Jully, Jean Louis; Gonzalez, Gerard; Dupui, Philippe; Paillard, Thierry
The aim of this study was to compare the effects of acute muscle fatigue of the ankle and knee musculature on postural control by immediate measures after performing fatiguing tasks (POST condition). One group of subjects (n = 8) performed a fatiguing task by voluntary contractions of the triceps surae (group TRI) and the other (n = 9) performed a fatiguing task by voluntary contractions of the quadriceps femoris (group QUA). Each muscle group was exercised until the loss of maximal voluntary contraction torque reached 50% (isokinetic dynamometer). Posture was assessed by measuring the centre of foot pressure (COP) with a force platform during a test of unipedal quiet standing posture with eyes closed. Initially (in PRE condition), the mean COP velocity was not significantly different between group TRI and group QUA. In POST condition, the mean COP velocity increased more in group QUA than in group TRI. The postural control was more impaired by knee muscle fatigue than by ankle muscle fatigue.
Castroflorio, T; Falla, D; Tartaglia, G M; Sforza, C; Deregibus, A
The effects of muscle pain and fatigue on the control of jaw elevator muscles are not well known. Furthermore, the myoelectric manifestations of fatigue and recovery from fatigue in the masticatory muscles are not reported in literature. The main aims of this study were (i) to evaluate the possible use of surface electromyography (sEMG) as an objective measure of fatigue of the jaw elevator muscles, (ii) to compare the myoelectric manifestations of fatigue in the temporalis anterior and masseter muscles bilaterally, (iii) to assess recovery of the investigated muscles after an endurance test and (iv) to compare fatigue and recovery of the jaw elevator muscles in healthy subjects and patients with muscle-related temporomandibular disorders (TMD). The study was performed on twenty healthy volunteers and eighteen patients with muscle-related TMD. An intra-oral compressive-force sensor was used to measure the voluntary contraction forces close to the intercuspal position and to provide visual feedback of submaximal forces to the subject. Surface EMG signals were recorded with linear electrode arrays during isometric contractions at 20%, 40%, 60% and 80% of the maximum voluntary contraction force, during an endurance test and during the recovery phase. The results showed that (i) the slope of the mean power spectral frequency (MNF) and the initial average rectified value (ARV) could be used to monitor fatigue of the jaw elevators, (ii) the temporalis anterior and masseter muscle show the same myoelectric manifestations of fatigue and recovery and (iii) the initial values of MNF and ARV were lower in patients with muscle-related TMD. The assessment of myoelectric manifestations of fatigue in the masticatory muscles may assist in the clinical assessment of TMDs. © 2012 Blackwell Publishing Ltd.
Karthick, P A; Venugopal, G; Ramakrishnan, S
Analysis of neuromuscular fatigue finds various applications ranging from clinical studies to biomechanics. Surface electromyography (sEMG) signals are widely used for these studies due to its non-invasiveness. During cyclic dynamic contractions, these signals are nonstationary and cyclostationary. In recent years, several nonstationary methods have been employed for the muscle fatigue analysis. However, cyclostationary based approach is not well established for the assessment of muscle fatigue. In this work, cyclostationarity associated with the biceps brachii muscle fatigue progression is analyzed using sEMG signals and Spectral Correlation Density (SCD) functions. Signals are recorded from fifty healthy adult volunteers during dynamic contractions under a prescribed protocol. These signals are preprocessed and are divided into three segments, namely, non-fatigue, first muscle discomfort and fatigue zones. Then SCD is estimated using fast Fourier transform accumulation method. Further, Cyclic Frequency Spectral Density (CFSD) is calculated from the SCD spectrum. Two features, namely, cyclic frequency spectral area (CFSA) and cyclic frequency spectral entropy (CFSE) are proposed to study the progression of muscle fatigue. Additionally, degree of cyclostationarity (DCS) is computed to quantify the amount of cyclostationarity present in the signals. Results show that there is a progressive increase in cyclostationary during the progression of muscle fatigue. CFSA shows an increasing trend in muscle fatiguing contraction. However, CFSE shows a decreasing trend. It is observed that when the muscle progresses from non-fatigue to fatigue condition, the mean DCS of fifty subjects increases from 0.016 to 0.99. All the extracted features found to be distinct and statistically significant in the three zones of muscle contraction (p < 0.05). It appears that these SCD features could be useful in the automated analysis of sEMG signals for different neuromuscular conditions.
Hussain, M. S.; Mamun, Md.
Muscle fatigue is the decline in ability of a muscle to create force. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. During a sustained muscle contraction, the power spectrum of the EMG shifts towards lower frequencies. These effects are due to muscle fatigue. Muscle fatigue is often a result of unhealthy work practice. In this research, the effectiveness of the wavelet transform applied to the surface EMG (SEMG) signal as a means of understanding muscle fatigue during walk is presented. Power spectrum and bispectrum analysis on the EMG signal getting from right rectus femoris muscle is executed utilizing various wavelet functions (WFs). It is possible to recognize muscle fatigue appreciably with the proper choice of the WF. The outcome proves that the most momentous changes in the EMG power spectrum are symbolized by WF Daubechies45. Moreover, this research has compared bispectrum properties to the other WFs. To determine muscle fatigue during gait, Daubechies45 is used in this research to analyze the SEMG signal.
Rondelli, Rafaella Rezende; Dal Corso, Simone; Simões, Alexandre; Malaguti, Carla
It has been well established that, in addition to the pulmonary involvement, COPD has systemic consequences that can lead to peripheral muscle dysfunction, with greater muscle fatigue, lower exercise tolerance and lower survival in these patients. In view of the negative repercussions of early muscle fatigue in COPD, the objective of this review was to discuss the principal findings in the literature on the metabolic and bioenergy determinants of muscle fatigue, its functional repercussions, as well as the methods for its identification and quantification. The anatomical and functional substrate of higher muscle fatigue in COPD appears to include lower levels of high-energy phosphates, lower mitochondrial density, early lactacidemia, higher serum ammonia and reduced muscle perfusion. These alterations can be revealed by contraction failure, decreased firing rates of motor units and increased recruitment of motor units in a given activity, which can be functionally detected by a reduction in muscle strength, power and endurance. This review article also shows that various types of muscle contraction regimens and protocols have been used in order to detect muscle fatigue in this population. With this understanding, rehabilitation strategies can be developed in order to improve the resistance to muscle fatigue in this population.
Zhou, X.; Kamiya, N.; Hara, T.; Fujita, H.; Chen, H.; Yokoyama, R.; Hoshi, H.
The information of abdominal wall is very important for the planning of surgical operation and abdominal organ recognition. In research fields of computer assisted radiology and surgery and computer-aided diagnosis, the segmentation and recognition of the abdominal wall muscles in CT images is a necessary pre-processing step. Due to the complexity of the abdominal wall structure and indistinctive in CT images, the automated segmentation of abdominal wall muscles is a difficult issue and has not been solved completely. We propose an approach to segment the abdominal wall muscles and divide it into three categories (front abdominal muscles including rectus abdominis; left and right side abdominal muscles including external oblique, internal oblique and transversus abdominis muscles) automatically. The approach, first, makes an initial classification of bone, fat, and muscles and organs based on the CT number. Then a layer structure is generated to describe the 3-D anatomical structures of human torso by stretching the torso region onto a thin-plate for easy recognition. The abdominal wall muscles are recognized on the layer structures using the spatial relations to the skeletal structure and CT numbers. Finally, the recognized regions are mapped back to the 3-D CT images using an inverse transformation of the stretching process. This method is applied to 20 cases of torso CT images and evaluations are based on visual comparison of the recognition results and the original CT images by an expert in anatomy. The results show that our approach can segment and recognize abdominal wall muscle regions effectively. (orig.)
Jung, Halim; Jung, Sangwoo; Joo, Sunghee; Song, Changho
[Purpose] The purpose of this study was to compare changes in the mobility of the pelvic floor muscle during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. [Subjects] Thirty healthy adults participated in this study (15 men and 15 women). [Methods] All participants performed a bridge exercise and abdominal curl-up during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. Pelvic floor mobility...
Chan, Mandy Ky; Chow, Ka Wai; Lai, Alfred Ys; Mak, Noble Kc; Sze, Jason Ch; Tsang, Sharon Mh
Core stabilization has been utilized for rehabilitation and prevention of lower limb musculoskeletal injuries. Previous studies showed that activation of the abdominal core muscles enhanced the hip muscle activity in hip extension and abduction exercises. However, the lack of the direct measurement and quantification of the activation level of the abdominal core muscles during the execution of the hip exercises affect the level of evidence to substantiate the proposed application of core exercises to promote training and rehabilitation outcome of the hip region. The aim of the present study was to examine the effects of abdominal core activation, which is monitored directly by surface electromyography (EMG), on hip muscle activation while performing different hip exercises, and to explore whether participant characteristics such as gender, physical activity level and contractile properties of muscles, which is assessed by tensiomyography (TMG), have confounding effect to the activation of hip muscles in enhanced core condition. Surface EMG of bilateral internal obliques (IO), upper gluteus maximus (UGMax), lower gluteus maximus (LGMax), gluteus medius (GMed) and biceps femoris (BF) of dominant leg was recorded in 20 young healthy subjects while performing 3 hip exercises: Clam, side-lying hip abduction (HABD), and prone hip extension (PHE) in 2 conditions: natural core activation (NC) and enhanced core activation (CO). EMG signals normalized to percentage of maximal voluntary isometric contraction (%MVIC) were compared between two core conditions with the threshold of the enhanced abdominal core condition defined as >20%MVIC of IO. Enhanced abdominal core activation has significantly promoted the activation level of GMed in all phases of clam exercise (P recruitment in Clam, HABD and PHE exercises, and this enhancement is correlated with higher physical activity and stiffer hip muscle. Our results suggest the potential application of abdominal core activation for
Tanaka, Noriko I; Murakami, Haruka; Ohmori, Yumi; Aiba, Naomi; Morita, Akemi; Watanabe, Shaw; Miyachi, Motohiko
Quantitative evaluation of visceral fat mass and skeletal muscle mass is important for health promotion. Recently, some studies suggested the existence of adipocyte-myocyte negative crosstalk. If so, abdominal skeletal muscles may easily and negatively affected not only by the age but also the visceral fat because age-related reduction in abdominal region is greater compared with limbs. We cross-sectionally examined the existence of quantitative associations between visceral fat area and abdominal skeletal muscle distribution in overweight people. A total of 230 Japanese males and females who aged 40-64 years and whose body mass index (BMI) was 28.0-44.8kg/m 2 participated in this study. The cross-sectional area (CSA) of the visceral fat, subcutaneous fat, and abdominal skeletal muscles, namely, the rectus abdominis, abdominal oblique, erector spinae, and iliopsoas muscles were measured by the computed tomography images. Stepwise regression analyses revealed the existence of sex difference in the relation between visceral fat CSA and other morphological variables. In males, BMI was a positive, and the iliopsoas muscle group CSA was a negative contributor of the visceral fat CSA. In females, both age and BMI were selected as positive contributors. These data suggested that the visceral fat CSA may negatively associated with iliopsoas muscle group CSA in males. In females, the visceral fat CSA was not significantly related to the distribution of the abdominal skeletal muscle groups. Copyright © 2016 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Full Text Available Objective: Several studies have shown the effects of muscular fatigue on proprioception and neuromuscular control. However all available researches have studied just the effect of local fatigue in ankle joint muscles on postural control, and no study have found about the effect of fatigue in proximal muscles of the lower extremity on postural control. To compare changes in postural control parameters after isokinetic fatigue of proximal and distal muscles of lower extremity. Materials & Methods: Subjects were twenty healthy men (age: 22.6±2.4 years, height: 173.7± 3.6 cm, weight: 63.3±7.9kg. There were 4 test sessions, with a randomized order according to site and plane of fatigue. During each session one of these muscle groups was fatigued using a Biodex isokinetic dynamometer: ankle plantar / dorsi flexors, ankle evertor / inventors, hip flexor / extensors and hip abductor/adductors. The biodex stability system was used to perform dynamic balance test before and after muscle fatigue in each session. Overall, anterior / posterior, and medial/lateral stability indices were recorded. The higher the stability indices, the lower the balancing skill. Results: Analysis of pre-and post fatigue balance results of all sessions, demonstrated significant increase (P<0.05 in all stability indices. Repeated measures ANOVA performed on the rate of changes in stability indices during each session revealed that hip muscle fatigue caused much more increase in stability indices than ankle muscle fatigue (P<0.05. Conclusion: Isokinetic fatigue of both ankle and hip muscles significantly decreases postural control ability in healthy young men. In addition, our findings suggest that the hip joint musculature plays a more prominent role in postural control.
Full Text Available Introduction: Repetitive strain injuries are one of the most prevalent problems in occupational diseases. Repetition, vibration and bad postures of the extremities are physical risk factors related to work that can cause chronic musculoskeletal disorders. Repetitive work on a computer with low level contraction requires the posture to be maintained for a long time, which can cause muscle fatigue. Muscle fatigue in shoulders and neck is one of the most prevalent problems reported with computer users especially during typing. Surface electromyography (SEMG signals are used for detecting muscle fatigue as a non-invasive method. Material and Methods: Nine healthy females volunteered for signal recoding during typing. EMG signals were recorded from the trapezius muscle, which is subjected to muscle fatigue during typing. After signal analysis and feature extraction, detecting and predicting muscle fatigue was performed by using the MLP artificial neural network. Results: Recorded signals were analyzed in time and frequency domains for feature extraction. Results of classification showed that the MLP neural network can detect and predict muscle fatigue during typing with 80.79 % ± 1.04% accuracy. Conclusion: Intelligent classification and prediction of muscle fatigue can have many applications in human factors engineering (ergonomics, rehabilitation engineering and biofeedback equipment for mitigating the injuries of repetitive works.
Smale, Kenneth B; Shourijeh, Mohammad S; Benoit, Daniel L
The objective of this study was to supplement continuous wavelet transforms with muscle synergies in a fatigue analysis to better describe the combination of decreased firing frequency and altered activation profiles during dynamic muscle contractions. Nine healthy young individuals completed the dynamic tasks before and after they squatted with a standard Olympic bar until complete exhaustion. Electromyography (EMG) profiles were analyzed with a novel concatenated non-negative matrix factorization method that decomposed EMG signals into muscle synergies. Muscle synergy analysis provides the activation pattern of the muscles while continuous wavelet transforms output the temporal frequency content of the EMG signals. Synergy analysis revealed subtle changes in two-legged squatting after fatigue while differences in one-legged squatting were more pronounced and included the shift from a general co-activation of muscles in the pre-fatigue state to a knee extensor dominant weighting post-fatigue. Continuous wavelet transforms showed major frequency content decreases in two-legged squatting after fatigue while very few frequency changes occurred in one-legged squatting. It was observed that the combination of methods is an effective way of describing muscle fatigue and that muscle activation patterns play a very important role in maintaining the overall joint kinetics after fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.
Voermans, N C; Knoop, H; Bleijenberg, G; van Engelen, B G
Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders characterised by joint hypermobility, skin hyperextensibility and tissue fragility. It has recently been shown that muscle weakness occurs frequently in EDS, and that fatigue is a common and clinically important symptom. The aim of this study was to investigate the relationship between fatigue severity and subjective and objective measures of muscle weakness. Furthermore, the predictive value of muscle weakness for fatigue severity was determined, together with that of pain and physical activity. An explorative, cross-sectional, observational study. Thirty EDS patients, recruited from the Dutch patient association, were investigated at the neuromuscular outpatient department of a tertiary referral centre in The Netherlands. Muscle strength measured with manual muscle strength testing and hand-held dynamometry. Self-reported muscle weakness, pain, physical activity levels and fatigue were assessed with standardised questionnaires. Fatigue severity in EDS was significantly correlated with measured and self-reported muscle weakness (r=-0.408 for manual muscle strength, r=0.461 for hand-held dynamometry and r=0.603 for self-reported muscle weakness). Both muscle weakness and pain severity were significant predictors of fatigue severity in a multiple regression analysis. The results suggest a positive and direct relationship between fatigue severity and muscle weakness in EDS. Future research should focus on the relationship between fatigue, muscle weakness and objectively measured physical activity, preferably in a larger cohort of EDS patients. Copyright © 2010 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.
Jensen, Lauren; Dancisak, Michael; Korndorffer, James
A localized, intermittent muscle-cooling protocol was implemented to determine cooling garment efficacy in reducing upper extremity muscular fatigue and tremor in novice ( n = 10) and experienced surgeons ( n = 9). Subjects wore a muscle-cooling garment while performing multiple trials of a forearm exercise and paired suturing task to induce muscular fatigue and exercise-induced tremor. A reduction in tremor amplitude and an extension in time to fatigue were expected with muscle cooling as compared with control trials. Each subject completed an intervention session (5°C cooling condition) and a control session (32°C or thermal neutral condition). A paired samples t test indicated that tremor amplitude was significantly reduced ( t  = 1.89458; p effect was not significant. Time to fatigue and suture time improved in both cohorts with muscle cooling, but the effect did not reach significance. Results from the pilot work suggest muscle cooling as an intervention for reduction of fatigue and tremor is very promising, warranting further investigation. Surgical specialties that require prolonged procedures might benefit more from this intervention.
Full Text Available Muscle fatigue is an established area of research and various types of muscle fatigue have been clinically investigated in order to fully understand the condition. This paper demonstrates a non-invasive technique used to automate the fatigue detection and prediction process. The system utilises the clinical aspects such as kinematics and surface electromyography (sEMG of an athlete during isometric contractions. Various signal analysis methods are used illustrating their applicability in real-time settings. This demonstrated system can be used in sports scenarios to promote muscle growth/performance or prevent injury. To date, research on localised muscle fatigue focuses on the clinical side and lacks the implementation for detecting/predicting localised muscle fatigue using an autonomous system. Results show that automating the process of localised muscle fatigue detection/prediction is promising. The autonomous fatigue system was tested on five individuals showing 90.37% accuracy on average of correct classification and an error of 4.35% in predicting the time to when fatigue will onset.
Al-Mulla, Mohamed R.; Sepulveda, Francisco; Colley, Martin
Muscle fatigue is an established area of research and various types of muscle fatigue have been clinically investigated in order to fully understand the condition. This paper demonstrates a non-invasive technique used to automate the fatigue detection and prediction process. The system utilises the clinical aspects such as kinematics and surface electromyography (sEMG) of an athlete during isometric contractions. Various signal analysis methods are used illustrating their applicability in real-time settings. This demonstrated system can be used in sports scenarios to promote muscle growth/performance or prevent injury. To date, research on localised muscle fatigue focuses on the clinical side and lacks the implementation for detecting/predicting localised muscle fatigue using an autonomous system. Results show that automating the process of localised muscle fatigue detection/prediction is promising. The autonomous fatigue system was tested on five individuals showing 90.37% accuracy on average of correct classification and an error of 4.35% in predicting the time to when fatigue will onset. PMID:22319367
Abboud, Jacques; Nougarou, François; Lardon, Arnaud; Dugas, Claude; Descarreaux, Martin
Introduction: When the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g., attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear. Using high-density electromyography (EMG) may help understand how the nervous system chooses to deal with an unknown perturbation in different physiological and/or mechanical perturbation environments. Aim: To characterize trunk neuromuscular adaptations following repeated sudden external perturbations after a back muscle fatigue task using high-density EMG. Methods: Twenty-five healthy participants experienced a series of 15 sudden external perturbations before and after back muscle fatigue. Erector spinae muscle activity was recorded using high-density EMG. Trunk kinematics during perturbation trials were collected using a 3-D motion analysis system. A two-way repeated measure ANOVA was conducted to assess: (1) the adaptation effect across trials; (2) the fatigue effect; and (3) the interaction effect (fatigue × adaptation) for the baseline activity, the reflex latency, the reflex peak and trunk kinematic variables (flexion angle, velocity and time to peak velocity). Muscle activity spatial distribution before and following the fatigue task was also compared using t-tests for dependent samples. Results: An attenuation of muscle reflex peak was observed across perturbation trials before the fatigue task, but not after. The spatial distribution of muscle activity was significantly higher before the fatigue task compared to post-fatigue trials. Baseline activity showed a trend to higher values after muscle
Full Text Available IntroductionWhen the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g. attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear. Using high-density electromyography (EMG may help understand how the nervous system chooses to deal with an unknown perturbation in different physiological and/or mechanical perturbation environments. AimTo characterize trunk neuromuscular adaptations following repeated sudden external perturbations after a back muscle fatigue task using high-density EMG.MethodsTwenty-five healthy participants experienced a series of 15 sudden external perturbations before and after back muscle fatigue. Erector spinae muscle activity was recorded using high-density EMG. Trunk kinematics during perturbation trials were collected using a 3-D motion analysis system. A two-way repeated measure ANOVA was conducted to assess 1 the adaptation effect across trials, 2 the fatigue effect, and 3 the interaction effect (fatigue x adaptation for the baseline activity, the reflex latency, the reflex peak and trunk kinematic variables (flexion angle, velocity and time to peak velocity. Muscle activity spatial distribution before and following the fatigue task was also compared using t-tests for dependent samples. ResultsAn attenuation of muscle reflex peak was observed across perturbation trials before the fatigue task, but not after. The spatial distribution of muscle activity was significantly higher before the fatigue task compared to post-fatigue trials. Baseline activity showed a trend to higher values after muscle
Zanca, Gisele Garcia; Grüninger, Bruno; Mattiello, Stela Márcia
Scapular kinematics alterations have been found following muscle fatigue. Considering the importance of the lower trapezius in coordinated scapular movement, this study aimed to investigate the effects of elastic taping (Kinesio taping, KT) for muscle facilitation on scapular kinematics of healthy overhead athletes following muscle fatigue. Twenty-eight athletes were evaluated in a crossover, single-blind, randomized design, in three sessions: control (no taping), KT (KT with tension) and sham (KT without tension). Scapular tridimensional kinematics and EMG of clavicular and acromial portions of upper trapezius, lower trapezius and serratus anterior were evaluated during arm elevation and lowering, before and after a fatigue protocol involving repetitive throwing. Median power frequency decline of serratus anterior was significantly lower in KT session compared to sham, possibly indicating lower muscle fatigue. However, the effects of muscle fatigue on scapular kinematics were not altered by taping conditions. Although significant changes were found in scapular kinematics following muscle fatigue, they were small and not considered relevant. It was concluded that healthy overhead athletes seem to present an adaptive mechanism that avoids the disruption of scapular movement pattern following muscle fatigue. Therefore, these athletes do not benefit from the use of KT to assist scapular movement under the conditions tested. Copyright © 2015 Elsevier Ltd. All rights reserved.
Full Text Available Abstract Introduction: The training of the pelvic floor muscles is widely used for treating pelvic floor dysfunctions, like urinary incontinence. During the training, abdominal contractions are avoided; however several studies support the use of the synergy between these muscle groups. Objective: Carrying out a systematic review of studies that seek to identify the presence of synergy between the muscles of the abdomen and the pelvic floor and its functionality in women without pelvic floor dysfunction. Methodology: To conduct the review, we have followed the recommendations proposed by the Cochrane Collaboration for systematic reviews. The literature search included the databases SCIELO, PEDro, MEDLINE, Cochrane CENTRAL and EMBASE, and manual research, the starting date of the databases until August 2013. We included cross observational studies with healthy women who were assessed to find the presence of synergy between the abdominal muscles and the pelvic floor. Results: We included 10 articles and they all showed the existence of synergy between the abdominal and pelvic floor muscles in healthy women in the supine, sitting and standing positions. Conclusion: Thus, we can conclude that there is synergy between the muscles of the abdomen and the pelvic floor in healthy women. Better understanding the behavior of these muscles and synergy may favor the development of strategies for the prevention and treatment of disorders of the female pelvic floor muscles.
Sridhar P. Arjunan
Full Text Available The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC. Six features were considered in this study: normalised spectral index (NSM5, median frequency, root mean square, waveform length, normalised root mean square (NRMS, and increase in synchronization (IIS index. Analysis of variance (ANOVA and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P0.05.
Arjunan, Sridhar P; Kumar, Dinesh K; Naik, Ganesh
The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study: normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P 0.05).
Yoon, Seung-Hyun; Jung, Myung-Chul; Park, Seong Yong
The aim of this study was to document the physical stress experienced by a surgeon during thoracoscopic pulmonary lobectomy and mediastinal lymph node dissection for lung cancer by measuring the intraoperative electromyography (EMG). Surface EMG was recorded during 12 cases of thoracoscopic lobectomy. During the operation, 16 channels of a wireless EMG were used to measure muscle activity and fatigue from the bilateral muscles of the splenius capitis (SC), upper trapezius (UT), middle deltoid (MD), flexor carpi radialis (FCR), extensor carpi radialis (ECR), lumbar erector spinae (LES), rectus femoralis (RF), and tibialis anterior (TA). The EMG signals were processed to collect the values of the root mean square for muscle activity and median frequency (MF) for muscle fatigue. All operations were completed without adverse events. The mean operating time was 99.16±35.15 minutes. During the operation, the mean muscle activity of all muscles was 21.91±12.85 mV. High muscle activity was observed in the bilateral FCR and ECR, whereas low muscle activity was observed in the bilateral SC and LES. The final MFs in the bilateral SC and LES were found to be decreased from the initial status, which implied increased muscle fatigue. The muscles of the right and left LES were significantly fatigued by up to 29% and 37% compared to their initial status (P=0.021 and P=0.007, respectively). The MFs of the bilateral LES decreased with time (an average decreases of 0.008/5 minutes, P=0.002 in right LES and 0.004/5 minutes, P=0.018 in left LES). During thoracoscopic lobectomy, muscle fatigue was observed in muscles related to a static posture, such as the bilateral SC, UT, and ES. Further studies are required to investigate the ergonomic adjustments needed to reduce muscle fatigue in these static muscles.
Haji Omid Kalte
Full Text Available Introduction and purpose: Work fatigue is one of the main causes of workrelated musculoskeletal disorders and reduced productivity in industry. Therefore, it is vital to evaluate work fatigue, especially muscle fatigue, to determine the permissible workload. This study aimed to evaluate muscle fatigue of brick field workers. Methods: This cross-sectional study was conducted on transportation sector workers in Pey Dezh Brick Production Company, Golestan, Iran in 2015. In this research, the qualitative of Muscle Fatigue Assessment (MFA method was used to assess the level of fatigue. Duration of each task and frequency of efforts were determined using the level of effort to obtain a numerical result for comparison with the standard level. Results: The evaluated task was to remove paired bricks from the conveyor and transfer them to trailer truck by workers. The final results revealed that lower back tolerated the most amount of pressure (score=323, followed by the shoulders and wrist of the right hand (scores=313, which were assigned to the fatigue level. Therefore, the highest total fatigue of workload was imposed on these body parts. Conclusion: According to the results of this study, the upper limbs of workers incurred the highest burden in lifting bricks, and there was a in risk of WMSDS due to high workload. Therefore, it is recommended that working systems be improved through rotating work and reducing the number of transferred bricks to avoid risks caused by accumulation of fatigue.
Bingham, Adrian; Arjunan, Sridhar P; Kumar, Dinesh K
In this study we investigated a technique for estimating the progression of localized muscle fatigue. This technique measures the dependence between motor units using high density surface electromyogram (HD-sEMG) and is based on the Normalized Mutual Information (NMI) measure. The NMI between every pair combination of the electrode array is computed to measure the interactions between electrodes. Participants in the experiment had an array of 64 electrodes (16 by 4) placed over the TA of their dominate leg such that the columns of the array ran parallel with the muscle fibers. The HD-sEMG was recorded whilst the participants maintained an isometric dorsiflexion with their dominate foot until task failure at 40% and 80% of their maximum voluntary contraction (MVC). The interactions between different locations over the muscle were computed using the recorded HD-sEMG signals. The results show that the average interactions between various locations over the TA significantly increased during fatigue at both levels of contraction. This can be attributed to the dependence in the motor units.
Steens, Anneke; de Vries, Astrid; Hemmen, Jolien; Heersema, Thea; Heerings, Marco; Maurits, Natasha; Zijdewind, Inge
Background. Fatigue is a debilitating symptom in multiple sclerosis (MS). Previous studies showed no association between fatigue as perceived by the patient and physiological measures of fatigability. Objective. The authors investigated associations between perceived fatigue and measures of
Bangsbo, Jens; Madsen, K.; Kiens, Bente
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...
Wang, Yong-Hui; Yin, Ming-Jing; Fan, Zhen-Zhen; Arendt-Nielsen, Lars; Ge, Hong-You; Yue, Shou-Wei
Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats. Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle. The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all pbands were significantly lower than those at the 1st and 5th stimuli (all pbands than for non-taut bands (both pband itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.
Full Text Available The slow component (VO2sc that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre fatigue condition or rest for 33 minutes (control condition according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-second maximal sprints at a fixed pedaling cadence of 90 rev·min-1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and VO2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03, the VO2sc was not significantly different between the pre fatigue (464 ± 301 mL·min-1 and the control (556 ± 223 mL·min-1 condition (P = 0.50. Blood lactate response was not significantly different between conditions (P = 0.48 but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01 suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the VO2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the VO2sc is strongly associated with locomotor muscle fatigue.
Hernández, B; Peña, E; Pascual, G; Rodríguez, M; Calvo, B; Doblaré, M; Bellón, J M
The aims of this study are to experimentally characterize the passive elastic behaviour of the rabbit abdominal wall and to develop a mechanical constitutive law which accurately reproduces the obtained experimental results. For this purpose, tissue samples from New Zealand White rabbits 2150±50 (g) were mechanically tested in vitro. Mechanical tests, consisting of uniaxial loading on tissue samples oriented along the craneo-caudal and the perpendicular directions, respectively, revealed the anisotropic non-linear mechanical behaviour of the abdominal tissues. Experiments were performed considering the composite muscle (including external oblique-EO, internal oblique-IO and transverse abdominis-TA muscle layers), as well as separated muscle layers (i.e., external oblique, and the bilayer formed by internal oblique and transverse abdominis). Both the EO muscle layer and the IO-TA bilayer demonstrated a stiffer behaviour along the transversal direction to muscle fibres than along the longitudinal one. The fibre arrangement was measured by means of a histological study which confirmed that collagen fibres are mainly responsible for the passive mechanical strength and stiffness. Furthermore, the degree of anisotropy of the abdominal composite muscle turned out to be less pronounced than those obtained while studying the EO and IO-TA separately. Moreover, a phenomenological constitutive law was used to capture the measured experimental curves. A Levenberg-Marquardt optimization algorithm was used to fit the model constants to reproduce the experimental curves. Copyright © 2010 Elsevier Ltd. All rights reserved.
Toumi, Hechmi; Poumarat, Georges; Best, Thomas M; Martin, Alain; Fairclough, John; Benjamin, Mike
The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch-shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90 degrees of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle-tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.
Full Text Available Background and Aim: Endogenous opioids and addictive opiate drugs change many body functions. . Previous studies have referred to the effects of morphine on smooth and pulmonary muscles ., but the effects of opioids on skeletal muscles is not known well. Thus, the current study aimed at assessing the effect of a single dose of morphine on muscle fatigue in male rats. Materials and Methods: In this experimental study, 40 male Wistar rats weighing 220-270 g were randomly divided into four equal groups: control (the mice were kept in their cages and received food and water, morphine receiving group, fatigue group (the mice in this group were kept running on a treadmill . for120 minutes at a rate of 20 meters per minute, and morphine plus fatigue group. At the end of the experiments, blood samples were obtained from the corner of their eyes and were sent to the laboratory for measurement of muscle fatigue indexes including lactate dehydrogenase (LDH and creatine phosphokinase (CPK. Results: Administration of morphine to the fatigue group decreased running time compared with the control group (P=0.009. Furthermore, administration of morphine to the fatigue group significantly increased serum levels of LDH (P=0.009 and CPK (P=0.008. Conclusion: The present study showed that administration of a single dose of morphine in rats increases muscle fatigue biomarkers (LDH, CPK.
Mohamed R. Al-Mulla
Full Text Available Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results.
Al-Mulla, Mohamed R.; Sepulveda, Francisco; Colley, Martin
Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results. PMID:22163810
Gerwyn, Morris; Maes, Michael
Here, we review potential causes of muscle dysfunction seen in many patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) such as the effects of oxidative and nitrosative stress (O&NS) and mitochondrial impairments together with reduced heat shock protein production and a range of metabolic abnormalities. Several studies published in the last few years have highlighted the existence of chronic O&NS, inflammation, impaired mitochondrial function and reduced heat shock protein production in many patients with ME/CFS. These studies have also highlighted the detrimental effects of chronically elevated O&NS on muscle functions such as reducing the time to muscle fatigue during exercise and impairing muscle contractility. Mechanisms have also been revealed by which chronic O&NS and or impaired heat shock production may impair muscle repair following exercise and indeed the adaptive responses in the striated muscle to acute and chronic increases in physical activity. The presence of chronic O&NS, low-grade inflammation and impaired heat shock protein production may well explain the objective findings of increased muscle fatigue, impaired contractility and multiple dimensions of exercise intolerance in many patients with ME/CFS.
Jung, Halim; Jung, Sangwoo; Joo, Sunghee; Song, Changho
[Purpose] The purpose of this study was to compare changes in the mobility of the pelvic floor muscle during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. [Subjects] Thirty healthy adults participated in this study (15 men and 15 women). [Methods] All participants performed a bridge exercise and abdominal curl-up during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. Pelvic floor mobility was evaluated as the distance from the bladder base using ultrasound. [Results] According to exercise method, bridge exercise and abdominal curl-ups led to significantly different pelvic floor mobility. The pelvic floor muscle was elevated during the abdominal drawing-in maneuver and descended during maximal expiration. Finally, pelvic floor muscle mobility was greater during abdominal curl-up than during the bridge exercise. [Conclusion] According to these results, the abdominal drawing-in maneuver induced pelvic floor muscle contraction, and pelvic floor muscle contraction was greater during the abdominal curl-up than during the bridge exercise.
Dong, L-R; Zhu, Y-M; Xu, Q; Cao, C-X; Zhang, B-Z
This study investigated whether extraperitoneal colostomy without damaging the muscle layer of the abdominal wall is an improved surgical procedure compared with conventional sigmoid colostomy in patients undergoing abdominoperineal resection. Patients with rectal cancer undergoing abdominoperineal resection were selected and randomly divided into two groups: the study group received extraperitoneal colostomy without damaging the muscle layer of the abdominal wall and the control group received conventional colostomy. Clinical data from both groups were analysed. A total of 128 patients were included: 66 received extraperitoneal colostomy without damaging the muscle layer of the abdominal wall and 62 received conventional colostomy. Significant differences between the two groups were found in relation to colostomy operating time, defaecation sensation, bowel control and overall stoma-related complications. Duration of postoperative hospital stay was also significantly different between the study groups. Extraperitoneal colostomy without damaging the muscle layer of the abdominal wall was found to be an improved procedure compared with conventional sigmoid colostomy in abdominoperineal resection, and may reduce colostomy-related complications, shorten operating time and postoperative hospital stay, and potentially improve patients' quality of life.
ShahAli, Shabnam; Arab, Amir Massoud; Talebian, Saeed; Ebrahimi, Esmaeil; Bahmani, Andia; Karimi, Noureddin; Nabavi, Hoda
The study was designed to evaluate the intra-examiner reliability of ultrasound (US) thickness measurement of abdominal muscles activity when supine lying and during two isometric endurance tests in subjects with and without Low back pain (LBP). A total of 19 women (9 with LBP, 10 without LBP) participated in the study. Within-day reliability of the US thickness measurements at supine lying and the two isometric endurance tests were assessed in all subjects. The intra-class correlation coefficient (ICC) was used to assess the relative reliability of thickness measurement. The standard error of measurement (SEM), minimal detectable change (MDC) and the coefficient of variation (CV) were used to evaluate the absolute reliability. Results indicated high ICC scores (0.73-0.99) and also small SEM and MDC scores for within-day reliability assessment. The Bland-Altman plots of agreement in US measurement of the abdominal muscles during the two isometric endurance tests demonstrated that 95% of the observations fall between the limits of agreement for test and retest measurements. Together the results indicate high intra-tester reliability for the US measurement of the thickness of abdominal muscles in all the positions tested. According to the study's findings, US imaging can be used as a reliable method for assessment of abdominal muscles activity in supine lying and the two isometric endurance tests employed, in participants with and without LBP. Copyright © 2014 Elsevier Ltd. All rights reserved.
Roberts, B. M. [1225 Center Drive, HPNP Building Room 1142, Department of Physical Therapy, University of Florida, Gainesville, FL 32610 (United States); Frye, G. S.; Ahn, B.; Ferreira, L. F. [1864 Stadium Road, Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32610 (United States); Judge, A.R., E-mail: email@example.com [1225 Center Drive, HPNP Building Room 1142, Department of Physical Therapy, University of Florida, Gainesville, FL 32610 (United States)
Highlights: •C-26 cancer cachexia causes a significant decrease in limb muscle absolute force. •C-26 cancer cachexia causes a significant decrease in limb muscle specific force. •C-26 cancer cachexia decreases fatigue resistance in the soleus muscle. •C-26 cancer cachexia prolongs time to peak twitch tension in limb muscle. •C-26 cancer cachexia prolongs one half twitch relaxation time in limb muscle. -- Abstract: Cancer cachexia is a complex metabolic syndrome that is characterized by the loss of skeletal muscle mass and weakness, which compromises physical function, reduces quality of life, and ultimately can lead to mortality. Experimental models of cancer cachexia have recapitulated this skeletal muscle atrophy and consequent decline in muscle force generating capacity. However, more recently, we provided evidence that during severe cancer cachexia muscle weakness in the diaphragm muscle cannot be entirely accounted for by the muscle atrophy. This indicates that muscle weakness is not just a consequence of muscle atrophy but that there is also significant contractile dysfunction. The current study aimed to determine whether contractile dysfunction is also present in limb muscles during severe Colon-26 (C26) carcinoma cachexia by studying the glycolytic extensor digitorum longus (EDL) muscle and the oxidative soleus muscle, which has an activity pattern that more closely resembles the diaphragm. Severe C-26 cancer cachexia caused significant muscle fiber atrophy and a reduction in maximum absolute force in both the EDL and soleus muscles. However, normalization to muscle cross sectional area further demonstrated a 13% decrease in maximum isometric specific force in the EDL and an even greater decrease (17%) in maximum isometric specific force in the soleus. Time to peak tension and half relaxation time were also significantly slowed in both the EDL and the solei from C-26 mice compared to controls. Since, in addition to postural control, the oxidative
Roberts, B.M.; Frye, G.S.; Ahn, B.; Ferreira, L.F.; Judge, A.R.
Highlights: •C-26 cancer cachexia causes a significant decrease in limb muscle absolute force. •C-26 cancer cachexia causes a significant decrease in limb muscle specific force. •C-26 cancer cachexia decreases fatigue resistance in the soleus muscle. •C-26 cancer cachexia prolongs time to peak twitch tension in limb muscle. •C-26 cancer cachexia prolongs one half twitch relaxation time in limb muscle. -- Abstract: Cancer cachexia is a complex metabolic syndrome that is characterized by the loss of skeletal muscle mass and weakness, which compromises physical function, reduces quality of life, and ultimately can lead to mortality. Experimental models of cancer cachexia have recapitulated this skeletal muscle atrophy and consequent decline in muscle force generating capacity. However, more recently, we provided evidence that during severe cancer cachexia muscle weakness in the diaphragm muscle cannot be entirely accounted for by the muscle atrophy. This indicates that muscle weakness is not just a consequence of muscle atrophy but that there is also significant contractile dysfunction. The current study aimed to determine whether contractile dysfunction is also present in limb muscles during severe Colon-26 (C26) carcinoma cachexia by studying the glycolytic extensor digitorum longus (EDL) muscle and the oxidative soleus muscle, which has an activity pattern that more closely resembles the diaphragm. Severe C-26 cancer cachexia caused significant muscle fiber atrophy and a reduction in maximum absolute force in both the EDL and soleus muscles. However, normalization to muscle cross sectional area further demonstrated a 13% decrease in maximum isometric specific force in the EDL and an even greater decrease (17%) in maximum isometric specific force in the soleus. Time to peak tension and half relaxation time were also significantly slowed in both the EDL and the solei from C-26 mice compared to controls. Since, in addition to postural control, the oxidative
Thomsen, GF; Johnson, PW; Svendsen, Susanne Wulff
ABSTRACT: BACKGROUND: To examine the hypothesis that forearm pain with palpation tenderness in computer users is associated with increased extensor muscle fatigue. METHODS: Eighteen persons with pain and moderate to severe palpation tenderness in the extensor muscle group of the right forearm...... response was not explained by differences in the MVC or body mass index. CONCLUSION: Computer users with forearm pain and moderate to severe palpation tenderness had diminished forearm extensor muscle fatigue response. Additional studies are necessary to determine whether this result reflects an adaptive...... and twenty gender and age matched referents without such complaints were enrolled from the Danish NUDATA study of neck and upper extremity disorders among technical assistants and machine technicians. Fatigue of the right forearm extensor muscles was assessed by muscle twitch forces in response to low...
Hopker, James G; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M
The [Formula: see text] slow component ([Formula: see text]) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min -1 . Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and [Formula: see text] determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue ( P = 0.03), the [Formula: see text] was not significantly different between the pre-fatigue (464 ± 301 mL·min -1 ) and the control (556 ± 223 mL·min -1 ) condition ( P = 0.50). Blood lactate response was not significantly different between conditions ( P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition ( P locomotor muscle fatigue does not significantly alter the [Formula: see text] kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the [Formula: see text] is strongly associated with locomotor muscle fatigue.
Full Text Available Studying muscle fatigue plays an important role in preventing the risks associated with musculoskeletal disorders. The effect of elbow-joint angle on time-frequency parameters during a repetitive motion provides valuable information in finding the most accurate position of the angle causing muscle fatigue. Therefore, the purpose of this study is to analyze the effect of muscle fatigue on the spectral and time-frequency domain parameters derived from electromyography (EMG signals using the Continuous Wavelet Transform (CWT. Four male participants were recruited to perform a repetitive motion (flexion and extension movements from a non-fatigue to fatigue condition. EMG signals were recorded from the biceps muscle. The recorded EMG signals were then analyzed offline using the complex Morlet wavelet. The time-frequency domain data were analyzed using the time-averaged wavelet spectrum (TAWS and the Scale-Average Wavelet Power (SAWP parameters. The spectral domain data were analyzed using the Instantaneous Mean Frequency (IMNF and the Instantaneous Mean Power Spectrum (IMNP parameters. The index of muscle fatigue was observed by calculating the increase of the IMNP and the decrease of the IMNF parameters. After performing a repetitive motion from non-fatigue to fatigue condition, the average of the IMNF value decreased by 15.69% and the average of the IMNP values increased by 84%, respectively. This study suggests that the reliable frequency band to detect muscle fatigue is 31.10-36.19Hz with linear regression parameters of 0.979mV^2Hz^(-1 and 0.0095mV^2Hz^(-1 for R^2 and slope, respectively.
Neefjes, Elisabeth C W; van den Hurk, Renske M; Blauwhoff-Buskermolen, Susanne; van der Vorst, Maurice J D L; Becker-Commissaris, Annemarie; de van der Schueren, Marian A E; Buffart, Laurien M; Verheul, Henk M W
Cancer-related fatigue (CRF) reduces quality of life and the activity level of patients with cancer. Cancer related fatigue can be reduced by exercise interventions that may concurrently increase muscle mass. We hypothesized that low muscle mass is directly related to higher CRF. A total of 233 patients with advanced cancer starting palliative chemotherapy for lung, colorectal, breast, or prostate cancer were studied. The skeletal muscle index (SMI) was calculated as the patient's muscle mass on level L3 or T4 of a computed tomography scan, adjusted for height. Fatigue was assessed with the Functional Assessment of Chronic Illness Therapy-fatigue questionnaire (cut-off for fatigue fatigue score was 36 (interquartile range 26-44). A higher SMI on level L3 was significantly associated with less CRF for men (B 0.447, P 0.004) but not for women (B - 0.401, P 0.090). No association between SMI on level T4 and the Functional Assessment of Chronic Illness Therapy-fatigue score was found (n = 82). The association between SMI and CRF may lead to the suggestion that male patients may be able to reduce fatigue by exercise interventions aiming at an increased muscle mass. In women with advanced cancer, CRF is more influenced by other causes, because it is not significantly related to muscle mass. To further reduce CRF in both men and women with cancer, multifactorial assessments need to be performed in order to develop effective treatment strategies. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.
Full Text Available This investigation aimed to determine the force and muscle surface electromyography (EMG responses to different frequencies of electrical stimulation (ES in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB and vastus lateralis (VL when activated by ES at three frequencies (10, 35, and 50Hz. Ten healthy adults (mean age: 23.2 ± 3.0 years were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1 identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC at each ES frequency and 2 evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05. However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.
Mademli, Lida; Arampatzis, Adamantios; Karamanidis, Kiros
Many studies report that muscle strength loss may alter the human system's capacity to generate rapid force for balance corrections after perturbations, leading to deficient recovery behaviours. Yet little is known regarding the effect of modifications in the neuromuscular system induced by fatigue on dynamic stability control during postural perturbations. This study investigates the effect of muscle strength decline induced by fatiguing contractions on the dynamic stability control of young and older adults during forward falls. Eleven young and eleven older male adults had to regain balance after sudden falls before and after submaximal fatiguing knee extension-flexion contractions. Young subjects had a higher margin of stability than older ones before and after the fatiguing task. This reflects their enhanced ability in using mechanisms for maintaining dynamic stability (i.e. a greater base of support). The margin of stability, the boundary of the base of support and the position of the extrapolated centre of mass, remained unaffected by the reduction in muscle strength induced by the fatiguing contractions, indicating an appropriate adjustment of the motor commands to compensate the deficit in muscle strength. Both young and older adults were able to counteract the decreased horizontal ground reaction forces after the fatiguing task by flexing their knee to a greater extent, leading to similar decreases in the horizontal velocity of centre of mass as in the pre fatigue condition. The results demonstrate the ability of the central nervous system to rapidly modify the execution of postural corrections including mechanisms for maintaining dynamic stability.
Chowdhury, Suman Kanti; Nimbarte, Ashish D; Jaridi, Majid; Creese, Robert C
Assessment of neuromuscular fatigue is essential for early detection and prevention of risks associated with work-related musculoskeletal disorders. In recent years, discrete wavelet transform (DWT) of surface electromyography (SEMG) has been used to evaluate muscle fatigue, especially during dynamic contractions when the SEMG signal is non-stationary. However, its application to the assessment of work-related neck and shoulder muscle fatigue is not well established. Therefore, the purpose of this study was to establish DWT analysis as a suitable method to conduct quantitative assessment of neck and shoulder muscle fatigue under dynamic repetitive conditions. Ten human participants performed 40min of fatiguing repetitive arm and neck exertions while SEMG data from the upper trapezius and sternocleidomastoid muscles were recorded. The ten of the most commonly used wavelet functions were used to conduct the DWT analysis. Spectral changes estimated using power of wavelet coefficients in the 12-23Hz frequency band showed the highest sensitivity to fatigue induced by the dynamic repetitive exertions. Although most of the wavelet functions tested in this study reasonably demonstrated the expected power trend with fatigue development and recovery, the overall performance of the "Rbio3.1" wavelet in terms of power estimation and statistical significance was better than the remaining nine wavelets. Copyright © 2013 Elsevier Ltd. All rights reserved.
Omar, Abdul Rahman; Saman, Alias Mohd; Othman, Ibrahim
Objectives The objectives of this study were to determine the psychological fatigue and analyze muscle activity of production workers who are performing processes jobs while standing for prolonged time periods. Methods The psychological fatigue experienced by the workers was obtained through questionnaire surveys. Meanwhile, muscle activity has been analyzed using surface electromyography (sEMG) measurement. Lower extremities muscles include: erector spinae, tibialis anterior, and gastrocnemius were concurrently measured for more than five hours of standing. Twenty male production workers in a metal stamping company participated as subjects in this study. The subjects were required to undergo questionnaire surveys and sEMG measurement. Results Results of the questionnaire surveys found that all subjects experienced psychological fatigue due to prolonged standing jobs. Similarly, muscle fatigue has been identified through sEMG measurement. Based on the non-parametric statistical test using the Spearman's rank order correlation, the left erector spinae obtained a moderate positive correlation and statistically significant (rs = 0.552, p fatigue and to muscle fatigue among the production workers. PMID:22953228
Søgaard, K; Blangsted, A K; Jørgensen, L V
The focus of the present study is the long term element of muscle fatigue provoked by prolonged intermittent contractions at submaximal force levels and analysed by force, surface electromyography (EMG) and mechanomyogram (MMG). It was hypothesized that fatigue related changes in mechanical...... performance of the biceps muscle are more strongly reflected in low than in high force test contractions, more prominent in the MMG than in the EMG signal and less pronounced following contractions controlled by visual compared to proprioceptive feedback. Further, it was investigated if fatigue induced by 30...... min intermittent contractions at 30% as well as 10% of maximal voluntary contraction (MVC) lasted more than 30 min recovery. In six male subjects the EMG and MMG were recorded from the biceps brachii muscle during three sessions with fatiguing exercise at 10% with visual feedback and at 30% MVC...
Stokes, M J; Colter, C; Klestov, A; Cooper, R G
Paraspinal muscle fatigue mechanisms were compared in 14 primary fibromyalgia patients and 14 age and sex matched normal subjects using a standardized 60-s isometric endurance test of the paraspinal muscles, during which surface integrated electromyographic (IEMG) activity was recorded. Fatigue-induced IEMG increases were similar for both groups during the initial 40 s (up to 112 +/- 20% and 111 +/- 6% of initial values in patients and normal subjects respectively). Thereafter, IEMG fell significantly in patients (P BMI, range 19-25 in controls) those with a BMI BMI > 26 (n = 9) showed greater IEMG declines after 40 s than either normal subjects or in the fibromyalgia group as a whole. Paraspinal muscle fatigue mechanisms appear normal in primary fibromyalgia patients. Isometric force maintenance in overweight patients, despite IEMG declines, illustrates the action of intrinsic fatigue resistance mechanisms which were presumably utilized to a greater extent in these patients to cope with the extra load.
McClung, Joseph M.; DeRuisseau, Keith C.; Whidden, Melissa A.; Van Remmen, Holly; Richardson, Arlan; Song, Wook; Vrabas, Ioannis S.; Powers, Scott K.
Low levels of reactive oxygen species (ROS) production are necessary to optimize muscle force production in unfatigued muscle. In contrast, sustained high levels of ROS production have been linked to impaired muscle force production and contraction-induced skeletal muscle fatigue. Using genetically engineered mice, we tested the hypothesis that the independent transgenic overexpression of catalase (CAT), copper/zinc superoxide dismutase (CuZnSOD; SOD1) or manganese superoxide dismutase (MnSOD; SOD2) antioxidant enzymes would negatively affect force production in unfatigued diaphragm muscle but would delay the development of muscle fatigue and enhance force recovery after fatiguing contractions. Diaphragm muscle from wild-type littermates (WT) and from CAT, SOD1 and SOD2 overexpressing mice were subjected to an in vitro contractile protocol to investigate the force–frequency characteristics, the fatigue properties and the time course of recovery from fatigue. The CAT, SOD1 and SOD2 overexpressors produced less specific force (in N cm−2) at stimulation frequencies of 20–300 Hz and produced lower maximal tetanic force than WT littermates. The relative development of muscle fatigue and recovery from fatigue were not influenced by transgenic overexpression of any antioxidant enzyme. Morphologically, the mean cross-sectional area (in μm2) of diaphragm myofibres expressing myosin heavy chain type IIA was decreased in both CAT and SOD2 transgenic animals, and the percentage of non-contractile tissue increased in diaphragms from all transgenic mice. In conclusion, our results do not support the hypothesis that overexpression of independent antioxidant enzymes protects diaphragm muscle from contraction-induced fatigue or improves recovery from fatigue. Moreover, our data are consistent with the concept that a basal level of ROS is important to optimize muscle force production, since transgenic overexpression of major cellular antioxidants is associated with
Norren, van K.; Helvoort, van A.; Agriles, J.M.; Tuijl, van S.; Arts, K.; Gorselink, M.; Laviano, A.; Kegler, D.; Haagsman, H.P.; Beek, van der E.M.
Chemotherapy-induced fatigue is a multidimensional symptom. Oxidative stress has been proposed as a working mechanism for anthracycline-induced cardiotoxicity. In this study, doxorubicin (DOX) was tested on skeletal muscle function. Doxorubicin induced impaired ex vivo skeletal muscle relaxation
Carregaro, Rodrigo; Cunha, Rafael; Oliveira, Carlos Gomes; Brown, Lee E.; Bottaro, Martim
Purpose: Preload of antagonist muscles can be achieved by reciprocal actions (RAs) or by opposing muscle actions. However, evidence concerning neuromuscular and fatigue responses are scarce. Objective: To compare the effects of different knee flexor (KF) preload methods on knee extension (KE) vastus
Full Text Available Abstract Background There are limited number of studies investigating extrapulmonary manifestations of bronchiectasis. The purpose of this study was to compare peripheral muscle function, exercise capacity, fatigue, and health status between patients with bronchiectasis and healthy subjects in order to provide documented differences in these characteristics for individuals with and without bronchiectasis. Methods Twenty patients with bronchiectasis (43.5 ± 14.1 years and 20 healthy subjects (43.0 ± 10.9 years participated in the study. Pulmonary function, respiratory muscle strength (maximal expiratory pressure – MIP - and maximal expiratory pressure - MEP, and dyspnea perception using the Modified Medical Research Council Dyspnea Scale (MMRC were determined. A six-minute walk test (6MWT was performed. Quadriceps muscle, shoulder abductor, and hand grip strength (QMS, SAS, and HGS, respectively using a hand held dynamometer and peripheral muscle endurance by a squat test were measured. Fatigue perception and health status were determined using the Fatigue Severity Scale (FSS and the Leicester Cough Questionnaire (LCQ, respectively. Results Number of squats, 6MWT distance, and LCQ scores as well as lung function testing values and respiratory muscle strength were significantly lower and MMRC and FSS scores were significantly higher in patients with bronchiectasis than those of healthy subjects (p p p p p Conclusions Peripheral muscle endurance, exercise capacity, fatigue and health status were adversely affected by the presence of bronchiectasis. Fatigue was associated with dyspnea and health status. Respiratory muscle strength was related to peripheral muscle strength and health status, but not to fatigue, peripheral muscle endurance or exercise capacity. These findings may provide insight for outcome measures for pulmonary rehabilitation programs for patients with bronchiectasis.
Evelyne Patrícia Fernandes Lima
Full Text Available INTRODUÇÃO - A flacidez muscular surge com maior frequência nas mulheres, o que causa fator ruim para a estética corporal. OBJETIVO - Analisar os resultados da corrente russa no fortalecimento da musculatura abdominal. MÉTODOS - Revisão bibliográfica com base nas publicações acessíveis pelas seguintes bases de dados: Medline/Pubmed, Scielo, Lilacs com cruzamento dos descritores corrente russa, flacidez, abdômen. O uso da eletroestimulação age tanto sobre as fibras brancas, que respondem pela velocidade, como também sobre as fibras vermelhas dado à sua sustentação, e ainda sobre as fibras intermediárias. CONCLUSÃO - Os dados publicados mostram a satisfação e êxito do tratamento, enfatizando que a corrente russa favorece o aumento da hipertrofia e força muscular.INTRODUCTION - Muscle weakness appears most often in women, the factor that causes bad esthetics. OBJECTIVE - To analyze the results of the Russian current strengthening the abdominal muscles. METHODS - Literature review based on publications available in the following databases: Medline / Pubmed, Scielo, Lilacs with crossing headings Russian current, sagging, abdomen. The use of electrical stimulation acts both on the white fibers, which account for the speed, but also on the red fibers given their support, and on intermediate fibers. CONCLUSION - The data published show the satisfaction and success of treatment, emphasizing that the Russian current promotes increase of muscle strength and hypertrophy.
Harmsen, Wouter J; Ribbers, Gerard M; Zegers, Bart; Sneekes, Emiel M; Praet, Stephan F E; Heijenbrok-Kal, Majanka H; Khajeh, Ladbon; van Kooten, Fop; Neggers, Sebastiaan J C M M; van den Berg-Emons, Rita J
Patients with aneurysmal subarachnoid hemorrhage (a-SAH) show long-term fatigue and face difficulties in resuming daily physical activities. Impaired muscle strength, especially of the lower extremity, impacts the performance of daily activities and may trigger the onset of fatigue complaints. The present study evaluated knee muscle strength and fatigue in patients with a-SAH. This study included 33 patients, 6 months after a-SAH, and 33 sex-matched and age-matched healthy controls. Isokinetic muscle strength of the knee extensors and flexors was measured at 60 and 180°/s. Maximal voluntary muscle strength was defined as peak torque and measured in Newton-meter. Fatigue was examined using the Fatigue Severity Scale. In patients with a-SAH, the maximal knee extension was 22% (60°/s) and 25% (180°/s) lower and maximal knee flexion was 33% (60°/s) and 36% (180°/s) lower compared with that of matched controls (P≤0.001). The Fatigue Severity Scale score was related to maximal knee extension (60°/s: r=-0.426, P=0.015; 180°/s: r=-0.376, P=0.034) and flexion (60°/s: r=-0.482, P=0.005; 180°/s: r=-0.344, P=0.083). The knee muscle strength was 28-47% lower in fatigued (n=13) and 11-32% lower in nonfatigued (n=20) patients; deficits were larger in fatigued patients (P<0.05), particularly when the muscle strength (peak torque) was measured at 60°/s. The present results indicate that patients with a-SAH have considerably impaired knee muscle strength, which is related to more severe fatigue. The present findings are exploratory, but showed that knee muscle strength may play a role in the severity of fatigue complaints, or vice versa. Interventions targeting fatigue after a-SAH seem necessary and may consider strengthening exercise training in order to treat a debilitating condition.
Sara Abolahrari Shirazi
Full Text Available Background: Hyperlordosis is defined as an abnormal increase in the lumbar arch of >40°. This study compared two taping techniques include abdominal muscles and hamstrings taping for the treatment of lumbar hyperlordosis. Materials and Methods: The randomized clinical trial was performed in Shiraz, Iran, during June and September 2014. Thirty women aged 20–45 years old with at least 40° lumbar lordosis participated. The women were randomized into two groups (n = 15. Abdominal muscles taping was performed for the first group, whereas the other group underwent hamstrings taping with 30% tension. Lumbar lordosis was measured before, immediately after, and 24 h after taping. The two-way repeated measures analysis of variance was used to compare the two groups for lumbar lordosis angle. Results: No significant differences were detected between the lumbar lordosis angles before and immediately after taping in the two groups (P > 0.05. However, a significant reduction was observed in lordosis angle in the abdominal group and the hamstring group 24 h after taping relative to before intervention (P < 0.01. Conclusion: Taping of the abdominal and hamstring muscles was not effective immediately, whereas it decreased lordosis after 24 h.
Papa, Evan V.; Foreman, K. Bo; Dibble, Lee E.
BACKGROUND Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. METHODS A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-minutes (T15) and 30-minutes (T30) of rest. FINDINGS Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. INTERPRETATION Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 minutes of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. PMID:26351001
Papa, Evan V; Foreman, K Bo; Dibble, Leland E
Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-min (T15) and 30-min (T30) of rest. Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 min of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. Copyright © 2015 Elsevier Ltd. All rights reserved.
Chang, Kang-Ming; Liu, Shin-Hong; Wu, Xuan-Han
Surface electromyography (sEMG) is an important measurement for monitoring exercise and fitness. Because if its high sampling frequency requirement, wireless transmission of sEMG data is a challenge. In this article a wireless sEMG measurement system with a sampling frequency of 2 KHz is developed based upon a MSP 430 microcontroller and Bluetooth transmission. Standard isotonic and isometric muscle contraction are clearly represented in the receiving user interface. Muscle fatigue detection is an important application of sEMG. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. A more negative slope value represents a higher muscle fatigue condition. To test the system performance, muscle fatigue detection was examined by having subjects run on a pedaled-multifunctional elliptical trainer for approximately 30 minutes at three loading levels. Ten subjects underwent a total of 60 exercise sessions to provide the experimental data. Results showed that the regression slope gradually decreases as expected, and there is a significant gender difference. PMID:22368481
Full Text Available Surface electromyography (sEMG is an important measurement for monitoring exercise and fitness. Because if its high sampling frequency requirement, wireless transmission of sEMG data is a challenge. In this article a wireless sEMG measurement system with a sampling frequency of 2 KHz is developed based upon a MSP 430 microcontroller and Bluetooth transmission. Standard isotonic and isometric muscle contraction are clearly represented in the receiving user interface. Muscle fatigue detection is an important application of sEMG. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. A more negative slope value represents a higher muscle fatigue condition. To test the system performance, muscle fatigue detection was examined by having subjects run on a pedaled-multifunctional elliptical trainer for approximately 30 minutes at three loading levels. Ten subjects underwent a total of 60 exercise sessions to provide the experimental data. Results showed that the regression slope gradually decreases as expected, and there is a significant gender difference.
Guo, Feng; Sun, Yong-Jun; Zhang, Ri-Hui
The aim of this study was to explore the mechanism on perceived exertion during muscle fatigue. A total of 15 individuals in the fatigue group and 13 individuals in the nonfatigue group were recruited into this study, performing 200 intermittent handgrip contractions with 30% maximal voluntary contraction. The force, surface electromyography (sEMG), movement-related cortical potentials (MRCPs), and rating perception of effort (RPE) were combined to evaluate the perceived exertion during muscle fatigue. The maximal handgrip force significantly decreased (Pfatigue. The RPE scores reported by the individuals and the motor potential amplitude of MRCPs in the fatigue group significantly increased (Pfatigue but could also reflect the peripheral local muscle fatigue.
Kothiyal, K P; Ibramsha, M
Fatigue in muscle is a complex biological phenomenon which has so far eluded a definite explanation. Many biochemical and physiological models have been suggested in the literature to account for the decrement in the ability of muscle to sustain a given level of force for a long time. Some of these models have been critically analysed in this paper and are shown to be not able to explain all the experimental observations. A new compartmental model based on the intracellular calcium ion movement in muscle is proposed to study the mechanical responses of a muscle fibre. Computer simulation is performed to obtain model responses in isometric contraction to an impulse and a train of stimuli of long duration. The simulated curves have been compared with experimentally observed mechanical responses of the semitendinosus muscle fibre of Rana pipiens. The comparison of computed and observed responses indicates that the proposed calcium ion model indeed accounts very well for the muscle fatigue.
del Pozo-Cruz, Borja; Mocholi, Miguel H; del Pozo-Cruz, Jesus; Parraca, Jose A; Adsuar, Jose C; Gusi, Narcis
Despite the widespread use of trunk endurance tests, the reliability and validity of these tests in office workers with subacute nonspecific low back pain are unknown. This cross-sectional study involved 190 subjects: 30 men and 42 women without low back pain and 47 men and 71 women with low back pain. All subjects underwent timed prone and supine isometric lumbar and abdominal trunk endurance tests that were performed until subjective fatigue occurred. All subjects also completed the Roland Morris and Oswestry self-reported disability questionnaires. A test-retest study (7 days) was conducted with 31 participants with low back pain from the study. For the abdominal trunk endurance test, males and females with low back pain had mean (SD) values of 62.06 (36.87) and 46.06 (29.28) seconds, respectively, both significantly lower than the asymptomatic workers. For the lumbar test, males and females with low back pain had mean (SD) values of 79.57 (30.66) and 75.49 (28.97) seconds, respectively, again, both significantly lower than the asymptomatic workers. The intraclass correlation coefficients of both tests exceeded 0.90 and the Kappa indices were excellent for both men and women. Receiver-operating curve analyses revealed areas under the curve very close to or exceeding 0.70 for both men and women for both tests. The lumbar and abdominal trunk muscle endurance tests appeared to be reliable and valid measures in office workers with subacute low back pain.
Macdonald, W A; Stephenson, D G
Slow-twitch mechanically skinned fibres from rat soleus muscle were bathed in solutions mimicking the myoplasmic environment but containing different [ADP] (0.1 microm to 1.0 mm). The effect of ADP on sarcoplasmic reticulum (SR) Ca2+-content was determined from the magnitude of caffeine-induced force responses, while temporal changes in SR Ca2+-content allowed determination of the effective rates of the SR Ca2+-pump and of the SR Ca2+-leak. The SR Ca2+-pump rate, estimated at pCa (-log10[Ca2+]) 7.8, was reduced by 20% as the [ADP] was increased from 0.1 to 40 microm, with no further alteration when the [ADP] was increased to 1.0 mm. The SR Ca2+-leak rate constant was not altered by increasing [ADP] from 0.1 to 40 microm, but was increased by 26% when the [ADP] was elevated to 1.0 mm. This ADP-induced SR Ca2+-leak was insensitive to ruthenium red but was abolished by 2,5-di(tert-butyl)-1,4-hydroquinone (TBQ), indicating that the leak pathway is via the SR Ca2+-pump and not the SR Ca2+-release channel. The decrease in SR Ca2+-pump rate and SR Ca2+-leak rate when [ADP] was increased led to a 40% decrease in SR Ca2+-loading capacity. Elevation of [ADP] had only minor direct effects on the contractile apparatus of slow-twitch fibres. These results suggest that ADP has only limited depressing effects on the contractility of slow-twitch muscle fibres. This is in contrast to the marked effects of ADP on force responses in fast-twitch muscle fibres and may contribute to the fatigue-resistant nature of slow-twitch muscle fibres.
Larkin-Kaiser, Kelly A; Borsa, Paul A; Baweja, Harsimran S; Moore, Molly A; Tillman, Mark D; George, Steven Z; Christou, Evangelos A
Photobiomodulation (PBM) therapy has been implicated as an effective ergogenic aid to delay the onset of muscle fatigue. The purpose of this study was to examine the dose-response ergogenic properties of PBM therapy and its ability to prolong time to task failure by enhancing muscle activity and delaying the onset of muscle fatigue using a static positioning task. Nine participants (24.3 ± 4.9 years) received three doses of near-infrared (NIR) light therapy randomly on three separate sessions (sham, 240, and 480 J). For the positioning task, participants held a 30 % one-repetition maximum (1-RM) load using the index finger until volitional fatigue. Surface electromyography (sEMG) of the first dorsal interosseous muscle was recorded for the length of the positioning task. Outcomes included time to task failure (TTF), muscle fatigue, movement accuracy, motor output variability, and muscle activity (sEMG). The 240-J dose significantly extended TTF by 26 % (p = 0.032) compared with the sham dose. TTF for the 240-J dose was strongly associated with a decrease in muscle fatigue (R (2) = 0.54, p = 0.024). Our findings show that a 240-J dose of NIR light therapy is efficacious in delaying the onset and extent of muscle fatigue during submaximal isometric positioning tasks. Our findings suggest that NIR light therapy may be used as an ergogenic aid during functional tasks or post-injury rehabilitation.
Pietrangelo, T; Toniolo, L; Paoli, A; Fulle, S; Puglielli, C; Fanò, G; Reggiani, C
Chronic fatigue syndrome (CFS) is a disabling condition characterized by unexplained chronic fatigue that impairs normal activities. Although immunological and psychological aspects are present, symptoms related to skeletal muscles, such as muscle soreness, fatigability and increased lactate accumulation, are prominent in CFS patients. In this case-control study, the phenotype of the same biopsy samples was analyzed by determining i) fibre-type proportion using myosin isoforms as fibre type molecular marker and gel electrophoresis as a tool to separate and quantify myosin isoforms, and ii) contractile properties of manually dissected, chemically made permeable and calcium-activated single muscle fibres. The results showed that fibre-type proportion was significantly altered in CSF samples, which showed a shift from the slow- to the fast-twitch phenotype. Cross sectional area, force, maximum shortening velocity and calcium sensitivity were not significantly changed in single muscle fibres from CSF samples. Thus, the contractile properties of muscle fibres were preserved but their proportion was changed, with an increase in the more fatigue-prone, energetically expensive fast fibre type. Taken together, these results support the view that muscle tissue is directly involved in the pathogenesis of CSF and it might contribute to the early onset of fatigue typical of the skeletal muscles of CFS patients.
Cashaback, Joshua G A; Cluff, Tyler; Potvin, Jim R
Nonlinear dynamical techniques offer a powerful approach for the investigation of physiological time series. Multiscale entropy analyses have shown that pathological and aging systems are less complex than healthy systems and this finding has been attributed to degraded physiological control processes. A similar phenomenon may arise during fatiguing muscle contractions where surface electromyography signals undergo temporal and spectral changes that arise from the impaired regulation of muscle force production. Here we examine the affect of fatigue and contraction intensity on the short and long-term complexity of biceps brachii surface electromyography. To investigate, we used an isometric muscle fatigue protocol (parsed into three windows) and three contraction intensities (% of maximal elbow joint moment: 40%, 70% and 100%). We found that fatigue reduced the short-term complexity of biceps brachii activity during the last third of the fatiguing contraction. We also found that the complexity of surface electromyography is dependent on contraction intensity. Our results show that multiscale entropy is sensitive to muscle fatigue and contraction intensity and we argue it is imperative that both factors be considered when evaluating the complexity of surface electromyography signals. Our data contribute to a converging body of evidence showing that multiscale entropy can quantify subtle information content in physiological time series. Copyright © 2012 Elsevier Ltd. All rights reserved.
Contessa, Paola; De Luca, Carlo J; Kline, Joshua C
Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. Copyright © 2016 the American Physiological Society.
Coelho, A C; Cannon, D T; Cao, R; Porszasz, J; Casaburi, R; Knorst, M M; Rossiter, H B
A rapid switch from hyperbolic to isokinetic cycling allows the velocity-specific decline in maximal power to be measured, i.e., fatigue. We reasoned that, should the baseline relationship between isokinetic power (Piso) and electromyography (EMG) be reproducible, then contributions to fatigue may be isolated from 1) the decline in muscle activation (muscle activation fatigue); and 2) the decline in Piso at a given activation (muscle fatigue). We hypothesized that the EMG-Piso relationship is linear, velocity dependent, and reliable for instantaneous fatigue assessment at intolerance during and following whole body exercise. Healthy participants (n = 13) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize baseline EMG-Piso. Repeated ramp incremental exercise tests were terminated with maximal isokinetic cycling (5 s) at 70 rpm. Individual baseline EMG-Piso relationships were linear (r(2) = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Piso at intolerance (two legs, 335 ± 88 W) was ∼45% less than baseline [630 ± 156 W, confidence interval of the difference (CIDifference) 211, 380 W, P fatigue and muscle fatigue (one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias ± limits of agreement for reproducibility were as follows: baseline Piso 1 ± 30 W; Piso at 0-min recovery 3 ± 35 W; and EMG at Piso 3 ± 14%. EMG power is linear, velocity dependent, and reproducible. Deviation from this relationship at the limit of tolerance can quantify the "activation" and "muscle" related components of fatigue during cycling. Copyright © 2015 the American Physiological Society.
During each session, postural control was assessed during two 30-s trials of bipedal stance with eyes close before and after the fatigue protocol. Fatigue protocols were performed by 60% of their unfatigued Maximum Voluntary Contraction of unilateral ankle plantar flexors, bilateral lumbar extensors and bilateral neck ...
... of the same muscles during the activity. However, conventional ergometric testing modes such as stationary cycling or treadmill exercise do not readily lend themselves to quantitating the progressive increase in muscle fatigue...
Allahyari, Teimour; Mortazavi, Narges; Khalkhali, Hamid Reza; Sanjari, Mohammad Ali
Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10). Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.
Pajoutan, Mojdeh; Ghesmaty Sangachin, Mahboobeh; Cavuoto, Lora A
Fatigue increases the likelihood of developing work-related musculoskeletal disorders and injury. Due to the physiological and neuromuscular changes that accompany obesity, it may alter the fatigue development mechanism and exacerbate injury risk. The upper extremities have the highest incidence rates for work-related musculoskeletal disorders. Therefore, the goals of this study were to investigate the effect of obesity on central vs. peripheral fatigue as well as on the physical signs of fatigue on the middle deltoid muscle. A measure of central activation ratio was used to quantify central fatigue by considering the increment in the torque output by superimposed twitch relative to its corresponding maximum voluntary contraction. For this purpose, electrical stimulation was delivered at the middle deltoid muscles of 22 non-obese (18 obese (30 motor units (p = 0.001) with fatigue was observed for individuals who are obese. Contrary to the effect of obesity on central fatigue, a trend toward reduced peripheral fatigue (p = 0.06) was observed for the obese group compared to the non-obese group. On average, a 14% higher rate of torque loss per second was observed among individuals with obesity in comparison to non-obese participants. The observed greater contribution of central fatigue during the sustained endurance tasks suggests that among young healthy obese individuals, the faster fatigue development with obesity, commonly reported in the literature, is most likely due to the central elements rather than the peripheral factors. This finding has implications for fatigue prevention programs during sustained exertions and can help to develop training, work, and rest schedules considering obesity.
Lee, Yun-Ju; Hoozemans, Marco J M; van Dieën, Jaap H
Cyclic activation of the external and internal oblique muscles contributes to twisting moments during normal gait. During pushing while walking, it is not well understood how these muscles respond to presence of predictable (cyclic push-off forces) and unpredictable (external) perturbations that occur in pushing tasks. We hypothesized that the predictable perturbations due to the cyclic push-off forces would be associated with cyclic muscle activity, while external perturbations would be counteracted by cocontraction of the oblique abdominal muscles. Eight healthy male subjects pushed at two target forces and two handle heights in a static condition and while walking without and with external perturbations. For all pushing tasks, the median, the static (10th percentile) and the peak levels (90th percentile) of the electromyographic amplitudes were determined. Linear models with oblique abdominal EMGs and trunk angles as input were fit to the twisting moments, to estimate trunk stiffness. There was no significant difference between the static EMG levels in pushing while walking compared to the peak levels in pushing while standing. When pushing while walking, the additional dynamic activity was associated with the twisting moments, which were actively modulated by the pairs of oblique muscles as in normal gait. The median and static levels of trunk muscle activity and estimated trunk stiffness were significantly higher when perturbations occurred than without perturbations. The increase baseline of muscle activity indicated cocontraction of the antagonistic muscle pairs. Furthermore, this cocontraction resulted in an increased trunk stiffness around the longitudinal axis. Copyright 2010 Elsevier Ltd. All rights reserved.
Koutsos, Ermis; Cretu, Vlad; Georgiou, Pantelis
Electromyography analysis can provide information about a muscle's fatigue state by estimating Muscle Fibre Conduction Velocity (MFCV), a measure of the travelling speed of Motor Unit Action Potentials (MUAPs) in muscle tissue. MFCV better represents the physical manifestations of muscle fatigue, compared to the progressive compression of the myoelectic Power Spectral Density, hence it is more suitable for a muscle fatigue tracking system. This paper presents a novel algorithm for the estimation of MFCV using single threshold bit-stream conversion and a dedicated application-specified integrated circuit (ASIC) for its implementation, suitable for a compact, wearable and easy to use muscle fatigue monitor. The presented ASIC is implemented in a commercially available AMS 0.35 [Formula: see text] CMOS technology and utilizes a bit-stream cross-correlator that estimates the conduction velocity of the myoelectric signal in real time. A test group of 20 subjects was used to evaluate the performance of the developed ASIC, achieving good accuracy with an error of only 3.2% compared to Matlab.
Dominelli, Paolo B; Molgat-Seon, Yannick; Griesdale, Donald E G; Peters, Carli M; Blouin, Jean-Sébastien; Sekhon, Mypinder; Dominelli, Giulio S; Henderson, William R; Foster, Glen E; Romer, Lee M; Koehle, Michael S; Sheel, A William
High work of breathing and exercise-induced arterial hypoxaemia (EIAH) can decrease O 2 delivery and exacerbate exercise-induced quadriceps fatigue in healthy men. Women have a higher work of breathing during exercise, dedicate a greater fraction of whole-body V̇O2 towards their respiratory muscles and develop EIAH. Despite a greater reduction in men's work of breathing, the attenuation of quadriceps fatigue was similar between the sexes. The degree of EIAH was similar between sexes, and regardless of sex, those who developed the greatest hypoxaemia during exercise demonstrated the most attenuation of quadriceps fatigue. Based on our previous finding that women have a greater relative oxygen cost of breathing, women appear to be especially susceptible to work of breathing-related changes in quadriceps muscle fatigue. Reducing the work of breathing or eliminating exercise-induced arterial hypoxaemia (EIAH) during exercise decreases the severity of quadriceps fatigue in men. Women have a greater work of breathing during exercise, dedicate a greater fraction of whole-body V̇O2 towards their respiratory muscles, and demonstrate EIAH, suggesting women may be especially susceptible to quadriceps fatigue. Healthy subjects (8 male, 8 female) completed three constant load exercise tests over 4 days. During the first (control) test, subjects exercised at ∼85% of maximum while arterial blood gases and work of breathing were assessed. Subsequent constant load exercise tests were iso-time and iso-work rate, but with EIAH prevented by inspiring hyperoxic gas or work of breathing reduced via a proportional assist ventilator (PAV). Quadriceps fatigue was assessed by measuring force in response to femoral nerve stimulation. For both sexes, quadriceps force was equally reduced after the control trial (-27 ± 2% baseline) and was attenuated with hyperoxia and PAV (-18 ± 1 and -17 ± 2% baseline, P Physiology © 2017 The Physiological Society.
Full Text Available This study aimed to investigate the fatiguing characteristics of muscle-tendon units (MTUs within skeletal muscles during static isometric contraction tasks. The deltoid was selected as the target muscle and three head-related static isometric contraction tasks were designed to activate three heads of the deltoid in different modes. Nine male subjects participated in this study. Surface electromyography (SEMG signals were collected synchronously from the three heads of the deltoid. The performances of five SEMG parameters, including root mean square (RMS, mean power frequency (MPF, the first coefficient of autoregressive model (ARC1, sample entropy (SE and Higuchi’s fractal dimension (HFD, in quantification of fatigue, were evaluated in terms of sensitivity to variability ratio (SVR and consistency firstly. Then, the HFD parameter was selected as the fatigue index for further muscle fatigue analysis. The experimental results demonstrated that the three deltoid heads presented different activation modes during three head-related fatiguing contractions. The fatiguing characteristics of the three heads were found to be task-dependent, and the heads kept in a relatively high activation level were more prone to fatigue. In addition, the differences in fatiguing rate between heads increased with the increase in load. The findings of this study can be helpful in better understanding the underlying neuromuscular control strategies of the central nervous system (CNS. Based on the results of this study, the CNS was thought to control the contraction of the deltoid by taking the three heads as functional units, but a certain synergy among heads might also exist to accomplish a contraction task.
McKenna, Michael J; Bangsbo, Jens; Renaud, Jean-Marc
(+)-ATPase activity during exercise stabilizes Na(+) and K(+) concentration gradients and membrane excitability and thus protects against fatigue. However, during intense contraction some Na(+)-K(+) pumps are inactivated and together with further ionic disturbances, likely precipitate muscle fatigue.......Membrane excitability is a critical regulatory step in skeletal muscle contraction and is modulated by local ionic concentrations, conductances, ion transporter activities, temperature, and humoral factors. Intense fatiguing contractions induce cellular K(+) efflux and Na(+) and Cl(-) influx......, causing pronounced perturbations in extracellular (interstitial) and intracellular K(+) and Na(+) concentrations. Muscle interstitial K(+) concentration may increase 1- to 2-fold to 11-13 mM and intracellular K(+) concentration fall by 1.3- to 1.7-fold; interstitial Na(+) concentration may decline by 10 m...
KENT-BRAUN, JANE A.; CALLAHAN, DAMIEN M.; FAY, JESSICA L.; FOULIS, STEPHEN A.; BUONACCORSI, JOHN P.
Introduction Whereas deficits in muscle function, particularly power production, develop in old age and are risk factors for mobility impairment, a complete understanding of muscle fatigue during dynamic contractions is lacking. We tested hypotheses related to torque-producing capacity, fatigue resistance, and variability of torque production during repeated maximal contractions in healthy older, mobility-impaired older, and young women. Methods Knee extensor fatigue (decline in torque) was measured during 4 min of dynamic contractions. Torque variability was characterized using a novel 4-component logistic regression model. Results Young women produced more torque at baseline and during the protocol than older women (P torque variability differed by group (P = 0.022) and was greater in older impaired compared with young women (P = 0.010). Conclusions These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments. PMID:23674266
Kahl, Lorenz; Hofmann, Ulrich G
This work compared the performance of six different fatigue detection algorithms quantifying muscle fatigue based on electromyographic signals. Surface electromyography (sEMG) was obtained by an experiment from upper arm contractions at three different load levels from twelve volunteers. Fatigue detection algorithms mean frequency (MNF), spectral moments ratio (SMR), the wavelet method WIRM1551, sample entropy (SampEn), fuzzy approximate entropy (fApEn) and recurrence quantification analysis (RQA%DET) were calculated. The resulting fatigue signals were compared considering the disturbances incorporated in fatiguing situations as well as according to the possibility to differentiate the load levels based on the fatigue signals. Furthermore we investigated the influence of the electrode locations on the fatigue detection quality and whether an optimized channel set is reasonable. The results of the MNF, SMR, WIRM1551 and fApEn algorithms fell close together. Due to the small amount of subjects in this study significant differences could not be found. In terms of disturbances the SMR algorithm showed a slight tendency to out-perform the others. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.
Full Text Available Abstract Background Side bridge endurance protocols have been suggested to evaluate lateral trunk flexor and/or spine stabilizer muscles. To date, no study has investigated muscle recruitment and fatigability during these protocols. Therefore the purpose of our study was to quantify fatigue parameters in various trunk muscles during a modified side bridge endurance task (i.e. a lateral isometric hold test on a 45° roman chair apparatus and determine which primary trunk muscles get fatigued during this task. It was hypothesized that the ipsilateral external oblique and lumbar erector spinae muscles will exhibit the highest fatigue indices. Methods Twenty-two healthy subjects participated in this study. The experimental session included left and right lateral isometric hold tasks preceded and followed by 3 maximal voluntary contractions in the same position. Surface electromyography (EMG recordings were obtained bilaterally from the external oblique, rectus abdominis, and L2 and L5 erector spinae. Statistical analysis were conducted to compare the right and left maximal voluntary contractions (MVC, surface EMG activities, right vs. left holding times and decay rate of the median frequency as the percent change from the initial value (NMFslope. Results No significant left and right lateral isometric hold tests differences were observed neither for holding times (97.2 ± 21.5 sec and 96.7 ± 24.9 sec respectively nor for pre and post fatigue root mean square during MVCs. However, participants showed significant decreases of MVCs between pre and post fatigue measurements for both the left and right lateral isometric hold tests. Statistical analysis showed that a significantly NMFslope of the ipsilateral external oblique during both conditions, and a NMFslope of the contralateral L5 erector spinae during the left lateral isometric hold test were steeper than those of the other side’s respective muscles. Although some participants
Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles
In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.
Shields, Richard K; Chang, Ya-Ju; Dudley-Javoroski, Shauna; Lin, Cheng-Hsiang
The fatigability of paralyzed muscle limits its ability to deliver physiological loads to paralyzed extremities during repetitive electrical stimulation. The purposes of this study were to determine the reliability of measuring paralyzed muscle fatigue and to develop a model to predict the temporal changes in muscle fatigue that occur after spinal cord injury (SCI). Thirty-four subjects underwent soleus fatigue testing with a modified Burke electrical stimulation fatigue protocol. The between-day reliability of this protocol was high (intraclass correlation, 0.96). We fit the fatigue index (FI) data to a quadratic-linear segmental polynomial model. FI declined rapidly (0.3854 per year) for the first 1.7 years, and more slowly (0.01 per year) thereafter. The rapid decline of FI immediately after SCI implies that a "window of opportunity" exists for the clinician if the goal is to prevent these changes. Understanding the timing of change in muscle endurance properties (and, therefore, load-generating capacity) after SCI may assist clinicians when developing therapeutic interventions to maintain musculoskeletal integrity.
Full Text Available This study has developed a technique for identifying the presence of muscle fatigue based on the spatial changes of the normalised mutual information (NMI between multiple high density surface electromyography (HD-sEMG channels. Muscle fatigue in the tibialis anterior (TA during isometric contractions at 40% and 80% maximum voluntary contraction levels was investigated in ten healthy participants (Age range: 21 to 35 years; Mean age = 26 years; Male = 4, Female = 6. HD-sEMG was used to record 64 channels of sEMG using a 16 by 4 electrode array placed over the TA. The NMI of each electrode with every other electrode was calculated to form an NMI distribution for each electrode. The total NMI for each electrode (the summation of the electrode’s NMI distribution highlighted regions of high dependence in the electrode array and was observed to increase as the muscle fatigued. To summarise this increase, a function, M(k, was defined and was found to be significantly affected by fatigue and not by contraction force. The technique discussed in this study has overcome issues regarding electrode placement and was used to investigate how the dependences between sEMG signals within the same muscle change spatially during fatigue.
Full Text Available In this work, an attempt has been made to differentiate muscle non-fatigue and fatigue conditions using sEMG signals and texture representation of the time-frequency images. The sEMG signals are recorded from the biceps brachii muscle of 25 healthy adult volunteers during dynamic fatiguing contraction. The first and last curls of these signals are considered as the non-fatigue and fatigue zones, respectively. These signals are preprocessed and the time-frequency spectrum is computed using short time fourier transform (STFT. Gray-Level Co-occurrence Matrix (GLCM is extracted from low (15–45 Hz, medium (46–95 Hz and high (96–150 Hz frequency bands of the time-frequency images. Further, the features such as contrast, correlation, energy and homogeneity are calculated from the resultant matrices. The results show that the high frequency band based features are able to differentiate non-fatigue and fatigue conditions. The features such as correlation, contrast and homogeneity extracted at angles 0°, 45°, 90°, and 135° are found to be distinct with high statistical significance (p < 0.0001. Hence, this framework can be used for analysis of neuromuscular disorders.
Full Text Available Repetitive or prolonged muscle contractions induce muscular fatigue, defined as the inability of the muscle to maintain the initial tension or power output. In the present experiments, made on intact fiber bundles from FDB mouse, fatigue and recovery from fatigue were investigated at 24°C and 35°C. Force and stiffness were measured during tetani elicited every 90 s during the pre-fatigue control phase and recovery and every 1.5 s during the fatiguing phase made of 105 consecutive tetani. The results showed that force decline could be split in an initial phase followed by a later one. Loss of force during the first phase was smaller and slower at 35°C than at 24°C, whereas force decline during the later phase was greater at 35°C so that total force depression at the end of fatigue was the same at both temperatures. The initial force decline occurred without great reduction of fiber stiffness and was attributed to a decrease of the average force per attached crossbridge. Force decline during the later phase was accompanied by a proportional stiffness decrease and was attributed to a decrease of the number of attached crossbridge. Similarly to fatigue, at both 24 and 35°C, force recovery occurred in two phases: the first associated with the recovery of the average force per attached crossbridge and the second due to the recovery of the pre-fatigue attached crossbridge number. These changes, symmetrical to those occurring during fatigue, are consistent with the idea that, i initial phase is due to the direct fast inhibitory effect of [Pi]i increase during fatigue on crossbridge force; ii the second phase is due to the delayed reduction of Ca(2+ release and /or reduction of the Ca(2+ sensitivity of the myofibrils due to high [Pi]i.
Bülow, P M; Nørregaard, J; Mehlsen, J
The aim of the study was to examine if the twitch interpolation technique could be used to objectively measure fatigue in the quadriceps muscle in subjects performing submaximally. The 'true' maximum isometric quadriceps torque was determined in 21 healthy subject using the twitch interpolation...... technique. Then an endurance test was performed in which the subjects made repeated isometric contractions at 50% of the 'true' maximum torque for 4 s, separated by 6 s rest periods. During the test, the force response to single electrical stimulation (twitch amplitude) was measured at 50% and 25......). In conclusion, the twitch technique can be used for objectively measuring fatigue of the quadriceps muscle....
Herrera, V; Romero, J F; Amestegui, M
This work propose a detection and alert algorithm for muscle fatigue in paraplegic patients undergoing electro-therapy sessions. The procedure is based on a mathematical chaotic model emulating physiological signals and Continuous Wavelet Transform (CWT). The chaotic model developed is based on a logistic map that provides suitable data accomplishing some physiological signal class patterns. The CWT was applied to signals generated by the model and the resulting vector was obtained through Total Wavelet Entropy (TWE). In this sense, the presented work propose a viable and practical alert and detection algorithm for muscle fatigue.
Herrera, V; Romero, J F [Engineering, Modeling and Applied Social Sciences Center, ABC Federal University, Santo Andr - SP (Brazil); Amestegui, M, E-mail: firstname.lastname@example.org [Engineering Faculty, Electronics Engineering, Universidad Mayor de San Andres, La Paz (Bolivia, Plurinational State of)
This work propose a detection and alert algorithm for muscle fatigue in paraplegic patients undergoing electro-therapy sessions. The procedure is based on a mathematical chaotic model emulating physiological signals and Continuous Wavelet Transform (CWT). The chaotic model developed is based on a logistic map that provides suitable data accomplishing some physiological signal class patterns. The CWT was applied to signals generated by the model and the resulting vector was obtained through Total Wavelet Entropy (TWE). In this sense, the presented work propose a viable and practical alert and detection algorithm for muscle fatigue.
Boucher, Victor J.
Purpose: The objective was to identify acoustic correlates of laryngeal muscle fatigue in conditions of vocal effort. Method: In a previous study, a technique of electromyography (EMG) served to define physiological signs of "voice fatigue" in laryngeal muscles involved in voicing. These signs correspond to spectral changes in contraction…
Conclusion: Prolonged sitting led to increased body discomfort in the neck, shoulder, upper back, low back, and buttock. No sign of trunk muscle fatigue was detected over 1 hour of sitting in the upright and forward leaning postures. Prolonged slumped sitting may relate to IO/TrA muscle fatigue, which may compromise the stability of the spine, making it susceptible to injury.
Krueger, Eddy; Popović-Maneski, Lana; Nohama, Percy
A motor neural prosthesis based on surface functional electrical stimulation (sFES) can restore functional movement (e.g., standing, walking) in patients with a spinal cord injury (SCI). sFES generates muscle contractions in antigravity muscles and allows balance-assisted standing. This induced standing has several benefits, such as improved cardiovascular function, decreased incidence of urinary infections, reduced joint contractures, and muscle atrophy. The duration of sFES assisted standing is limited due to the quick onset of muscle fatigue. Currently, there is no method available to reliably estimate real-time muscle fatigue during sFES. Simply monitoring the M-wave changes is not suitable due to the high signal disturbances that arise during multi-channel electrical stimulation. Mechanomyography (MMG) is immune to electrical stimulation artifacts and can be used to detect subtle vibrations on the surface of the skin related to activation of the underlying muscle's motor units (MU). The aim of this study was to develop a method for detecting muscle fatigue brought on by sFES. The method was tested in three different heads of the quadriceps muscle in SCI patients during electrically elicited quasi-isometric contraction. Six spinal cord-injured male volunteers, with no voluntary control of the quadriceps muscle participated in the study. Electrical bursts of voltage-controlled monophasic square pulses at frequencies of 1 kHz (50% duty cycle) at 50 Hz (15% duty cycle) were used to generate thigh muscle contractions that controlled the knee joint in the sagittal plane. The pulse amplitudes were set to position the knee joint at a 5° angle from the horizontal plane and when the knee angle dropped to 20° (e.g., the quadriceps were unable to hold the lower leg in the desired position), the test was terminated. Two data segments lasting 10 s each, at the beginning and end of each test, were analyzed. The muscle contraction was assessed by MMG sensors positioned on
Mohseni Bandpei, Mohammad A; Rahmani, Nahid; Majdoleslam, Basir; Abdollahi, Iraj; Ali, Shabnam Shah; Ahmad, Ashfaq
The purpose of this study was to review the literature to determine whether surface electromyography (EMG) is a reliable tool to assess paraspinal muscle fatigue in healthy subjects and in patients with low back pain (LBP). A literature search for the period of 2000 to 2012 was performed, using PubMed, ProQuest, Science Direct, EMBASE, OVID, CINAHL, and MEDLINE databases. Electromyography, reliability, median frequency, paraspinal muscle, endurance, low back pain, and muscle fatigue were used as keywords. The literature search yielded 178 studies using the above keywords. Twelve articles were selected according to the inclusion criteria of the study. In 7 of the 12 studies, the surface EMG was only applied in healthy subjects, and in 5 studies, the reliability of surface EMG was investigated in patients with LBP or a comparison with a control group. In all of these studies, median frequency was shown to be a reliable EMG parameter to assess paraspinal muscles fatigue. There was a wide variation among studies in terms of methodology, surface EMG parameters, electrode location, procedure, and homogeneity of the study population. The results suggest that there seems to be a convincing body of evidence to support the merit of surface EMG in the assessment of paraspinal muscle fatigue in healthy subject and in patients with LBP. Copyright © 2014 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.
Wanitphakdeedecha, Rungsima; Iamphonrat, Thanawan; Thanomkitti, Kanchalit; Lektrakul, Nittaya; Manuskiatti, Woraphong
Cellulite is a frequent skin condition for which treatment remains a challenge. A wide variety of treatments are available but most procedures offer suboptimal clinical effect and/or delayed therapeutic outcome. Only few therapeutic options have proven efficacy in the treatment of cellulite. To determine the efficacy and the safety profiles of radiofrequency and dynamic muscle activation technology in treatment of abdominal cellulite and circumference reduction. Twenty-five females with abdominal cellulite received 6 weekly radiofrequency and dynamic muscle activation treatments. Treatment areas included the abdomen and both sides of flanks. Subjects were evaluated using standardized photographs, and measurements of body weight and abdominal circumference at baseline, before every treatment visit, and 1 week and four weeks after the final treatment. Subcutaneous tissue thickness was recorded by ultrasound at baseline and 4 weeks after completion of treatment protocol. Physicians' evaluation and patient's satisfaction of clinical improvement were also measured. All subjects completed the treatment protocol and attended every follow-up visits. There was significant abdominal circumference reduction of 2.96 and 2.52 cm at 1-, and 4-week follow-up visits (p last treatment, the average circumferential reduction was sustained. Most of the patients were rated to have 25-49% improvement at 5th treatment, and 1- and 4-week follow-up visits. Ninety-two percent of the patients were satisfied with the treatment outcome. Radiofrequency provided beneficial effects on the reduction of abdomen and cellulite appearance. The benefit of muscle activation is yet to be determined.
Full Text Available Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP. This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control.Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE, variable error (VE as well as absolute error (AE in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG.Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm. Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm and AE (13.71 ± 3.45 Nm mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm and AE (16.29 ± 2.82 Nm mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores.Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration
Abboud, Jacques; Nougarou, François; Normand, Martin C.
Introduction Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. Methods Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). Results Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. Conclusions Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle
Full Text Available During isometric contractions, slow twitch soleus muscles (SOL from rats with chronic heart failure (chf are more fatigable than those of sham animals. However, a muscle normally shortens during activity and fatigue development is highly task dependent. Therefore, we examined the development of skeletal muscle fatigue during shortening (isotonic contractions in chf and sham-operated rats. Six weeks following coronary artery ligation, infarcted animals were classified as failing (chf if left ventricle end diastolic pressure was >15 mmHg. During isoflurane anaesthesia, SOL with intact blood supply was stimulated (1s on 1s off at 30 Hz for 15 min and allowed to shorten isotonically against a constant afterload. Muscle temperature was maintained at 37°C. In resting muscle, maximum isometric force (F(max and the concentrations of ATP and CrP were not different in the two groups. During stimulation, F(max and the concentrations declined in parallel sham and chf. Fatigue, which was evident as reduced shortening during stimulation, was also not different in the two groups. The isometric force decline was fitted to a bi-exponential decay equation. Both time constants increased transiently and returned to initial values after approximately 200 s of the fatigue protocol. This resulted in a transient rise in baseline tension between stimulations, although this effect which was less prominent in chf than sham. Myosin light chain 2s phosphorylation declined in both groups after 100 s of isotonic contractions, and remained at this level throughout 15 min of stimulation. In spite of higher energy demand during isotonic than isometric contractions, both shortening capacity and rate of isometric force decline were as well or better preserved in fatigued SOL from chf rats than in sham. This observation is in striking contrast to previous reports which have employed isometric contractions to induce fatigue.
Biagini, Maria Rosa; Tozzi, Alessandro; Grippo, Antonello; Galli, Andrea; Milani, Stefano; Amantini, Aldo
AIM: To evaluate the myoelectric manifestations of peripheral fatigability in patients with primary biliary cirrhosis in comparison to healthy subjects. METHODS: Sixteen women with primary biliary cirrhosis without comorbidity and 13 healthy women matched for age and body mass index (BMI) completed the self-reported questionnaire fatigue impact scale. All subjects underwent surface electromyography assessment of peripheral fatigability. Anterior tibial muscle isometric voluntary contraction was executed for 20 s at 80% of maximal voluntary isometric contraction. During the exercise electromyographic signal series were recorded and root mean square (expression of central drive) as well as mean and median of electromyographic signal frequency spectrum (estimates of muscle fatigability) were computed. Each subject executed the trial two times. EMG parameters were normalized, then linear regression was applied and slopes were calculated. RESULTS: Seven patients were fatigued (median fatigue impact scale score: 38, range: 26-66) and 9 were not fatigued (median fatigue impact scale score: 7, range: 0-17). The maximal voluntary isometric contraction was similar in patients (82, 54-115 N) and controls (87, 74-101 N), and in patients with high (81, 54-115 N) and low fatigue impact scale scores (86, 65-106 N). Root mean square as well as mean and median of frequency spectrum slopes were compared with the Mann-Whitney U test, and no significant difference was found between fatigued and non-fatigued patients and controls. CONCLUSION: No instrumental evidence of peripheral fatigability can be found in women with primary biliary cirrhosis but no comorbidity, suggesting that fatigue in such patients may be of central origin. PMID:16937530
Niederer, Daniel; Vogt, Lutz; Pippig, Torsten; Wall, Rudolf; Banzer, Winfried
The authors aimed to further explore the effects of local muscle fatigue on cervical 3D kinematics and the interrelationship between these kinematic characteristics and local muscle endurance capacity in the unimpaired cervical spine. Twenty healthy subjects (38 ± 10 years; 5 women) performed 2 × 10 maximal cervical flexion-extension movements. Isometric muscle endurance tests (prone/supine lying) were applied between sets to induce local muscle fatigue quantified by Borg scale rates of perceived exertion (RPE) and slope in mean power frequency (MPF; surface electromyography; m. sternocleidomastoideus, m. splenius capitis). Cervical motion characteristics (maximal range of motion [ROM], coefficient of variation of the 10 repetitive movements, mean angular velocity, conjunct movements in transversal and frontal plane) were calculated from raw 3D ultrasonic movement data. Average isometric strength testing duration for flexion and extension correlated to the cervical ROM (r = .49/r = .48; p .05). Although subjects' cervical muscle endurance capacity and motor output seems to be conjugated, no impact of local cervical muscle fatigue on motor function was shown. These findings underline the importance of complementary measures to address muscular performance and kinematic characteristics in outcome assessment and functional rehabilitation of the cervical spine.
Cumming, M.J.; Hall, A.J.; Burbridge, B.E.
The diagnosis of a ruptured abdominal aortic aneurysm (RAAA) is usually made on the basis of the classic clinical presentation of hypotension, abdominal or back pain, and a pulsating abdominal mass. However, given the large differential diagnosis for abdominal or back pain, the diagnosis can be elusive in a stable patient. The importance of a rapid diagnosis of a RAAA is emphasized by the 32%-70% operative mortality rate and the 77%-94% overall mortality rate. The case reported here demonstrates unusual clinical and radiological findings in a patient with a RAAA. The patient presented with back pain and a progressive radiculopathy in the L4 distribution. The diagnosis of RAAA was delayed 6 weeks because of the investigation of a suspected nerve root entrapment. Consecutive computed tomographic (CT) imaging over a 6-day period showed the evolution of a psoas muscle hematoma secondary to a RAAA. This case emphasizes the importance of considering a RAAA in elderly patients with a prolonged history of back pain. (author)
Klaver-Krol, E.G.; Rasker, Johannes J.; Henriquez, N.R.; Verheijen, W.G.; Zwarts, M.J.
Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and
Full Text Available It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS, but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS.Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB and abdominal muscle paralysis group (BIPAPAP. All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35-60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment.For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml and oxygenation index (293±36 vs. 226±31 mmHg, lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7 and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9 in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1.Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury.
Zhang, Xianming; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Du, Juan; Chen, Rongchang
It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35-60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury.
Full Text Available Objective: Fatigue process in patients with neck pain was happened more quickly than healthy persons and neck muscle fatigue increased body sway during standing, but there is less evidence about the behavior of these muscles in dynamic conditions such as external perturbation, so this study was done to investigate the effect of muscle fatigue on onset latency of upper trapezius muscle in posterior-anterior perturbation among patients with chronic neck pain and healthy individuals. Materials & Methods: In this quasi experimental and interventional study 16 patients with chronic neck pain (intervention group and 16 healthy individuals (control group were selected by simple and convenient sampling and based on inclusive and exclusive criteria. Data collection was done by using questionnaire and doing some tests and the main equipments were dynamometer, accelerometer and surface electromyography. The weight equal to 30% of maximum voluntary contraction used to produce fatigue process and 10% of body weight used to produce perturbation. Independent T test, Paired T test and Repeated ANOVA were used for data analysis. Results: There was significant difference in onset latency of upper Trapezius muscle in posterior – anterior perturbation between two groups, before (P=0.006 and after (P=0.026 fatigue. This means that the onset latency was increased in healthy individuals and decreased in patients after fatigue. Also, there was significant difference in onset latency of Trapezius muscle in posterior – anterior perturbation between before and after fatigue in patients group (P<0.001 and healthy persons group (P=0.04. Conclusion: Pain can change the onset latency of trapezius muscle and possibly it can decrease muscle activity in deep muscle and change the pattern of muscle activation. Fatigue as an exaggerated risk factor can decrease onset latency of superficial muscle in patients with chronic neck pain to stabilize the system, that it can increase
Zafeiridis, Andreas; Giagazoglou, Paraskevi; Dipla, Konstantina; Salonikidis, Konstantinos; Karra, Chrisanthi; Kellis, Eleftherios
This study examined fatigue profile during intermittent exercise in 10 men with mild to moderate mental retardation (MR) and 10 men without mental retardation (C). They performed 4 x 30 s maximal knee extensions and flexions with 1-min rest on an isokinetic dynamometer. Peak torque of flexors (PTFL) and extensors (PTEX), total work (TW), and…
Lee, Dong-Kyu; Kang, Min-Hyeok; Kim, Ji-Won; Kim, Yang-Gon; Park, Ji-Hyuk; Oh, Jae-Seop
Abdominal strengthening exercises are important for stroke patients; however, there is a lack of research on therapeutic exercises for increasing abdominal muscle activity in stroke patients. We investigated the effects of non-paretic arm exercises using a tubing band on abdominal muscle activity in stroke patients. In total, 18 hemiplegic subjects (13 males, 5 females) were recruited. All subjects performed non-paretic arm exercises involving three different shoulder movements (extension, flexion, and horizontal abduction) using an elastic tubing band. Surface electromyography (EMG) signals were recorded from the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles bilaterally during non-paretic arm exercises. EMG activities of abdominal muscles during non-paretic arm extension and horizontal abduction were increased significantly versus shoulder flexion when subjects performed the arm exercise in a seated position. Muscle activity of the EO was significantly greater in the paretic than the non-paretic side during non-paretic arm extension and horizontal abduction. We suggest that non-paretic arm extension and horizontal abduction exercises using an elastic tubing band may be effective in increasing abdominal muscle activity.
Stoter, Inge K; MacIntosh, Brian R; Fletcher, Jared R; Pootz, Spencer; Zijdewind, Inge; Hettinga, Florentina J
PURPOSE: To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500m speed skating and cycling time-trials, when a faster or slower start is instructed. METHODS: Nine speed skaters and nine cyclists, all competing at regional or national level, performed two 1500m
Bosch, T.; Looze, M.P. de; Dieën, J.H. van
Optimization of the temporal aspects of task design requires a better understanding of the development of muscle fatigue in the neck and shoulder region over time. The objective of the study was to investigate this in two production companies and to determine the relationship between objective and
Jensen, K. K.; Kjær, Michael; Jorgensen, L. N.
Purpose To determine the reliability of measurements obtained by the Good Strength dynamometer, determining isometric abdominal wall and back muscle strength in patients with ventral incisional hernia (VIH) and healthy volunteers with an intact abdominal wall. Methods Ten patients with VIH and ten...... and extension showed excellent test–retest reliability for both patients with VIH (ICC 0.91 and 0.99) and healthy controls (ICC 0.97 and 0.96). Bland and Altman plots showed that no systematic bias was present for neither truncal flexion nor extension when assessing reliability. For patients with VIH...... and IPAQ was found. Conclusions The Good Strength dynamometer provided a reliable, low-cost measure of truncal flexion and extension in patients with VIH....
Shirazi, Zahra Rojhani; Jahromi, Fatemeh Nikhalat
The maintenance of balance is an essential requirement for the performance of daily tasks and sporting activities and muscular fatigue is a factor to impair postural control, so this study was done to compare the effect of selected muscle groups fatigue on postural control during bipedal stance in healthy subjects. Fifteen healthy female students (24.3 ± 2.6 years) completed three testing session with a break period of at least 2 days. During each session, postural control was assessed during two 30-s trials of bipedal stance with eyes close before and after the fatigue protocol. Fatigue protocols were performed by 60% of their unfatigued Maximum Voluntary Contraction of unilateral ankle plantar flexors, bilateral lumbar extensors and bilateral neck extensors. One of the three fatigue protocols was performed on each session. The result showed that fatigue had a significant effect on COP velocity and it increase COP velocity but there was not found any difference in postural sway between muscle groups. Localized muscle fatigue caused deficits in postural control regardless of the location of fatigue. Authors suggest the possibility of the contributions of central mechanisms to postural deficits due to fatigue and it seems that difference was not between muscle groups due to central fatigue.
Barszap, Alexander G; Skavhaug, Ida-Maria; Joshi, Sanjay S
Electromyography-based human-computer interface development is an active field of research. However, knowledge on the effects of muscle fatigue for specific devices is limited. We have developed a novel myoelectric human-computer interface in which subjects continuously navigate a cursor to targets by manipulating a single surface electromyography (sEMG) signal. Two-dimensional control is achieved through simultaneous adjustments of power in two frequency bands through a series of dynamic low-level muscle contractions. Here, we investigate the potential effects of muscle fatigue during the use of our interface. In the first session, eight subjects completed 300 cursor-to-target trials without breaks; four using a wrist muscle and four using a head muscle. The wrist subjects returned for a second session in which a static fatiguing exercise took place at regular intervals in-between cursor-to-target trials. In the first session we observed no declines in performance as a function of use, even after the long period of use. In the second session, we observed clear changes in cursor trajectories, paired with a target-specific decrease in hit rates. Copyright © 2016 Elsevier B.V. All rights reserved.
Joshi, Mithun; Thigpen, Charles A.; Bunn, Kevin; Karas, Spero G.; Padua, Darin A.
Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Interventions: We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular
Full Text Available Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC. A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045. The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04. Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03. MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively, and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04. This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the
Adriano Rodrigues Oliveira
Full Text Available INTRODUCTION: Muscle weakness is the most prominent impairment in Duchenne muscular dystrophy (DMD and often involves the loss of functional ability as well as other limitations related to daily living. Thus, there is a need to maintain muscle strength in large muscle groups, such as the femoral quadriceps, which is responsible for diverse functional abilities. However, the load and duration of training for such rehabilitation has proven to be a great unknown, mainly due to the undesired appearance of muscle fatigue, which is a severe factor for the injury of muscle fibers. OBJECTIVES: The aim of the present study was to determine a fatigue index by means of surface electromyography (EMG for the parameterization of muscle strengthening physiotherapy training. METHODS: A cross-sectional study (case series was carried out involving four patients with DMD. Three pairs of surface electrodes were placed on the motor point of the Rectus femoris, Vastus lateralis and Vastus medialis of the dominant limb, maintaining the knee at 60º of flexion. The participants were instructed to perform the extension movement of this joint at four strength levels (100%, 80%, 60% and 40% of maximal voluntary isometric contraction. RESULTS: The slope of the linear regression line was used for the determination of the fatigue index, performed by Pearson's test on the median frequency of each strength level. CONCLUSION: Electromyographic measurements of the strength index for muscle training proved to be a simple accessible assessment method, as well as an extremely valuable tool, allowing the design of a muscle strength training program with an individualized load threshold.
... to help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease. Medical problems, treatments, and personal habits can add to fatigue. These include Taking certain medicines, such as antidepressants, ...
Rijkelijkhuizen, J.M.; de Ruiter, C.J.; Huijing, P.A.J.B.M.; de Haan, A.
Low-frequency fatigue (LFF) and post-tetanic potentiation (PTP) were quantified at different muscle lengths in rat medial gastrocnemius (GM) muscle. In situ experiments were performed on GM muscle-tendon complexes of anaesthetised (urethane, 1.5 g kg
Chang, Kang-Ming; Liu, Shing-Hong; Wang, Jia-Jung; Cheng, Da-Chuan
Surface electromyography (sEMG) is an important measurement for monitoring exercise and fitness. A wireless Bluetooth transmission sEMG measurement system with a sampling frequency of 2 KHz is developed. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. As fatigue increases, the power spectrum of the sEMG shifts toward lower frequencies. The goal of this study is to evaluate the sensitivity of empirical mode decomposition (EMD) quantifying the electrical manifestations of the local muscle fatigue during exercising in health people. We also compared this method with the raw data and discrete wavelet transform (DWT). Five male and five female volunteers participated. Each subject was asked to run on a multifunctional pedaled elliptical trainer for about 30 minutes, twice a week, and there were a total of six recording times for each subject with a wireless EMG recording system. The results show that sensitivity of the highest frequency component of EMD is better than the highest frequency component of DWT, and raw data.
Yinjun Tu; Zhe Zhang; Xudong Gu; Qiang Fang
Muscle fatigue analysis has been an important topic in sport and rehabilitation medicine due to its role in muscle performance evaluation and pathology investigation. This paper proposes a surface electromyography (sEMG) based muscle fatigue analysis approach which was specifically designed for stroke rehabilitation applications. 14 stroke patients from 5 different Brunnstrom recovery stage groups were involved in the experiment and features including median frequency and mean power frequency were extracted from the collected sEMG samples for investigation. After signal decomposition, the decline of motor unit firing rate of patients from different groups had also been studied. Statistically significant presence of fatigue had been observed in deltoideus medius and extensor digitorum communis of patients at early recovery stages (P0.01). It had also been discovered that the motor unit firing frequency declines with a range positively correlated to the recovery stage during repetitive movements. Based on the experiment result, it can be verified that as the recovery stage increases, the central nervous system's control ability strengthens and the patient motion becomes more stable and resistive to fatigue.
Zebis, M K; Bencke, J; Andersen, L L
In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle...... function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested...
Conclusion: Abdominal muscles respond to postural changes and these muscles are automatically targeted by decreasing the seated stability. In non–specific chronic low back pain patients, activity of Transvers Abdominis was decreased and activity of Rectus Abdominis was increased.
Ye, Xin; Beck, Travis W.; Wages, Nathan P.; Carr, Joshua C.
Objectives: To examine non-local muscle fatigue (NLMF) in both contralateral homologous and non-related heterogonous muscles for both sexes. Methods: Ten men and nine women participated in this study. After the familiarization visit, subjects completed four separate randomly sequenced experimental visits, during which the fatiguing interventions (six sets of 30-second maximal isometric contractions) were performed on either their right elbow flexors or knee extensors. Before (Pre-) and after (Post-) the fatiguing interventions, the isometric strength and the corresponding surface electromyographic (EMG) amplitude were measured for the non-exercised left elbow flexors or knee extensors. Results: For the non-exercised elbow flexors, the isometric strength decreased for both sexes (sex combined mean±SE: Pre vs. Post=339.67±18.02 N vs. 314.41±16.37 N; pisometric knee extension strength for men (Pre vs. Post =845.02±66.26 N vs. 817.39±67.64 N; p=0.019), but not for women. Conclusions: The presence of NMLF can be affected by factors such as sex and muscle being tested. Women are less likely to demonstrate NLMF in lower body muscle groups. PMID:29504584
Xie, Hong-Bo; Guo, Jing-Yi; Zheng, Yong-Ping
In the present contribution, a complexity measure is proposed to assess surface electromyography (EMG) in the study of muscle fatigue during sustained, isometric muscle contractions. Approximate entropy (ApEn) is believed to provide quantitative information about the complexity of experimental data that is often corrupted with noise, short data length, and in many cases, has inherent dynamics that exhibit both deterministic and stochastic behaviors. We developed an improved ApEn measure, i.e., fuzzy approximate entropy (fApEn), which utilizes the fuzzy membership function to define the vectors' similarity. Tests were conducted on independent, identically distributed (i.i.d.) Gaussian and uniform noises, a chirp signal, MIX processes, Rossler equation, and Henon map. Compared with the standard ApEn, the fApEn showed better monotonicity, relative consistency, and more robustness to noise when characterizing signals with different complexities. Performance analysis on experimental EMG signals demonstrated that the fApEn significantly decreased during the development of muscle fatigue, which is a similar trend to that of the mean frequency (MNF) of the EMG signal, while the standard ApEn failed to detect this change. Moreover, fApEn of EMG demonstrated a better robustness to the length of the analysis window in comparison with the MNF of EMG. The results suggest that the fApEn of an EMG signal may potentially become a new reliable method for muscle fatigue assessment and be applicable to other short noisy physiological signal analysis.
Rossana Anelice Gomez
Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p324 L-carnitine, considered to be of great value in metabolic processes, plays an important role in the mitochondrial β-oxidation process. It may be used to improve athletic performance and to maintain a higher workload during exercise. This study aimed to investigate the effect of L-carnitine supplementation on muscle fatigue in sciatic nerve-gastrocnemius muscle preparations in sedentary and trained rats. The animals were divided into 4 groups: non-supplemented sedentary (NSS, supplemented sedentary (SS, non-supplemented trained (NST, and supplemented trained (ST rats. The animals were trained in daily 1-h sessions (5 days/week and received chronic oral L-carnitine supplementation (1 mg/mL for 4 weeks. Muscle fatigue was determined by supramaximal tetanic stimulation of the sciatic nerve (50 Hz. Time values for strength reduction were significantly different (p<0.05 between NSS vs. SS and NST vs. ST rats. No significant differences were observed between SS vs. ST and NST vs. NSS rats. These findings demonstrate that L-carnitine lengthen the time required for induction of muscle fatigue.
Mohamed R. Al-Mulla
Full Text Available Surface Electromyography (sEMG activity of the biceps muscle was recorded from ten subjects performing isometric contraction until fatigue. A novel feature (1D spectro_std was used to extract the feature that modeled three classes of fatigue, which enabled the prediction and detection of fatigue. Initial results of class separation were encouraging, discriminating between the three classes of fatigue, a longitudinal classification on Non-Fatigue and Transition-to-Fatigue shows 81.58% correct classification with accuracy 0.74 of correct predictions while the longitudinal classification on Transition-to-Fatigue and Fatigue showed lower average correct classification of 66.51% with a positive classification accuracy 0.73 of correct prediction. Comparison of the 1D spectro_std with other sEMG fatigue features on the same dataset show a significant improvement in classification, where results show a significant 20.58% (p < 0.01 improvement when using the 1D spectro_std to classify Non-Fatigue and Transition-to-Fatigue. In classifying Transition-to-Fatigue and Fatigue results also show a significant improvement over the other features giving 8.14% (p < 0.05 on average of all compared features.
Bronwen Jane Ackermann
Full Text Available Wind instrumentalists require a sophisticated functioning of their respiratory system to control their air stream, which provides the power for optimal musical performance. The air supply must be delivered into the instrument in a steady and controlled manner and with enough power by the action of the expiratory musculature to produce the desired level of sound at the correct pitch. It is suggested that playing posture may have an impact on the abdominal muscle activity controlling this expired air, but there is no research on musicians to support this theory. This study evaluated chest and abdominal expansion, via respiratory inductive plethysmography, as well as activation patterns of lower and upper abdominal musculature, using surface electromyography, during performance of a range of typical orchestral repertoire by 113 woodwind and brass players. Each of the five orchestral excerpts was played in one of four randomly allocated postures: standing; sitting flat; sitting inclined forwards; and sitting inclined backwards.Musicians showed a clear preference for playing in standing rather than sitting. In standing, the chest expansion range and maximum values were greater (p<0.01, while the abdominal expansion was less than in all sitting postures (p<0.01. Chest expansion patterns did not vary between the three sitting postures, while abdominal expansion was reduced in the forward inclined posture compared to the other sitting postures (p<0.05. There was no significant variation in abdominal muscle activation between the sitting postures, but the level of activation in sitting was only 2/3 of the significantly higher level observed in standing (p<0.01.This study has demonstrated significant differences in respiratory mechanics between sitting and standing postures in wind musicians during playing of typical orchestral repertoire. Further research is needed to clarify the complex respiratory mechanisms supporting musical performance.
Karthick, P A; Makaram, Navaneethakrishna; Ramakrishnan, S
Muscle fatigue is a neuromuscular condition where muscle performance decreases due to sustained or intense contraction. It is experienced by both normal and abnormal subjects. In this work, an attempt has been made to analyze the progression of muscle fatigue in biceps brachii muscles using surface electromyography (sEMG) signals. The sEMG signals are recorded from fifty healthy volunteers during dynamic contractions under well defined protocol. The acquired signals are preprocessed and segmented in to six equal parts for further analysis. The features, such as activity, mobility, complexity, sample entropy and spectral entropy are extracted from all six zones. The results are found showing that the extracted features except complexity feature have significant variations in differentiating non-fatigue and fatigue zone respectively. Thus, it appears that, these features are useful in automated analysis of various neuromuscular activities in normal and pathological conditions.
Mänty, Minna; Mendes de Leon, Carlos F.; Rantanen, Taina
history, as well as performance-based assessment of walking speed and maximal isometric strength of knee extension, body extension, and handgrip. Results. In the cross-sectional baseline analysis, one unit increase in fatigue score was associated with 0.03 m/s (b = −.03, p ... the degree to which muscle strength accounts for this association. Methods. The study is based on baseline (n = 523) and 5-year follow-up data (n = 292) from a cohort of 75-year-old persons. Standardized assessments include self-report measures of mobility-related fatigue (score range 0–6) and medical......, p strength accounted up to 21% and among men up to 24% for the association. In the prospective analysis, fatigue at baseline was predictive of change in walking speed...
Carlos A. V. Bruniera
Full Text Available OBJECTIVE: This study sought to analyze the effect of muscle fatigue induced by active isotonic resistance training at a moderate intensity by measuring the knee extension motion during the stabilometric response in a single-leg stance among healthy university students who perform resistance training on a regular basis. METHOD: Eleven healthy university students were subjected to a one-repetition maximum (1RM test. In addition, stabilometric assessment was performed before and after the intervention and consisted of a muscle fatiguing protocol, in which knee extension was selected as the fatiguing task. The Shapiro-Wilk test was used to investigate the normality of the data, and the Wilcoxon test was used to compare the stabilometric parameters before and after induction of muscle fatigue, at a significance level of p≤0.05. Descriptive statistics were used in the analysis of the volunteers' age, height, body mass, and body mass index (BMI. RESULTS: The sample population was 23.1±2.7 years of age, averaged 1.79.2±0.07 m in height and 75.6±8.0 Kg in weight, and had a BMI of 23.27±3.71 Kg.m-2. The volunteers performed exercises 3.36±1.12 days/week and achieved a load of 124.54±22.07 Kg on 1RM and 74.72±13.24 Kg on 60% 1RM. The center of pressure (CoP oscillation on the mediolateral plane before and after fatigue induction was 2.89±0.89 mm and 4.09±0.59 mm, respectively, while the corresponding values on the anteroposterior plane were 2.5±2.2 mm and 4.09±2.26 mm, respectively. The CoP oscillation amplitude on the anteroposterior and mediolateral planes exhibited a significant difference before and after fatigue induction (p=0.04 and p=0.05, respectively. CONCLUSIONS: The present study showed that muscle fatigue affects postural control, particularly with the mediolateral and anteroposterior CoP excursion.
Soylu, Abdullah Ruhi; Arpinar-Avsar, Pinar
The effects of fatigue on maximum voluntary contraction (MVC) parameters were examined by using force and surface electromyography (sEMG) signals of the biceps brachii muscles (BBM) of 12 subjects. The purpose of the study was to find the sEMG time interval of the MVC recordings which is not affected by the muscle fatigue. At least 10s of force and sEMG signals of BBM were recorded simultaneously during MVC. The subjects reached the maximum force level within 2s by slightly increasing the force, and then contracted the BBM maximally. The time index of each sEMG and force signal were labeled with respect to the time index of the maximum force (i.e. after the time normalization, each sEMG or force signal's 0s time index corresponds to maximum force point). Then, the first 8s of sEMG and force signals were divided into 0.5s intervals. Mean force, median frequency (MF) and integrated EMG (iEMG) values were calculated for each interval. Amplitude normalization was performed by dividing the force signals to their mean values of 0s time intervals (i.e. -0.25 to 0.25s). A similar amplitude normalization procedure was repeated for the iEMG and MF signals. Statistical analysis (Friedman test with Dunn's post hoc test) was performed on the time and amplitude normalized signals (MF, iEMG). Although the ANOVA results did not give statistically significant information about the onset of the muscle fatigue, linear regression (mean force vs. time) showed a decreasing slope (Pearson-r=0.9462, pfatigue starts after the 0s time interval as the muscles cannot attain their peak force levels. This implies that the most reliable interval for MVC calculation which is not affected by the muscle fatigue is from the onset of the EMG activity to the peak force time. Mean, SD, and range of this interval (excluding 2s gradual increase time) for 12 subjects were 2353, 1258ms and 536-4186ms, respectively. Exceeding this interval introduces estimation errors in the maximum amplitude calculations
Boudarham, Julien; Roche, Nicolas; Pradon, Didier; Delouf, Eric; Bensmail, Djamel; Zory, Raphael
The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients. PMID:24718087
Taelman, Joachim; Vanderhaegen, Joke; Robijns, Mieke; Naulaers, Gunnar; Spaepen, Arthur; Van Huffel, Sabine
This study looks at various parameters, derived from surface electromyography (sEMG) and Near Infrared Spectroscopy (NIRS) and their relationship in muscle fatigue during a static elbow flexion until exhaustion as well as during a semidynamic exercise.We found a linear increasing trend for a corrected amplitude parameter and a linear decreasing slope for the frequency content of the sEMG signal. The tissue oxygenation index (TOI) extracted from NIRS recordings showed a four-phase response for all the subjects. A strong correlation between frequency content of the sEMG signal and TOI was established. We can conclude that both sEMG and NIRS give complementary information concerning muscle fatigue.
Roerdink, M.; Hlavackova, P.; Vuillerme, N.
Control of bipedal posture is highly automatized but requires attentional investment, the amount of which varies between participants and with postural constraints, such as plantar-flexor muscle fatigue. Elevated attentional demands for standing with fatigued plantar flexors have been demonstrated
Park, Seong-Doo; Yu, Seong-Hun
The purpose of this study was to effects of abdominal draw-in maneuver and core exercise with 4 weeks using the musculoskeletal ultrasonography on muscle thickness and disability in subjects with low back pain. Twenty patients with nonspecific back pain (abdominal draw-in maneuver group: n= 10, core exercise group: n= 10) were recruited in the study. Both group received exercise intervention 3 times a week for 4weeks. The test were based on muscle thickness (transversus abdominis; Tra, internal oblique; IO and external oblique; EO), disability (Oswestry disability index; ODI) measured immediately before and after intervention. The data was measured by SPSS program 12.0 version and analyzed by Paired t-test and Independent t-test. The following results were obtained. The thickness of IO, EO for both group significantly improved except for muscle thickness of Tra. The ODI were significant difference for both groups. As the results of this study, we suggest that it may be effective method to apply to increase for the thickness of Tra, EO using abdominal draw-in maneuver and thickness of IO using core exercise.
Broxterman, R M; Craig, J C; Smith, J R; Wilcox, S L; Jia, C; Warren, S; Barstow, T J
Critical power represents an important threshold for neuromuscular fatigue development and may, therefore, dictate intensities for which exercise tolerance is determined by the magnitude of fatigue accrued. Peripheral fatigue appears to be constant across O2 delivery conditions for large muscle mass exercise, but this consistency is equivocal for smaller muscle mass exercise. We sought to determine the influence of blood flow occlusion during handgrip exercise on neuromuscular fatigue development and to examine the relationship between neuromuscular fatigue development and W '. Blood flow occlusion influenced the development of both peripheral and central fatigue, thus providing further evidence that the magnitude of peripheral fatigue is not constant across O2 delivery conditions for small muscle mass exercise. W ' appears to be related to the magnitude of fatigue accrued during exercise, which may explain the reported consistency of intramuscular metabolic perturbations and work performed for severe-intensity exercise. The influence of the muscle metabolic milieu on peripheral and central fatigue is currently unclear. Moreover, the relationships between peripheral and central fatigue and the curvature constant (W ') have not been investigated. Six men (age: 25 ± 4 years, body mass: 82 ± 10 kg, height: 179 ± 4 cm) completed four constant power handgrip tests to exhaustion under conditions of control exercise (Con), blood flow occlusion exercise (Occ), Con with 5 min post-exercise blood flow occlusion (Con + Occ), and Occ with 5 min post-exercise blood flow occlusion (Occ + Occ). Neuromuscular fatigue measurements and W ' were obtained for each subject. Each trial resulted in significant peripheral and central fatigue. Significantly greater peripheral (79.7 ± 5.1% vs. 22.7 ± 6.0%) and central (42.6 ± 3.9% vs. 4.9 ± 2.0%) fatigue occurred for Occ than for Con. In addition, significantly greater peripheral (83.0 ± 4.2% vs. 69.0 ± 6.2%) and central
Full Text Available Abstract Objective This research work is dedicated to occupational health problems caused by ergonomic risks. The research object was road building industry, where workers have to work very intensively, have long work hours, are working in forced/constrained work postures and overstrain during the work specific parts of their bodies. The aim of this study was to evaluate the work heaviness degree and to estimate the muscle fatigue of workers after one week work cycle. The study group consisted of 10 road construction and maintenance workers and 10 pavers aged between 20 and 60 years. Methods Physical load were analyzed by measuring heart rate (HR, work postures (OWAS and perceived exertion (RPE. Assessments of the muscles strain and functional state (tone were carried out using myotonometric (MYO measurements. The reliability of the statistical processing of heart rate monitoring and myotonometry data was determined using correlating analysis. Results This study showed that that road construction and repairing works should be considered as a hard work according to average metabolic energy consumption 8.1 ± 1.5 kcal/min; paving, in its turn, was a moderately hard work according to 7.2 ± 1.1 kcal/min. Several muscle tone levels were identified allowing subdivision of workers into three conditional categories basing on muscle tone and fatigue: I – absolute muscle relaxation and ability to relax; II – a state of equilibrium, when muscles are able to adapt to the work load and are partly able to relax; and III – muscle fatigue and increased tone. It was also found out that the increase of muscle tone and fatigue mainly depend on workers physical preparedness and length of service, and less – on their age. Conclusion We have concluded that a complex ergonomic analysis consisting of heart rate monitoring, assessment of compulsive working postures and myotonometry is appropriate to assess the work heaviness degree and can provide prognosis of
Full Text Available The aim of this study was to investigate the relationship between changes in serum free amino acids, muscle fatigue and exercise-induced muscle damage during a half-ironman triathlon. Twenty-six experienced triathletes (age = 37.0 ± 6.8 yr; experience = 7.4 ± 3.0 yr competed in a real half-ironman triathlon in which sector times and total race time were measured by means of chip timing. Before and after the race, a countermovement jump and a maximal isometric force test were performed, and blood samples were withdrawn to measure serum free amino acids concentrations, and serum creatine kinase levels as a blood marker of muscle damage. Total race time was 320 ± 37 min and jump height (-16.3 ± 15.2%, P 20%. However, neither the changes in serum free amino acids nor the tryptophan/BCAA ratio were related muscle fatigue or muscle damage during the race.
Ferguson, Sue A; Allread, W Gary; Le, Peter; Rose, Joseph; Marras, William S
The objective of this study was to quantify shoulder muscle fatigue during repetitive exertions similar to motions found in automobile assembly tasks. Shoulder musculoskeletal disorders (MSDs) are a common and costly problem in automotive manufacturing. Ten subjects participated in the study. There were three independent variables: shoulder angle, frequency, and force. There were two types of dependent measures: percentage change in near-infrared spectroscopy (NIRS) measures and change in electromyography (EMG) median frequency. The anterior deltoid and trapezius muscles were measured for both NIRS and EMG. Also, EMG was collected on the middle deltoid and biceps muscles. The results showed that oxygenated hemoglobin decreased significantly due to the main effects (shoulder angle, frequency, and force). The percentage change in oxygenated hemoglobin had a significant interaction attributable to force and repetition for the anterior deltoid muscle, indicating that as repetition increased, the magnitude of the differences between the forces increased. The interaction of repetition and shoulder angle was also significant for the percentage change in oxygenated hemoglobin. The median frequency decreased significantly for the main effects; however, no interactions were statistically significant. There was significant shoulder muscle fatigue as a function of shoulder angle, task frequency, and force level. Furthermore, percentage change in oxygenated hemoglobin had two statistically significant interactions, enhancing our understanding of these risk factors. Ergonomists should examine interactions of force and repetition as well as shoulder angle and repetition when evaluating the risk of shoulder MSDs.
Reyes, Nicholas L.; Banks, Glen B.; Tsang, Mark; Margineantu, Daciana; Gu, Haiwei; Djukovic, Danijel; Chan, Jacky; Torres, Michelle; Liggitt, H. Denny; Hirenallur-S, Dinesh K.; Hockenbery, David M.; Raftery, Daniel; Iritani, Brian M.
Mammalian skeletal muscle is broadly characterized by the presence of two distinct categories of muscle fibers called type I “red” slow twitch and type II “white” fast twitch, which display marked differences in contraction strength, metabolic strategies, and susceptibility to fatigue. The relative representation of each fiber type can have major influences on susceptibility to obesity, diabetes, and muscular dystrophies. However, the molecular factors controlling fiber type specification remain incompletely defined. In this study, we describe the control of fiber type specification and susceptibility to metabolic disease by folliculin interacting protein-1 (Fnip1). Using Fnip1 null mice, we found that loss of Fnip1 increased the representation of type I fibers characterized by increased myoglobin, slow twitch markers [myosin heavy chain 7 (MyH7), succinate dehydrogenase, troponin I 1, troponin C1, troponin T1], capillary density, and mitochondria number. Cultured Fnip1-null muscle fibers had higher oxidative capacity, and isolated Fnip1-null skeletal muscles were more resistant to postcontraction fatigue relative to WT skeletal muscles. Biochemical analyses revealed increased activation of the metabolic sensor AMP kinase (AMPK), and increased expression of the AMPK-target and transcriptional coactivator PGC1α in Fnip1 null skeletal muscle. Genetic disruption of PGC1α rescued normal levels of type I fiber markers MyH7 and myoglobin in Fnip1-null mice. Remarkably, loss of Fnip1 profoundly mitigated muscle damage in a murine model of Duchenne muscular dystrophy. These results indicate that Fnip1 controls skeletal muscle fiber type specification and warrant further study to determine whether inhibition of Fnip1 has therapeutic potential in muscular dystrophy diseases. PMID:25548157
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.
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
Brown, Stephen H M; Carr, John Austin; Ward, Samuel R; Lieber, Richard L
Abdominal wall muscles have a unique morphology suggesting a complex role in generating and transferring force to the spinal column. Studying passive mechanical properties of these muscles may provide insights into their ability to transfer force among structures. Biopsies from rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were harvested from male Sprague-Dawley rats, and single muscle fibers and fiber bundles (4-8 fibers ensheathed in their connective tissue matrix) were isolated and mechanically stretched in a passive state. Slack sarcomere lengths were measured and elastic moduli were calculated from stress-strain data. Titin molecular mass was also measured from single muscle fibers. No significant differences were found among the four abdominal wall muscles in terms of slack sarcomere length or elastic modulus. Interestingly, across all four muscles, slack sarcomere lengths were quite long in individual muscle fibers (>2.4 µm), and demonstrated a significantly longer slack length in comparison to fiber bundles (p resistance to lengthening at long muscle lengths. Titin molecular mass was significantly less in TrA compared to each of the other three muscles (p < 0.0009), but this difference did not correspond to hypothesized differences in stiffness. Copyright © 2012 Orthopaedic Research Society.
Preedy, V R; Smith, D G; Salisbury, J R; Peters, T J
AIMS--To investigate in detail various biochemical and pathophysiological indices of muscle pathology in acute onset post-viral fatigue syndrome (PVFS). METHODS--Twenty three patients with PVFS (of mean duration 4.6 years) were subjected to needle biopsy for histomorphometry and total RNA contents. Plasma analysis included serology and creatine kinase activities. Indices of whole body mass were also measured--namely, whole body potassium content and plasma carnosinase activities. RESULTS--Abo...
Gogola, Anna; Gnat, Rafał; Zaborowska, Małgorzata; Dziub, Dorota; Gwóźdź, Michalina
The aim of the study was to evaluate the symmetry and pattern of activation of lateral abdominal muscles (LAM) in response to neurodevelopmental traction technique. Measurements of LAM thickness were performed in four experimental conditions: during traction with the force of 5% body weight (5% traction): 1) in neutral position, 2) in 20° posterior trunk inclination; during traction with the force of 15% body weight (15% traction): 3) in neutral position, 4) in 20° posterior trunk inclination. Thirty-seven healthy children participated in the study. Not applicable. To evaluate LAM activation level ultrasound technology was employed (two Mindray DP660 devices (Mindray, Shenzhen, China) with 75L38EA linear probes). An experiment with repeated measurements of the dependent variables was conducted. Side-to-side LAM activation asymmetry showed relatively high magnitude, however, significant difference was found only in case of the obliquus externus (OE) during stronger traction (P muscle differences were most pronounced between the OE and TrA (P muscles showing less intense activation. In statistical terms, the only signs of side-to-side asymmetry of LAM activation are visible in case of the OE, however, the magnitude of asymmetry is relatively high. The results allow to identify patterns of activation of LAM in children showing typical development that will serve as a reference in future studies in children with neurological disorder. Copyright © 2017 Elsevier Ltd. All rights reserved.
Full Text Available Background/Aim. Transcranial magnetic stimulation (TMS is a standard technique for noninvasive assessment of changes in central nervous system excitability. The aim of this study was to examine changes in responses to TMS in patients suffering from Parkinson’s disease (PD during sustained submaximal isometric voluntary contraction [60% of maximal voluntary contraction (MVC] of the adductor pollicis muscle, as well as during a subsequent recovery period. Methods. Cortical excitability was tested by single TMS pulses of twice of the motor threshold intensity applied over the vertex. Testing was carried out during the sustained contraction phase every 10 s before and every 5 s after the endurance point, as well as at rest and during brief 60% MVC contractions before (control, immediately after the sustained contraction, and at 5 min intervals during the recovery period. Results. Although the PD patients could sustain the contraction at the required level for as long period of time as the healthy subjects (though contraction level subsided more rapidly after the endurance point, effects of muscle fatigue on the responses to TMS were different. In contrast to the findings observed in the healthy people where motor evoked potentials (MEP and EMG silent period (SP in fatigued muscle gradually diminished during contraction up to the endurance point, and increased thereafter, in the majority of patients no changes occurred in MEP size (peak and area of the adductor pollicis muscle, either before or after the endurance point. On the other hand, changes in the SP of this muscle differed among the subjects, showing a gradual increase, a decrease or no changes in duration. The trends of changes in both MEP size and SP duration in the musculus brachioradialis varied among the tested PD patients, without any consistent pattern, which was in contrast with the findings in the healthy people where both measures showed a gradual increase from the beginning of
Abdul Aziz Khadijah Akmal
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.
Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G
soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip...... decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery...... (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing...
Jensen, K K; Kjaer, M; Jorgensen, L N
To determine the reliability of measurements obtained by the Good Strength dynamometer, determining isometric abdominal wall and back muscle strength in patients with ventral incisional hernia (VIH) and healthy volunteers with an intact abdominal wall. Ten patients with VIH and ten healthy volunteers with an intact abdominal wall were each examined twice with a 1 week interval. Examination included the assessment of truncal flexion and extension as measured with the Good Strength dynamometer, the completion of the International Physical Activity Questionnaire (IPAQ) and the self-assessment of truncal strength on a visual analogue scale (SATS). The test-retest reliability of truncal flexion and extension was assessed by interclass correlation coefficient (ICC), and Bland and Altman graphs. Finally, correlations between truncal strength, and IPAQ and SATS were examined. Truncal flexion and extension showed excellent test-retest reliability for both patients with VIH (ICC 0.91 and 0.99) and healthy controls (ICC 0.97 and 0.96). Bland and Altman plots showed that no systematic bias was present for neither truncal flexion nor extension when assessing reliability. For patients with VIH, no significant correlations between objective measures of truncal strength and IPAQ or SATS were found. For healthy controls, both truncal flexion (τ 0.58, p = 0.025) and extension (τ 0.58, p = 0.025) correlated significantly with SATS, while no other significant correlation between truncal strength measures and IPAQ was found. The Good Strength dynamometer provided a reliable, low-cost measure of truncal flexion and extension in patients with VIH.
García-Manso, Juan Manuel; Rodríguez-Ruiz, David; Rodríguez-Matoso, Dario; de Saa, Yves; Sarmiento, Samuel; Quiroga, Miriam
In this study, we used tensiomyography (TMG) to assess muscle status immediately after an ultra-endurance triathlon. Maximal radial displacement or deformation of the muscle belly, contraction time, delay time, sustain time, and relaxation time were measured for both legs, and dependent t-tests were used to compare means between the beginning and end of the race. The 19 men assessed (age 37.9 ± 7.1 years; height 177.5 ± 4.6 cm; weight: 73.6 ± 6.5 kg) participated in the 2009 edition of the Lanzarote Ironman. Deterioration in the neural response was observed for contraction time (P = 0.008) and relaxation time (P = 0.011), with a moderate decrease in the response time (sustain time) and a loss in muscle stiffness (deformation of the muscle belly). The effect of muscle fatigue on the rectus femoris and biceps femoris was different. Barely any changes in contraction time, relaxation time, sustain time, and deformation of the muscle belly were observed, while only the contraction response time decreased to a significant extent (reduction in delay time; P = 0.003). The considerable loss in contractile capacity induced by a long-distance race was reflected in changes in the neuromuscular response and fluctuations in the contractile capacity of the muscle. These modifications, derived from a prolonged, exhausting effort, can be assessed in a simple, non-aggressive, non-invasive way using tensiomyography.
Full Text Available Background: Training induced muscle fatigue (hereinafter also referred as TIMF is leading to unwanted consequences among sportsmen and actively sporting people such as decreased muscle strength and additional painful discomfort and mobility issues. The knowledge about the mechanisms of influencing the fatigue induced processes in muscle tissue is not comprehensive. The conventional manual techniques, cold patches and conventional physiotherapy have some effect in improving these conditions, however, finding effective methods to influence these consequences appears beneficial in sports medicine. Such method could be Radiofrequency therapy up to 0.5 MHz, known as Targeted Radiofrequency Therapy (hereinafter also referred as TR-Therapy. Aim of this self-controlled study is to evaluate the effect of the TR-Therapy for over-exertion management including the effect on decreased muscle strength, limited range of motion and possible painful discomfort. Materials: 7 healthy and actively sporting participants underwent through 2 stages (Active stage – including overexertion of the forearm flexors and subsequent TR-Therapy session; and Control stage - including overexertion of the forearm flexors and subsequent resting period. Data for muscle strength in kg, active Range of Motion (ROM in (º and Pain and discomfort perception by 10 point Visual Analog Scale (VAS were obtained and evaluated. Results: 31% increase in the muscle strength during the active stage was observed and respectively 12% during the control stage, with level of significance p0.05. Conclusions: The results of this study suggest TR-Therapy as effective solution for muscle strength restoration after TIMF.
Vary, T.C.; Siegel, J.H.; Tall, B.D.; Morris, J.G.; Smith, J.A.
Chronic sepsis is always associated with profound wasting leading to increased release of amino acids from skeletal muscle. Net protein catabolism may be due to decreased rate of synthesis, increased rate of degradation, or both. To determine whether protein synthesis is altered in chronic sepsis, the rate of protein synthesis in vivo was estimated by measuring the incorporation of [ 3 H]-phenylalanine in skeletal muscle protein in a chronic (5-day) septic rat model induced by creation of a stable intra-abdominal abscess using an E. coli + B. fragilis-infected sterile fecal-agar pellet as foreign body nidus. Septic rats failed to gain weight at rates similar to control animals, therefore control animals were weight matched to the septic animals. The skeletal muscle protein content in septic animals was significantly reduced relative to control animals (0.18 +/- 0.01 vs. 0.21 +/- 0.01 mg protein/gm wet wt; p less than 0.02). The rate of incorporation of [ 3 H]-phenylalanine into skeletal muscle protein from control animals was 39 +/- 4 nmole/gm wet wt/hr or a fractional synthetic rate of 5.2 +/- 0.5%/day. In contrast to control animals, the fractional synthetic rate in septic animals (2.6 +/- 0.2%/day) was reduced by 50% compared to control animals (p less than 0.005). The decreased rate of protein synthesis in sepsis was not due to an energy deficit, as high-energy phosphates and ATP/ADP ratio were not altered. This decrease in protein synthesis occurred even though septic animals consumed as much food as control animals
Beijers, Rosanne J H C G; van de Bool, Coby; van den Borst, Bram; Franssen, Frits M E; Wouters, Emiel F M; Schols, Annemie M W J
It is well established that low muscle mass affects physical performance in chronic obstructive pulmonary disease (COPD). We hypothesize that combined low muscle mass and abdominal obesity may also adversely influence the cardiometabolic risk profile in COPD, even in those with normal weight. The cardiometabolic risk profile and the responsiveness to 4 months high-intensity exercise training was assessed in normal-weight patients with COPD with low muscle mass stratified by abdominal obesity. This is a cross-sectional study including 81 clinically stable patients with COPD (age 62.5 ± 8.2 years; 50.6% males; forced expiratory volume in 1 second 55.1 ± 19.5 percentage predicted) with fat-free mass index risk profile. Triglycerides showed a significant decrease, while the HOMA-IR increased. Abdominal obesity is highly prevalent in normal-weight patients with COPD with low muscle mass who showed an increased cardiometabolic risk compared with patients without abdominal obesity. This cardiometabolic risk profile was not altered after 4 months of exercise training. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.
Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G; Krustrup, Peter; Mohr, Magni
We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement ( p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.
Full Text Available We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12 participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05 at 0 h post-match with knee flexors (14 ± 3% and hip abductors (6 ± 1% demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05 for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin and 24 h into recovery (creatine kinase, respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02. In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.
Lin, Cheng-Feng; Lee, Wan-Chin; Chen, Yi-An; Hsue, Bih-Jen
Fatigue in ballet dancers may lead to injury, particularly in the lower extremities. However, few studies have investigated the effects of fatigue on ballet dancers' performance and movement patterns. Thus, the current study examines the effect of fatigue on the balance, movement pattern, and muscle activities of the lower extremities in ballet dancers. Twenty healthy, female ballet dancers performed releve on demi-pointe before and after fatigue. The trajectory of the whole body movement and the muscle activities of the major lower extremity muscles were recorded continuously during task performance. The results show that fatigue increases the medial-lateral center of mass (COM) displacement and hip and trunk motion, but decreases the COM velocity and ankle motion. Moreover, fatigue reduces the activities of the hamstrings and tibialis anterior, but increases that of the soleus. Finally, greater proximal hip and trunk motions are applied to compensate for the effects of fatigue, leading to a greater COM movement. Overall, the present findings show that fatigue results in impaired movement control and may therefore increase the risk of dance injury.
Eken, Maaike M.; Houdijk, Han; Doorenbosch, Caroline A. M.; Kiezebrink, Francisca E. M.; van Bennekom, Coen A. M.; Harlaar, Jaap; Dallmeijer, Annet J.
To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. In this case-control study, knee extensor muscle endurance was estimated from
Dieën, J.H. van; Westebring van der; Putten, E.P.; Kingma, I.; Looze, M.P. de
This study was designed to determine whether trunk extensor fatigue occurs during low-level activity and whether this is associated with a drop in muscle tissue oxygenation. Electromyography (EMG) feedback was used to impose constant activity in a part of the trunk extensor muscles. We hypothesized
Eken, Maaike M; Houdijk, Han; Doorenbosch, Caroline A M; Kiezebrink, Francisca E.M.; van Bennekom, Coen A.M.; Harlaar, Jaap; Dallmeijer, Annet J.
Aim: To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. Method: In this case–control study, knee extensor muscle endurance was
Vogiatzis, Ioannis; Athanasopoulos, Dimitris; Boushel, Robert Christopher
We investigated whether the greater degree of exercise-induced diaphragmatic fatigue previously reported in highly trained athletes in hypoxia (compared with normoxia) could have a contribution from limited respiratory muscle blood flow. Seven trained cyclists completed three constant load 5 min...... exercise tests at inspired O(2) fractions (FIO2) of 0.13, 0.21 and 1.00 in balanced order. Work rates were selected to produce the same tidal volume, breathing frequency and respiratory muscle load at each FIO2 (63 +/- 1, 78 +/- 1 and 87 +/- 1% of normoxic maximal work rate, respectively). Intercostals......(-1) and 95.1 +/- 7.8 ml (100 ml)(-1) min(-1), respectively). Neither IMBF was different across hypoxia, normoxia and hyperoxia (53.6 +/- 8.5, 49.9 +/- 5.9 and 52.9 +/- 5.9 ml (100 ml)(-1) min(-1), respectively). We conclude that when respiratory muscle energy requirement is not different between...
Neto Gabriel R.
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.
Mori, R. L.; Bergsman, A. E.; Holmes, M. J.; Yates, B. J.
Changes in posture can affect the resting length of respiratory muscles, requiring alterations in the activity of these muscles if ventilation is to be unaffected. Recent studies have shown that the vestibular system contributes to altering respiratory muscle activity during movement and changes in posture. Furthermore, anatomical studies have demonstrated that many bulbospinal neurons in the medial medullary reticular formation (MRF) provide inputs to phrenic and abdominal motoneurons; because this region of the reticular formation receives substantial vestibular and other movement-related input, it seems likely that medial medullary reticulospinal neurons could adjust the activity of respiratory motoneurons during postural alterations. The objective of the present study was to determine whether functional lesions of the MRF affect inspiratory and expiratory muscle responses to activation of the vestibular system. Lidocaine or muscimol injections into the MRF produced a large increase in diaphragm and abdominal muscle responses to vestibular stimulation. These vestibulo-respiratory responses were eliminated following subsequent chemical blockade of descending pathways in the lateral medulla. However, inactivation of pathways coursing through the lateral medulla eliminated excitatory, but not inhibitory, components of vestibulo-respiratory responses. The simplest explanation for these data is that MRF neurons that receive input from the vestibular nuclei make inhibitory connections with diaphragm and abdominal motoneurons, whereas a pathway that courses laterally in the caudal medulla provides excitatory vestibular inputs to these motoneurons.
Adam, Alexander; De Luca, Carlo J
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.
Stoter, Inge K; MacIntosh, Brian R; Fletcher, Jared R; Pootz, Spencer; Zijdewind, Inge; Hettinga, Florentina J
To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500-m speed-skating and cycling time trials when a faster or slower start is instructed. Nine speed skaters and 9 cyclists, all competing at regional or national level, performed two 1500-m time trials in their sport. Athletes were instructed to start faster than usual in 1 trial and slower in the other. Mean velocity was measured per 100 m. Blood lactate concentrations were measured. Maximal voluntary contraction (MVC), voluntary activation (VA), and potentiated twitch (PT) of the quadriceps muscles were measured to estimate central and peripheral contributions to muscle fatigue. In speed skating, knee, hip, and trunk angles were measured to evaluate technique. Cyclists showed a more explosive start than speed skaters in the fast-start time trial (cyclists performed first 300 m in 24.70 ± 1.73 s, speed skaters in 26.18 ± 0.79 s). Both trials resulted in reduced MVC (12.0% ± 14.5%), VA (2.4% ± 5.0%), and PT (25.4% ± 15.2%). Blood lactate concentrations after the time trial and the decrease in PT were greater in the fast-start than in the slow-start trial. Speed skaters showed higher trunk angles in the fast-start than in the slow-start trial, while knee angles remained similar. Despite similar instructions, behavioral adaptations in pacing differed between the 2 sports, resulting in equal central and peripheral contributions to muscle fatigue in both sports. This provides evidence for the importance of neurophysiological aspects in the regulation of pacing. It also stresses the notion that optimal pacing needs to be studied sport specifically, and coaches should be aware of this.
Lee, JiHyun; Yun, Chang-Kyo
[Purpose] The purpose of this study is to investigate the effect of hippotherapy exercise on the thickness of deep abdominal muscles and daily activities of children with intellectual disabilities. [Subjects and Methods] Seven children with intellectual disabilities were treated with hippotherapy for 30 minutes twice a week for 6 weeks. The thickness of deep abdominal muscles and Functional Independence Measure (FIM) of the subjects were measured by ultrasonography before and after the experiment. [Results] There was no significant change in the thickness of the External Oblique and Internal Oblique muscles, but there was a statistically significant change in Transverse Adbominis thickness and FIM score after treatment compared to before treatment. [Conclusion] Hippotherapy exercise has a positive effect on the improvement of Transverse Abdominis (TrA) and activity of daily livings of children with intellectual disabilities.
Moon, Ji-Hyun; Hong, Sang-Min; Kim, Chang-Won; Shin, Yun-A
Pilates and resistance exercises are used for lumbar stabilization training. However, it is unclear which exercise is more effective for lumbar stabilization. In our study, we aimed to compare surface muscle activity and deep muscle thickness during relaxation and spinal stabilization exercise in experienced Pilates and resistance exercise instructors. This study is a retrospective case control study set in the Exercise Prescription Laboratory and Sports Medicine Center. The participants included Pilates instructors (mean years of experience, 3.20±1.76; n=10), resistance exercise instructors (mean years of experience, 2.53±0.63; n=10), and controls (n=10). The participants performed 4 different stabilization exercises: abdominal drawing-in maneuver, bridging, roll-up, and one-leg raise. During the stabilization exercises, surface muscle activity was measured with electromyography, whereas deep muscle thickness was measured by ultrasound imaging. During the 4 stabilization exercises, the thickness of the transverse abdominis (TrA) was significantly greater in the Pilates-trained group than the other 2 other groups. The internal oblique (IO) thickness was significantly greater in the Pilates- and resistance-trained group than the control group, during the 4 exercises. However, the surface muscle activities were similar between the groups. Both Pilates and resistance exercise instructors had greater activation of deep muscles, such as the TrA and IO, than the control subjects. Pilates and resistance exercise are both effective for increasing abdominal deep muscle thickness.
Mehta, Ranjana K; Agnew, Michael J
Most occupational tasks involve some level of mental/cognitive processing in addition to physical work; however, the etiology of work-related musculoskeletal disorders (WMSDs) due to these demands remains unclear. The aim of this study was to quantify the interactive effects of physical and mental workload on muscle endurance, fatigue, and recovery during intermittent work. Twelve participants, balanced by gender, performed intermittent static shoulder abductions to exhaustion at 15, 35, and 55% of individual maximal voluntary contraction (MVC), in the absence (control) and presence (concurrent) of a mental arithmetic task. Changes in muscular capacity were determined using endurance time, strength decline, electromyographic (EMG) fatigue indicators, muscle oxygenation, and heart rate measures. Muscular recovery was quantified through changes in strength and physiological responses. Mental workload was associated with shorter endurance times, specifically at 35% MVC, and greater strength decline. EMG and oxygenation measures showed similar changes during fatigue manifestation during concurrent conditions compared to the control, despite shorter endurance times. Moreover, decreased heart rate variability during concurrent demand conditions indicated increased mental stress. Although strength recovery was not influenced by mental workload, a slower heart rate recovery was observed after concurrent demand conditions. The findings from this study provide fundamental evidence that physical capacity (fatigability and recovery) is adversely affected by mental workload. Thus, it is critical to determine or evaluate occupational demands based on modified muscular capacity (due to mental workload) to reduce risk of WMSD development.
Haddad, Monoem; Chaouachi, Anis; Wong, Del P; Castagna, Carlo; Hambli, Mourad; Hue, Olivier; Chamari, Karim
The aim of this study was to assess the effects of the Hooper's Index variations (i.e., self-ratings of fatigue, stress, delayed onset muscle soreness (DOMS), and sleep) on rating of perceived exertion during a 10 min submaximal exercise training session (RPE-10 min) and then check the stability and the internal consistency of RPE-10 min. Seventeen junior soccer players took part in this study. The individual Hooper's indices taken before each training session were correlated with RPE-10 min during a constant intensity and duration effort (10 min) using Pearson product moment correlation. Intraclass correlation (ICC) was used to assess the internal consistency of the RPE-10 min. All individual correlations between RPE-10 min and quality of sleep and quantity of fatigue, stress, and DOMS were non-significant (p>0.05). No significant correlations were resulted between RPE-10 min and Hooper's Index in all athletes. The ICC of RPE-10 min was 0.77 thus demonstrating internal consistency. The results of the present study demonstrated the objectivity and utility of RPE as a psychological tool for monitoring training during traditional soccer training. Therefore, the results of the present study suggest that fatigue, stress, DOMS and sleep are not major contributors of perceived exertion during traditional soccer training without excessive training loads. It seems that psychobiological factors other than fatigue, stress, DOMS and sleep may have mediated the 10 min exercise perceptual intensity. © 2013.
James, A; Green, S
The relationship between power output and the time that it can be sustained during exercise (i.e., endurance) at high intensities is curvilinear. Although fatigue is implicit in this relationship, there is little evidence pertaining to it. To address this, we developed a phenomenological model that predicts the temporal response of muscle power during submaximal and maximal exercise and which was based on the type, contractile properties (e.g., fatiguability), and recruitment of motor units (MUs) during exercise. The model was first used to predict power outputs during all-out exercise when fatigue is clearly manifest and for several distributions of MU type. The model was then used to predict times that different submaximal power outputs could be sustained for several MU distributions, from which several power-endurance curves were obtained. The model was simultaneously fitted to two sets of human data pertaining to all-out exercise (power-time profile) and submaximal exercise (power-endurance relationship), yielding a high goodness of fit (R(2) = 0.96-0.97). This suggested that this simple model provides an accurate description of human power output during submaximal and maximal exercise and that fatigue-related processes inherent in it account for the curvilinearity of the power-endurance relationship.
Papa, Evan V; Garg, Hina; Dibble, Leland E
Falls are the leading cause of traumatic brain injury and fractures and the No. 1 cause of emergency department visits by older adults. Although declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. In an effort to increase awareness of the detrimental effects of skeletal muscle fatigue on postural control, we sought to systematically review research studies examining this issue. The specific purpose of this review was to provide a detailed assessment of how anticipatory and reactive postural control tasks are influenced by acute muscle fatigue in healthy older individuals. An extensive search was performed using the CINAHL, Scopus, PubMed, SPORTDiscus, and AgeLine databases for the period from inception of each database to June 2013. This systematic review used standardized search criteria and quality assessments via the American Academy for Cerebral Palsy and Developmental Medicine Methodology to Develop Systematic Reviews of Treatment Interventions (2008 version, revision 1.2, AACPDM, Milwaukee, Wisconsin). A total of 334 citations were found. Six studies were selected for inclusion, whereas 328 studies were excluded from the analytical review. The majority of articles (5 of 6) utilized reactive postural control paradigms. All studies incorporated extrinsic measures of muscle fatigue, such as declines in maximal voluntary contraction or available active range of motion. The most common biomechanical postural control task outcomes were spatial measures, temporal measures, and end-points of lower extremity joint kinetics. On the basis of systematic review of relevant literature, it appears that muscle fatigue induces clear deteriorations in reactive postural control. A paucity of high-quality studies examining anticipatory postural control supports the need for further research in this area. These results should serve to heighten
Bjerkefors, Anna; Squair, Jordan W; Chua, Romeo; Lam, Tania; Chen, Zhen; Carpenter, Mark G
To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.
McBride, Jeffrey M; Porcari, John P; Scheunke, Mark D
This investigation was designed to determine if vibration during fatiguing resistance exercise would alter associated patterns of muscle activity. A cross-over design was employed with 8 subjects completing a resistance exercise bout once with a vibrating dumbbell (V) (44 Hz, 3 mm displacement) and once without vibration (NV). For both exercise bouts, 10 sets were performed with a load that induced concentric muscle failure during the 10th repetition. The appropriate load for each set was determined during a pretest. Each testing session was separated by 1 week. Electromyography (EMG) was obtained from the biceps brachii muscle at 12 different time points during a maximum voluntary contraction (MVC) at a 170 degrees elbow angle after each set of the dumbbell exercise. The time points were as follows: pre (5 minutes before the resistance exercise bout), T1-T10 (immediately following each set of resistance exercise), and post (15 minutes after the resistance exercise bout). EMG was analyzed for median power frequency (MPF) and maximum (mEMG). NV resulted in a significant decrease in MPF at T1-T4 (p recruitment of high threshold motor units during fatiguing contractions. This may indicate the usage of vibration with resistance exercise as an effective tool for strength training athletes.
Ballak, Sam B; Busé-Pot, Tinelies; Harding, Peter J; Yap, Moi H; Deldicque, Louise; de Haan, Arnold; Jaspers, Richard T; Degens, Hans
We hypothesize that the attenuated hypertrophic response in old mouse muscle is (1) partly due to a reduced capillarization and angiogenesis, which is (2) accompanied by a reduced oxidative capacity and fatigue resistance in old control and overloaded muscles, that (3) can be rescued by the antioxidant resveratrol. To investigate this, the hypertrophic response, capillarization, oxidative capacity, and fatigue resistance of m. plantaris were compared in 9- and 25-month-old non-treated and 25-month-old resveratrol-treated mice. Overload increased the local capillary-to-fiber ratio less in old (15 %) than in adult (59 %) muscle (P muscles of old mice had a higher succinate dehydrogenase (SDH) activity (P < 0.05) and a slower fiber type profile (P < 0.05), the isometric fatigue resistance was similar in 9- and 25-month-old mice. In both age groups, the fatigue resistance was increased to the same extent after overload (P < 0.01), without a significant change in SDH activity, but an increased capillary density (P < 0.05). Attenuated angiogenesis during overload may contribute to the attenuated hypertrophic response in old age. Neither was rescued by resveratrol supplementation. Changes in fatigue resistance with overload and aging were dissociated from changes in SDH activity, but paralleled those in capillarization. This suggests that capillarization plays a more important role in fatigue resistance than oxidative capacity.
Kamelska, Anna M; Kot, Bartosz
The first step in identifying risk factors for injuries is to characterize the myoelectric activity of different muscles after ground contact, especially when fatigue is a limiting factor. This study aimed at: (a) recording the myoelectric activity of calf muscles after ground contact during different types of jumps and (b) investigating the effect of motor learning and fatigue on muscle pre-activation. Twenty four male students aged 24.3 ± 1.2 years old performed three different motor activities: (a) Jump from a box with counter landing (JCL) on 30x30 cm plate (b) Drop jump with bounce drop jump (BDJ) and (c) BDJ followed by a jump on 51-cm step. The surface EMG was used to examine the following muscles: m. tibialis anterior (TA), m. gastrocnemius medialis (GM), m. gastrocnemius lateralis (GL), and m. soleus (S). The measurements were taken during different jumps before and after motor learning and fatigue stimulus. There were significant differences in pre-activation for TA between JCL and BDJ followed by a jump under the influence of fatigue (p<0.05). The differences were observed also during BDJ between non-fatigued and fatigued conditions. There was a statistically significant difference for GL between BDJ pre- and post-movement motor learning and BDJ pre- and post-fatigue influence. Current results indicate that myoelectric activity of muscles during motor activities is different, and the effect of motor learning and fatigue was shown. Thus, it could be important in the injury prevention in sport.
Segala, David B; Gates, Deanna H; Dingwell, Jonathan B; Chelidze, David
Tracking or predicting physiological fatigue is important for developing more robust training protocols and better energy supplements and/or reducing muscle injuries. Current methodologies are usually impractical and/or invasive and may not be realizable outside of laboratory settings. It was recently demonstrated that smooth orthogonal decomposition (SOD) of phase space warping (PSW) features of motion kinematics can identify fatigue in individual muscle groups. We hypothesize that a nonlinear extension of SOD will identify more optimal fatigue coordinates and provide a lower-dimensional reconstruction of local fatigue dynamics than the linear SOD. Both linear and nonlinear SODs were applied to PSW features estimated from measured kinematics to reconstruct muscle fatigue dynamics in subjects performing a sawing motion. Ten healthy young right-handed subjects pushed a weighted handle back and forth until voluntary exhaustion. Three sets of joint kinematic angles were measured from the right upper extremity in addition to surface electromyography (EMG) recordings. The SOD coordinates of kinematic PSW features were compared against independently measured fatigue markers (i.e., mean and median EMG spectrum frequencies of individual muscle groups). This comparison was based on a least-squares linear fit of a fixed number of the dominant SOD coordinates to the appropriate local fatigue markers. Between subject variability showed that at most four to five nonlinear SOD coordinates were needed to reconstruct fatigue in local muscle groups, while on average 15 coordinates were needed for the linear SOD. Thus, the nonlinear coordinates provided a one-order-of-magnitude improvement over the linear ones.
Webster, Kathryn A.; Pietrosimone, Brian G.; Gribble, Phillip A.
Context: Ankle instability is a common condition in physically active individuals. It often occurs during a jump landing or lateral motion, particularly when participants are fatigued. Objective: To compare muscle activation during a lateral hop prefatigue and postfatigue in individuals with or without chronic ankle instability (CAI). Design: Cross-sectional study. Setting: Sports medicine research laboratory. Patients or Other Participants: A total of 32 physically active participants volunteered for the study. Sixteen participants with CAI (8 men, 8 women; age = 20.50 ± 2.00 years, height = 172.25 ± 10.87 cm, mass = 69.13 ± 13.31 kg) were matched with 16 control participants without CAI (8 men, 8 women; age = 22.00 ± 3.30 years, height = 170.50 ± 9.94 cm, mass = 69.63 ± 14.82 kg) by age, height, mass, sex, and affected side. Intervention(s): Electromyography of the tibialis anterior, peroneus longus, gluteus medius, and gluteus maximus was measured before and after a functional fatigue protocol. Main Outcome Measure(s): Activation of 4 lower extremity muscles was measured 200 milliseconds before and after landing from a lateral hop. Results: We observed no interactions. The group main effects for the peroneus longus demonstrated higher muscle activation in the CAI group (52.89% ± 11.36%) than in the control group (41.12% ± 11.36%) just before landing the lateral hop (F1,30 = 8.58, P = .01), with a strong effect size (d = 1.01). The gluteus maximus also demonstrated higher muscle activation in the CAI group (45.55% ± 12.08%) than in the control group (36.81% ± 12.08%) just before landing the lateral hop (F1,30 = 4.19, P = .049), with a moderate effect size (d = 0.71). We observed a main effect for fatigue for the tibialis anterior, with postfatigue activation higher than prefatigue activation (F1,30 = 7.45, P = .01). No differences were present between groups for the gluteus medius. Conclusions: Our results support the presence of a centralized feed
Full Text Available Introduction: It appears that the level of fear of movement changes deep trunk muscle activity in the patients with low back pain (LBP. There is no study to investigate the relationship between deep trunk muscle activity and fear of movement in the patients with LBP. Thus, the purpose of this study was to assess the relationship between abdominal muscle activity and pain, disability and fear of movement during standing postural tasks in females with chronic nonspecific LBP. Materials and Methods: Forty four females participated were asked to maintain their balance during standing on the platform stability levels of Biodex Balance System (BBS. Concurrently, ultrasonography (US data about abdominal muscles thickness measurement were transferred and saved to process offline. The pain intensity, disability and fear of movement were assessed by valid scales and questionnaire. Results: There was not significant correlation between abdominal muscle thickness changes and pain and disability intensity (P>0.05, while significant and inverse correlation between deep abdominal muscle thickness changes and fear of movement was observed in the patients (P<0.05, although this correlation is weak (r= -0.36- -0.32. Conclusion: It seems that increases in fear of movement decrease significantly deep abdominal muscles activity in the patients with LBP. This relationship demonstrates the importance of cognitive behavioral therapy and controlling fear of movement on improvement of deep abdominal muscle activity in the patients with LBP
Jordan, Matthew J; Aagaard, Per; Herzog, Walter
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...
Irani, Ramin; Nasrollahi, Kamal; Moeslund, Thomas B.
their exercises when the level of the fatigue might be dangerous for the patients. The current technology for measuring tiredness, like Electromyography (EMG), requires installing some sensors on the body. In some applications, like remote patient monitoring, this however might not be possible. To deal...... with such cases, in this paper we present a contactless method based on computer vision techniques to measure tiredness by detecting, tracking, and analyzing some facial feature points during the exercise. Experimental results on several test subjects and comparing them against ground truth data show...... that the proposed system can properly find the temporal point of tiredness of the muscles when the test subjects are doing physical exercises....
Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Hasnan, Nazirah; Abdul Wahab, Ahmad Khairi; Davis, Glen M
Rapid muscle fatigue during functional electrical stimulation (FES)-evoked muscle contractions in individuals with spinal cord injury (SCI) is a significant limitation to attaining health benefits of FES-exercise. Delaying the onset of muscle fatigue is often cited as an important goal linked to FES clinical efficacy. Although the basic concept of fatigue-resistance has a long history, recent advances in biomedical engineering, physiotherapy and clinical exercise science have achieved improved clinical benefits, especially for reducing muscle fatigue during FES-exercise. This review evaluated the methodological quality of strategies underlying muscle fatigue-resistance that have been used to optimize FES therapeutic approaches. The review also sought to synthesize the effectiveness of these strategies for persons with SCI in order to establish their functional impacts and clinical relevance. Published scientific literature pertaining to the reduction of FES-induced muscle fatigue was identified through searches of the following databases: Science Direct, Medline, IEEE Xplore, SpringerLink, PubMed and Nature, from the earliest returned record until June 2015. Titles and abstracts were screened to obtain 35 studies that met the inclusion criteria for this systematic review. Following the evaluation of methodological quality (mean (SD), 50 (6) %) of the reviewed studies using the Downs and Black scale, the largest treatment effects reported to reduce muscle fatigue mainly investigated isometric contractions of limited functional and clinical relevance (n = 28). Some investigations (n = 13) lacked randomisation, while others were characterised by small sample sizes with low statistical power. Nevertheless, the clinical significance of emerging trends to improve fatigue-resistance during FES included (i) optimizing electrode positioning, (ii) fine-tuning of stimulation patterns and other FES parameters, (iii) adjustments to the mode and frequency of exercise training
Morufu Olusola Ibitoye
Full Text Available Rapid muscle fatigue during functional electrical stimulation (FES-evoked muscle contractions in individuals with spinal cord injury (SCI is a significant limitation to attaining health benefits of FES-exercise. Delaying the onset of muscle fatigue is often cited as an important goal linked to FES clinical efficacy. Although the basic concept of fatigue-resistance has a long history, recent advances in biomedical engineering, physiotherapy and clinical exercise science have achieved improved clinical benefits, especially for reducing muscle fatigue during FES-exercise. This review evaluated the methodological quality of strategies underlying muscle fatigue-resistance that have been used to optimize FES therapeutic approaches. The review also sought to synthesize the effectiveness of these strategies for persons with SCI in order to establish their functional impacts and clinical relevance.Published scientific literature pertaining to the reduction of FES-induced muscle fatigue was identified through searches of the following databases: Science Direct, Medline, IEEE Xplore, SpringerLink, PubMed and Nature, from the earliest returned record until June 2015. Titles and abstracts were screened to obtain 35 studies that met the inclusion criteria for this systematic review.Following the evaluation of methodological quality (mean (SD, 50 (6 % of the reviewed studies using the Downs and Black scale, the largest treatment effects reported to reduce muscle fatigue mainly investigated isometric contractions of limited functional and clinical relevance (n = 28. Some investigations (n = 13 lacked randomisation, while others were characterised by small sample sizes with low statistical power. Nevertheless, the clinical significance of emerging trends to improve fatigue-resistance during FES included (i optimizing electrode positioning, (ii fine-tuning of stimulation patterns and other FES parameters, (iii adjustments to the mode and frequency of exercise
Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Hasnan, Nazirah; Abdul Wahab, Ahmad Khairi; Davis, Glen M.
Background Rapid muscle fatigue during functional electrical stimulation (FES)-evoked muscle contractions in individuals with spinal cord injury (SCI) is a significant limitation to attaining health benefits of FES-exercise. Delaying the onset of muscle fatigue is often cited as an important goal linked to FES clinical efficacy. Although the basic concept of fatigue-resistance has a long history, recent advances in biomedical engineering, physiotherapy and clinical exercise science have achieved improved clinical benefits, especially for reducing muscle fatigue during FES-exercise. This review evaluated the methodological quality of strategies underlying muscle fatigue-resistance that have been used to optimize FES therapeutic approaches. The review also sought to synthesize the effectiveness of these strategies for persons with SCI in order to establish their functional impacts and clinical relevance. Methods Published scientific literature pertaining to the reduction of FES-induced muscle fatigue was identified through searches of the following databases: Science Direct, Medline, IEEE Xplore, SpringerLink, PubMed and Nature, from the earliest returned record until June 2015. Titles and abstracts were screened to obtain 35 studies that met the inclusion criteria for this systematic review. Results Following the evaluation of methodological quality (mean (SD), 50 (6) %) of the reviewed studies using the Downs and Black scale, the largest treatment effects reported to reduce muscle fatigue mainly investigated isometric contractions of limited functional and clinical relevance (n = 28). Some investigations (n = 13) lacked randomisation, while others were characterised by small sample sizes with low statistical power. Nevertheless, the clinical significance of emerging trends to improve fatigue-resistance during FES included (i) optimizing electrode positioning, (ii) fine-tuning of stimulation patterns and other FES parameters, (iii) adjustments to the mode and
Rashid, A.; Ayub, M.
On exposure to prolonged cold temperature, the body responds for effective heat production both by shivering and non-shivering thermo genesis. Cold exposure increases the production of reactive oxygen species which influence the sarcoplasmic reticulum Ca/sup ++/ release from the skeletal muscles and affect their contractile properties. The role of ascorbic acid supplementation on force of contraction during fatigue of cold exposed skeletal muscles was evaluated in this study. Method: Ninety healthy, male Sprague Dawley rats were randomly divided into three groups of control, cold exposed, and cold exposed with ascorbic acid 500 mg/L supplementation mixed in drinking water. Group II and III were given cold exposure by keeping their cages in ice-filled tubs for 1 hr/day for one month. After one month, the extensor digitorum longus muscle was dissected out and force of contraction during fatigue in the skeletal muscle fibres was analysed on a computerised data acquisition system. Results: The cold exposed group showed a significant delay in the force of contraction during fatigue of skeletal muscle fibres compared to control group. Group III showed easy fatigability and a better force of contraction than the cold exposed group. Conclusions: Ascorbic acid increases the force of contraction and decreases resistance to fatigue in the muscles exposed to chronic cold. (author)
Fulco, C S; Lewis, S F; Frykman, Peter
and during exercise. MVC force was 578 +/- 29 N in normoxia and 569 +/- 29 N in hypobaria before exercise and fell, at exhaustion, to similar levels (265 +/- 10 and 284 +/- 20 N for normoxia and hypobaria, respectively; P > 0.05) that were higher (P ...Using an exercise device that integrates maximal voluntary static contraction (MVC) of knee extensor muscles with dynamic knee extension, we compared progressive muscle fatigue, i.e., rate of decline in force-generating capacity, in normoxia (758 Torr) and hypobaric hypoxia (464 Torr). Eight...... healthy men performed exhaustive constant work rate knee extension (21 +/- 3 W, 79 +/- 2 and 87 +/- 2% of 1-leg knee extension O2 peak uptake for normoxia and hypobaria, respectively) from knee angles of 90-150 degrees at a rate of 1 Hz. MVC (90 degrees knee angle) was performed before dynamic exercise...
Bürger-Mendonça, Marcos; Bielavsky, Monica; Barbosa, Fernanda C R
Triathlon competition is dependent on the athletes' ability to perform each discipline at optimal time, without excessive fatigue influencing the next one. Determine the effects of a long distance triathlon on biochemistry parameters related to liver function. Blood samples from six athletes were collected before (T = 0) and immediately after the triathlon competition (T = 1). AST, ALT and alkaline phosphatase (ALP) values were assessed. Significant changes after triathlon competition were found for AST and ALP and no significant changes were found for ALT over time. A series of metabolically alterations, mainly related to energy production and also to muscle and skeletal adaptations occurs during and after strenuous exercise. The altered status of those metabolical changes cannot directly reflect the intensity of any possible muscular or hepatic damage or overload and elevated AST/ALT ratio is better associated to skeletal muscle lesion during competition.
Nielsen, Joachim; Cheng, Arthur J; Ørtenblad, Niels
In skeletal muscle fibres, glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); and (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator...... of sarcoplasmic reticulum Ca(2+) release. The aim of the present study was to test directly how the decrease in cytoplasmic free Ca(2+) ([Ca(2+)]i) during repeated tetanic contractions relates to the subcellular glycogen distribution. Single fibres of mouse flexor digitorum brevis muscles were fatigued with 70 Hz...... in tetanic [Ca(2+)]i, and hence force, is accompanied by major reductions in inter- and intramyofibrillar glycogen. The stronger correlation between decreased tetanic [Ca(2+)]i and reduced intramyofibrillar glycogen implies that sarcoplasmic reticulum Ca(2+) release critically depends on energy supply from...
Hubley-Kozey, Cheryl L; Butler, Heather L; Kozey, John W
Muscle synergies are important for spinal stability, but few studies examine temporal responses of spinal muscles to dynamic perturbations. This study examined activation amplitudes and temporal synergies among compartments of the back extensor and among abdominal wall muscles in response to dynamic bidirectional moments of force. We further examined whether responses were different between men and women. 19 women and 18 men performed a controlled transfer task. Surface electromyograms from bilateral sites over 6 back extensor compartments and 6 abdominal wall muscle sites were analyzed using principal component analysis. Key features were extracted from the measured electromyographic waveforms capturing amplitude and temporal variations among muscle sites. Three features explained 97% of the variance. Scores for each feature were computed for each measured waveform and analysis of variance found significant (pWomen had more differences among muscle sites than men for the lateral flexion moment feature. For the abdominal wall muscles the oblique muscles responded with synergies related to fiber orientation, with women having higher amplitudes and more responsiveness to the lateral flexion moment than men. Synergies between the abdominal and back extensor sites as the moment demands change are discussed. These findings illustrate differential activation among erector spinae compartments and abdominal wall muscle sites supporting a highly organized pattern of response to bidirectional external moments with asynchronies more apparent in women. Copyright © 2012 Elsevier B.V. All rights reserved.
Smith, Michael P.; Sizer, Phillip S.; James, C. Roger
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 comp...
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.
Oksa, Juha; Ducharme, Michel B; Rintamäki, Hannu
This study compared the effect of repetitive work in thermoneutral and cold conditions on forearm muscle electromyogram (EMG) and fatigue. We hypothesize that cold and repetitive work together cause higher EMG activity and fatigue than repetitive work only, thus creating a higher risk for overuse injuries. Eight men performed six 20-min work bouts at 25 degrees C (W-25) and at 5 degrees C while exposed to systemic (C-5) and local cooling (LC-5). The work was wrist flexion-extension exercise at 10% maximal voluntary contraction. The EMG activity of the forearm flexors and extensors was higher during C-5 (31 and 30%, respectively) and LC-5 (25 and 28%, respectively) than during W-25 (P forearm flexors at the end of W-25 was 15%. The corresponding values at the end of C-5 and LC-5 were 37% (P < 0.05 in relation to W-25) and 20%, respectively. Thus repetitive work in the cold causes higher EMG activity and fatigue than repetitive work in thermoneutral conditions.
Marshall, Paul W. M.; Lovell, Ric; Jeppesen, Gitte K.; Andersen, Kristoffer; Siegler, Jason C.
Purpose To examine changes in hamstring muscle fatigue and central motor output during a 90-minute simulated soccer match, and the concomitant changes in hamstring maximal torque and rate of torque development. Method Eight amateur male soccer players performed a 90-minute simulated soccer match, with measures performed at the start of and every 15-minutes during each half. Maximal torque (Nm) and rate of torque development (RTD; Nm.s–1) were calculated from maximal isometric knee flexor contractions performed at 10° of flexion. Hamstring peripheral fatigue was assessed from changes in the size and shape of the resting twitch (RT). Hamstring central motor output was quantified from voluntary activation (%) and normalized biceps femoris (BF) and medial hamstrings (MH) electromyographic amplitudes (EMG/M). Results Maximal torque was reduced at 45-minutes by 7.6±9.4% (phamstring peripheral fatigue. Conclusion Centrally mediated reductions in maximal torque and rate of torque development provide insight into factors that may explain hamstring injury risk during soccer. Of particular interest were early reductions during the first-half of hamstring rate of torque development, and the decline in maximal EMG/M of biceps femoris in the latter stages of the half. These are important findings that may help explain why the hamstrings are particularly vulnerable to strain injury during soccer. PMID:25047547
Brown, Denver M Y; Bray, Steven R
Physical performance is impaired following cognitive control exertion. Incentives can ameliorate adverse carryover effects of cognitive control exertion but have not been investigated for physical endurance. This study examined the effect of monetary incentives on physical performance and muscle activation following exposure to a mentally fatiguing, cognitive control task. Participants (N = 82) performed two isometric endurance handgrip trials separated by a 12-min cognitive control manipulation using a 2 (high cognitive control [HCC]/low cognitive control [LCC]) × 2 (incentive/no incentive) design. Mental fatigue was significantly higher in the HCC conditions. Performance decreased in the HCC/no incentive condition but was unaffected in the HCC/incentive condition, which did not differ from the low cognitive control conditions. Electromyography data revealed increased muscle activation in the HCC/no incentive condition, which was also attenuated in the HCC/incentive condition. Findings show that incentives counteract the negative effects of HCC on physical endurance and alter central drive to motor units.
Pettorossi, V E; Della Torre, G; Bortolami, R; Brunetti, O
1. The role of group III and IV afferent fibres of the lateral gastrocnemious muscle (LG) in modulating the homonymous monosynaptic reflex was investigated during muscle fatigue in spinalized rats. 2. Muscle fatigue was induced by a series of increasing tetanic electrical stimuli (85 Hz, 600 ms) delivered to the LG muscle nerve. Series consisted of increasing train numbers from 1 to 60. 3. Potentials from the spinal cord LG motor pool and from the ventral root were recorded in response to proprioceptive afferent stimulation and analysed before and during tetanic muscle activations. Both the pre- and postsynaptic waves showed an initial enhancement and, after a '12-train' series, an increasing inhibition. 4. The enhancement of the responses to muscle fatiguing stimulation disappeared after L3-L6 dorsal root section, while a partial reflex inhibition was still present. Conversely, after section of the corresponding ventral root, there was only a reduction in the inhibitory effect. 5. The monosynaptic reflex was also studied in animals in which a large number of group III and IV muscle afferents were eliminated by injecting capsaicin (10 mM) into the LG muscle. As a result of capsaicin treatment, the fatigue-induced inhibition of the pre- and postsynaptic waves disappeared, while the response enhancement remained. 6. We concluded that the monosynaptic reflex inhibition, but not the enhancement, was mediated by those group III and IV muscle afferents that are sensitive to the toxic action of capsaicin. The afferents that are responsible for the response enhancement enter the spinal cord through the dorsal root, while those responsible for the inhibition enter the spinal cord through both the ventral and dorsal roots.
Full Text Available This research study aims at addressing the paradigm of whole body fatigue and local muscle fatigue detection for squat lifting. For this purpose, a comparison was made between perceived exertion with the heart rate and normalized mean power frequency (NMPF of eight major muscles. The sample consisted of 25 healthy males (age: 30 ± 2.2 years. Borg’s CR-10 scale was used for perceived exertion for two segments of the body (lower and upper and the whole body. The lower extremity of the body was observed to be dominant compared to the upper and whole body in perceived response. First mode of principal component analysis (PCA was obtained through the covariance matrix for the eight muscles for 25 subjects for NMPF of eight muscles. The diagonal entries in the covariance matrix were observed for each muscle. The muscle with the highest absolute magnitude was observed across all the 25 subjects. The medial deltoid and the rectus femoris muscles were observed to have the highest frequency for each PCA across 25 subjects. The rectus femoris, having the highest counts in all subjects, validated that the lower extremity dominates the sense of whole body fatigue during squat lifting. The findings revealed that it is significant to take into account the relation between perceived and measured effort that can help prevent musculoskeletal disorders in repetitive occupational tasks.
Ahmad, Imran; Kim, Jung-Yong
This research study aims at addressing the paradigm of whole body fatigue and local muscle fatigue detection for squat lifting. For this purpose, a comparison was made between perceived exertion with the heart rate and normalized mean power frequency (NMPF) of eight major muscles. The sample consisted of 25 healthy males (age: 30 ± 2.2 years). Borg’s CR-10 scale was used for perceived exertion for two segments of the body (lower and upper) and the whole body. The lower extremity of the body was observed to be dominant compared to the upper and whole body in perceived response. First mode of principal component analysis (PCA) was obtained through the covariance matrix for the eight muscles for 25 subjects for NMPF of eight muscles. The diagonal entries in the covariance matrix were observed for each muscle. The muscle with the highest absolute magnitude was observed across all the 25 subjects. The medial deltoid and the rectus femoris muscles were observed to have the highest frequency for each PCA across 25 subjects. The rectus femoris, having the highest counts in all subjects, validated that the lower extremity dominates the sense of whole body fatigue during squat lifting. The findings revealed that it is significant to take into account the relation between perceived and measured effort that can help prevent musculoskeletal disorders in repetitive occupational tasks.
Zebis, M K; Bencke, J; Andersen, L L; Alkjaer, T; Suetta, C; Mortensen, P; Kjaer, M; Aagaard, P
In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested for neuromuscular activity [electromyography (EMG)] during a sidecutting maneuver on a force plate, pre and post a simulated handball match. MVC was obtained during maximal isometric quadriceps and hamstring contraction. The simulated handball match consisted of exercises mimicking handball match activity. Whereas the simulated handball match induced a decrease in MVC strength for both the quadriceps and hamstring muscles (Phandball match play. Thus, screening procedures should involve functional movements to reveal specific fatigue-induced deficits in ACL-agonist muscle activation during high-risk phases of match play. © 2010 John Wiley & Sons A/S.
Rymer, William Z.; Lowery, Madeleine M.; Suresh, Nina L.
The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contraction and after a recovery period. EMG activity was recorded during abduction of the first dorsal interosseous in 12 subjects at 20% maximum voluntary contraction (MVC), before and directly after a 30% MVC fatiguing contraction to task failure, with additional 20% MVC contractions following a 10-min rest. The amplitude, duration and mean firing rate (MFR) of MUAPs extracted with a sEMG decomposition system were analyzed, together with sEMG root-mean-square (RMS) amplitude and median frequency (MPF). MUAP duration and amplitude increased immediately postfatigue and were correlated with changes to sEMG MPF and RMS, respectively. After 10 min, MUAP duration and sEMG MPF recovered to prefatigue values but MUAP amplitude and sEMG RMS remained elevated. MU MFR and recruitment thresholds decreased postfatigue and recovered following rest. The increase in MUAP and sEMG amplitude likely reflects recruitment of larger MUs, while recruitment compression is an additional compensatory strategy directly postfatigue. Recovery of MU MFR in parallel with MUAP duration suggests a possible role for metabolically sensitive afferents in MFR depression postfatigue. This study provides insight into fatigue-induced neuromuscular changes by examining the properties of a large population of concurrently recorded single MUs and outlines possible compensatory strategies involving alterations in MU recruitment and MFR. PMID:25761952
... sleep. Fatigue is a lack of energy and motivation. Drowsiness and apathy (a feeling of not caring ... Call your provider right away if you have any of the following: Confusion or dizziness Blurred vision Little or no urine, or recent ...
Ney Marcos da Luz Pedroso
Full Text Available The purpose of this study was to evaluate the Localized Muscular endurance (LME of the abdominal region in relation to distinct muscle groups (hip and lumbar spine fl exor of individuals in differing physical conditions. One hundred twenty subjects were selected at random (60 male and 60 female 50% of whom worked out and 50% who didn’t. The AAHPERD Test (1976 and PAULA Test (1990 were used to measure the LME of hip and lumbar spine fl exor, respectively. Results indicated that subjects who worked out differ significantly (p RESUMO Este trabalho teve como objetivo avaliar a Resistência Muscular Localizada (RML da região abdominal em relação a grupos musculares distintos (fl exores do quadril e fl exores da coluna vertebral de indivíduos com condicionamento físico diferentes. Para tal foram selecionados aleatoriamente 120 indivíduos (60 masculinos e 60 femininos sendo 50% destes treinados e os outros 50% destreinados. Utilizou-se o teste da AAHPER e o teste de PAULA para mensurar a RML dos fl exores de quadril e fl exores da coluna vertebral, respectivamente. Os resultados demonstram que indivíduos treinados e destreinados diferem signifi cativamente (p<0,01 quanto a RML dos fl exores da coluna vertebral em ambos os sexos, e também nos fl exores do quadril no sexo feminino (p<0,05; fi cando somente os fl exores do quadril do sexo masculino sem diferenças estatisticamente signifi cativas. Existiram correlações de baixas a moderadas entre flexores do quadril e fl exores da coluna vertebral para treinadas (r=0,45 e destreinadas (r=0,44 do sexo feminino, sendo moderada em treinados do sexo masculino (r=057 e baixa para destreinados (r=0,36. Apesar destes valores de correlação terem sido signifi cativos estatisticamente (p<0,05 em mulheres treinadas e destreinadas e homens treinados, os valores de r2 demonstraram um baixo grau de variação conjunta entre os grupos musculares (variando entre 13,32% a 33,52%. Pode-se concluir que nenhum
Larsen, Lars Henrik; Østergaard, Gert Værge; Brogner, Heidi Marie
Low-back pain (LBP) is a major problem. Spine control and stability mechanisms are important but the knowledge of these parameters in functions is sparse. 7 healthy / 5 recurrent mild-to-moderate LBP patients participated in assessment of abdominal, lumbar and gluteal muscles' surface EMG and video...
Full Text Available PURPOSE: To compare the lateral abdominal muscle thickness and other possible functional risk factors in young soccer players with and without low back pain (LBP.METHOD: In total, 30 young soccer players between 16 and 20 years old, with and without LBP, from the premier league participated in this study. The thicknesses of external oblique, internal oblique and transversus abdominis on both sides were measured via ultrasound imaging. In addition, hamstring flexibility, active lumbar forward flexion, and isometric muscle endurance of trunk extensors were measured and were compared regarding the history of LBP.RESULTS: Mean ± SD age of the subjects was 17.4 ± 1.1 years. There was no statistically significant difference regarding age, BMI, weekly training hours and age of starting to compete between groups. Subjects with sports-life, last year and last month history ofLBP had a statistically significant lower external oblique muscle thickness in both right and left side, and both dominant and non-dominant feet (p<0.05. Subjects with sportslife history of LBP had lower internal oblique muscle thickness in both side and both feet (p<0.05. Moreover, those with a sports-life history of LBP had a significantly higher degree of hamstring muscle tightness than non-LBP group on the dominant foot (p <0.05.CONCLUSION: In this sample group of young soccer players, abdominal muscles seem to have an important role in the stability of the spine and prevention of LBP. Further longitudinal studies are needed to evaluate the role of these muscles as a risk factor for soccer players.
Parker, Michael G; Broughton, Alex J; Larsen, Ben R; Dinius, Josh W; Cimbura, Mac J; Davis, Matthew
The purpose of this study was to compare electrically induced contraction levels produced by three patterns of alternating current in fatigued and nonfatigued skeletal muscles. Eighteen male volunteers without health conditions, with a mean (SD) age of 24.9 (3.4) yrs were randomly exposed to a fatiguing volitional isometric quadriceps contraction and one of three patterns of 2.5-KHz alternating current; two were modulated at 50 bursts per second (10% burst duty cycle with five cycles per burst and 90% burst duty cycle with 45 cycles per burst), and one pattern was modulated at 100 bursts per second (10% burst duty cycle with 2.5 cycles per burst). The electrically induced contraction levels produced by the three patterns of electrical stimulation were compared before and after the fatiguing contraction. The 10% burst duty cycles produced 42.9% (95% confidence interval, 29.1%-56.7%) and 32.1% (95% confidence interval, 18.2%-45.9%) more muscle force (P stronger muscle contractions. Furthermore, the stimulation patterns had no influence on the difference in muscle force before and after the fatiguing quadriceps contraction. Consequently, for clinical applications in which high forces are desired, the patterns using the 10% burst duty cycle may be helpful.
Avin, Keith G; Law, Laura A Frey
During senescence, despite the loss of strength (force-generating capability) associated with sarcopenia, muscle endurance may improve for isometric contractions. The purpose of this study was to perform a systematic meta-analysis of young versus older adults, considering likely moderators (ie, contraction type, joint, sex, activity level, and task intensity). A 2-stage systematic review identified potential studies from PubMed, CINAHL, PEDro, EBSCOhost: ERIC, EBSCOhost: Sportdiscus, and The Cochrane Library. Studies reporting fatigue tasks (voluntary activation) performed at a relative intensity in both young (18-45 years of age) and old (≥ 55 years of age) adults who were healthy were considered. Sample size, mean and variance outcome data (ie, fatigue index or endurance time), joint, contraction type, task intensity (percentage of maximum), sex, and activity levels were extracted. Effect sizes were (1) computed for all data points; (2) subgrouped by contraction type, sex, joint or muscle group, intensity, or activity level; and (3) further subgrouped between contraction type and the remaining moderators. Out of 3,457 potential studies, 46 publications (with 78 distinct effect size data points) met all inclusion criteria. A lack of available data limited subgroup analyses (ie, sex, intensity, joint), as did a disproportionate spread of data (most intensities ≥ 50% of maximum voluntary contraction). Overall, older adults were able to sustain relative-intensity tasks significantly longer or with less force decay than younger adults (effect size=0.49). However, this age-related difference was present only for sustained and intermittent isometric contractions, whereas this age-related advantage was lost for dynamic tasks. When controlling for contraction type, the additional modifiers played minor roles. Identifying muscle endurance capabilities in the older adult may provide an avenue to improve functional capabilities, despite a clearly established decrement in
Head, Stewart I.; Greenaway, Bronwen; Chan, Stephen
Background Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. Methods and Results The extensor digitorum longus muscle from mice aged 12–14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i) before fatigue; (ii) immediately after a fatigue protocol; and (iii) after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. Conclusion Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation. PMID:21850234
Stewart I Head
Full Text Available BACKGROUND: Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. METHODS AND RESULTS: The extensor digitorum longus muscle from mice aged 12-14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i before fatigue; (ii immediately after a fatigue protocol; and (iii after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. CONCLUSION: Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca(2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation.
Full Text Available BACKGROUND: The role of the anterolateral abdominal wall muscles (AAWMs during the vesical filling and evacuation has not been sufficiently addressed in the literature. We have investigated the hypothesis that the AAWMs exhibit the increased electromyographic (EMG activity on the vesical distension and contraction which presumably assists vesical evacuation. METHODS: The effects of the vesical balloon distension on the vesical pressure (VP, vesical neck (VNP pressures and the AAWMs' EMG activity were studied in 28 healthy volunteers aged 40.7 ± 9.7 years (18 men, 10 women. These effects were tested after the individual anesthetization of the bladder and AAWMs and after saline infiltration. RESULTS: The VP and the VNP showed a gradual increase upon the incremental vesical balloon distension which started at a distending volume of 120–140 ml. At a mean volume of 364.6 ± 23.8 ml, the VP increased to a mean of 36.6 ± 3.2 cmH2O, the VNP decreased to 18.4 ± 2.4 cmH2O, and the AAWMs EMG registered a significant increase. This effect disappeared in the individual bladder and in the AAWMs' anesthetization. However, it did not disappear in the saline administration. CONCLUSIONS: The AAWMs appear to contract simultaneously with vesical contraction. This action presumably increases the IAP and it
BACKGROUND: The role of the anterolateral abdominal wall muscles (AAWMs during the vesical filling and evacuation has not been sufficiently addressed in the literature. We have investigated the hypothesis that the AAWMs exhibit the increased electromyographic (EMG activity on the vesical distension and contraction which presumably assists vesical evacuation.
METHODS: The effects of the vesical balloon distension on the vesical pressure (VP, vesical neck (VNP pressures and the AAWMs' EMG activity were studied in 28 healthy volunteers aged 40.7 ± 9.7 years (18 men, 10 women. These effects were tested after the individual anesthetization of the bladder and AAWMs and after saline infiltration.
RESULTS: The VP and the VNP showed a gradual increase upon the incremental vesical balloon distension which started at a distending volume of 120–140 ml. At a mean volume of 364.6 ± 23.8 ml, the VP increased to a mean of 36.6 ± 3.2 cmH2O, the VNP decreased to 18.4 ± 2.4 cmH2O, and the AAWMs EMG registered a significant increase. This effect disappeared in the individual bladder and in the AAWMs' anesthetization. However, it did not disappear in the saline administration.
CONCLUSIONS: The AAWMs appear to contract simultaneously with vesical contraction. This action presumably increases the IAP and it
Madrid, Antonio; Madinabeitia-Mancebo, Elena; Cudeiro, Javier; Arias, Pablo
The central drive to the muscle reduces when muscle force wanes during sustained MVC, and this is generally considered the neurophysiological footprint of central fatigue. The question is if force loss and the failure of central drive to the muscle are responsible mechanisms of fatigue induced by un-resisted repetitive movements. In various experimental blocks, we validated a 3D-printed hand-fixation system permitting the execution of finger-tapping and maximal voluntary contractions (MVC). Subsequently, we checked the suitability of the system to test the level of central drive to the muscle and developed an algorithm to test it at the MVC force plateau. Our main results show that the maximum rate of finger-tapping dropped at 30 s, while the excitability of inhibitory M1-intracortical circuits and corticospinal excitability increased (all by approximately 15%). Furthermore, values obtained immediately after finger-tapping showed that MVC force and the level of central drive to the muscle remained unchanged. Our data suggest that force and central drive to the muscle are not determinants of fatigue induced by short-lasting un-resisted repetitive finger movements, even in the presence of increased inhibition of the motor cortex. According to literature, this profile might be different in longer-lasting, more complex and/or resisted repetitive movements.
Parastatidis, Ioannis; Weiss, Daiana; Joseph, Giji; Taylor, W Robert
Objective Elevated levels of oxidative stress have been reported in abdominal aortic aneurysms (AAA), but which reactive oxygen species (ROS) promotes the development of AAA remains unclear. Here we investigate the effect of the hydrogen peroxide (H2O2) degrading enzyme catalase on the formation of AAA. Approach and Results AAA were induced with the application of calcium chloride (CaCl2) on mouse infrarenal aortas. The administration of PEG-catalase, but not saline, attenuated the loss of tunica media and protected against AAA formation (0.91±0.1 mm vs. 0.76±0.09 mm). Similarly, in a transgenic mouse model, catalase over-expression in the vascular smooth muscle cells (VSMC) preserved the thickness of tunica media and inhibited aortic dilatation by 50% (0.85±0.14 mm vs. 0.57±0.08 mm). Further studies showed that injury with CaCl2 decreased catalase expression and activity in the aortic wall. Pharmacologic administration or genetic over-expression of catalase restored catalase activity and subsequently decreased matrix metalloproteinase activity. In addition, a profound reduction in inflammatory markers and VSMC apoptosis was evident in aortas of catalase over-expressing mice. Interestingly, as opposed to infusion of PEG-catalase, chronic over-expression of catalase in VSMC did not alter the total aortic H2O2 levels. Conclusions The data suggest that a reduction in aortic wall catalase activity can predispose to AAA formation. Restoration of catalase activity in the vascular wall enhances aortic VSMC survival and prevents AAA formation primarily through modulation of matrix metalloproteinase activity. PMID:23950141
Figueiredo, Vânia F; Amorim, Juleimar S C; Pereira, Aline M; Ferreira, Paulo H; Pereira, Leani S M
Low back pain (LBP) and urinary incontinence (UI) are highly prevalent among elderly individuals. In young adults, changes in trunk muscle recruitment, as assessed via ultrasound imaging, may be associated with lumbar spine stability. To assess the associations between LBP, UI, and the pattern of transversus abdominis (TrA), internal (IO), and external oblique (EO) muscle recruitment in the elderly as evaluated by ultrasound imaging. Fifty-four elderly individuals (mean age: 72±5.2 years) who complained of LBP and/or UI as assessed by the McGill Pain Questionnaire, Incontinence Questionnaire-Short Form, and ultrasound imaging were included in the study. The statistical analysis comprised a multiple linear regression model, and a p-value recruitment. These results suggest that age-related factors may have interfered with the findings of the study, thus emphasizing the need to perform ultrasound imaging-based studies to measure abdominal muscle recruitment in the elderly.
Koga, Keiko; Miura, Iwao
Energy metabolism during exercise and recovery process of rabbit skeletal muscle was obserbed by in vivo 31 P MRS. The small value of the ratio of the intensities between inorganic phosphate and phosphocreatine at rest indicated that the observed moiety of muscle had high fast-twitch fiber content. More than half of ATP and almost all of phosphocreatine were depleted by electric stimulation at 4Hz. The extreme intracellular pH was 5.9. The recovery from this metabolic state was very slow, and only a small amount of ATP was resynthesized after 40 minutes of recovery. These phenomena show the characteristic features of the energy metabolism in the fatigue of fast-twitch muscle. The metabolic state as indicated by the intensity of phosphocreatine and intracellular pH during exercise was not always parallel to contraction power measured by straingauge. Two inorganic phosphate peaks were observed, which are regarded as the signals from fast-twitch fiber and slow-twitch fiber from their pH values. The ratios of these two peaks were different between 1Hz, 2Hz, and 4Hz electric stimulation. We conclude that we are observing the different recruitment of fiber types at different exercise level in vivo. (author)
Thorlund, Jonas Bloch; Michalsik, L B; Madsen, Klavs
The purpose of the present study was to determine the acute fatigue development in muscle mechanical properties and neuromuscular activity in response to handball match play. Male elite handball players (n = 10) were tested before and after a simulated handball match for maximal isometric strength...... work (6.8%, P handball match play, which...
de Ruiter, C J; Jones, D A; Sargeant, A J; de Haan, A
The purpose of the present study was to investigate the effect of temperature on the rates of isometric force development and relaxation in electrically activated fresh and fatigued human adductor pollicis muscle. Following immersion of the lower arm for 20 min in water baths of four different
Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G
We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated...
Nahid Rahmani; Mohammad Ali Mohseni-Bandpei; Iraj Abdollahi
Objective: Evaluation of paraspinal muscles endurance in patients with chronic low back pain (LBP) seems to be of great importance. Many studies demonstrated that surface electromyography has merit to assess muscle fatigue using frequency spectrum. The purpose of this study was to systematically review the eligibility of the surface electromyography in the assessment of paraspinal muscles fatigue changes following different interventions in patients with chronic LBP. Materials & Methods: ...
Ibitoye, Morufu Olusola; Estigoni, Eduardo H; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M
The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population.
Morufu Olusola Ibitoye
Full Text Available The evoked electromyographic signal (eEMG potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05 between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI population.
Karthick, P A; Ghosh, Diptasree Maitra; Ramakrishnan, S
Surface electromyography (sEMG) based muscle fatigue research is widely preferred in sports science and occupational/rehabilitation studies due to its noninvasiveness. However, these signals are complex, multicomponent and highly nonstationary with large inter-subject variations, particularly during dynamic contractions. Hence, time-frequency based machine learning methodologies can improve the design of automated system for these signals. In this work, the analysis based on high-resolution time-frequency methods, namely, Stockwell transform (S-transform), B-distribution (BD) and extended modified B-distribution (EMBD) are proposed to differentiate the dynamic muscle nonfatigue and fatigue conditions. The nonfatigue and fatigue segments of sEMG signals recorded from the biceps brachii of 52 healthy volunteers are preprocessed and subjected to S-transform, BD and EMBD. Twelve features are extracted from each method and prominent features are selected using genetic algorithm (GA) and binary particle swarm optimization (BPSO). Five machine learning algorithms, namely, naïve Bayes, support vector machine (SVM) of polynomial and radial basis kernel, random forest and rotation forests are used for the classification. The results show that all the proposed time-frequency distributions (TFDs) are able to show the nonstationary variations of sEMG signals. Most of the features exhibit statistically significant difference in the muscle fatigue and nonfatigue conditions. The maximum number of features (66%) is reduced by GA and BPSO for EMBD and BD-TFD respectively. The combination of EMBD- polynomial kernel based SVM is found to be most accurate (91% accuracy) in classifying the conditions with the features selected using GA. The proposed methods are found to be capable of handling the nonstationary and multicomponent variations of sEMG signals recorded in dynamic fatiguing contractions. Particularly, the combination of EMBD- polynomial kernel based SVM could be used to
Full Text Available Since the elderly population is increasing rapidly in developing countries which may decrease the physical activity and exercise and in turn could affect the elderly’s quality of life, this study aimed to investigate the effect of progressive muscle relaxation on the elderly’s quality of life in Iran. In a randomized clinical trial, participants were randomly divided into intervention and control groups. For the intervention group, muscular progressive relaxation was run three days per week for three months (totally 36 sessions. In relaxation, a patient contract a group of his/her muscles in each step and relaxes them after five seconds and finally loosens all muscles and takes five deep breaths. Each session lasts for 45 minutes. The instrument of data gathering consisted of questionnaires on individual’s demographic data and quality of life SF-36. After intervention, quality of life increased significantly in the patients undergoing muscular progressive relaxation and fatigue severity decreased significantly in the intervention group compared to prior to intervention. In addition, there was a statistically significant difference in mean score of physical performance, restricted activity after physical problem, energy, socially function, physical pain, overall hygiene, and quality of life between intervention and control groups. By implementing regular and continuous progressive muscle relaxation, quality of life could be increased in different dimensions in the elderly and the context could be provided to age healthily and enjoy higher health and autonomy. Therefore, all of the therapeutic staffs are recommended to implement this plan to promote the elderly’s quality of life.
Ørtenblad, Niels; Sjøgaard, G; Madsen, Klavs
during the first 0.5-1 h the metabolic state recovered to resting levels, and a slow phase from 1-3 h characterized by a rather slow recovery of the mechanical properties. The recovery of SR Ca(2+) release rate was closely correlated to +dF/dt during the slow phase of recovery (r(2) = 0.51; P ... to 66% that persisted for 1 h, followed by a gradual recovery to 87% of prefatigue release rate at 3 h recovery. Tetanic force and rate of force development (+dF/dt) and relaxation (-dF/dt) were depressed by approximately 80% after stimulation. Recovery occurred in two phases: an initial phase, in which......The purpose of the study was to characterize the sarcoplasmic reticulum (SR) function and contractile properties before and during recovery from fatigue in the rat extensor digitorum longus muscle. Fatiguing contractions (60 Hz, 150 ms/s for 4 min) induced a reduction of the SR Ca(2+) release rate...
Vânia F. Figueiredo
Full Text Available Background: Low back pain (LBP and urinary incontinence (UI are highly prevalent among elderly individuals. In young adults, changes in trunk muscle recruitment, as assessed via ultrasound imaging, may be associated with lumbar spine stability. Objective: To assess the associations between LBP, UI, and the pattern of transversus abdominis (TrA, internal (IO, and external oblique (EO muscle recruitment in the elderly as evaluated by ultrasound imaging. Method: Fifty-four elderly individuals (mean age: 72±5.2 years who complained of LBP and/or UI as assessed by the McGill Pain Questionnaire, Incontinence Questionnaire-Short Form, and ultrasound imaging were included in the study. The statistical analysis comprised a multiple linear regression model, and a p-value <0.05 was considered significant. Results: The regression models for the TrA, IO, and EO muscle thickness levels explained 2.0% (R2=0.02; F=0.47; p=0.628, 10.6% (R2=0.106; F=3.03; p=0.057, and 10.1% (R2=0.101; F=2.70; p=0.077 of the variability, respectively. None of the regression models developed for the abdominal muscles exhibited statistical significance. A significant and negative association (p=0.018; β=-0.0343 was observed only between UI and IO recruitment. Conclusion: These results suggest that age-related factors may have interfered with the findings of the study, thus emphasizing the need to perform ultrasound imaging-based studies to measure abdominal muscle recruitment in the elderly.
Estigoni, Eduardo H.; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M.; Davis, Glen M.
This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery. PMID:25479324
Manoharan, Palanikumar; Radzyukevich, Tatiana L.; Hakim Javadi, Hesamedin; Stiner, Cory A.; Landero Figueroa, Julio A.; Lingrel, Jerry B
The Na+-K+-ATPase α2-isoform in skeletal muscle is rapidly stimulated during muscle use and plays a critical role in fatigue resistance. The acute mechanisms that stimulate α2-activity are not completely known. This study examines whether phosphorylation of phospholemman (PLM/FXYD1), a regulatory subunit of Na+-K+-ATPase, plays a role in the acute stimulation of α2 in working muscles. Mice lacking PLM (PLM KO) have a normal content of the α2-subunit and show normal exercise capacity, in contrast to the greatly reduced exercise capacity of mice that lack α2 in the skeletal muscles. Nerve-evoked contractions in vivo did not induce a change in total PLM or PLM phosphorylated at Ser63 or Ser68, in either WT or PLM KO. Isolated muscles of PLM KO mice maintain contraction and resist fatigue as well as wild type (WT). Rb+ transport by the α2-Na+-K+-ATPase is stimulated to the same extent in contracting WT and contracting PLM KO muscles. Phosphorylation of sarcolemmal membranes prepared from WT but not PLM KO skeletal muscles stimulates the activity of both α1 and α2 in a PLM-dependent manner. The stimulation occurs by an increase in Na+ affinity without significant change in Vmax and is more effective for α1 than α2. These results demonstrate that phosphorylation of PLM is capable of stimulating the activity of both isozymes in skeletal muscle; however, contractile activity alone is not sufficient to induce PLM phosphorylation. Importantly, acute stimulation of α2, sufficient to support exercise and oppose fatigue, does not require PLM or its phosphorylation. PMID:26468207
Jiang, Ting; Huang, Dong-Xu
To analyze the influence of occlusal splint on resistance capability of masticatory muscles to fatigue. In the study, 25 young male volunteers were randomly divided to 5 groups according to different splint placements: (1) no splint, (2) 1.5 mm thick soft splint, (3) 2 mm thick resin stability splint, (4) 4 mm thick resin stability splint, (5) buccolingual mock splint. Near infrared spectroscopy (NIRS) was used to measure blood oxygen content in human masticatory muscles during constant strong biting before and after the splint placement at seven time points: before, baseline after, 1 week after, and 2 weeks after splint placement, and immediately after, 1 week after, and 5 weeks after removing of splints. The strength of the biting force was maintained constantly at 30% level of the maximum biting force of each subject by biofeedback to the displayed value of an electro-myographic monitor. The time points of muscular fatigue and pain that appeared were recorded and the correlation between the subjective feeling and the NIRS measurement result was analyzed. The NIRS measurement curve had a point of inflection that had no significant difference with the time point of the muscle pain that appeared. Two weeks after placement of soft splint, the time point of the muscular fatigue and pain that appeared were 2.75 s and 8.00 s delayed respectively compared with that before placement of splint (P0.05) in the group of mock splint. The metabolic status of human masticatory muscles could be monitored in real time by using NIRS; soft splint delayed the appearing of muscle fatigue and muscle pain after two weeks of placement.
García-Ramos, Amador; Torrejón, Alejandro; Feriche, Belén; Morales-Artacho, Antonio J; Pérez-Castilla, Alejandro; Padial, Paulino; Jaric, Slobodan
This study explored the feasibility of the force-velocity relationship (F-V) to detect the acute effects of different fatigue protocols on the selective changes of the maximal capacities of upper body muscles to produce force, velocity, and power. After determining the bench press one-repetition maximum (1RM), participants' F-V relationships were assessed during the bench press throw exercise on five separate sessions after performing one of the following fatiguing protocols: 60%1RM failure, 60%1RM non-failure, 80%1RM failure, 80%1RM non-failure, and no-fatigue. In the non-failure protocols, participants performed half the maximum number of repetitions than in their respective failure protocols. The main findings revealed that (1) all F-V relationships were highly linear (median r = 0.997 and r = 0.982 for averaged across participants and individual data, respectively), (2) the fatiguing protocols were ranked based on the magnitude of power loss as follows: 60%1RM failure > 80%1RM failure > 60%1RM non-failure > 80%1RM non-failure, while (3) the assessed maximum force and velocity outputs showed a particularly prominent reduction in the protocols based on the lowest and highest levels of fatigue (i.e., 80%1RM non-failure and 60%1RM failure), respectively. The results support the use of F-V to assess the effects of fatigue on the distinctive capacities of the muscles to produce force, velocity, and power output while performing multi-joint tasks, while the assessed maximum force and velocity capacities showed a particularly prominent reduction in the protocols based on the lowest and highest levels of fatigue (i.e., 80%1RM non-failure and 60%1RM failure), respectively.
Gogola, Anna; Gnat, Rafał; Dziub, Dorota; Gwóźdź, Michalina; Zaborowska, Małgorzata
The aim of the study was to evaluate the activation of lateral abdominal muscles (LAM) in response to neurodevelopmental traction technique as assessed by ultrasounds as well as to compare the effects of different traction forces. An experiment with repeated measurements of the dependent variables was conducted. Thirty-seven children (22 girls) participated. Measurements of LAM thickness (indicating LAM activation) were performed bilaterally during traction of 5% body weight: 1) in neutral position, 2) in 20° posterior trunk inclination; during traction of 15% body weight: 3) in neutral position, 4) in 20° posterior trunk inclination. The ultrasound technology was employed. When applying the lighter traction the superficial LAM (external and internal oblique muscles) showed significant changes. The mean thickness of both muscles during traction increased (both p 0.05). Stronger traction elicited smaller changes. External and internal oblique muscles showed significant increases (p stronger traction (p Stronger traction induces smaller LAM thickness changes than lighter traction.
Abboud, Jacques; Lardon, Arnaud; Boivin, Frédéric; Dugas, Claude; Descarreaux, Martin
Introduction: Trunk neuromuscular responses have been shown to adapt under the influence of muscle fatigue, as well as spinal tissue creep or even with the presence of low back pain (LBP). Despite a large number of studies exploring how these external perturbations affect the spinal stability, characteristics of such adaptations remains unclear. Aim: The purpose of this systematic review was to assess the quality of evidence of studies investigating trunk neuromuscular responses to unexpected trunk perturbation. More specifically, the targeted neuromuscular responses were trunk muscle activity reflex and trunk kinematics under the influence of muscle fatigue, spinal creep, and musculoskeletal pain. Methods: A research of the literature was conducted in Pubmed, Embase, and Sport-Discus databases using terms related to trunk neuromuscular reflex responses, measured by electromyography (baseline activity, reflex latency, and reflex amplitude) and/or trunk kinematic, in context of unexpected external perturbation. Moreover, independent variables must be either trunk muscle fatigue or spinal tissue creep or LBP. All included articles were scored for their electromyography methodology based on the "Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM)" and the "International Society of Electrophysiology and Kinesiology (ISEK)" recommendations whereas overall quality of articles was scored using a specific quality checklist modified from the Quality Index. Meta-analysis was performed on reflex latency variable. Results: A final set of 29 articles underwent quality assessments. The mean quality score was 79%. No effect of muscle fatigue on erector spinae reflex latency following an unexpected perturbation, nor any other distinctive effects was found for back muscle fatigue and reflex parameters. As for spinal tissue creep effects, no alteration was found for any of the trunk reflex variables. Finally, the meta-analysis revealed an increased erector
Fulton, Rick C; Strutton, Paul H; McGregor, Alison H; Davey, Nick J
This study examined post-exercise changes in corticospinal excitability in five 'elite' rowers and six nonrowers. Transcranial magnetic stimulation (TMS) was delivered to the motor cortex and bilateral electromyographic (EMG) recordings were made from erector spinae (ES) muscles at L3/L4 spinal level and from the first dorsal interosseous (FDI) muscle of the dominant hand. Each subject completed two exercise protocols on a rowing ergometer: a light exercise protocol at a sub-maximal output for 10 min and an intense exercise protocol at maximum output for 1 min. A trial of ten magnetic stimuli was delivered before each of the protocols and, on finishing exercise, further trials of ten stimuli were delivered every 2 min for a 16 min period. Amplitudes of motor-evoked potentials (MEPs) in each of the three test muscles were measured before exercise and during the recovery period after exercise. The non-rowers showed a brief facilitation of MEPs in ES 2 min after light and intense exercise that was only present in the elite rowers after intense exercise. In the period 4-16 min after light exercise, the mean (+/- S.E.M.) MEP amplitude (relative to pre-exercise levels) was less depressed in the elite rowers (79.4 +/- 2.1%) than in the non-rowers (60.9 +/- 2.5%) in the left ES but not significantly so in the right ES. MEP amplitudes in FDI were significantly larger in the elite rowers, averaging 119.0 +/- 3.1% pre-exercise levels, compared with 101.2 +/- 5.8% in the non-rowers. Pre-exercise MEP latencies were no different in the two groups. After light exercise MEP latencies became longer in the elite rowers (left ES, 16.1 +/- 0.5 ms; right ES, 16.1 +/- 0.4 ms; dominant FDI, 23.4 +/- 0.2 ms) than in the non-rowers (left ES, 15.0 +/- 0.3 ms; right ES, 15.2 +/- 0.3 ms; dominant FDI, 21.5 +/- 0.2 ms). There were no differences in MEP depression or latency between elite rowers and non-rowers after intense exercise. We conclude that the smaller degree of MEP depression in the
Barbosa, Alexandre C; Martins, Fábio M; Silva, Angélica F; Coelho, Ana C; Intelangelo, Leonardo; Vieira, Edgar R
Barbosa, AC, Martins, FM, Silva, AF, Coelho, AC, Intelangelo, L, and Vieira, ER. Activity of lower limb muscles during squat with and without abdominal drawing-in and Pilates breathing. J Strength Cond Res 31(11): 3018-3023, 2017-The purpose of this study was to assess the effects of abdominal drawing-in and Pilates breathing on the activity of lower limb muscles during squats. Adults (n = 13, 22 ± 3 years old) with some Pilates experience performed three 60° squats under each of the following conditions in a random order: (I) normal breathing, (II) drawing-in maneuver with normal breathing, and (III) drawing-in maneuver with Pilates breathing. Peak-normalized surface electromyography of the rectus femoris, biceps femoris, gastrocnemius medialis, and tibialis anterior during the knee flexion and extension phases of squat exercises was analyzed. There were significant differences among the conditions during the knee flexion phase for the rectus femoris (p = 0.001), biceps femoris (p = 0.038), and tibialis anterior (p = 0.001), with increasing activation from conditions I to III. For the gastrocnemius medialis, there were significant differences among the conditions during the knee extension phase (p = 0.023), with increased activity under condition I. The rectus and biceps femoris activity was higher during the extension vs. flexion phase under conditions I and II. The tibialis anterior activity was higher during the flexion compared with the extension phase under all conditions, and the medial gastrocnemius activity was higher during the extension phase under condition I. Doing squats with abdominal drawing-in and Pilates breathing resulted in increased rectus, biceps femoris, and tibialis anterior activity during the flexion phase, increasing movement stability during squat exercises.
El-Abd, Aliaa M; Ibrahim, Abeer R; El-Hafez, Haytham M
Mechanical neck dysfunction (MND), with axioscapular muscles fatigue, is highly prevalent worldwide. While postural correction is commonly used for its treatment, efficacy of kinesiology tape (KT) has received considerable attention. To determine the effectiveness of KT versus correction exercises on neck disability, and axioscapular muscles fatigue in MND patients. 46 MND patients were randomly assigned into 1 of 2 groups receiving 4 weeks treatment of either KT or correction exercises. Neck disability and axioscapular muscles fatigue as median frequency of electromyography (EMG-MF) were measured pre and post treatment. Group-by-time interaction was not significant in the multivariable test. Post hoc tests revealed that KT produced more disability reduction than the postural exercises. However, there was no significant interaction for EMG-MF. KT has been found to be more effective than postural exercises to reduce neck disability. However, both modalities have similar effects to reduce axioscapular muscles fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.
Full Text Available Abstract Background Muscle contraction during short intervals of intense exercise causes oxidative stress, which can play a role in the development of overtraining symptoms, including increased fatigue, resulting in muscle microinjury or inflammation. Recently it has been said that hydrogen can function as antioxidant, so we investigated the effect of hydrogen-rich water (HW on oxidative stress and muscle fatigue in response to acute exercise. Methods Ten male soccer players aged 20.9 ± 1.3 years old were subjected to exercise tests and blood sampling. Each subject was examined twice in a crossover double-blind manner; they were given either HW or placebo water (PW for one week intervals. Subjects were requested to use a cycle ergometer at a 75 % maximal oxygen uptake (VO2 for 30 min, followed by measurement of peak torque and muscle activity throughout 100 repetitions of maximal isokinetic knee extension. Oxidative stress markers and creatine kinase in the peripheral blood were sequentially measured. Results Although acute exercise resulted in an increase in blood lactate levels in the subjects given PW, oral intake of HW prevented an elevation of blood lactate during heavy exercise. Peak torque of PW significantly decreased during maximal isokinetic knee extension, suggesting muscle fatigue, but peak torque of HW didn’t decrease at early phase. There was no significant change in blood oxidative injury markers (d-ROMs and BAP or creatine kinease after exercise. Conclusion Adequate hydration with hydrogen-rich water pre-exercise reduced blood lactate levels and improved exercise-induced decline of muscle function. Although further studies to elucidate the exact mechanisms and the benefits are needed to be confirmed in larger series of studies, these preliminary results may suggest that HW may be suitable hydration for athletes.
Full Text Available Deer antler is a well-known traditional Chinese medicine used in Asian countries for the tonic and the improvement of aging symptoms. The present study was designed to investigate the antifatigue effect and mechanism of Formosan sambar deer tip antler extract (FSDTAE. The swimming times to exhaustion of mice administered FSDTAE (8.2 mg/day for 28 days were apparently longer than those of the vehicle-treated mice in forced swim test. However, the indicators of fatigue, such as the reduction in glucose level and the increases in blood urea nitrogen and lactic acid levels, were not significantly inhibited by FSDTAE. Therefore, microarray analysis was further used to examine the anti-fatigue mechanism of FSDTAE. We selected genes with fold changes >2 or <−2 in skeletal muscle for pathway analysis. FSDTAE-affected genes were involved in 9 different signaling pathways, such as GnRH signaling pathway and insulin signaling pathway. All of the significantly expressed genes were classified into 8 different categories by their functions. The most enriched category was muscular system, and 6 upregulated genes, such as troponin I, troponin T1, cysteine and glycine-rich protein 2, myosin heavy polypeptide 7, tropomyosin 2, and myomesin family member 3, were responsible for the development and contraction of muscle. Real-time PCR analysis indicated that FSDTAE increased troponins mRNA expression in skeletal muscle. In conclusion, our findings suggested that FSDTAE might increase the muscle strength through the upregulation of genes responsible for muscle contraction and consequently exhibited the anti-fatigue effect in mice.
Remaud, Anthony; Thuong-Cong, Cécile; Bilodeau, Martin
Normal aging results in alterations in the visual, vestibular and somtaosensory systems, which in turn modify the control of balance. Muscle fatigue may exacerbate these age-related changes in sensory and motor functions, and also increase the attentional demands associated with dynamic postural control. The purpose of this study was to investigate the effect of aging on dynamic postural control and posture-related attentional demands before and after a plantar flexor fatigue protocol. Participants (young adults: n = 15; healthy seniors: n = 13) performed a dynamic postural task along the antero-posterior (AP) and the medio-lateral (ML) axes, with and without the addition of a simple reaction time (RT) task. The dynamic postural task consisted in following a moving circle on a computer screen with the representation of the center of pressure (COP). This protocol was repeated before and after a fatigue task where ankle plantar flexor muscles were targeted. The mean COP-target distance and the mean COP velocity were calculated for each trial. Cross-correlation analyses between the COP and target displacements were also performed. RTs were recorded during dual-task trials. Results showed that while young adults adopted an anticipatory control mode to move their COP as close as possible to the target center, seniors adopted a reactive control mode, lagging behind the target center. This resulted in longer COP-target distance and higher COP velocity in the latter group. Concurrently, RT increased more in seniors when switching from static stance to dynamic postural conditions, suggesting potential alterations in the central nervous system (CNS) functions. Finally, plantar flexor muscle fatigue and dual-tasking had only minor effects on dynamic postural control of both young adults and seniors. Future studies should investigate why the fatigue-induced changes in quiet standing postural control do not seem to transfer to dynamic balance tasks. PMID:26834626
de Ruiter, C.J.; Elzinga, M.J.; Verdijk, P.W.L.; van Mechelen, W.; de Haan, A.
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%
Discussion: As the subjects were professional, muscle fatigue did not have a significant effect on postural control, angles and angular velocity; but did affect the reaction force and accuracy of the throws before and after fatigue, which could ultimately affect the performance of athletes and competition results.
Helmhout, P.; Staal, B.; Dijk, J. van; Harts, C.; Bertina, F.; Bie, R. de
AIM: The aim of this exploratory study was to investigate the predictive value of a fatigue test of the lumbar extensor muscles for training progression in a group of 28 healthy but predominantly sedentary male students, in an 8-week resistance exercise program. METHODS: A three-phased fatigue test
Kim, Dong-Hee; Kim, Seok-Hwan; Jeong, Woo-Seok; Lee, Ha-Yan
The increase rate of utilization of branched-chain amino acids (BCAA) by muscle is reduced to its plasma concentration during prolonged exercise leading to glycogen. BCAA supplementation would reduce the serum activities of intramuscular enzymes associated with muscle damage. To examine the effects of BCAA administration on fatigue substances (serotonin, ammonia and lactate), muscle damage substances (CK and LDH) and energy metabolism substances (FFA and glucose) after endurance exercise. Subjects (n = 26, college-aged males) were randomly divided into an experimental (n = 13, EXP) and a placebo (n = 13, CON) group. Subjects both EXP and CON performed a bout of cycle training (70% VO2max intensity) to exhaustion. Subject in the EXP were administrated BCAA (78ml/kg·w) prior to the bout of cycle exercise. Fatigue substances, muscle damage substances and energy metabolism substances were measured before ingesting BCAAs and placebos, 10 min before exercise, 30 min into exercise, immediately after exercise, and 30 min after exercise. Data were analyzed by two-way repeated measure ANCOVA, correlation and statistical significance was set at p BCAA decreased serum concentrations of the intramuscular enzymes as CK and LDH following exhaustive exercise. This observation suggests that BCAA supplementation may reduce the muscle damage associated with endurance exercise.
Audrey E Brown
Full Text Available Post exertional muscle fatigue is a key feature in Chronic Fatigue Syndrome (CFS. Abnormalities of skeletal muscle function have been identified in some but not all patients with CFS. To try to limit potential confounders that might contribute to this clinical heterogeneity, we developed a novel in vitro system that allows comparison of AMP kinase (AMPK activation and metabolic responses to exercise in cultured skeletal muscle cells from CFS patients and control subjects.Skeletal muscle cell cultures were established from 10 subjects with CFS and 7 age-matched controls, subjected to electrical pulse stimulation (EPS for up to 24h and examined for changes associated with exercise.In the basal state, CFS cultures showed increased myogenin expression but decreased IL6 secretion during differentiation compared with control cultures. Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells. In contrast, CFS cultures showed no increase in AMPK phosphorylation or glucose uptake after 16 h EPS. However, glucose uptake remained responsive to insulin in the CFS cells pointing to an exercise-related defect. IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.EPS is an effective model for eliciting muscle contraction and the metabolic changes associated with exercise in cultured skeletal muscle cells. We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6. The retention of these differences in cultured muscle cells from CFS subjects points to a genetic/epigenetic mechanism, and provides a system to identify novel therapeutic targets.
Full Text Available Objective: Tensiomyography (TMG is an indirect measure of a muscle's contractile properties and has the potential as a technique for detecting exercise-induced skeletal muscle fatigue. Therefore, the aim of this study was to assess the sensitivity of tensiomyographic markers to identify reduced muscular performance in elite youth athletes.Methods: Fourteen male junior tennis players (age: 14.9 ± 1.2 years with an international (International Tennis Federation ranking position participated in this pre-post single group trial. They completed a 4-day high-intensity interval training (HIT microcycle, which was composed of seven training sessions. TMG markers; countermovement jump (CMJ performance (criterion measure of fatigue; delayed onset muscle soreness; and perceived recovery and stress were measured 24 h before and after the training program. The TMG measures included maximal radial deformation of the rectus femoris muscle belly (Dm, contraction time between 10 and 90% Dm (Tc and the rate of deformation until 10% (V10 and 90% Dm (V90, respectively. Diagnostic characteristics were assessed with a receiver-operating curve (ROC analysis and a contingency table, in which the area under the curve (AUC, Youden's index, sensitivity, specificity, and the diagnostic effectiveness (DE of TMG measures were reported. A minimum AUC of 0.70 and a lower confidence interval (CI >0.50 classified “good” diagnostic markers to assess performance changes.Results: Twenty-four hours after the microcycle, CMJ performance was observed to be significantly (p < 0.001 reduced (Effect Size [ES] = −0.68, and DOMS (ES = 3.62 as well as perceived stress were significantly (p < 0.001 increased. In contrast, Dm (ES = −0.35, Tc (ES = 0.04, V10 (ES = −0.32, and V90 (ES = −0.33 remained unchanged (p > 0.05 throughout the study. ROC analysis and the data derived from the contingency table revealed that none of the tensiomyographic markers were effective diagnostic
Conclusion: The findings from this study suggest that the RA could be targeted during rehabilitation regimens; however, the force generated by this muscle may not be sufficient for the maintenance of trunk stability without optimal support from the EO and IO muscles.
... 21, 2014 Select a Language: Fact Sheet 551 Fatigue WHAT IS FATIGUE? IS FATIGUE IMPORTANT? HOW DO ... It can be physical or psychological. With physical fatigue , your muscles cannot do things as easily as ...
Bross, S; Schumacher, S; Scheepe, J R; Seif, C; Jünemann, K P; Alken, P
The presented study investigates the influence of different pause lengths between two consecutive stimulations of the S3 roots on intravesical pressure during bladder neurostimulation. In eight male foxhounds (aged 7-18 months), laminectomy and placement of a modified Brindley electrode were performed. In four series with different pause lengths between two consecutive stimulations (1, 3, 5, and 15 min), the maximum intravesical pressure was measured during stimulation. The changes in intravesical pressure were registered in these four series, each series with six stimulations. A 15-min interval elapsed before the commencement of each series. In the series with a pause length of 15 min, the consecutive stimulations did not result in significant changes in maximum intravesical pressure. In the 5-min series, a significant decrease in intravesical pressure was not observed after the third stimulation. In the 3-min series, a significant decrease was seen at almost every stimulation (average decrease of 3.8% per stimulation) and in the 1-min series, a significant decrease was also observed at almost every stimulation (average decrease of 5.9% per stimulation). The results of repeated bladder neurostimulation demonstrate that the maximum intravesical pressure is dependent on the pause length between two consecutive stimulations. The detrusor muscle showed reversible and short-lived signs of fatigue. This implies the importance of a minimum 5-min interval between two subsequent stimulations. A pause length <5 min leads to a falsification of the results and thus to lower validity of the investigation.
Ali, Asraf; Sundaraj, Kenneth; Badlishah Ahmad, R; Ahamed, Nizam Uddin; Islam, Anamul; Sundaraj, Sebastian
The objective of the present study was to investigate the time to fatigue and compare the fatiguing condition among the three heads of the triceps brachii muscle using surface electromyography during an isometric contraction of a controlled forceful hand grip task with full elbow extension. Eighteen healthy subjects concurrently performed a single 90 s isometric contraction of a controlled forceful hand grip task and full elbow extension. Surface electromyographic signals from the lateral, long and medial heads of the triceps brachii muscle were recorded during the task for each subject. The changes in muscle activity among the three heads of triceps brachii were measured by the root mean square values for every 5 s period throughout the total contraction period. The root mean square values were then analysed to determine the fatiguing condition for the heads of triceps brachii muscle. Muscle fatigue in the long, lateral, and medial heads of the triceps brachii started at 40 s, 50 s, and 65 s during the prolonged contraction, respectively. The highest fatiguing rate was observed in the long head (slope = -2.863), followed by the medial head (slope = -2.412) and the lateral head (slope = -1.877) of the triceps brachii muscle. The results of the present study concurs with previous findings that the three heads of the triceps brachii muscle do not work as a single unit, and the fiber type/composition is different among the three heads.
Valeria Regina Silva
Full Text Available ABSTRACT Introduction and objectives: Several studies have been investigated co-activation can enhance the effectveness of PFM training protocols allowing preventive and therapeutic goals in pelvic floor dysfunctions. The objective of the present study was to investigate if an abdominal-pelvic protocol of training (APT using gametherapy would allow co-activation of PFM and transversus abdominis/oblique internal (TrA/OI muscles. Patients and methods: Twenty-five nulliparous, continent, young females, with median age 24.76 (±3.76 years were evaluated using digital palpation (DP of PFM and surface electromyography of PFM and TrA/OI simultaneously, during maximal voluntary contraction (MVC, alternating PFM and TrA/OI contraction requests. All women participated on a supervised program of APT using gametherapy, that included exercises of pelvic mobilization associated to contraction of TrA/OI muscles oriented by virtual games, for 30 minutes, three times a week, in a total of 10 sessions. Electromyographic data were processed and analyzed by ANOVA - analysis of variance. Results: When MVC of TrA/OI was solicited, it was observed simultaneous increase of electromyographic activity of PFM (p=0.001 following ATP. However, EMG activity did not change significantly during MVC of PFM. Conclusion: Training using gametherapy allowed better co-activation of pelvic floor muscles in response to contraction of TrA, in young nulliparous and continent women.
Oliveira, Murilo X.; Toma, Renata L.; Jones, Brett J. L.; Cyprien, Thomas P.; Tier, Matthew R.; Wallace, Cameron A.; Renno, Ana C. M.; Sabapathy, Surendran; Laakso, E.-Liisa
Photobiomodulation therapy (PBMt) has been used to increase muscle performance and improve recovery when applied before exercise. We aimed to evaluate the effects of PBMt using LASER on muscle oxygenation and performance. The study was a randomized, participant and assessor-blinded, within-subject crossover trial with placebo control to test the viability of the methods. Five physically active young women were randomly assigned to either placebo, or active PBMt (12 diode cluster probe; 904 nm; 60 mW; 250 Hz; 43.2 J per site, 129.6 J total) in contact over rectus femoris (RF) muscle of the dominant limb immediately before an isokinetic fatigue protocol. A one-week wash-out period preceded cross-over. Electromyography and isokinetic performance measures were evaluated. Absolute concentrations of deoxygenated haemoglobin and myoglobin (deoxy[Hb + Mb]) of the RF, an index of local microvascular fractional O2 extraction, was monitored continuously by near-infrared spectroscopy (NIRS). Total haemoglobin concentration as an indicator of microvascular haematocrit was calculated as the sum of the deoxy[Hb + Mb] and oxy[Hb + Mb] signals. PBMt pre-conditioning reduced time to peak torque when compared to placebo (P0.05). PBMt before exercise improves indicators of muscle performance, potentially by increasing local matching of bulk and microvascular O2 delivery relative to skeletal muscle O2 utilisation. Further work is required to understand the effect of PBMt on haemodynamic and metabolic characteristics of muscle.
Michael P. Smith
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
Liu, Yi; Zhang, Heming; Zhao, Yanping; Liu, Zhiming
A growing body of literature indicated the cytosolic free Ca2+ concentration of skeletal muscle cells changes significantly during exercise-induced fatigue. But it is confusing whether cytosolic free Ca2+ concentration increase or decrease. Furthermore, current researches mainly adopt muscle tissue homogenate as experiment material, but the studies based on cellular and subcellular level is seldom. This study is aimed to establish rat skeletal muscle cell model of exercise-induced fatigue, and confirm the change of cytosolic free Ca2+ concentration of skeletal muscle cells in rats preand post- exercise-induced fatigue. In this research, six male Wistar rats were randomly divided into two groups: control group (n=3) and exercise-induced fatigue group (n=3). The former group were allowed to freely move and the latter were forced to loaded swimming to exhaustive. Three days later, all the rats were sacrificed, the muscle tissue from the same site of skeletal muscle were taken out and digested to cells. After primary culture of the two kinds of skeletal muscle cells from tissue, a fluorescent dye-Fluo-3 AM was used to label the cytosolic free Ca2+. The fluorescent of Ca2+ was recorded by confocal laser scanning microscopy. The results indicated that, the Ca2+ fluorescence intensity of cells from the rat of exercise-induced fatigue group was significantly higher than those in control group. In conclusion, cytosolic free Ca2+ concentration of skeletal muscle cells has a close relation with exercise-induced fatigue, and the increase of cytosolic free Ca2+ concentration may be one of the important factors of exercise-induced fatigue.
Bingham, Adrian; Arjunan, Sridhar P; Kumar, Dinesh K
In this study we have tested the hypothesis regarding the increase in synchronization with the onset of muscle fatigue. For this aim, we have investigated the difference in the synchronicity between high density surface electromyogram (sEMG) channels of the rested muscles and when at the limit of endurance. Synchronization was measured by computing and normalizing the mutual information between the sEMG signals recorded from the high-density array electrode locations. Ten volunteers (Age range: 21 and 35 years; Mean age = 26 years; Male = 6, Female = 4) participated in our experiment. The participants performed isometric dorsiflexion of their dominate foot at two levels of contraction; 40% and 80% of their maximum voluntary contraction (MVC) until task failure. During the experiment an array of 64 electrodes (16 by 4) placed over the TA parallel to the muscle fiber was used to record the HD-sEMG. Normalized Mutual Information (NMI) between electrodes was calculated using the HD-sEMG data and then analyzed. The results show that that the average NMI of the TA significantly increased during fatigue at both levels of contraction. There was a statistically significant difference between NMI of the rested muscle compared with it being at the point of task failure.
Rossman, Matthew J.; Groot, H. Jonathan; Van Reese; Zhao, Jia; Amann, Markus; Richardson, Russell S.
PURPOSE Oxidative stress may contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). This study sought to determine the effect of an acute oral antioxidant cocktail (AOC: vitamins C, E, and alpha-lipoic acid) on skeletal muscle function during dynamic quadriceps exercise in COPD. METHODS Ten patients with COPD performed knee extensor exercise to exhaustion and isotime trials following either the AOC or placebo (PL). Pre- to post-exercise changes in quadriceps maximal voluntary contractions (MVCs) and potentiated twitch forces (Qtw,pot) quantified quadriceps fatigue. RESULTS Under PL conditions, the plasma electron paramagnetic resonance (EPR) spectroscopy signal was inversely correlated with the forced expiratory volume in one second to forced vital capacity ratio (FEV1/FVC), an index of lung dysfunction (r=−0.61, p=0.02), and MVC force (r=−0.56, p=0.04). AOC consumption increased plasma ascorbate levels (10.1±2.2 to 24.1±3.8 ug/ml, p<0.05) and attenuated the area under the curve of the EPR spectroscopy free radical signal (11.6±3.7 to 4.8±2.2 AU, p<0.05), but did not alter endurance time or quadriceps fatigue. The ability of the AOC to decrease the EPR spectroscopy signal, however, was prominent in those with high basal free radicals (n=5, PL: 19.7±5.8 to AOC: 5.8±4.5 AU, p<0.05) with minimal effects in those with low levels (n=5, PL: 1.6±0.5 to AOC: 3.4±1.1 AU). DISCUSSION These data document a relationship between directly measured free radicals and lung dysfunction, and the ability of the AOC to decrease oxidative stress in COPD. Acute amelioration of free radicals, however, does not appear to impact dynamic quadriceps exercise performance. PMID:23299763
Full Text Available Abstract Quantitative trait loci (QTL for abdominal fatness and breast muscle weight were investigated in a three-generation design performed by inter-crossing two experimental meat-type chicken lines that were divergently selected on abdominal fatness. A total of 585 F2 male offspring from 5 F1 sires and 38 F1 dams were recorded at 8 weeks of age for live body, abdominal fat and breast muscle weights. One hundred-twenty nine microsatellite markers, evenly located throughout the genome and heterozygous for most of the F1 sires, were used for genotyping the F2 birds. In each sire family, those offspring exhibiting the most extreme values for each trait were genotyped. Multipoint QTL analyses using maximum likelihood methods were performed for abdominal fat and breast muscle weights, which were corrected for the effects of 8-week body weight, dam and hatching group. Isolated markers were assessed by analyses of variance. Two significant QTL were identified on chromosomes 1 and 5 with effects of about one within-family residual standard deviation. One breast muscle QTL was identified on GGA1 with an effect of 2.0 within-family residual standard deviation.
Uzun, S; Pourmoghaddam, A; Hieronymus, M; Thrasher, T A
Wheelchair basketball is the most popular exercise activity among individuals with spinal cord injury (SCI). The purpose of this study was to investigate muscular endurance and fatigue in wheelchair basketball athletes with SCI using surface electromyography (SEMG) and maximal torque values. SEMG characteristics of 10 wheelchair basketball players (WBP) were compared to 13 able-bodied basketball players and 12 sedentary able-bodied subjects. Participants performed sustained isometric elbow flexion at 50% maximal voluntary contraction until exhaustion. Elbow flexion torque and SEMG signals were recorded from three elbow flexor muscles: biceps brachii longus, biceps brachii brevis and brachioradialis. SEMG signals were clustered into 0.5-s epochs with 50% overlap. Root mean square (RMS) and median frequency (MDF) of SEMG signals were calculated for each muscle and epoch as traditional fatigue monitoring. Recurrence quantification analysis was used to extract the percentage of determinism (%DET) of SEMG signals. The slope of the %DET for basketball players and WBP showed slower increase with time than the sedentary able-bodied control group for three different elbow flexor muscles, while no difference was observed for the slope of the %DET between basketball and WBP. This result indicated that the athletes are less fatigable during the task effort than the nonathletes. Normalized MDF slope decay exhibited similar results between the groups as %DET, while the slope of the normalized RMS failed to show any significant differences among the groups (p > 0.05). MDF and %DET could be useful for the evaluation of muscle fatigue in wheelchair basketball training. No conclusions about special training for WBP could be determined.
Maithel, S K; Villegas, L; Stylopoulos, N; Dawson, S; Jones, D B
The direction of visual gaze may be an important ergonomic factor that affects operative performance. We designed a study to determine whether a head-mounted display (HMD) worn by the surgeon would improve task performance and/or reduce muscle fatigue during a laparoscopic task when compared to the use of a traditional video monitor display (VMD). Surgical residents (n = 30) were enrolled in the study. A junior group, consisting of 15 postgraduate year (PGY) = 1 subjects with no previous laparoscopic experience, and a senior group, consisting of 15 PGY 4 and PGY 5 subjects with experience, completed a laparoscopic task that was repeated four times using the Computer Enhanced Laparoscopic Training System (CELTS). Groups alternated between using the HMD with the task placed in a downward frontal position and the VMD with the task at a 30 degrees lateral angle. The CELTS module assessed task completion time, depth perception, path length of instruments, response orientation, motion smoothness; the system then generated an overall score. Electromyography (EMG) was used to record sternocleidomastoid muscle activity. Display preference was surveyed. The senior residents performed better than the junior residents overall on all parameters (p < 0.05) except for motion smoothness, where there was no difference. In both groups, the HMD significantly improved motion smoothness when compared to the VMD (p < 0.05). All other parameters were equal. There was less muscle fatigue when using the VMD (p < 0.05). We found that 66% of the junior residents but only 20% of the senior residents preferred the HMD. The CELTS module demonstrated evidence of construct validity by differentiating the performances of junior and senior residents. By aligning the surgeon's visual gaze with the instruments, HMD improved smoothness of motion. Experienced residents preferred the traditional monitor display. Although the VMD produced less muscle fatigue, inexperienced residents preferred the HMD
Ghoul, Nihel; Tabben, Montassar; Miarka, Bianca; Tourny, Claire; Chamari, Karim; Coquart, Jeremy
This study investigates the physiological/physical responses to a simulated mixed martial arts (MMA) competition over 24 hr. Twelve fighters performed a simulated MMA competition, consisting of three 5-min MMA matches. Physiological/physical data were assessed before (Trest), directly after round 1 (Trd1), round 2 (Trd2) and round 3 (Trd3), and then 30-min (Trecovery30min) and/or 24-hr (Trecovery24h) post-competition. Heart rate (HR), rating of perceived exertion (RPE) and blood lactate concentration ([La]) were assessed at Trest, Trd1, Trd2 and Trd3. Biological data were collected at Trest, Trd3, Trecovery30min and Trecovery24h. Physical tests were performed at Trest, Trecovery30min and Trecovery24h. HR, RPE and [La] were high during competition. Leukocytes, hemoglobin, total protein and glycemia were increased at Trd3 compared with all other time points (p<0.05). Cortisol was increased at Trd3 compared with Trest and Trecovery24h (p<0.05). Testosterone was higher at Trd3 and Trecovery30min than Trest (p<0.001). Higher values of uric acid were noted during recovery periods (p<0.001). Lactate dehydrogenase was lower at Trest compared with Trd3, Trecovery30min and Trecovery24h (p<0.05). Countermovement jump was higher at Trest than Trecovery30min (p=0.020). Consequently, MMA is a high-intensity intermittent combat sport that induces significant fatigue and muscle damage, both of which are still present 24-hr post-competition.
Johannes Fleckenstein, Jan Wilke, Lutz Vogt, Winfried Banzer
Full Text Available Objectives of the study were to compare the effects of a single bout of preventive or regenerative foam rolling (FR on exercise-induced neuromuscular exhaustion. Single-centre randomised-controlled study was designed. Forty-five healthy adults (22 female; 25±2 yrs were allocated to three groups: 1 FR of the lower limb muscles prior to induction of fatigue, 2 FR after induction of fatigue, 3 no-treatment control. Neuromuscular exhaustion was provoked using a standardized and validated functional agility short-term fatigue protocol. Main outcome measure was the maximal isometric voluntary force of the knee extensors (MIVF. Secondary outcomes included pain and reactive strength (RSI. Preventive (-16% and regenerative FR (-12% resulted in a decreased loss in MIVF compared to control (-21%; p 0.8, p < 0.1. Differences over time (p < 0.001 between groups regarding pain and RSI did not turn out to be clinically meaningful. A single bout of foam rolling reduces neuromuscular exhaustion with reference to maximal force production. Regenerative rather than preventive foam rolling seems sufficient to prevent further fatigue.
Broxterman, Ryan M; Layec, Gwenael; Hureau, Thomas J; Amann, Markus; Richardson, Russell S
Although all-out exercise protocols are commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear, and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorus magnetic resonance spectroscopy ( 31 P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in eight healthy men. Metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (P i ), diprotonated phosphate ([Formula: see text]), and pH. Peripheral fatigue was determined by exercise-induced alterations in potentiated quadriceps twitch force (Q tw ) evoked by supramaximal electrical femoral nerve stimulation. The oxidative ATP synthesis rate (ATP OX ) attained and then maintained peak values throughout the protocol, despite an ~63% decrease in quadriceps maximal force production. ThusATP OX normalized to force production (ATP OX gain) significantly increased throughout the exercise (1st min: 0.02 ± 0.01, 5th min: 0.04 ± 0.01 mM·min -1 ·N -1 ), as did the ATP cost of contraction (1st min: 0.048 ± 0.019, 5th min: 0.052 ± 0.015 mM·min -1 ·N -1 ). Additionally, the pre- to postexercise change in Q tw (-52 ± 26%) was significantly correlated with the exercise-induced change in intramuscular pH ( r = 0.75) and [Formula: see text] concentration ( r = 0.77). In conclusion, the all-out exercise protocol utilized in the present study elicited a "slow component-like" increase in intramuscular ATP OX gain as well as a progressive increase in the phosphate cost of contraction. Furthermore, the development of peripheral fatigue was closely related to the perturbation of specific fatigue-inducing intramuscular factors (i.e., pH and [Formula: see text] concentration). NEW & NOTEWORTHY The physiological mechanisms
Wang, He; Frame, Jeff; Ozimek, Elicia; Leib, Daniel; Dugan, Eric L.
Military personnel are commonly afflicted by lower-extremity overuse injuries. Load carriage and muscular fatigue are major stressors during military basic training. Purpose: To examine effects of load carriage and muscular fatigue on lower-extremity joint mechanics during walking. Method: Eighteen men performed the following tasks: unloaded…
Morishita, S; Tsubaki, A; Fu, J B; Mitobe, Y; Onishi, H; Tsuji, T
We investigated the difference in relationship between muscle strength and quality of life (QOL)/fatigue in long-term cancer survivors and healthy subjects. Thirty-six cancer survivors and 29 healthy subjects were assessed for body composition and bone status at the calcaneus using the Osteo Sono Assessment Index. Muscle strength was evaluated via handgrip and knee extensor strength. Health-related QOL was assessed using the Medical Outcome Study 36-item Short-Form Health Survey. Fatigue was measured using the brief fatigue inventory. Cancer survivors exhibited lower QOL scores in the physical functioning, physical role function, bodily pain and general health domains (p < .05). Grip and knee extension muscle strength in cancer survivors was positively correlated with the physical function and bodily pain of QOL (p < .05). The usual fatigue subscale score was only significantly higher in cancer survivors than in healthy subjects (p < .05). However, there were no correlations between muscle strength and fatigue in cancer survivors. Our results showed that muscle strength was an important factor for improving QOL in cancer survivors. We believe that the findings of this study will be relevant in the context of planning rehabilitation for cancer survivors. © 2018 John Wiley & Sons Ltd.
Guy Gosselin, Michael J. Fagan
Full Text Available Neck muscle fatigue has been shown to alter an individual’s balance in a similar way to that reported in subjects suffering from neck pain or subjects that have suffered a neck injury. The main purpose of the present study was to quantify the effects of neck fatigue on neck muscle electromyography (EMG activity, balance, perceived fatigue and perceived stability. Forty four elite amateur rugby league players resisted with their neck muscles approximately 35% maximum voluntary isometric contraction (MVIC force for 15 minutes in eight different directions. Sway velocity and surface electromyography were measured. Questionnaires were used to record perceived effort and stability. Repeated measures ANOVA showed that after 15 minutes isometric contraction, significant changes were seen in sway velocity, perceived sway and EMG median frequency. There were no differences in perceived efforts. The changes in sway velocity and median frequency were more pronounced after extension and right and left posterior oblique contractions but there was no significant difference in sway velocity after contraction in the right lateral flexion, right anterior oblique and left anterior oblique direction of contraction. All the subjects showed oriented whole-body leaning in the plane of the contraction. The experiment produced significantly altered and perceived altered balance in this group of physically fit individuals. The results may contribute to our understanding of normal functional capacities of athletes and will provide a basis for further investigation in healthy non-athletes and participants that have suffered neck injuries. This may ultimately help develop accurate and valid rehabilitation outcome measures.
Mariana Felipe Silva
Full Text Available The use of Pilates-based exercises for trunk strengthening has been reported in the literature. The objective of this study was to analyze and compare the electrical activity of the rectus abdominis and external oblique muscles during a traditional abdominal exercise program and an exercise program based on the Pilates method using a ball and an elastic band. The sample was composed of 10 healthy women, non-practitioners of Pilates, who performed the traditional abdominal exercise and roll-up with the ball and elastic band. The sign was normalized by the electromyographic peak of the dynamics activity and was adjusted for 2000 samples/s; the filter was set in a frequency band from 20 to 450 Hz. In the comparison between exercises, the external oblique muscle in the concentric phase had a higher recruitment in the roll-up with the ball (P =0.042. In the comparison between muscles in each exercise, the rectus abdominis showed a higher activation in the concentric phase (P = 0.009 and in the eccentric phase (P = 0.05 of the traditional abdominal exercise. Activation percentages ranged from 15% to 22%. The traditional abdominal exercise had the largest activation percentage.
Wang, Dan; De Vito, Giuseppe; Ditroilo, Massimiliano; Delahunt, Eamonn
The purpose of this study was to investigate the influence of sex and fatigue on knee extensor peak torque (PT), muscle stiffness (MS) of the vastus lateralis (VL) and knee joint musculoarticular stiffness (MAS) in young adults. Twenty-two male and 22 female recreational athletes participated. Males were characterised by higher relaxed [pre-: males 364.43 (52.00) N · m -1 , females 270.27 (37.25) N · m -1 ; post-: males 446.75 (83.27) N · m -1 , females 307.39 (38.58) N · m -1 ] and contracted [pre-: males 495.07 (71.04) N · m -1 , females 332.34 (85.42) N · m -1 ; post-: males 546.37 (90.74) N · m -1 , females 349.21 (85.55) N · m -1 ] MS of the VL, and knee joint MAS [pre-: males 1450.11 (507.98) N · m -1 , females 1027.99 (227.33) N · m -1 ; post-: males 1345.81 (404.90) N · m -1 , females 952.78 (192.38) N · m -1 ] than females pre- and post-fatigue. A similar finding was observed in pre-fatigue normalised knee extensor PT [pre-: males 2.77 (0.42) N · m kg -1 , females 2.41 (0.40) N · m kg -1 , post-: males 2.53 (0.54) N · m kg -1 , females 2.26 (0.44) N · m kg -1 ]. After the fatigue protocol, normalised knee extensor PT and knee joint MAS decreased, whilst relaxed and contracted MS of the VL increased in both sexes. These observed differences may contribute to the higher risk of knee injury in females and following the onset of fatigue.
Srikuea, Ratchakrit; Symons, T. Brock; Long, Douglas E.; Lee, Jonah D.; Shang, Yu; Chomentowski, Peter J.; Yu, Guoqiang; Crofford, Leslie J.; Peterson, Charlotte A.
Objective To identify muscle physiological properties that may contribute to post-exertional fatigue and malaise in women with fibromyalgia (FM). Methods Healthy postmenopausal women with (n=11) and without (n=11) fibromyalgia, age 51–70 years, participated in this study. Physical characteristics along with self-reported questionnaires were evaluated. Strength loss and tissue oxygenation in response to a fatiguing exercise protocol were used to quantify fatigability and the local muscle hemodynamic profile. Muscle biopsies were obtained to assess between-group differences in baseline muscle properties using histochemical, immunohistochemical and electron microscopic analyses. Results No significant difference in muscle fatigue in response to exercise was apparent between healthy controls and subjects with FM. However, self-reported fatigue and pain were correlated to prolonged loss of strength following 12-min of recovery in subjects with FM. Although there was no difference in percent SDH positive (type I) and SDH negative (type II) fibers or in mean fiber cross-sectional area between groups, subjects with FM showed greater size variability and altered fiber size distribution. Only in healthy controls, fatigue-resistance was strongly correlated with the size of SDH positive fibers and hemoglobin oxygenation. By contrast, subjects with FM with the highest percentage of SDH positive fibers recovered strength most effectively, which was correlated to capillary density. However, overall, capillary density was lower in subjects with FM. Conclusion Peripheral mechanisms i.e. altered muscle fiber size distribution and decreased capillary density may contribute to post-exertional fatigue in subjects with FM. Understanding these defects in fibromyalgic muscle may provide valuable insight for treatment. PMID:23124535
Knuth, S T; Dave, H; Peters, J R; Fitts, R H
Historically, an increase in intracellular H(+) (decrease in cell pH) was thought to contribute to muscle fatigue by direct inhibition of the cross-bridge leading to a reduction in velocity and force. More recently, due to the observation that the effects were less at temperatures closer to those observed in vivo, the importance of H(+) as a fatigue agent has been questioned. The purpose of this work was to re-evaluate the role of H(+) in muscle fatigue by studying the effect of low pH (6.2) on force, velocity and peak power in rat fast- and slow-twitch muscle fibres at 15 degrees C and 30 degrees C. Skinned fast type IIa and slow type I fibres were prepared from the gastrocnemius and soleus, respectively, mounted between a force transducer and position motor, and studied at 15 degrees C and 30 degrees C and pH 7.0 and 6.2, and fibre force (P(0)), unloaded shortening velocity (V(0)), force-velocity, and force-power relationships determined. Consistent with previous observations, low pH depressed the P(0) of both fast and slow fibres, less at 30 degrees C (4-12%) than at 15 degrees C (30%). However, the low pH-induced depressions in slow type I fibre V(0) and peak power were both significantly greater at 30 degrees C (25% versus 9% for V(0) and 34% versus 17% for peak power). For the fast type IIa fibre type, the inhibitory effect of low pH on V(0) was unaltered by temperature, while for peak power the inhibition was reduced at 30 degrees C (37% versus 18%). The curvature of the force-velocity relationship was temperature sensitive, and showed a higher a/P(0) ratio (less curvature) at 30 degrees C. Importantly, at 30 degrees C low pH significantly depressed the ratio of the slow type I fibre, leading to less force and velocity at peak power. These data demonstrate that the direct effect of low pH on peak power in both slow- and fast-twitch fibres at near-in vivo temperatures (30 degrees C) is greater than would be predicted based on changes in P(0), and that the
William S. Gear
Full Text Available There is little information available regarding how proprioceptive abilities decline as the amount of exertion increases during exercise. The purpose of this study was to determine the role of different levels of fatigue on knee joint position sense. A repeated measures design was used to examine changes in active joint reposition sense (AJRS prior to and following three levels of fatigue. Eighteen participants performed knee extension and flexion isokinetic exercise until torque output was 90%, 70%, or 50% of the peak hamstring torque for three consecutive repetitions. Active joint reposition sense at 15, 30, or 45 degrees was tested following the isokinetic exercise session. Following testing of the first independent measure, participants were given a 20 minute rest period. Testing procedures were repeated for two more exercise sessions following the other levels of fatigue. Testing of each AJRS test angle was conducted on three separate days with 48 hours between test days. Significant main effect for fatigue was indicated (p = 0.001. Pairwise comparisons indicated a significant difference between the pre-test and following 90% of peak hamstring torque (p = 0.02 and between the pre-test and following 50% of peak hamstring torque (p = 0.02. Fatigue has long been theorized to be a contributing factor in decreased proprioceptive acuity, and therefore a contributing factor to joint injury. The findings of the present study indicate that fatigue may have an effect on proprioception following mild and maximum fatigue.
Sun Wook Park
Full Text Available This study aimed to investigate the effects of exercise-induced muscle fatigue in the unaffected knee joint on postural control and kinematic changes in stroke patients. Forty participants (20 stroke patients, 20 age-matched healthy participants were recruited. To induce fatigue, maximum voluntary isometric contractions were performed in the unaffected knee joint in a Leg Extension Rehab exercise machine using the pneumatic resistance. We measured static and dynamic balance and lower-limb kinematics during gait. Changes in postural control parameters anteroposterior sway speed and total center of pressure distance differed significantly between the stroke and control groups. In addition, changes in gait kinematic parameters knee and ankle angles of initial contact differed significantly between stroke (paretic and non-paretic and control groups. Muscle fatigue in the unaffected knee and ankle impaired postural control and debilitates kinematic movement of ipsilateral and contralateral lower limbs, and may place the fatigued stroke patients at greater risk for falls.
Wolkorte, Ria; Heersema, Dorothea J; Zijdewind, Inge
Multiple sclerosis (MS) can be accompanied by motor, cognitive, and sensory impairments. Additionally, MS patients often report fatigue as one of their most debilitating symptoms. It is, therefore, expected that MS patients will have difficulties in performing cognitive-motor dual tasks (DTs), especially in a fatiguing condition. To determine whether MS patients are more challenged by a DT than controls in a fatiguing and less-fatiguing condition and whether DT performance is associated with perceived fatigue. A group of 19 MS patients and 19 age-, sex-, and education-matched controls performed a cognitive task (2-choice reaction time task) separately or concurrent with a low-force or a high-force motor task (index finger abduction at 10% or 30% maximal voluntary contraction). MS patients performed less well on a cognitive task than controls. Cognitive task performance under DT conditions decreased more for MS patients. Moreover, under high-force DT conditions, cognitive performance declined in both groups but to a larger degree for MS patients. Besides a decline in cognitive task performance, MS patients also showed a stronger decrease in motor performance under high-force DT conditions. DT costs were positively related to perceived fatigue as measured by questionnaires. Compared with controls, MS patients performed less well on DTs as demonstrated by a reduction in both cognitive and motor performances. This performance decrease was stronger under fatiguing conditions and was related to the sense of fatigue of MS patients. These data illustrate problems that MS patients may encounter in daily life because of their fatigue. © The Author(s) 2014.
Zabihhosseinian, Mahboobeh; Holmes, Michael W R; Ferguson, Brad; Murphy, Bernadette
The cervical flexion relaxation ratio is lower in neck pain patients compared to healthy controls. Fatigue modulates the onset and offset angles of the silent period in both the lumbar and cervical spine in healthy individuals; however, this response has not been studied with neck pain patients. The purpose of this study was to determine if cervical extensor fatigue would alter the parameters of the cervical flexion relaxation more in a neck pain group than a healthy control group. Thirteen healthy and twelve neck pain patients participated. Cervical extensor activity was examined bilaterally and kinematics of the neck and head were collected. An isometric, repetitive neck extension task at 70% of maximum elicited fatigue. Participants performed 3 trials of maximal cervical flexion both pre and post fatigue. The healthy controls and neck pain groups fatigued after 56 (41) and 39 (31) repetitions, respectively. There was a significant interaction effect for the flexion relaxation ratio between the control and neck pain groups from pre to post fatigue trials (F1,96=22.67, P=0.0001), but not for onset and offset angles (F1, 96=0.017, P=0.897), although the onset and offset angles did decrease significantly for both groups following fatigue (F1,96=9.26, P=0.002). Individuals with mild to moderate neck pain have significant differences in their neuromuscular control relative to controls, experienced myoelectric fatigue with fewer repetitions in a shorter time, had a lower cervical flexion relaxation ratio at baseline and had an inability to decrease this ratio further in response to fatigue. Copyright © 2015 Elsevier Ltd. All rights reserved.
Horvath, Deanna M; Murphy, Robyn M; Mollica, Janelle P; Hayes, Alan; Goodman, Craig A
This study investigated the effect of taurine and β-alanine supplementation on muscle function and muscle taurine transporter (TauT) protein expression in mdx mice. Wild-type (WT) and mdx mice (5 months) were supplemented with taurine or β-alanine for 4 weeks, after which in vitro contractile properties, fatigue resistance and force recovery, and the expression of the TauT protein and proteins involved in excitation-contraction (E-C) coupling were examined in fast-twitch muscle. There was no difference in basal TauT protein expression or basal taurine content between mdx than WT muscle. Supplementation with taurine and β-alanine increased and reduced taurine content, respectively, in muscle from WT and mdx mice but had no effect of TauT protein. Taurine supplementation reduced body and muscle mass, and enhanced fatigue resistance and force recovery in mdx muscle. β-Alanine supplementation enhanced fatigue resistance in WT and mdx muscle. There was no difference in the basal expression of key E-C coupling proteins [ryanodine receptor 1 (RyR1), dihydropyridine receptor (DHPR), sarco(endo)plasmic reticulum Ca 2+ -ATPase 1 (SERCA1) or calsequestrin 1 (CSQ1)] between WT and mdx mice, and the expression of these proteins was not altered by taurine or β-alanine supplementation. These findings suggest that TauT protein expression is relatively insensitive to changes in muscle taurine content in WT and mdx mice, and that taurine and β-alanine supplementation may be viable therapeutic strategies to improve fatigue resistance of dystrophic skeletal muscle.
Hettinga, Florentina J; Konings, Marco J; Cooper, Chris E
Due to the technical nature of speed skating, that is affecting physiological mechanisms such as oxygenation and blood flow, this sport provides a unique setting allowing us to uncover novel mechanistic insights of the physiological response to exercise in elite middle-distance and endurance sports. The present study aimed to examine the influence of skating mode (short-track vs. long-track) on muscle oxygenation, perceived fatigue, and recovery in elite speed skating. Muscle oxygenation of 12 talented short-track speed skaters was continuously monitored during a long-track (LT) and a short-track (ST) skating time-trial of maximal effort using near-infrared spectroscopy (NIRS) on the m. vastus lateralis for both legs. Video captures were made of each testing session for further interpretation of the muscle oxygenation. To determine recovery, perceived exertion was measured 2 and 4 h after each testing sessions. Repeated measures ANOVA's were used for statistical analysis ( p skating (TSI%-slope: left = 0.050 ± 0.052, right = 0.001 ± 0.053, p skating modes in muscle oxygenation. Respectively, two ( ST = 5.8 ± 2.0; LT = 4.2 ± 1.5) and 4 h ( ST = 4.6 ± 1.9; LT = 3.1 ± 1.6) after the time-trials, a higher rate of perceived exertion was found for ST. Based on our results, ST seems more physiologically demanding, and longer periods of recovery are needed after training compared to LT. Technical aspects unique to the exercise mode seem to impact on oxygenation, affecting processes related to the regulation of exercise intensity such as fatigue and recovery.
Full Text Available This paper aims to investigate the effect of light emitting diode therapy (LEDT on exercise-induced hand muscle fatigue by measuring the surface electromyography (sEMG of flexor digitorum superficialis. Ten healthy volunteers were randomly placed in the equal sized LEDT group and control group. All subjects performed a sustained fatiguing isometric contraction with the combination of four fingertips except thumb at 30% of maximal voluntary contraction (MVC until exhaustion. The active LEDT or an identical passive rest therapy was then applied to flexor digitorum superficialis. Each subject was required to perform a re-fatigue task immediately after therapy which was the same as the pre-fatigue task. Average rectified value (ARV and fractal dimension (FD of sEMG were calculated. ARV and FD were significantly different between active LEDT and passive rest groups at 20%–50%, 70%–80%, and 100% of normalized contraction time (P<0.05. Compared to passive rest, active LEDT induced significantly smaller increase in ARV values and decrease in FD values, which shows that LEDT is effective on the recovery of muscle fatigue. Our preliminary results also suggest that ARV and FD are potential replacements of biochemical markers to assess the effects of LEDT on muscle fatigue.
Cheng, Chih-Hsiu; Chien, Andy; Hsu, Wei-Li; Yen, Ling-Wei; Lin, Yang-Hua; Cheng, Hsin-Yi Kathy
Previous studies have identified sensorimotor disturbances and greater fatigability of neck muscles in patients with neck pain. The purpose of this study was to investigate the effect of neck pain and neck flexor fatigue on standing balance following postural perturbations. Twenty patients with chronic neck pain (CNP) (24.7±3.6 year-old) and 20 age-matched asymptomatic subjects (22.1±2.2 year-old) were recruited. Subjects stood barefoot on a force plate and experienced backward perturbations before and after neck flexor fatigue. Center of pressure, electromyography of cervical and lumbar muscles, and head/trunk accelerations were recorded. Two-way ANOVA (pain×fatigue) was used for statistical analysis. CNP group showed larger body sway during quiet standing but not during perturbed standing compared with asymptomatic adults. In both groups, neck flexor fatigue resulted in greater body sway during the quiet standing but smaller body sway during perturbed standing, increased neck muscle activations and decreased lumbar muscle activations, as well as increased time to maximal head acceleration. Disturbed balance control was observed in CNP patients during the quiet standing. However, a rigid strategy was used to minimize the postural sway and to protect the head against backward perturbations in both CNP and asymptomatic young adults after neck flexor fatigue. The results facilitate the understanding of how the subjects with chronic neck pain and with neck muscle fatigue deal with the challenging condition. Further studies are needed to verify if such phenomenon could be changed after the intervention of specific flexor muscle retraining and balance control exercises. Copyright © 2015 Elsevier B.V. All rights reserved.
Gonzalez-Izal, Miriam; Lusa Cadore, Eduardo; Izquierdo, Mikel
Concentric (CON) and eccentric (ECC) contractions may involve different mechanisms related to changes in sarcolemma status and the consequent alteration of action potential transmission along muscle fibers. Muscle conduction velocity (CV), surface electromyography signal (sEMG), muscle quality, and blood lactate concentrations were analyzed during CON and ECC actions. Compared with ECC, the CON protocol resulted in greater muscle force losses, blood lactate concentrations, and changes in sEMG parameters. Similar reductions in CV were detected in both protocols. Higher echo intensity values were observed 2 days after ECC due to greater muscle damage. The effects of the muscle damage produced by ECC exercise on the transmission of action potentials along muscle fibers (measured as the CV) may be comparable with the effects of hydrogen accumulation produced by CON exercise (related to greater lactate concentrations), which causes greater force loss and change in other sEMG variables during CON than during ECC actions.
Pethick, Jamie; Winter, Samantha L; Burnley, Mark
The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1-S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-α scaling exponent (DFA-α). The MVC torque was reduced in trials below CT [by 19 ± 4% (means ± SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 ± 0.03 to 0.75 ± 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = -0.23, 0.10; DFA-α from 1.36 ± 0.01 to 1.32 ± 0.03, 95% CI -0.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 ± 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 ± 0.06 to 0.14 ± 0.01, 95% CI = -0.72, -0.33; DFA-α from 1.38 ± 0.03 to 1.58 ± 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. Copyright © 2016 the American Physiological Society.
Kristensen, Michael; Hansen, T.; Juel, C.
while trying to manipulate the opening probability or transport capacity of these proteins during electrical stimulation of isolated soleus muscles. All experiments were made with excised muscle from male Wistar rats. Kir2.1 channels were almost undetectable in the sarcolemmal membrane but present...... muscle contractions, whereas Kir2.1 and NKCC1 may have a role in K+ reuptake. channels and cotransporters; T tubule...
W?st, Rob C. I.; Morse, Christopher I.; de Haan, Arnold; Rittweger, J?rn; Jones, David A.; Degens, Hans
Although smoking-related diseases, such as chronic obstructive pulmonary disease (COPD), are often accompanied by increased peripheral muscle fatigability, the extent to which this is a feature of the disease or a direct effect of smoking per se is not known. Skeletal muscle function was investigated in terms of maximal voluntary isometric torque, activation, contractile properties and fatigability, using electrically evoked contractions of the quadriceps muscle of 40 smokers [19 men and 21 w...
Full Text Available Wolfgang Kemmler, Simon von StengelInstitute of Medical Physics, University of Erlangen-Nürnberg, Erlangen, GermanyBackground: The primary aim of this study was to determine the effect of 12 months of whole-body electromyostimulation (WB-EMS exercise on appendicular muscle mass and abdominal fat mass in subjects specifically at risk for sarcopenia and abdominal obesity, but unable or unwilling to exercise conventionally.Methods: Forty-six lean, nonsportive (<60 minutes of exercise per week, elderly women (aged 75 ± 4 years with abdominal obesity according to International Diabetes Federation criteria were randomly assigned to either a WB-EMS group (n=23 which performed 18 minutes of intermittent, bipolar WB-EMS (85 Hz three sessions in 14 days or an "active" control group (n=23. Whole-body and regional body composition was assessed by dual energy X-ray absorptiometry to determine appendicular muscle mass, upper leg muscle mass, abdominal fat mass, and upper leg fat mass. Maximum strength of the leg extensors was determined isometrically by force plates.Results: After 12 months, significant intergroup differences were detected for the primary endpoints of appendicular muscle mass (0.5% ± 2.0% for the WB-EMS group versus −0.8% ± 2.0% for the control group, P=0.025 and abdominal fat mass (−1.2% ± 5.9% for the WB-EMS group versus 2.4% ± 5.8% for the control group, P=0.038. Further, upper leg lean muscle mass changed favorably in the WB-EMS group (0.5% ± 2.5% versus −0.9% ± 1.9%, in the control group, P=0.033, while effects for upper leg fat mass were borderline nonsignificant (−0.8% ± 3.5% for the WB-EMS group versus 1.0% ± 2.6% for the control group, P=0.050. With respect to functional parameters, the effects for leg extensor strength were again significant, with more favorable changes in the WB-EMS group (9.1% ± 11.2% versus 1.0% ± 8.1% in the control group, P=0.010.Conclusion: In summary, WB-EMS showed positive effects on the
Sergio G. Monteiro
increase this rate more than did the AP alone. Our findings suggest abdominal weight increases propioception related to the respiratory movements and descent of the diaphragm. The loads on the abdomen produce minor changes in mechanics of the diaphragm (1/3 of the load required to develop fatigue in normal subjects. Al least in normal subjects these changes appear to be insufficient to produce respiratory muscle training.
Maher, Chris G.; Latimer, Jane; Hodges, Paul W.; Shirley, Debra
Ultrasound (US) measures are used by clinicians and researchers to evaluate improvements in activity of the abdominal muscles in patients with low back pain. Studies evaluating the reproducibility of these US measures provide some information; however, little is known about the reproducibility of these US measures over time in patients with low back pain. The objectives of this study were to estimate the reproducibility of ultrasound measurements of automatic activation of the lateral abdominal wall muscles using a leg force task in patients with chronic low back pain. Thirty-five participants from an existing randomised, blinded, placebo-controlled trial participated in the study. A reproducibility analysis was undertaken from all patients using data collected at baseline and after treatment. The reproducibility of measurements of thickness, muscle activation (thickness changes) and muscle improvement/deterioration after intervention (differences in thickness changes from single images made before and after treatment) was analysed. The reproducibility of static images (thickness) was excellent (ICC2,1 = 0.97, 95% CI = 0.96–0.97, standard error of the measurement (SEM) = 0.04 cm, smallest detectable change (SDC) = 0.11 cm), the reproducibility of thickness changes was moderate (ICC2,1 = 0.72, 95% CI 0.65–0.76, SEM = 15%, SDC 41%), while the reproducibility of differences in thickness changes from single images with statistical adjustment for duplicate measures was poor (ICC2,1 = 0.44, 95% CI 0.33–0.58, SEM = 21%, SDC = 66.5%). Improvements in the testing protocol must be performed in order to enhance reproducibility of US as an outcome measure for abdominal muscle activation. PMID:19415347
Florentina Johanna Hettinga
Full Text Available Due to the technical nature of speed skating, that is affecting physiological mechanisms such as oxygenation and blood flow, this sport provides a unique setting allowing us to uncover novel mechanistic insights of the physiological response to exercise in elite middle-distance and endurance sports. The present study aimed to examine the influence of skating mode (short-track vs. long-track on muscle oxygenation, perceived fatigue, and recovery in elite speed skating. Muscle oxygenation of twelve talented short-track speed skaters was continuously monitored during a long-track (LT and a short-track (ST skating time-trials of maximal effort using near-infrared spectroscopy (NIRS on the m. vastus lateralis for both legs. Video captures were made of each testing session for further interpretation of the muscle oxygenation. To determine recovery, perceived exertion was measured two and four hours after each testing sessions. Repeated measures ANOVA’s were used for statistical analysis (p<.05. After a rapid desaturation in both legs directly after the start, an asymmetry in muscle oxygenation between both legs was found during LT (tissue saturation-index (TSI%-slope: left=0.053±0.032; right=0.023±0.020, p<.05 and ST speed skating (TSI%-slope: left=0.050±0,052, right=0.001 ±0.053, p<.05. Re-Resaturation of the right leg was relatively lower in ST compared to LT. For the left leg, no difference was found between skating modes in muscle oxygenation. Respectively, two (ST=5.8±2.0; LT=4.2±1.5 and four hours (ST=4.6±1.9; LT=3.1±1.6 after the time-trials, a higher rate of perceived exertion was found for ST. Based on our results, ST seems more physiologically demanding, and longer periods of recovery are needed after training compared to LT. Technical aspects unique to the exercise mode seem to impact on oxygenation, affecting processes related to the regulation of exercise intensity such as fatigue and recovery.
Butler, JE; Ribot-Ciscar, E; Zijdewind, Inge; Thomas, CK
The aim of this study was to evaluate whether increases in blood pressure, and presumably muscle perfusion pressure, improve the endurance of thenar muscles paralyzed chronically by cervical spinal cord injury (SCI). Resting mean arterial pressure (MAP) was low in all eight subjects (64 +/- 2 mmHg).
Nielsen, A.N.; Mizuno, M.; Ratkevicius, Aivaras
Antioxidative vitamins, coenzyme Q 10 electrical stimulation, isometric exercise, low frequency fatigue......Antioxidative vitamins, coenzyme Q 10 electrical stimulation, isometric exercise, low frequency fatigue...
Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T
changes in human muscle. The aim of this study was to develop a method by which EMG and NMR spectroscopy measurements could be performed simultaneously. All measurements were performed in a whole body 1.5 Tesla NMR scanner. A calf muscle ergometer, designed for use in a whole body NMR scanner, was used....... The subject had the left foot strapped to the ergometer. The anterior tibial EMG was recorded by bipolar surface electrodes. A surface coil was strapped to the anterior tibial muscle next to the EMG electrodes. Simultaneous measurements of surface EMG and surface coil 31P NMR spectroscopy were performed...
Lau, Emily; Mazer, Jeffrey; Carino, Gerardo
A 49-year-old man with chronic obstructive pulmonary disease (COPD) presented with significant tachypnoea, fevers, productive cough and increased work of breathing for the previous 4 days. Laboratory data showed elevated lactate of 3.2 mEq/L. Continuous inhaled ipratropium and albuterol nebuliser treatments were administered. Lactate levels increased to 5.5 and 3.9 mEq/L, at 6 and 12 h, respectively. No infectious source was found and the lactic acidosis cleared as the patient improved. The lactic acidosis was determined to be secondary to respiratory muscle fatigue and inhaled β-agonist therapy, two under-recognised causes of lactic acidosis in patients presenting with respiratory distress. Lactic acidosis is commonly used as a clinical marker for sepsis and shock, but in the absence of tissue hypoperfusion and severe hypoxia, alternative aetiologies for elevated levels should be sought to avoid unnecessary and potentially harmful medical interventions.
Noormohammadpour, Pardis; Hosseini Khezri, Alireza; Linek, Paweł; Mansournia, Mohammad Ali; Hassannejad, Alireza; Younesian, Ali; Farahbakhsh, Farzin; Kordi, Ramin
Low back pain (LBP) is a common complaint amongst adolescent athletes. While different studies have shown association between LBP and trunk muscle thickness in the general population, few articles have studied it in adolescent athletes. The aim of this study is to compare lateral abdominal muscle thickness and function, and cross sectional area (CSA) of lumbar multifidus (LM) in adolescent soccer players with and without LBP. In total, 28 adolescent soccer players with and without LBP, from the premier league participated in this study. The thickness of external oblique, internal oblique and transversus abdominis and the CSA of the LM muscles at L4 level on both sides were measured at rest and contraction via ultrasound imaging (USI). In addition, leg length discrepancy, hamstring flexibility, active lumbar forward flexion, and isometric muscle endurance of trunk extensors were measured in both groups. (study design/setting: case control study). The mean (SD) age in LBP group and non-LBP group were 14.0 (1.1) and 14.1 (0.9) years, respectively. There was no significant difference in baseline characteristics of participants between groups. Findings showed no significant difference between LBP and non-LBP groups comparing all measured variables. The data obtained support that there is not a correlation between abdominal muscle thickness and CSA of the lumbar multifidi and LBP in adolescent soccer players. These findings suggest that other factors rather than the thickness of deep trunk muscles may play a more significant role in the etiology of LBP in adolescent soccer players.
Rolland-Debord, Camille; Morelot-Panzini, Capucine; Similowski, Thomas; Duranti, Roberto; Laveneziana, Pierantonio
Exercise induces release of cytokines and increase of circulating natural killers (NK) lymphocyte during strong activation of respiratory muscles. We hypothesised that non-fatiguing respiratory muscle loading during exercise causes an increase in NK cells and in metabolic stress indices. Heart rate (HR), ventilation (VE), oesophageal pressure (Pes), oxygen consumption (VO 2 ), dyspnoea and leg effort were measured in eight healthy humans (five men and three women, average age of 31 ± 4 years and body weight of 68 ± 10 kg), performing an incremental exercise testing on a cycle ergometer under control condition and expiratory flow limitation (FL) achieved by putting a Starling resistor. Blood samples were obtained at baseline, at peak of exercise and at iso-workload corresponding to that reached at the peak of FL exercise during control exercise. Diaphragmatic fatigue was evaluated by measuring the tension time index of the diaphragm. Respiratory muscle overloading caused an earlier interruption of exercise. Diaphragmatic fatigue did not occur in the two conditions. At peak of flow-limited exercise compared to iso-workload, HR, peak inspiratory and expiratory Pes, NK cells and norepinephrine were significantly higher. The number of NK cells was significantly related to ΔPes (i.e. difference between the most and the less negative Pes) and plasmatic catecholamines. Loading of respiratory muscles is able to cause an increase of NK cells provided that activation of respiratory muscles is intense enough to induce a significant metabolic stress.
Villafañe, Jorge H; Gobbo, Massimiliano; Peranzoni, Matteo; Naik, Ganesh; Imperio, Grace; Cleland, Joshua A; Negrini, Stefano
This systematic literature review aimed at examining the validity and applicability in everyday clinical rehabilitation practise of methods for the assessment of back muscle fatiguability in patients with chronic non-specific low back pain (CNSLBP). Extensive research was performed in MEDLINE, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Embase, Physiotherapy Evidence Database (PEDro) and Cochrane Central Register of Controlled Trials (CENTRAL) databases from their inception to September 2014. Potentially relevant articles were also manually looked for in the reference lists of the identified publications. Studies examining lumbar muscle fatigue in people with CNSLBP were selected. Two reviewers independently selected the articles, carried out the study quality assessment and extracted the results. A modified Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) scale was used to evaluate the scientific rigour of the selected works. Twenty-four studies fulfilled the selection criteria and were included in the systematic review. We found conflicting data regarding the validity of methods used to examine back muscle fatigue. The Biering-Sorensen test, performed in conjunction with surface electromyography spectral analysis, turned out to be the most widely used and comparatively, the most optimal modality currently available to assess objective back muscle fatigue in daily clinical practise, even though critical limitations are discussed. Future research should address the identification of an advanced method for lower back fatigue assessment in patients with CNSLBP which, eventually, might provide physical therapists with an objective and reliable test usable in everyday clinical practise. Implications for Rehabilitation Despite its limitations, the Biering-Sorensen test is currently the most used, convenient and easily available fatiguing test for lumbar muscles. To increase validity and reliability of the Biering
Ruliati, L. P.; Adiputra, N.; Sutjana, I. D. P.; Sutajaya, I. M.
Rice mill is one of the businesses in informal sector. From the rice milling process, ergonomic problems arise when employees work with bent position that done repeatedly to lift grain sacks to be transferred to peeler machine. This situation will affect the comfort of work, thus increasing the workload, muscle tension, and fatigue. The consequence will certainly affect the health and productivity of workers. In this study introduces ergo Tri Hita Karana (ergo THK) as an ergonomics intervention model which solves ergonomics problems of the cultural aspects of THK. The study aim is to determine the modification of working conditions based Ergo THK to reduce workload, muscle tension and fatigue. This research uses Randomized Pretest and Posttest Control Group Design experimental design. The subjects were 30 male rice mill workers with an age range of 16 until 56 years, and then divided into 15 subjects in the control group and 15 subjects in the treatment group. The results showed that the average posttest workloads in the control group are 136.950 more less 0.297 and in the treatment group are 107.60 more less 0.396. Significance analysis showed that after the two groups done their activities, the average workload significantly different p less than 0.005. The amount of reduction in the workload between the two groups was 21.43 percent. In muscle tension posttest showed that the mean score of the muscle tension in the control group was 62.67 more less 7.31 and the treatment group was 20.96 more less 2.96. Significance analysis showed that both groups mean muscle-tension results were significantly different p less than 0.005. The amount of reduction in tension between the control group and the treatment group while working was 66.55 percent. At fatigue posttest showed that the mean score of fatigue in the control group was 76.40 more less 13.51 and the treatment group was 55.53 more less 9.51. Significant analysis showed that the mean fatigue of both groups
O. A. Melnychuk
Full Text Available Alcohol intoxication and ischemic injury of skeletal muscles often accompany each other. It is shown that patients hospitalized with chronic alcoholism develop muscle fatigue. Skeletal muscle dysfunction in alcohol-dependent patients is caused by ethanol-associated myofibrillar atrophy and metabolic disbalance, while compression-ischemic lesions result from unconsciousness of the patient, in case of taking the critical alcohol dose. Therefore, the aim of this study is to discover typical m. gastrocnemius (cap. med. tetanic kinetics changes in alcohol intoxicated rats with experimentally induced vascular ischemia of hindlimb muscles under conditions of low-frequency progressive muscle fatigue. Experiments were carried out on 10 young male Wistar rats (149.5 ± 5.8 g kept under standard vivarium conditions and diet. The investigation was conducted in two phases: chronic (30 days and acute (3 hours experiment. All surgical procedures were carried out aseptically under general anesthesia. Ishemic m. gastrocnemius (cap. med. tetanic kinetic changes and force productivity in alcohol intoxicated rats were investigated in the isometric mode, with direct electrical stimulation. The fatigue of m. gastrocnemius (cap. med. was evaluated by three characteristic criteria: the first sag effect, the secondary force rise, the second sag effect. There have been 10 similar experiments: 5 series in each study group with 10 tetanic runs in each series. The highest amplitude of the native m. gastrocnemius (cap. med. tetanus relative to isoline was taken as 100% force response. The same pattern of m. gastrocnemius (cap. med. low-frequency fatigue development was found in both rat groups under study. It is evidenced by the absence of substantial m. gastrocnemius (cap. med. tetanus kinetics differences in alcohol intoxicated rats, compared with non-alcohol intoxicated rats during fatigue test. However, the appreciable m. gastrocnemius (cap. med. tetanic force reduction
Hasselager, Rune; Gögenur, Ismail
PURPOSE: Risk stratification of patients prior to surgery is important for reduction of postoperative morbidity and mortality. The frailty concept has been put forward as a good predictor of surgical outcomes. Sarcopenia (depletion of muscle mass) can be used to measure frailty. We aimed to syste......PURPOSE: Risk stratification of patients prior to surgery is important for reduction of postoperative morbidity and mortality. The frailty concept has been put forward as a good predictor of surgical outcomes. Sarcopenia (depletion of muscle mass) can be used to measure frailty. We aimed...
Matkowski, Boris; Lepers, Romuald; Martin, Alain
The aim of this study was to analyze the neuromuscular mechanisms involved in the torque decrease induced by submaximal electromyostimulation (EMS) of the quadriceps muscle. It was hypothesized that torque decrease after EMS would reflect the fatigability of the activated motor units (MUs), but also a reduction in the number of MUs recruited as a result of changes in axonal excitability threshold. Two experiments were performed on 20 men to analyze 1) the supramaximal twitch superimposed and evoked at rest during EMS (Experiment 1, n = 9) and 2) the twitch response and torque-frequency relation of the MUs activated by EMS (Experiment 2, n = 11). Torque loss was assessed by 15 EMS-evoked contractions (50 Hz; 6 s on/6 s off), elicited at a constant intensity that evoked 20% of the maximal voluntary contraction (MVC) torque. The same stimulation intensity delivered over the muscles was used to induce the torque-frequency relation and the single electrical pulse evoked after each EMS contraction (Experiment 2). In Experiment 1, supramaximal twitch was induced by femoral nerve stimulation. Torque decreased by ~60% during EMS-evoked contractions and by only ~18% during MVCs. This was accompanied by a rightward shift of the torque-frequency relation of MUs activated and an increase of the ratio between the superimposed and posttetanic maximal twitch evoked during EMS contraction. These findings suggest that the torque decrease observed during submaximal EMS-evoked contractions involved muscular mechanisms but also a reduction in the number of MUs recruited due to changes in axonal excitability. Copyright © 2015 the American Physiological Society.
Ratkevicius, A; Skurvydas, A; Povilonis, E; Quistorff, B; Lexell, J
The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square (EMGrms) of the vastus lateralis muscle was evaluated. The 20-Hz torque:100-Hz torque (20:100 Hz torque) ratio was reduced more after electrically induced than after voluntary exercise (P exercise, the decrease in 20:100 Hz torque ratio was gradually (P exercise, the decrease in 20:100 Hz torque ratio and the increase in EMGrms were greater in protocol 1 (P exercise and that the electrically induced exercise produced a more pronounced LFF compared to voluntary exercise of submaximal intensity. It is suggested that compensatory recruitment of faster-contracting motor units is an additional factor affecting the severity of LFF during voluntary exercise.
Zhuang, Cheng-Le; Mao, Xiang-Yu; Liu, Shu; Chen, Wei-Zhe; Huang, Dong-Dong; Zhang, Chang-Jing; Chen, Bi-Cheng; Shen, Xian; Yu, Zhen
Ginsenoside Rb1 is reported to possess anti-fatigue activity, but the mechanisms remain unknown. The aim of this study was to investigate the molecular mechanisms responsible for the anti-fatigue effect of ginsenoside Rb1 on postoperative fatigue syndrome induced by major small intestinal resection (MSIR) in aged rat. Aged rats with MSIR were administrated with ginsenoside Rb1 (15 mg/kg) once a day from 3 days before surgery to the day of sacrifice, or with saline as corresponding controls. Rats without MSIR but going through the same surgery procedure were administrated with saline as blank controls. Anti-fatigue effect was assessed by an open field test; superoxide dismutase, reactive oxygen species and malondialdehyde in skeletal muscle were determined. The mRNA levels of Akt2 and Nrf2 in skeletal muscle were measured by real-time quantitative PCR. The activation of Akt and Nrf2 was examined by western blot and immunohistofluorescence. Our results revealed that ginsenoside Rb1 significantly increased the journey and the rearing frequency, decreased the time of rest in aged rats with MSIR. In addition, ginsenoside Rb1 significantly reduced reactive oxygen species and malondialdehyde release and increased the superoxide dismutase activity of skeletal muscle in aged rats with MSIR. Ginsenoside Rb1 also increased the expression of Akt2 and Nrf2 mRNA, up-regulated Akt phosphorylation and Nrf2 nuclear translocation. These findings indicate that ginsenoside Rb1 has an anti-fatigue effect on postoperative fatigue syndrome in aged rat, and the mechanism possibly involves activation of the PI3K/Akt pathway with subsequent Nrf2 nuclear translocation and induction of antioxidant enzymes. Copyright © 2014 Elsevier B.V. All rights reserved.
Pearen, Michael A.; Eriksson, Natalie A.; Fitzsimmons, Rebecca L.; Goode, Joel M.; Martel, Nick; Andrikopoulos, Sofianos; Muscat, George E. O.
Nuclear hormone receptors (NR) have been implicated as regulators of lipid and carbohydrate metabolism. The orphan NR4A subgroup has emerged as regulators of metabolic function. Targeted silencing of neuron-derived orphan receptor 1 (Nor-1)/NR4A3 in skeletal muscle cells suggested that this NR was necessary for oxidative metabolism in vitro. To investigate the in vivo role of Nor-1, we have developed a mouse model with preferential expression of activated Nor-1 in skeletal muscle. In skeletal...
Bruton, Joseph D; Place, Nicolas; Yamada, Takashi; Silva, José P; Andrade, Francisco H; Dahlstedt, Anders J; Zhang, Shi-Jin; Katz, Abram; Larsson, Nils-Göran; Westerblad, Håkan
Skeletal muscle often shows a delayed force recovery after fatiguing stimulation, especially at low stimulation frequencies. In this study we focus on the role of reactive oxygen species (ROS) in this fatigue-induced prolonged low-frequency force depression. Intact, single muscle fibres were dissected from flexor digitorum brevis (FDB) muscles of rats and wild-type and superoxide dismutase 2 (SOD2) overexpressing mice. Force and myoplasmic free [Ca(2+)] ([Ca(2+)](i)) were measured. Fibres were stimulated at different frequencies before and 30 min after fatigue induced by repeated tetani. The results show a marked force decrease at low stimulation frequencies 30 min after fatiguing stimulation in all fibres. This decrease was associated with reduced tetanic [Ca(2+)](i) in wild-type mouse fibres, whereas rat fibres and mouse SOD2 overexpressing fibres instead displayed a decreased myofibrillar Ca(2+) sensitivity. The SOD activity was approximately 50% lower in wild-type mouse than in rat FDB muscles. Myoplasmic ROS increased during repeated tetanic stimulation in rat fibres but not in wild-type mouse fibres. The decreased Ca(2+) sensitivity in rat fibres could be partially reversed by application of the reducing agent dithiothreitol, whereas the decrease in tetanic [Ca(2+)](i) in wild-type mouse fibres was not affected by dithiothreitol or the antioxidant N-acetylcysteine. In conclusion, we describe two different causes of fatigue-induced prolonged low-frequency force depression, which correlate to differences in SOD activity and ROS metabolism. These findings may have clinical implications since ROS-mediated impairments in myofibrillar function can be counteracted by reductants and antioxidants, whereas changes in SR Ca(2+) handling appear more resistant to interventions.
da Silva, Rubens A; Vieira, Edgar R; Cabrera, Marcos; Altimari, Leandro R; Aguiar, Andreo F; Nowotny, Alexandre H; Carvalho, Adriana F; Oliveira, Marcio R
The purpose of this study was to compare back muscle fatigue of younger and older participants with and without chronic low back pain (CLBP). Twenty participants without and 20 with nonspecific CLBP participated in this study. Each group contained 10 younger (50% males; mean age: 31 ± 6 yrs) and 10 older adults (50% males; age mean: 71 ± 7 yrs). Two isometric fatigue protocols were presented randomly: (1) to maintain the unsupported trunk at the horizontal position while on a 45° Roman chair for a minute, and (2) to maintain a 10% of body weight box close to the trunk in the upright position for a minute. Surface electromyography (EMG) signals from the back (multifidus and iliocostalis) and one hip (biceps femoris) muscles were recorded bilaterally, and the median frequency fatigue estimate from linear regression slopes of the EMG time-series was computed. There were no significant (P > 0.05) age effects, and group-by-age interaction in both isometric and functional fatigue tasks. However, the CLBP groups (both younger and old) displayed more back fatigue than people without CLBP in both fatigue protocols (P size varying of d = 0.17-0.32). This study was sensitive to discriminate that individuals with CLBP did present significantly more pronounced EMG back fatigue than people without CLBP, in both younger and older adults. These results have significant clinical implications for low back pain rehabilitation programs with regard to endurance assessment in both younger and older. Copyright © 2015 Elsevier Ltd. All rights reserved.
Peoples, Gregory E; McLennan, Peter L
Oxygen efficiency influences skeletal muscle contractile function during physiological hypoxia. Dietary fish oil, providing docosahexaenoic acid (DHA), reduces the oxygen cost of muscle contraction. This study used an autologous perfused rat hindlimb model to examine the effects of a fish oil diet on skeletal muscle fatigue during an acute hypoxic challenge. Male Wistar rats were fed a diet rich in saturated fat (SF), long-chain (LC) n-6 polyunsaturated fatty acids (n-6 PUFA), or LC n-3 PUFA DHA from fish oil (FO) (8 weeks). During anaesthetised and ventilated conditions (normoxia 21% O 2 (SaO 2 -98%) and hypoxia 14% O 2 (SaO 2 -89%)) the hindlimb was perfused at a constant flow and the gastrocnemius-plantaris-soleus muscle bundle was stimulated via sciatic nerve (2 Hz, 6-12V, 0.05 ms) to established fatigue. Caffeine (2.5, 5, 10 mM) was supplied to the contracting muscle bundle via the arterial cannula to assess force recovery. Hypoxia, independent of diet, attenuated maximal twitch tension (normoxia: 82 ± 8; hypoxia: 41 ± 2 g·g -1 tissue w.w.). However, rats fed FO sustained higher peak twitch tension compared with the SF and n-6 PUFA groups (P recovery was enhanced in the FO-fed animals (SF: 41 ± 3; n-6 PUFA: 40 ± 4; FO: 52 ± 7% recovery; P < 0.05). These results support a physiological role of DHA in skeletal muscle membranes when exposed to low-oxygen stress that is consistent with the attenuation of muscle fatigue under physiologically normoxic conditions.
Fulco, C S; Lewis, S F; Frykman, Peter
, a product of a contraction rate (1 Hz), force measured at the ankle, and distance of ankle movement from 90 degrees to 150 degrees of KE, was precisely controlled. Lack of rise in myoelectric activity in biceps femoris of the active leg during DKE and MVC was consistent with restriction of muscle action...
The locomotory muscles represent an important determinant of the athletic potential of the horse and hence the ability to compete at a high level. For efficient raising and training, it would be useful to predict the potential of a horse early in life based on the characteristics of the locomotory
Voermans, N.C.; Knoop, H.; Bleijenberg, G.; Engelen, B.G.M. van
OBJECTIVES: Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders characterised by joint hypermobility, skin hyperextensibility and tissue fragility. It has recently been shown that muscle weakness occurs frequently in EDS, and that
Morse, C.I.; Wust, R.C.I.; Jones, D.A.; de Haan, A.; Degens, H.
Aim: To determine whether muscle function is compromised in healthy smokers in comparison with activity-matched non-smokers. Methods: Nine male smokers (aged 22.2 ± 2.5 years: mean ± SD) with a smoking history of 2.5 ± 3.1 pack years, and ten male control participants (25.4 ± 2.9 years) matched for
and neuromuscular activation, but also with an impaired position and torque control at submaximal torque levels, an altered EMG-torque relationship and a higher performance fatigability of the quadriceps muscle. It is recommended that the rehabilitation includes strengthening and fatiguing exercises at maximal and submaximal force levels.
Full Text Available Chronic constipation in patients with multiple sclerosis (MS is common and the current methods of treatment are ineffective in some patients. Anecdotal observations suggest that functional electrical stimulation (FES of the abdominal muscles may be effective in the management of constipation in these patients. Patients and Methods. In this exploratory investigation we studied the effects of FES on the whole gut transit time (WGTT and the colonic transit time (CTT. In addition, we evaluated the treatment effect on the patients’ constipation-related quality of life and on the use of laxatives and the use of manual bowel evacuation. FES was given for 30 minutes twice a day for a period of six weeks. Four female patients were studied. Results. The WGTT and CTT and constipation-related quality of life improved in all patients. The patients’ use of laxatives was reduced. No adverse effects of FES treatment were reported. Conclusion. The findings of this pilot study suggest that FES applied to the abdominal muscles may be an effective treatment modality for severe chronic constipation in patients with MS.
Kroll, Walter; And Others
There is a degree of uniqueness in fatigue patterns, particularly between different levels of absolute maximum strength. Caution should be used when analyzing fatigue curves among subjects with unspecified strength levels. (CJ)
Fonvig, Cilius E; Bille, Dorthe S; Chabanova, Elizaveta
The degree of fat deposition in muscle and its implications for obesity-related complications in children and youths are not well understood. One hundred and fifty-nine patients (mean age: 13.3 years; range: 6-20) with a body mass index (BMI) >90(th) percentile for age and sex were included. Muscle...... fat content (MFC) was measured in the psoas muscle by proton magnetic resonance spectroscopy. The patients were assigned to two groups: MFC...
Full Text Available Background: Fatigue considerably affects rehabilitation and ergonomics. Many approaches to this complex phenomenon, ranging from physiological to psychological, have been used to obtain meaningful fatigue measurements. However, none of the methods in the literature measure fatigue directly. It is therefore of considerable interest to determine which indirect methods best represent the state. Method: Fatiguing contraction was measured at maximum voluntary contraction (MVC and 40% MVC in the biceps brachii, quadriceps and erector spinae muscles (three separate experiments. The most-reported objective measurements (contraction force, median electromyographic frequency, heart rate, muscle bed oxygenation and muscle blood volume and subjective measurements (visual analog score, body part discomfort rating and perceived exertion rate were simultaneously recorded. The data from the three experiments underwent separate statistical analysis. Descriptive statistics, linear mixed effects (to examine force fatigue predictability and trend analysis (with between and within-subject correlations were calculated. Results: Univariate ANOVA on all objective variables showed that gender was a significant factor (pContexto: A fadiga afeta consideravelmente a reabilitação e ergonomia. Muitas abordagens a este fenômeno complexo, incluindo fisiológicas e psicológicas, têm sido utilizadas para obter medidas significativas da fadiga. No entanto, nenhum dos métodos descritos na literatura mede diretamente a fadiga. É, portanto de interesse a determinação de quais dos métodos indiretos melhor representa a condição de fadiga. Método: A fadiga por contração foi medida na contração voluntária máxima (CVM e 40% da CVM em músculos bíceps braquial, quadríceps e músculos eretores da coluna (três avaliações independentes. As medidas objetivas mais relatadas (força de contração, freqüência mediana na eletromiografia, freqüência cardíaca, oxigena
Moon, Younghye; Cao, Yenong; Zhu, Jingjing; Xu, Yuanyuan; Balkan, Wayne; Buys, Emmanuel S.; Diaz, Francisca; Kerrick, W. Glenn; Hare, Joshua M.
Abstract Aim: Nitric oxide (NO) plays important, but incompletely defined roles in skeletal muscle. NO exerts its regulatory effects partly though S-nitrosylation, which is balanced by denitrosylation by enzymes such as S-nitrosoglutathione reductase (GSNOR), whose functions in skeletal muscle remain to be fully deciphered. Results: GSNOR null (GSNOR−/−) tibialis anterior (TA) muscles showed normal growth and were stronger and more fatigue resistant than controls in situ. However, GSNOR−/− lumbrical muscles showed normal contractility and Ca2+ handling in vitro, suggesting important differences in GSNOR function between muscles or between in vitro and in situ environments. GSNOR−/− TA muscles exhibited normal mitochondrial content, and capillary densities, but reduced type IIA fiber content. GSNOR inhibition did not impact mitochondrial respiratory complex I, III, or IV activities. These findings argue that enhanced GSNOR−/− TA contractility is not driven by changes in mitochondrial content or activity, fiber type, or blood vessel density. However, loss of GSNOR led to RyR1 hypernitrosylation, which is believed to increase muscle force output under physiological conditions. cGMP synthesis by soluble guanylate cyclase (sGC) was decreased in resting GSNOR−/− muscle and was more responsive to agonist (DETANO, BAY 41, and BAY 58) stimulation, suggesting that GSNOR modulates cGMP production in skeletal muscle. Innovation: GSNOR may act as a “brake” on skeletal muscle contractile performance under physiological conditions by modulating nitrosylation/denitrosylation balance. Conclusions: GSNOR may play important roles in skeletal muscle contractility, RyR1 S-nitrosylation, fiber type specification, and sGC activity. Antioxid. Redox Signal. 26, 165–181. PMID:27412893
Novelli, G.P.; Bracciotti, G.; Falsini, S. (Univ. of Florence (Italy))
The involvement of free radicals in endurance to muscle effort is suggested by experimental and clinical data. Therefore, experiments have been performed to observe the effect of trapping free radicals on endurance to swimming in mice. Animals were injected intraperitoneally with each of three spin-trappers (N-tert-Butyl-alpha-Phenyl-Nitrone (PBN),alpha-4-Pyridyil-1-Oxide-N-tert-Butyl-Nitrone (POBN) and 5,5-Dimethyl-1-Pirrolyn-N-Oxide (DMPO): 0.2 ml of 10(-1) molar solution). Each mouse was submitted to a swimming test to control resistance to exhaustion (a) without any treatment, (b) after administration of each spin-trapper in a random order (c) after saline. Control experiments were performed with saline and with vitamin E. Endurance to swimming was greatly prolonged by pretreatment with all the spin-trappers (DMPO less than 0.0001; POBN less than 0.0001; PBN less than 0.001) and with Vitamin E. Experiments state that compared to treatment with spin-trappers or Vitamin E, administration of saline alone did not enhance time to exhaustion so that the increase in time to exhaustion with the various free radical scavengers was not the effect of training. Therefore, free radicals could be considered as one of the factors terminating muscle effort in mice.
Full Text Available Objective: The purpose of the present study was to assess the effect of local muscle fatigue induced at proximal and distal segments of lower extremity on sagittal plane mover on visual dependency in quiet standing postural stability. Materials & Methods: In this Quasi–experimental study (before – after comparison sagittal plane prime movers of the ankle and hip musculature were fatigued using isokinetic contractions at two test sessions with a randomized order and one week interval. Twenty five healthy young female students were َselected by using non probability selection and sample of convenience and asked to maintain single leg upright posture as immobile as possible. RMS and SD of Center of Pressure displacements were assessed in 30 seconds and consequently, the eyes were closed after 15 seconds. A analysis of variance (ANOVA for repeated measures was used to analyze the effect of the following factors over two periods of 5 seconds immediately before and after eye closure: (1 fatigue, (2 vision, (3 segment of fatigue. Results: The main effects of each within-subject factors (fatigue, vision and segment of fatigue were significant (P<0.05. The analysis of RMS and SD of Center of Pressure demonstrated a significant interaction between fatigue and vision, and fatigue and segment of fatigue so that the effects of Fatigue on Proximal segment and eye closed conditions were increased. Conclusion: The visual dependency for control of postural stability incremented following muscle fatigue. Proximal muscle fatigue lead to exaggeration of visual dependency for control of postural stability. Based on the present results, emphasis on the proprioception of proximal segment of lower extremity may be recommended for postural stability training.
Rudroff, Thorsten; Weissman, Jessica A; Bucci, Marco; Seppänen, Marko; Kaskinoro, Kimmo; Heinonen, Ilkka; Kalliokoski, Kari K
The purpose of this study was to investigate blood flow and its heterogeneity within and among the knee muscles in five young (26 ± 6 years) and five old (77 ± 6 years) healthy men with similar levels of physical activity while they performed two types of submaximal fatiguing isometric contraction that required either force or position control. Positron emission tomography (PET) and [15O]-H2O were used to determine blood flow at 2 min (beginning) and 12 min (end) after the start of the tasks. Young and old men had similar maximal forces and endurance times for the fatiguing tasks. Although muscle volumes were lower in the older subjects, total muscle blood flow was similar in both groups (young men: 25.8 ± 12.6 ml min−1; old men: 25.1 ± 15.4 ml min−1; age main effect, P = 0.77) as blood flow per unit mass of muscle in the exercising knee extensors was greater in the older (12.5 ± 6.2 ml min−1 (100 g)−1) than the younger (8.6 ± 3.6 ml min−1 (100 g)−1) men (age main effect, P = 0.001). Further, blood flow heterogeneity in the exercising knee extensors was significantly lower in the older (56 ± 27%) than the younger (67 ± 34%) men. Together, these data show that although skeletal muscles are smaller in older subjects, based on the intact neural drive to the muscle and the greater, less heterogeneous blood flow per gram of muscle, old fit muscle achieves adequate exercise hyperaemia. Key points The results of previous studies that attempted to demonstrate the effects of ageing on skeletal muscle blood flow are controversial because these studies used indirect assessments of skeletal muscle blood flow obtained via whole limb blood flow measurements that provide no information on the distribution of blood flow within particular muscles. We used positron emission tomography to measure blood flow per gram of muscle in old and young men with similar levels of physical activity
Hamada, Taku; Kimura, Tetsuya; Moritani, Toshio
The aim of the present study was to elucidate the electrophysiological manifestations of selective fast motor unit (MU) activation by electrical stimulation (ES) of knee extensor muscles. In six male subjects, test contraction measurement at 40% maximal voluntary contraction (MVC) was performed before and at every 5 min (5, 10, 15 and 20 min) during 20-min low intensity intermittent exercise of either ES or voluntary contractions (VC) at 10% MVC (5-s isometric contraction and 5-s rest cycles). Both isolated intramuscular MU spikes obtained from three sets of bipolar fine-wire electrodes and surface electromyogram (EMG) were simultaneously recorded and were analyzed by means of a computer-aided intramuscular spike amplitude-frequency analysis and frequency power spectral analysis, respectively. Results indicated that mean MU spike amplitude, particularly those MUs with relatively large amplitude, was significantly reduced while those MUs with small spike amplitude increased their firing rate during the 40% MVC test contraction after the ES. This was accompanied by the increased amplitude of surface EMG (rmsEMG). However, no such significant changes in the intramuscular and surface EMGs were observed after VC. These findings indicated differential MU activation patterns in terms of MU recruitment and rate coding characteristics during ES and VC, respectively. Our data strongly suggest the possibility of "an inverse size principle" of MU recruitment during ES.
Higgins, M F; Tallis, J; Price, M J; James, R S
This study examined the effects of elevated buffer capacity [~32 mM HCO₃(-)] through administration of sodium bicarbonate (NaHCO₃) on maximally stimulated isolated mouse soleus (SOL) and extensor digitorum longus (EDL) muscles undergoing cyclical length changes at 37 °C. The elevated buffering capacity was of an equivalent level to that achieved in humans with acute oral supplementation. We evaluated the acute effects of elevated [HCO₃(-)] on (1) maximal acute power output (PO) and (2) time to fatigue to 60 % of maximum control PO (TLIM60), the level of decline in muscle PO observed in humans undertaking similar exercise, using the work loop technique. Acute PO was on average 7.0 ± 4.8 % greater for NaHCO₃-treated EDL muscles (P < 0.001; ES = 2.0) and 3.6 ± 1.8 % greater for NaHCO₃-treated SOL muscles (P < 0.001; ES = 2.3) compared to CON. Increases in PO were likely due to greater force production throughout shortening. The acute effects of NaHCO₃ on EDL were significantly greater (P < 0.001; ES = 0.9) than on SOL. Treatment of EDL (P = 0.22; ES = 0.6) and SOL (P = 0.19; ES = 0.9) with NaHCO₃ did not alter the pattern of fatigue. Although significant differences were not observed in whole group data, the fatigability of muscle performance was variable, suggesting that there might be inter-individual differences in response to NaHCO₃ supplementation. These results present the best indication to date that NaHCO₃ has direct peripheral effects on mammalian skeletal muscle resulting in increased acute power output.
Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A
Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (pfatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583
Jangö, Hanna; Gräs, Søren; Christensen, Lise
INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP and then e...... showed a significantly higher strength than the group with MPEG-PLGA alone (p = 0.034). CONCLUSION: Tissue-engineering with MFFs seeded on a scaffold of biodegradable MPEG-PLGA might be an interesting adjunct to future POP repair.......INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP...
Effect of the Abdominal Hollowing and Bracing Maneuvers on Activity Pattern of the Lumbopelvic Muscles During Prone Hip Extension in Subjects With or Without Chronic Low Back Pain: A Preliminary Study.
Kahlaee, Amir H; Ghamkhar, Leila; Arab, Amir M
The purpose of this study was to compare the effect of abdominal hollowing (AH) and abdominal bracing (AB) maneuvers on the activity pattern of lumbopelvic muscles during prone hip extension (PHE) in participants with or without nonspecific chronic low back pain (CLBP). Twenty women with or without CLBP participated in this cross-sectional observational study. The electromyographic activity (amplitude and onset time) of the contralateral erector spinae (CES), ipsilateral erector spinae (IES), gluteus maximus, and biceps femoris muscles was measured during PHE with and without abdominal maneuvers. A 3-way mixed model analysis of variance and post hoc tests were used for statistical analysis. Between-group comparisons showed that the CES onset delay during PHE alone was greater (P = .03) and the activity level of IES, CES, and biceps femoris in all maneuvers (P .05). Performance of the AH maneuver decreased the erector spinae muscle AMP in both groups, and neither maneuver altered the onset delay of any of the muscles in either group. The low back pain group showed higher levels of activity in all muscles (not statistically significant in gluteus maximus during all maneuvers). The groups were similar according to the onset delay of any of the muscles during either maneuver. Copyright © 2016. Published by Elsevier Inc.
T. Rubio; M. T. Gaztelu; A. Calvo; M. Repiso; H. Sarasíbar; F. Jiménez Bermejo; A. Martínez Echeverría
La tuberculosis abdominal cursa con un cuadro inespecífico, con difícil diagnóstico diferencial respecto a otras entidades de similar semiología. Presentamos el caso de un varón que ingresa por presentar dolor abdominal, pérdida progresiva y notoria de peso corporal y fiebre de dos meses de evolución. El cultivo de la biopsia de colon mostró presencia de bacilo de Koch.Abdominal tuberculosis develops according to a non-specific clinical picture, with a difficult differential diagnosis with re...
Casal Núñez, José Enrique; Martínez, María Teresa García; Poblador, Alejandro Ruano
Presacral venous haemorrhage during rectal movement is low, but is often massive, and even fatal. Our objective is the "in vitro" determination of the results of electrocoagulation applied to a fragment of muscle on the sacral bone surface during rectal resection due to a malignant neoplasm of the rectum. Single-pole coagulation was applied "in vitro" with the selector at maximum power on a 2×2 cms muscle fragment, applied to the anterior side of the IV sacral vertebra until reaching boiling point. The method was used on 6 patients with bleeding of the presacral venous plexus. In the "in vitro" study, boiling point was reached in 90 seconds from applying the single-pole current on the muscle fragment. Electrocoagulation was applied to a 2×2 cm rectal muscle fragment in 6 patients with presacral venous haemorrhage, using pressure on the surface of the presacral bone, with the stopping of the bleeding being achieved in all cases. The use of indirect electrocoagulation on a fragment of the rectus abdominis muscle is a straightforward and highly effective technique for controlling presacral venous haemorrhage. Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.
Cao, Liu; Wang, Ying; Hao, Dongmei; Rong, Yao; Yang, Lin; Zhang, Song; Zheng, Dingchang
The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF) magnetic stimulation on surface electromyography (SEMG) signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body) with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects). The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject's deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS), median frequency (MDF), and sample entropy (SampEn), were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant ( p 0.05). In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p < 0.001) and MDF and SampEn were significantly smaller (all p < 0.001).
Full Text Available The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF magnetic stimulation on surface electromyography (SEMG signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects. The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject’s deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS, median frequency (MDF, and sample entropy (SampEn, were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant (p0.05. In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p<0.001 and MDF and SampEn were significantly smaller (all p<0.001.
Haddas, Ram; Sawyer, Steven F; Sizer, Phillip S; Brooks, Toby; Chyu, Ming-Chien; James, C Roger
Recurrent lower back pain (rLBP) and neuromuscular fatigue are independently thought to increase the risk of lower extremity (LE) injury. Volitional preemptive abdominal contraction (VPAC) is thought to improve lumbar spine and pelvis control in individuals with rLBP. The effects of VPAC on fatigued landing performance in individuals with rLBP are unknown. To determine the effects of VPAC and LE fatigue on landing performance in a rLBP population. Cross-sectional pretest-posttest cohort control design. A clinical biomechanics laboratory. 32 rLBP (age 21.2 ± 2.7 y) but without current symptoms and 33 healthy (age 20.9 ± 2.3 y) subjects. (i) Volitional preemptive abdominal contraction using abdominal bracing and (ii) fatigue using submaximal free-weight squat protocol with 15% body weight until task failure was achieved. Knee and ankle angles, moments, electromyographic measurements from semitendinosus and vastus medialis muscles, and ground reaction force (GRF) were collected during 0.30 m drop-jump landings. The VPAC resulted in significantly earlier muscle onsets across all muscles with and without fatigue in both groups (mean ± SD, 0.063 ± 0.016 s earlier; P ≤ .001). Fatigue significantly delayed semitendinosus muscle onsets (0.033 ± 0.024 s later; P ≤ .001), decreased GRF (P ≤ .001), and altered landing kinematics in a variety of ways. The rLBP group exhibited delayed semitendinosus and vastus medialis muscle onsets (0.031 ± 0.028 s later; P ≤ .001) and 1.8° less knee flexion at initial contact (P ≤ .008). The VPAC decreases some of the detrimental effects of fatigue on landing biomechanics and thus may reduce LE injury risk in a rLBP population.
Tayashiki, Kota; Hirata, Kosuke; Ishida, Kiraku; Kanehisa, Hiroaki; Miyamoto, Naokazu
Muscle size of the hamstring and gluteus maximus (GM) as well as intra-abdominal pressure (IAP) are considered as factors affecting the torque development during hip extension. This study examined the associations of torque development during maximal voluntary isometric hip extension with IAP and muscle size of the hamstring and GM. Anatomical cross-sectional area (ACSA) of the hamstring and thickness of GM were determined in 20 healthy young males using an ultrasonography apparatus (Experiment 1). Torque and IAP were simultaneously measured while subjects performed maximal voluntary isometric hip extension. The IAP was measured using a pressure transducer placed in the rectum and determined at the time at which the developed torque reached to the maximal. In Experiment 2, torque and IAP were measured during maximal voluntary isometric hip flexion in 18 healthy young males. The maximal hip extension torque was significantly correlated with the IAP (r = 0.504, P = 0.024), not with the ACSA of the hamstring (r = 0.307, P = 0.188) or the thickness of GM (r = 0.405, P = 0.076). The relationship was still significant even when the ACSA of the hamstring and the thickness of GM were adjusted statistically (r = 0.486, P = 0.041). The maximal hip flexion torque was not significantly correlated with the IAP (r = -0.118, P = 0.642). The current results suggest that IAP can contribute independently of the muscle size of the agonists to maximal voluntary hip extension torque.
Miyagawa, Kotaro; Ogata, Takehiro; Ueyama, Tomomi; Kasahara, Takeru; Nakanishi, Naohiko; Naito, Daisuke; Taniguchi, Takuya; Hamaoka, Tetsuro; Maruyama, Naoki; Nishi, Masahiro; Kimura, Taizo; Yamada, Hiroyuki; Aoki, Hiroki; Matoba, Satoaki
Abdominal aortic aneurysm (AAA) is relatively common in elderly patients with atherosclerosis. MURC (muscle-restricted coiled-coil protein)/Cavin-4 modulating the caveolae function of muscle cells is expressed in cardiomyocytes, skeletal muscle cells and smooth muscle cells. Here, we show a novel functional role of MURC/Cavin-4 in vascular smooth muscle cells (VSMCs) and AAA development. Both wild-type (WT) and MURC/Cavin-4 knockout (MURC -/- ) mice subjected to periaortic application of CaCl 2 developed AAAs. Six weeks after CaCl 2 treatment, internal and external aortic diameters were significantly increased in MURC -/- AAAs compared with WT AAAs, which were accompanied by advanced fibrosis in the tunica media of MURC -/- AAAs. The activity of JNK and matrix metalloproteinase (MMP) -2 and -9 were increased in MURC -/- AAAs compared with WT AAAs at 5 days after CaCl 2 treatment. At 6 weeks after CaCl 2 treatment, MURC -/- AAAs exhibited attenuated JNK activity compared with WT AAAs. There was no difference in the activity of MMP-2 or -9 between saline and CaCl 2 treatments. In MURC/Cavin-4-knockdown VSMCs, TNFα-induced activity of JNK and MMP-9 was enhanced compared with control VSMCs. Furthermore, WT, MURC -/- , apolipoprotein E -/- (ApoE -/- ), and MURC/Cavin-4 and ApoE double-knockout (MURC -/- ApoE -/- ) mice were subjected to angiotensin II (Ang II) infusion. In both ApoE -/- and MURC -/- ApoE -/- mice infused for 4 weeks with Ang II, AAAs were promoted. The internal aortic diameter was significantly increased in Ang II-infused MURC -/- ApoE -/- mice compared with Ang II-infused ApoE -/- mice. In MURC/Cavin-4-knockdown VSMCs, Ang II-induced activity of JNK and MMP-9 was enhanced compared with control VSMCs. Our results suggest that MURC/Cavin-4 in VSMCs modulates AAA progression at the early stage via the activation of JNK and MMP-9. MURC/Cavin-4 is a potential therapeutic target against AAA progression. Copyright © 2017 Elsevier Inc. All rights reserved.
Gultom, Syamsul; Darma Sitepu, Indra; Hasibuan, Nurman
Fatigue due to long and continuous computer usage can lead to problems of dominant fatigue associated with decreased performance and work motivation. Specific targets in the first phase have been achieved in this research such as: (1) Identified complaints on workers using computers, using the Bourdon Wiersma test kit. (2) Finding the right relaxation & work posture draft for a solution to reduce muscle fatigue in computer-based workers. The type of research used in this study is research and development method which aims to produce the products or refine existing products. The final product is a prototype of back-holder, monitoring filter and arranging a relaxation exercise as well as the manual book how to do this while in front of the computer to lower the fatigue level for computer users in Unimed’s Administration Center. In the first phase, observations and interviews have been conducted and identified the level of fatigue on the employees of computer users at Uniemd’s Administration Center using Bourdon Wiersma test and has obtained the following results: (1) The average velocity time of respondents in BAUK, BAAK and BAPSI after working with the value of interpretation of the speed obtained value of 8.4, WS 13 was in a good enough category, (2) The average of accuracy of respondents in BAUK, in BAAK and in BAPSI after working with interpretation value accuracy obtained Value of 5.5, WS 8 was in doubt-category. This result shows that computer users experienced a significant tiredness at the Unimed Administration Center, (3) the consistency of the average of the result in measuring tiredness level on computer users in Unimed’s Administration Center after working with values in consistency of interpretation obtained Value of 5.5 with WS 8 was put in a doubt-category, which means computer user in The Unimed Administration Center suffered an extreme fatigue. In phase II, based on the results of the first phase in this research, the researcher offers
Cilius E. Fonvig
Full Text Available The degree of fat deposition in muscle and its implications for obesity-related complications in youth are not well understood. One hundred and fifty-nine patients (mean age: 13.3 years; range: 6-20 with a body mass index (BMI >90th percentile for age and sex were included. Muscle fat content (MFC was measured in the psoas muscle by proton magnetic resonance spectroscopy. The patients were assigned to two groups: MFC <5% or ³5%. Visceral adipose tissue volume (VAT and subcutaneous adipose tissue volume (SAT were measured by magnetic resonance imaging. Blood samples were obtained from 119 patients, and liver enzyme concentrations and other variables were measured. The data were analysed to detect any associations between MFC and BMI standard deviation scores, VAT and SAT, blood values, and physical activity levels. The mean BMI standard deviation score (SDS was 3.04 (range 1.32-5.02. The mean MFC was 8.9% (range 0.8-46.7, and 118 (74.2% of 159 patients had an MFC ³5%. Children with a high MFC had a higher BMI SDS (P=0.03 and had a higher VAT, but not SAT or SAT/VAT ratio. Both intramyocellular lipid (IMCL and extramyocellular lipid (EMCL content were elevated in patients with an MFC ³5%. Blood values and physical activity levels did not differ between the two groups. Severely obese children and adolescents tend to have a high MFC, which is associated with elevated VAT and IMCL and EMCL content. An increased MFC may be associated with impaired metabolic processes, which may predispose young people to obesity-related complications.
Tomas-Carus, Pablo; Ortega-Alonso, Alfredo; Pietilainen, Kirsi H; Santos, Vitoria; Goncalves, Helena; Ramos, Jorge; Raimundo, Armando
The aim of this paper was to evaluate the effects of a 12-weeks combined aerobic-resistance exercise therapy on fatigue and isokinetic muscle strength, glycemic control and health-related quality of life (HRQoL) in moderately affected type 2 diabetes (T2DM) patients. A randomized controlled trial design was employed. Forty-three T2DM patients were assigned to an exercise group (N.=22), performing 3 weekly sessions of 60 minutes of combined aerobic-resistance exercise for 12-weeks; or a no exercise control group (N.=21). Both groups were evaluated at a baseline and after 12-weeks of exercise therapy for: 1) muscle strength and fatigue by isokinetic dynamometry; 2) plasma glycated hemoglobin A1C (HbA1C); and 3) HRQoL utilizing the SF-36 questionnaire. The exercise therapy led to improvements in muscle fatigue in knee extensors (-55%) and increased muscle strength in knee flexors and extensors (+15 to +30%), while HbA1C decreased (-18%). In addition, the exercising patients showed sizeable improvements in HRQoL: physical function (+53%), vitality (+21%) and mental health (+40%). Twelve-weeks of combined aerobic-resistance exercise was highly effective to improve muscle strength and fatigue, glycemic control and several aspects of HRQoL in T2DM patients. These data encourage the use of aerobic and resistance exercise in the good clinical care of T2DM.
Corsetti, Roberto; Barassi, Alessandra; Perego, Silvia; Sansoni, Veronica; Rossi, Alessandra; Damele, Clara Anna Linda; Melzi D'Eril, Gianlodovico; Banfi, Giuseppe; Lombardi, Giovanni
The aim of this study was to identify the relationship between metabolic effort, muscular damage/activity indices, and urinary amino acids profile over the course of a strenuous prolonged endurance activity, as a cycling stage race is, in order to identify possible fatigue markers. Nine professional cyclists belonging to a single team, competing in the Giro d'Italia cycling stage race, were anthropometrically characterized and sampled for blood and urine the day before the race started, and on days 12 and 23 of the race. Diet was kept the same over the race, and power output and energy expenditure were recorded. Sera were assayed for muscle markers (lactate dehydrogenase, aspartate aminotransferase, and creatine kinase activities, and blood urea nitrogen), and creatinine, all corrected for plasma volume changes. Urines were profiled for amino acid concentrations, normalized on creatinine excretion. Renal function, in terms of glomerular filtration rate, was monitored by MDRD equation corrected on body surface area. Creatine kinase activity and blood urea were increased during the race as did serum creatinine while kidney function remained stable. Among the amino acids, taurine, glycine, cysteine, leucine, carnosine, 1-methyl histidine, and 3-methyl histidine showed a net decreased, while homocysteine was increased. Taurine and the dipeptide carnosine (β-alanyl-L-histidine) were significantly correlated with the muscle activity markers and the indices of effort. In conclusion, the metabolic profile is modified strikingly due to the effort. Urinary taurine and carnosine seem useful tools to evaluate the muscle damage and possibly the fatigue status on a long-term basis.
... AAAs don’t cause symptoms unless they leak, tear, or rupture. If this happens, you may experience: sudden pain in your abdomen, groin, back, legs, or buttocks nausea and vomiting abnormal stiffness in your abdominal muscles problems with urination or bowel movements clammy, sweaty ...
Andersen, Birgit; Westlund, Barbro; Krarup, Christian
. This points to increased probability of repetitive spinal MN activation during fatigue even if some MNs in the pool failed to discharge. Silent period duration following cortical stimulation lengthened by an average of 55 ms after the contraction and recovered within a time course similar to that of the TST......During a sustained maximal effort a progressive decline in the ability to drive motoneurones (MNs) develops. We used the recently developed triple stimulation technique (TST) to study corticospinal conduction after fatiguing exercise in healthy subjects. This method employs a collision technique...... conventional transcranial magnetic stimulation (TMS) and responses to peripheral nerve stimulation were recorded following the same fatigue protocol. The size of both the MEPs and the peripheral responses increased after the contraction and were in direct contrast to the decrease in size of the TST response...
Kim, Beom-Ryong; Lee, Hye-Jin
The purpose of this study was to evaluate the effect of abdominal muscle strengthening training (AMST) using proprioceptive neuromuscular facilitation (PNF) on pulmonary function, pain, and functional disability index in chronic low back pain (CLBP) patients. Thirty CLBP patients were randomly assigned to the traditional physical therapy (control) group (n=15) and PNF-AMST group (n=15). Forced expiratory volume at 1 second (FEV 1 ) was measured to measure changes in pulmonary function. To measure the degree of pain, a visual analog scale (VAS) was used. The Oswestry Disability Index (ODI) was used to assess the disability level due to low back pain. A paired t -test was performed to compare differences within the groups before and after intervention. An independent t -test was performed to compare differences between the test and control groups. The level of significance was set at α=0.05. Within-group changes in FEV 1 were significantly different in the experimental group ( P disability index inpatients with CLBP. We expect it to be useful as one of the programs for CLBP patients in the future.
Andersen, Birgit; Westlund, Barbro; Krarup, Christian
During a sustained maximal effort a progressive decline in the ability to drive motoneurones (MNs) develops. We used the recently developed triple stimulation technique (TST) to study corticospinal conduction after fatiguing exercise in healthy subjects. This method employs a collision technique....... This points to increased probability of repetitive spinal MN activation during fatigue even if some MNs in the pool failed to discharge. Silent period duration following cortical stimulation lengthened by an average of 55 ms after the contraction and recovered within a time course similar to that of the TST...
The imaging search for a suspected abdominal abscess is common in hospitalized patients, especially after recent abdominal surgery. This paper examines the role of CT in the detection, localization, and treatment of abdominal abscess. The accuracy, limitations, and technical aspects of CT in this clinical setting are discussed. The diagnosis of an abscess is based on the demonstration of a circumscribed abnormal fluid collection. Although percutaneous aspiration with gram stain and culture is usually indicated to differentiate abscess from other fluid collections, the CT-based detection of extraluminal gas bubbles makes the diagnosis of an abscess highly likely. CT is compared with conventional radiographic studies, US, and radio-nuclide imaging. Specific CT and clinical features of abscesses in the following sites are emphasized: subphrenic space, liver, pancreas, kidneys, psoas muscle, appendix, and colonic diverticula. Most abdominal abscesses can be successfully treated with percutaneous drainage techniques. The techniques, results, and limitations of percutaneous abscess drainage are reviewed
Effects of local fatigue on myoelectrical activity of erector spine muscles and the center for pressure displacement of the feet during balance recovery following postural perturbation in kyphotic subjects
Full Text Available Background: kyphosis deformity affects postural control. Muscular fatigue is one of the factors that can impair the mechanism of body balance. The aim of this study was to determine the effects of local fatigue on the myoelectrical activity of erector spine muscles and the center for pressure displacement of the feet during balance recovery following postural perturbation in kyphotic subjects. Methods: In this quasi-experimental study, 12 male students with>40 degrees thoracic kyphosis and 12 controls were selected to participate in the study. A flexible ruler was used to measure thoracic kyphosis. For postural control assessment, each subject underwent unexpected, forward-backward perturbations while standing on a foot scan mounted on a movable plate triggered by a weight equivalent to 10% of the subjects’ body weight. Experimental procedure was measured before (3 trails and after (3 trials the fatigue protocol. The myoelectric activity of the erector spine and multi fidus was compared in the groups using repeated measures of ANOVA and independent t-test (P<0.05. Results: There was no significant difference in the foot center of pressure displacement in both groups after muscular fatigue. After fatigue, there was an increase in the activity of longissimus thoracis (P=0.001 and iliocostalis thoracis (P= 0.001 in control group, while no significant difference was reported for the muscular activity of multifidus (p=0.084. The activity of langisimus thoracis was significantly increased (P=0.028 in kyphtic group after fatigue. Conclusion: erector spine muscles fatigue could not significantly affect the postural control in both groups, but the electrical activity of erector spine muscles during balance recovery following postural perturbation in kyphotic subjects was different than the controls.
Toghill, Bradley J; Saratzis, Athanasios; Freeman, Peter J; Sylvius, Nicolas; Bown, Matthew J
Abdominal aortic aneurysm (AAA) is a deadly cardiovascular disease characterised by the gradual, irreversible dilation of the abdominal aorta. AAA is a complex genetic disease but little is known about the role of epigenetics. Our objective was to determine if global DNA methylation and CpG-specific methylation at known AAA risk loci is associated with AAA, and the functional effects of methylation changes. We assessed global methylation in peripheral blood mononuclear cell DNA from 92 individuals with AAA and 93 controls using enzyme-linked immunosorbent assays, identifying hyper-methylation in those with large AAA and a positive linear association with AAA diameter ( P AAA risk loci identified in genome-wide association studies, using bisulphite next-generation sequencing (NGS) in vascular smooth muscle cells (VSMCs) taken from aortic tissues of 44 individuals (24 AAAs and 20 controls). In IL6R , 2 CpGs were hyper-methylated ( P = 0.0145); in ERG , 13 CpGs were hyper-methylated ( P = 0.0005); in SERPINB9 , 6 CpGs were hypo-methylated ( P = 0.0037) and 1 CpG was hyper-methylated ( P = 0.0098); and in SMYD2 , 4 CpGs were hypo-methylated ( P = 0.0012).RT-qPCR was performed for each differentially methylated gene on mRNA from the same VSMCs and compared with methylation. This analysis revealed downregulation of SMYD2 and SERPINB9 in AAA, and a direct linear relationship between SMYD2 promoter methylation and SMYD2 expression ( P = 0.038). Furthermore, downregulation of SMYD2 at the site of aneurysm in the aortic wall was further corroborated in 6 of the same samples used for methylation and gene expression analysis with immunohistochemistry. This study is the first to assess DNA methylation in VSMCs from individuals with AAA using NGS, and provides further evidence there is an epigenetic basis to AAA. Our study shows that methylation status of the SMYD2 promoter may be linked with decreased SMYD2 expression in disease pathobiology. In
Mohr, Magni; Krustrup, Peter; Bangsbo, Jens
This review describes when fatigue may develop during soccer games and the potential physiological mechanisms that cause fatigue in soccer. According to time?-?motion analyses and performance measures during match-play, fatigue or reduced performance seems to occur at three different stages......, acidity or the breakdown of creatine phosphate. Instead, it may be related to disturbances in muscle ion homeostasis and an impaired excitation of the sarcolemma. Soccer players' ability to perform maximally is inhibited in the initial phase of the second half, which may be due to lower muscle...... concentrations in a considerable number of individual muscle fibres. In a hot and humid environment, dehydration and a reduced cerebral function may also contribute to the deterioration in performance. In conclusion, fatigue or impaired performance in soccer occurs during various phases in a game, and different...
Andersen, Birgit; Felding, Ulrik Ascanius; Krarup, Christian
Triple stimulation technique (TST) has previously shown that transcranial magnetic stimulation (TMS) fails to activate a proportion of spinal motoneurons (MNs) during motor fatigue. The TST response depression without attenuation of the conventional motor evoked potential suggested increased...... probability of repetitive spinal MN activation during exercise even if some MNs failed to discharge by the brain stimulus. Here we used a modified TST (Quadruple stimulation; QuadS and Quintuple stimulation; QuintS) to examine the influence of fatiguing exercise on second and third MN discharges after......, reflecting that a greater proportion of spinal MNs were activated 2 or 3 times by the transcranial stimulus. The size of QuadS responses did not return to pre-contraction levels during 10 min observation time indicating long-lasting increase in excitatory input to spinal MNs. In addition, the post...
Zwarts, M J; Bleijenberg, G; van Engelen, B G M
Fatigue is a multidimensional concept covering both physiological and psychological aspects. Chronic fatigue is a typical symptom of diseases such as cancer, multiple sclerosis (MS), Parkinson's disease (PD) and cerebrovascular disorders but is also presented by people in whom no defined somatic disease has been established. If certain criteria are met, chronic fatigue syndrome can be diagnosed. The 4-item Abbreviated Fatigue Questionnaire allows the extent of the experienced fatigue to be assessed with a high degree of reliability and validity. Physiological fatigue has been well defined and originates in both the peripheral and central nervous system. The condition can be assessed by combining force and surface-EMG measurements (including frequency analyses and muscle-fibre conduction estimations), twitch interpolation, magnetic stimulation of the motor cortex and analysis of changes in the readiness potential. Fatigue is a well-known phenomenon in both central and peripheral neurological disorders. Examples of the former conditions are multiple sclerosis, Parkinson's disease and stroke. Although it seems to be a universal symptom of many brain disorders, the unique characteristics of the concomitant fatigue also point to a specific relationship with several of these syndromes. As regards neuromuscular disorders, fatigue has been reported in patients with post-polio syndrome, myasthenia gravis, Guillain-Barré syndrome, facioscapulohumeral dystrophy, myotonic dystrophy and hereditary motor and sensory neuropathy type-I. More than 60% of all neuromuscular patients suffer from severe fatigue, a prevalence resembling that of patients with MS. Except for several rare myopathies with specific metabolic derangements leading to exercise-induced muscle fatigue, most studies have not identified a prominent peripheral cause for the fatigue in this population. In contrast, the central activation of the diseased neuromuscular system is generally found to be suboptimal. The
Gunnarsson, Thomas Gunnar Petursson; Christensen, Peter Møller; Thomassen, Martin
The effects of intensified training in combination with a reduced training volume on muscle ion kinetics, transporters and work capacity were examined. Eight well-trained cyclists replaced their regular training with speed-endurance training (12x30-s sprints) 2-3 times per wk and aerobic high...
The present review addresses mechanisms of importance for hyperthermia-induced fatigue during short intense activities and prolonged exercise in the heat. Inferior performance during physical activities with intensities that elicit maximal oxygen uptake is to a large extent related to perturbation...... of the cardiovascular function, which eventually reduces arterial oxygen delivery to the exercising muscles. Accordingly, aerobic energy turnover is impaired and anaerobic metabolism provokes peripheral fatigue. In contrast, metabolic disturbances of muscle homeostasis are less important during prolonged exercise...... in the heat, because increased oxygen extraction compensates for the reduction in systemic blood flow. The decrease in endurance seems to involve changes in the function of the central nervous system (CNS) that lead to fatigue. The CNS fatigue appears to be influenced by neurotransmitter activity...
de Ruiter, C J; Elzinga, M J H; Verdijk, P W L; van Mechelen, W; de Haan, A
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.
Abdominal injury is an important cause of morbidity and mortality in childhood. Ten percent of trauma-related deaths are due to abdominal injury. Thousands of children are involved in auto accidents annually; many suffer severe internal injury. Child abuse is a second less frequent but equally serious cause of internal abdominal injury. The descriptions of McCort and Eisenstein and their associates in the 1960s first brought to attention the frequency and severity of visceral injury as important manifestations of the child abuse syndrome. Blunt abdominal trauma often causes multiple injuries; in the past, many children have been subjected to exploratory surgery to evaluate the extent of possible hidden injury. Since the advent of noninvasive radiologic imaging techniques including radionuclide scans and ultrasound and, especially, computed tomography (CT), the radiologist has been better able to assess (accurately) the extent of abdominal injury and thus allow conservative therapy in many cases. Penetrating abdominal trauma occurs following gunshot wounds, stabbing, and other similar injury. This is fortunately, a relatively uncommon occurrence in most pediatric centers and will not be discussed specifically here, although many principles of blunt trauma diagnosis are valid for evaluation of penetrating abdominal trauma. If there is any question that a wound has extended intraperitonelly, a sinogram with water-soluble contrast material allows quick, accurate diagnosis. The presence of large amounts of free intraperitoneal gas suggests penetrating injury to the colon or other gas-containing viscus and is generally considered an indication for surgery
... your doctor to find a specific cause and treatment for your fatigue. The possibilities may include systemic inflammation, poor sleep, fibromyalgia, depression, hypothyroidism, muscle inflammation or side-effects of medications. Know ...
... I find more information and related topics? Functional Abdominal Pain (English, French or Spanish)—from The North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN). Gastro Kids , a ...
Hasan, N.; Razzaq, A.
Abdominal epilepsy (AE) is a rather uncommon clinical entity in children that might create diagnostic confusion especially when it lacks the typical manifestations of an epileptic seizure. We report the case of a young boy having apparently unexplained episodes of paroxysmal abdominal symptoms with no other suggestion of an underlying epileptic disorder. The case also explains how the clinical presentation can be misleading unless a high index of suspicion is maintained to reach the ultimate diagnosis. (author)
van den Tillaar, Roland; Saeterbakken, Atle
The aim of this study was to examine the effect of fatigue during one set of 6-RM bench pressing upon the muscle patterning and performance. Fourteen resistance-trained males (age 22.5±2.0 years, stature 1.82±0.07 m, body mass 82.0±7.8 kg) conducted a 6-RM bench press protocol. Barbell kinematics and EMG activity of pectoralis major, deltoid anterior, biceps brachii, triceps brachii, rectus abdominis, oblique external and erector spinae were measured in each repetition during the 6-RM bench press. Total lifting time increased and the velocity in the ascending movement decreased (p≤0.001). However, the kinematics in the descending phase deferred: the time decreased and velocity increased during the 6-RM (p≤0.001). Generally, muscles increased their EMG amplitude during the six repetitions in the ascending movement, while only three of the seven measured muscles showed an increase over the six repetitions in the descending part in 6-RM bench pressing. It was concluded that the bench pressing performance decreased (lower barbell velocities and longer lifting times) with increasing fatigue in the 6-RM execution. Furthermore EMG increased in the prime movers and the trunk stabilizers (abdominal and spine), while the antagonist muscle (biceps) activity was not affected by fatigue during the lifting phase in a single set of 6-RM bench pressing.
Full Text Available Background: Back pain is the common musculoskeletal condition with a high prevalence of up to 80% among the general and work force population at some times in their lives.Muscular injury, fatigue, or facet or disc degeneration can compromise the stabilizing effects resulting in shearing forces that cause pain.Abdominal drawing in maneuver is used to facilitate the re-education of neuromuscular control mechanisms provided by local stabilizing muscles. Objective of the study is to measure the gait parameters and pain control before and after abdominal drawing in maneuver in patient with chronic mechanical low back pain. Methods: Total number of 30 consecutive patients and they were divided into two groups by purposive sampling. Group A is subjects with low back pain and Group B is subjects without low back pain. Outcome measures were average step cycle, average step length, coefficient of variation, time on each foot, Ambulation index measured with Biodex gait trainer. Pain is measured with Revised-Oswestry low back pain questionnaire. Results: Significant difference between gait parameters were observed in both low back pain group and the group without low back pain group with abdominal drawing in maneuver and the changes without abdominal drawing in maneuver was minimal. There was no significant difference found between both groups with or without abdominal drawing in maneuver. Conclusion: Gait parameters and Pain control can be improved by training with abdominal drawing in maneuver thereby it reduces pain and improves gait symmetry in subjects with low back pain.
De Waele, Jan J
Abdominal infections are an important challenge for the intensive care physician. In an era of increasing antimicrobial resistance, selecting the appropriate regimen is important and, with new drugs coming to the market, correct use is important more than ever before and abdominal infections are an excellent target for antimicrobial stewardship programs. Biomarkers may be helpful, but their exact role in managing abdominal infections remains incompletely understood. Source control also remains an ongoing conundrum, and evidence is increasing that its importance supersedes the impact of antibiotic therapy. New strategies such as open abdomen management may offer added benefit in severely ill patients, but more data are needed to identify its exact role. The role of fungi and the need for antifungal coverage, on the other hand, have been investigated extensively in recent years, but at this point, it remains unclear who requires empirical as well as directed therapy.
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to L-carnitine and faster recovery from muscle fatigue after exercise (ID 738, 1492, 1493), skeletal muscle tissue repair (ID 738, 1492, 1493), increase in endurance
Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of health...... claims in relation to L-carnitine and faster recovery from muscle fatigue after exercise, skeletal muscle tissue repair, increase in endurance capacity, maintenance of normal blood LDL-cholesterol concentrations, contribution to normal spermatogenesis, “energy metabolism”, and increasing L...
Sheu, Y; Marshall, L M; Holton, K F
The effect of abdominal adiposity and muscle on fracture is unclear in older men; therefore, we examined the association among 749 men aged 65+. Among various adipose tissues and muscle groups, lower psoas muscle volume and higher fatty infiltration of abdominal muscle contribute to higher fractu...
Full text: There are numerous conditions that affect mainly or exclusively the pediatric population. These constitute true emergencies, related to patient's health. Delay in diagnosis and treatment of abdominal non-traumatic emergencies may result in rapid deterioration, peritonitis, sepsis, even death or in severe complications with subsequent morbidity. Abdominal emergencies in children mostly present with pain, tenderness, occasionally coupled by vomiting, fever, abdominal distension, and failure to pass meconium or stools. Diarrhea, blood per rectum, abnormal laboratory tests and lethargy may also be manifestations of acute abdominal conditions. Abdominal emergencies have a different aetiology, depending on age and whether the pain is acute or chronic. Symptoms have to be matched with age and gender. Newborns up to 1 months of age may have congenital diseases: atresia, low obstruction including Hirschsprung's disease, meconium ileus. Meconium plug is one of the commonest cause of low obstruction in newborns that may also develop necrotizing enterocolitis, incarcerated inguinal hernia and mid-gut volvulus. Past the immediate postnatal period, any duodenal obstruction should be considered midgut volvulus until proven otherwise and patients should undergo ultrasonography and/or properly performed upper GI contrast study that records the exact position of the deduno-jejunal junction. Infants 6 months-2 years carry the risk of intussusception, mid-gut volvulus, perforation, acute pyelonephritis. Preschool and school-aged children 2-12 years carry the risk of appendicitis, genito-urinary abnormalities including torsion, urachal abnormalities, haemolytic uremic syndrome and Henoch-Schonlein purpura. Children above 12 years suffer from the same conditions as in adults. Most conditions may affect any age despite age predilection. Abdominal solid organ ultrasonography (US) coupled with gastrointestinal ultrasonography is the principle imaging modality in radiosensitive
Use of prediction equations to determine the accuracy of whole-body fat and fat-free mass and appendicular skeletal muscle mass measurements from a single abdominal image using computed tomography in advanced cancer patients.
Kilgour, Robert D; Cardiff, Katrina; Rosenthall, Leonard; Lucar, Enriqueta; Trutschnigg, Barbara; Vigano, Antonio
Measurements of body composition using dual-energy X-ray absorptiometry (DXA) and single abdominal images from computed tomography (CT) in advanced cancer patients (ACP) have important diagnostic and prognostic value. The question arises as to whether CT scans can serve as surrogates for DXA in terms of whole-body fat-free mass (FFM), whole-body fat mass (FM), and appendicular skeletal muscle (ASM) mass. Predictive equations to estimate body composition for ACP from CT images have been proposed (Mourtzakis et al. 2008; Appl. Physiol. Nutr. Metabol. 33(5): 997-1006); however, these equations have yet to be validated in an independent cohort of ACP. Thus, this study evaluated the accuracy of these equations in estimating FFM, FM, and ASM mass using CT images at the level of the third lumbar vertebrae and compared these values with DXA measurements. FFM, FM, and ASM mass were estimated from the prediction equations proposed by Mourtzakis and colleagues (2008) using single abdominal CT images from 43 ACP and were compared with whole-body DXA scans using Spearman correlations and Bland-Altman analyses. Despite a moderate to high correlation between the actual (DXA) and predicted (CT) values for FM (rho = 0.93; p ≤ 0.001), FFM (rho = 0.78; p ≤ 0.001), and ASM mass (rho = 0.70; p ≤ 0.001), Bland-Altman analyses revealed large range-of-agreement differences between the 2 methods (29.39 kg for FFM, 15.47 kg for FM, and 3.99 kg for ASM mass). Based on the magnitude of these differences, we concluded that prediction equations using single abdominal CT images have poor accuracy, cannot be considered as surrogates for DXA, and may have limited clinical utility.
Edward W. J. Cadigan
Full Text Available Transcranial magnetic (TMS and motor point stimulation have been used to determine voluntary activation (VA. However, very few studies have directly compared the two stimulation techniques for assessing VA of the elbow flexors. The purpose of this study was to compare TMS and motor point stimulation for assessing VA in non-fatigued and fatigued elbow flexors. Participants performed a fatigue protocol that included twelve, 15 s isometric elbow flexor contractions. Participants completed a set of isometric elbow flexion contractions at 100, 75, 50, and 25% of maximum voluntary contraction (MVC prior to and following fatigue contractions 3, 6, 9, and 12 and 5 and 10 min post-fatigue. Force and EMG of the bicep and triceps brachii were measured for each contraction. Force responses to TMS and motor point stimulation and EMG responses to TMS (motor evoked potentials, MEPs and Erb's point stimulation (maximal M-waves, Mmax were also recorded. VA was estimated using the equation: VA% = (1−SITforce/PTforce × 100. The resting twitch was measured directly for motor point stimulation and estimated for both motor point stimulation and TMS by extrapolation of the linear regression between the superimposed twitch force and voluntary force. MVC force, potentiated twitch force and VA significantly (p < 0.05 decreased throughout the elbow flexor fatigue protocol and partially recovered 10 min post fatigue. VA was significantly (p < 0.05 underestimated when using TMS compared to motor point stimulation in non-fatigued and fatigued elbow flexors. Motor point stimulation compared to TMS superimposed twitch forces were significantly (p < 0.05 higher at 50% MVC but similar at 75 and 100% MVC. The linear relationship between TMS superimposed twitch force and voluntary force significantly (p < 0.05 decreased with fatigue. There was no change in triceps/biceps electromyography, biceps/triceps MEP amplitudes, or bicep MEP amplitudes throughout the fatigue protocol at
Iwata, Masato; Kuzumoto, Naoya; Akasaki, Yuka; Morioka, Masayo; Nakayama, Kana; Matsuzawa, Nobuyoshi; Kimoto, Katsuhiro; Shimomura, Toshiyuki
Becker muscular dystrophy (BMD) is a progressive neuromuscular disorder caused by mutations in the dystrophin gene. The sensitivity to non-depolarizing muscle relaxant in a patient with muscle dystrophy is reportedly higher than that in normal individuals, and the duration of the effect is known to be prolonged. In this report, we present the case of a 58-year-old man with BMD who underwent laparoscopic cholecystectomy for symptomatic cholelithiasis under total intravenous anesthesia without the use of muscle-relaxant drugs and supplemented with regional anesthesia. Anesthesia was induced and maintained with propofol, remifentanil, and fentanyl; ultrasound-guided bilateral rectus sheath block (RSB) and right-sided subcostal transversus abdominis plane block (TAP) were performed. The procedure required conversion to open surgery because of hard conglutination; intraoperative and postoperative periods were uneventful. Adequate analgesia was maintained after extubation because of the effect of RSB and TAP.
A proposta biomecânica para a avaliação de sobrecarga na coluna lombar: efeito de diferentes variáveis demográficas na fadiga muscular A biomechamical approach for assessment of overload on lumbar spine: the effects of different demographic variables on muscle fatigue
Fernando Sérgio Silva Barbosa
Full Text Available OBJETIVOS: Analisar a fadiga de músculos lombares e determinar as variáveis demográficas relacionadas com a fadiga destes músculos. MÉTODOS: A atividade eletromiográfica (EMG dos músculos iliocostal direito (IL-D, iliocostal esquerdo (IL-E, multífido direito (MU-D e multífido esquerdo (MU-E de 18 voluntários foi captada durante contrações isométricas sub-máximas. Valores de root mean square (RMS e freqüência mediana (FM foram correlacionados com o tempo de resistência isométrica (TRI. Slopes de RMS positivos e de FM negativos indicaram a ocorrência da fadiga muscular. Procedimentos de regressão múltipla foram realizados para verificar as variáveis demográficas relacionadas com a fadiga muscular. RESULTADOS: A fadiga foi identificada em todos os músculos e intensidades de contração (pOBJECTIVES: To assess low back muscles fatigue and to determine the demographic variables associated to fatigue on these muscles. METHODS: The electromyographic (EMG activity of the right iliocostal (R-IL, left iliocostal (L-IL, right multifidus (R-MU and left multifidus (L-MU of 18 volunteers was recorded during submaximal isometric contractions. Root mean square (RMS and median frequency (MF values were correlated with isometric endurance time (IET. Positive RMS and negative MF slopes indicated occurrence of muscle fatigue. Multiple regression procedures were performed in order to verify the demographic variables related with the muscle fatigue. RESULTS: Fatigue was identified in all muscles and contraction intensities (p<0.01, except for MU-E at 5% in RMS slope analysis. Significant differences were found between the endurance time of 5% and 15% (p=0.01, 5% and 20% (p=0.0002. Higher levels of fatigue were found bilaterally in the multifidus muscles in the MF slope analysis. The combination of endurance time, age and body mass of the volunteers was identified as the determinant factor for the occurrence of muscle fatigue in the assessed
Becker, G.J.; Stewart, J.; Holden, R.W.; Yune, H.Y.; Mail, J.T.; Klatte, E.C.
Abdominal angina due to occlusive disease of the mesenteric arteries has been the to become clinically manifest only in the presence of severe disease in at least two of the following vessels: celiac, SMA, and IMA. Still, many patients who gradually develop significant two-vessel disease have few or no associated symptoms. Differences in collateral circulation and in cardiac index account for some of the clinical variation. The usual clinical manifestations include severe post-prandial pain, sitophobia (fear of eating because of the anticipated symptoms), and profound weight loss. Uncommonly, diarrhea, nausea, or vomiting may be encountered. Smoking is a common historical feature. Most series document a female predilection. Aside from occasional abdominal bruits and (more commonly) findings of peripheral vascular occlusive disease, the physical exam discloses only cachexia. But the differential diagnosis of profound weight loss is extensive. Therefore, abdominal angina has always created a diagnostic challenge. Multiple imaging modalities are often employed, and a seemingly negative evaluation often culminates in biplane aortography. The latter typically reveals stenoses and/or occlusions in at least two of the three mesenteric arteries. The authors discuss how a variety of surgical treatments, including thromboendarterectomy and bypass grafting, have evolved. Recently reported results have been excellent
Galiano-Castillo, Noelia; Cantarero-Villanueva, Irene; Fernández-Lao, Carolina; Ariza-García, Angélica; Díaz-Rodríguez, Lourdes; Del-Moral-Ávila, Rosario; Arroyo-Morales, Manuel
The chronicity status of breast cancer survivors suggests a growing need for cancer rehabilitation. Currently, the use of technology is a promising strategy for providing support, as reflected in the emergence of research interest in Web-based interventions in cancer survivorship. A randomized controlled trial was conducted that included a total of 81 participants who had completed adjuvant therapy (except hormone treatment) for stage I to IIIA breast cancer. Participants were randomly assigned to an 8-week Internet-based, tailored exercise program (n = 40) or to a control group (n = 41).The instruments used at baseline, 8 weeks, and 6-month follow-up were the European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire Core 30 and its breast cancer module, the Brief Pain Inventory, the handgrip dynamometer, the isometric abdominal test, the back dynamometer, the multiple sit-to-stand test, and the Piper Fatigue Scale. After the intervention, the telerehabilitation group had significantly improved scores for global health status, physical, role, cognitive functioning, and arm symptoms (all P < .01) as well as pain severity (P = .001) and pain interference (P = .045) compared with the control group. Significant improvements also were observed favoring the telerehabilitation group for affected and nonaffected side handgrip (both P = .006), abdominal, back and lower body strength (all P < .01), and total fatigue (P < .001). These findings were maintained after 6 months of follow-up, except for role functioning, pain severity, and nonaffected side handgrip. Analysis was based on an intention-to-treat principle. This program may improve adverse effects and maintain benefits in breast cancer survivors. The results of this study have encouraging implications for cancer care. Cancer 2016;122:3166-74. © 2016 American Cancer Society. © 2016 American Cancer Society.
Matalon, Shanna A; Askari, Reza; Gates, Jonathan D; Patel, Ketan; Sodickson, Aaron D; Khurana, Bharti
Abdominal wall injuries occur in nearly one of 10 patients coming to the emergency department after nonpenetrating trauma. Injuries range from minor, such as abdominal wall contusion, to severe, such as abdominal wall rupture with evisceration of abdominal contents. Examples of specific injuries that can be detected at cross-sectional imaging include abdominal muscle strain, tear, or hematoma, including rectus sheath hematoma (RSH); traumatic abdominal wall hernia (TAWH); and Morel-Lavallée lesion (MLL) (closed degloving injury). These injuries are often overlooked clinically because of (a) a lack of findings at physical examination or (b) distraction by more-severe associated injuries. However, these injuries are important to detect because they are highly associated with potentially grave visceral and vascular injuries, such as aortic injury, and because their detection can lead to the diagnosis of these more clinically important grave traumatic injuries. Failure to make a timely diagnosis can result in delayed complications, such as bowel hernia with potential for obstruction or strangulation, or misdiagnosis of an abdominal wall neoplasm. Groin injuries, such as athletic pubalgia, and inferior costochondral injuries should also be considered in patients with abdominal pain after nonpenetrating trauma, because these conditions may manifest with referred abdominal pain and are often included within the field of view at cross-sectional abdominal imaging. Radiologists must recognize and report acute abdominal wall injuries and their associated intra-abdominal pathologic conditions to allow appropriate and timely treatment. © RSNA, 2017.
... Search Featured Resource New Mobile App DOWNLOAD Adrenal Fatigue October 2017 Download PDFs English Editors Irina Bancos, MD Additional Resources Mayo Clinic What is adrenal fatigue? The term “adrenal fatigue” has been used to ...
High-intensity resistance training in multiple sclerosis - An exploratory study of effects on immune markers in blood and cerebrospinal fluid, and on mood, fatigue, health-related quality of life, muscle strength, walking and cognition.
Kierkegaard, Marie; Lundberg, Ingrid E; Olsson, Tomas; Johansson, Sverker; Ygberg, Sofia; Opava, Christina; Holmqvist, Lotta Widén; Piehl, Fredrik
High-intensity resistance training is unexplored in people with multiple sclerosis. To evaluate effects of high-intensity resistance training on immune markers and on measures of mood, fatigue, health-related quality of life, muscle strength, walking and cognition. Further, to describe participants' opinion and perceived changes of the training. Twenty patients with relapsing-remitting multiple sclerosis performed high-intensity resistance training at an intensity of 80% of one-repetition maximum, twice a week for 12 weeks. Blood and optional cerebrospinal fluid samples, and data on secondary outcome measures were collected before and after intervention. A study-specific questionnaire was used for capturing participants' opinion. Seventeen participants completed the study. Plasma cytokine levels of tumor necrosis factor were significantly decreased post-intervention (p=0.001). Exploratory cytokine analyses in cerebrospinal fluid (n=8) did not reveal major changes. Significant and clinically important improvements were found in fatigue (p=0.001) and health-related quality of life (p=0.004). Measures of mood (p=0.002), muscle strength (p ≤ 0.001), walking speed (p=0.013) and cognition (p=0.04) were also improved. A majority of participants evaluated the training as very good and perceived changes to the better. High-intensity resistance training in persons with relapsing remitting multiple sclerosis with low disability had positive effects on peripheral pro-inflammatory cytokine levels, led to clinically relevant improvements in measures of fatigue and health-related quality of life, and was well tolerated. These results provide a basis for a larger randomized trial. Copyright © 2016 Elsevier B.V. All rights reserved.
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of a health claim related to citrulline-malate and faster recovery from muscle fatigue after exercise pursuant to Article 13(5) of Regulation (EC) No 1924/2006
Following an application from Biocodex, submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Belgium, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related...... to citrulline-malate and faster recovery from muscle fatigue after exercise. Citrulline-malate is sufficiently characterised. The claimed effect is “maintenance of ATP levels through reduction of lactates in excess for an improved recovery from muscle fatigue”. The target population proposed by the applicant...... is healthy children above six years of age and adults. The Panel considers that faster recovery from muscle fatigue after exercise contributing to the restoration of muscle function is a beneficial physiological effect. A total of 33 references were considered as pertinent to the claim by the applicant...
Lane, R; Soteriou, B; Zhang, H; Archard, L
Objective: To detect and characterise enterovirus RNA in skeletal muscle from patients with chronic fatigue syndrome (CFS) and to compare efficiency of muscle energy metabolism in enterovirus positive and negative CFS patients.
Meeusen, Romain; Roelands, Bart
Fatigue during exercise can be approached from different angles. Peripheral fatigue is usually described as an impairment located in the muscle and characterized by a metabolic end point, while central fatigue is defined as a failure of the central nervous system to adequately drive the muscle. The aim of the present narrative review paper is to look at the mechanisms involved in the occurrence of fatigue during prolonged exercise, predominantly from a brain neurochemical point of view. From studies in rodents it is clear that exercise increases the release of several neurotransmitters in different brain regions, and that the onset of fatigue can be manipulated when dopaminergic influx in the preoptic and anterior hypothalamus is increased, interfering with thermoregulation. This is however not as straightforward in humans, in which most studies manipulating brain neurotransmission failed to change the onset of fatigue in normal ambient temperatures. When the ambient temperature was increased, dopaminergic and combined dopaminergic and noradrenergic reuptake inhibition appeared to override a safety switch, allowing subjects to push harder and become much warmer, without changing their perception. In general, we can conclude that brain neurochemistry is clearly involved in the complex regulation of fatigue, but many other mediators also play a role.
Full Text Available PURPOSE: A lack of fatigue-related muscle contractile property changes at time of perceived physical exhaustion and greater central than peripheral fatigue detected by twitch interpolation technique have recently been reported in cancer survivors with fatigue symptoms. Based on these observations, it was hypothesized that compared to healthy people, myoelectrical manifestation of fatigue in the performing muscles would be less significant in these individuals while sustaining a prolonged motor task to self-perceived exhaustion (SPE since their central fatigue was more prominent. The purpose of this study was to test this hypothesis by examining electromyographic (EMG signal changes during fatiguing muscle performance. METHODS: Twelve individuals who had advanced solid cancer and cancer-related fatigue (CRF, and 12 age- and gender-matched healthy controls performed a sustained elbow flexion at 30% maximal voluntary contraction till SPE. Amplitude and mean power frequency (MPF of EMG signals of the biceps brachii, brachioradialis, and triceps brachii muscles were evaluated when the individuals experienced minimal, moderate, and severe fatigue. RESULTS: CRF patients perceived physical "exhaustion" significantly sooner than the controls. The myoelectrical manifestation of muscular fatigue assessed by EMG amplitude and MPF was less significant in CRF than controls. The lower MPF even at minimal fatigue stage in CRF may indicate pathophysiologic condition of the muscle. CONCLUSIONS: CRF patients experience less myoelectrical manifestation of muscle fatigue than healthy individuals near the time of SPE. The data suggest that central nervous system fatigue plays a more important role in limiting endurance-type of motor performance in patients with CRF.
...)Veterans matched for age, height and weight. Serum OK, incidence of elevated OK, and muscle histology and fatigue rate and level of oxygen uptake relative to 02 delivery during forearm exercise were similar in both groups...
Kallenberg, L.A.C.; Hermens, Hermanus J.
Surface electromyography parameters such as root-mean-square value (RMS) and median power frequency (FMED) are commonly used to assess the input of the central nervous system (CNS) to a muscle. However, RMS and FMED are influenced not only by CNS input, but also by peripheral muscle properties. The
Gala-Alarcón, Paula; Calvo-Lobo, César; Serrano-Imedio, Ana; Garrido-Marín, Alejandro; Martín-Casas, Patricia; Plaza-Manzano, Gustavo
The purpose of this study was to describe ultrasound (US) changes in muscle thickness produced during automatic activation of the transversus abdominis (TrAb), internal oblique (IO), external oblique (EO), and rectus abdominis (RA), as well as the cross-sectional area (CSA) of the lumbar multifidus (LM), after 1 year of Pilates practice. A 1-year follow-up case series study with a convenience sample of 17 participants was performed. Indeed, TrAb, IO, EO, and RA thickness, as well as LM CSA changes during automatic tests were measured by US scanning before and after 1 year of Pilates practice twice per week. Furthermore, quality of life changes using the 36-Item Short Form Health Survey and US measurement comparisons of participants who practiced exercises other than Pilates were described. Statistically significant changes were observed for the RA muscle thickness reduction during the active straight leg raise test (P = .007). Participants who practiced other exercises presented a larger LM CSA and IO thickness, which was statistically significant (P .05). A direct moderate correlation was observed (r = 0.562, P = .019) between the TrAb thickness before and after a 1-year follow-up. Long-term Pilates practice may reduce the RA thickness automatic activation during active straight leg raise. Furthermore, LM CSA and IO thickness increases were observed in participants who practice other exercise types in conjunction with Pilates. Despite a moderate positive correlation observed for TrAb thickness, the quality of life did not seem to be modified after long-term Pilates practice. Copyright © 2018. Published by Elsevier Inc.
Enoka, Roger M.; Duchateau, Jacques
Despite flourishing interest in the topic of fatigue—as indicated by the many presentations on fatigue at the 2015 annual meeting of the American College of Sports Medicine—surprisingly little is known about its impact on human performance. There are two main reasons for this dilemma: (1) the inability of current terminology to accommodate the scope of the conditions ascribed to fatigue, and (2) a paucity of validated experimental models. In contrast to current practice, a case is made for a unified definition of fatigue to facilitate its management in health and disease. Based on the classic two-domain concept of Mosso, fatigue is defined as a disabling symptom in which physical and cognitive function is limited by interactions between performance fatigability and perceived fatigability. As a symptom, fatigue can only be measured by self-report, quantified as either a trait characteristic or a state variable. One consequence of such a definition is that the word fatigue should not be preceded by an adjective (e.g., central, mental, muscle, peripheral, and supraspinal) to suggest the locus of the changes responsible for an observed level of fatigue. Rather, mechanistic studies should be performed with validated experimental models to identify the changes responsible for the reported fatigue. As indicated by three examples (walking endurance in old adults, time trials by endurance athletes, and fatigue in persons with multiple sclerosis) discussed in the review, however, it has proven challenging to develop valid experimental models of fatigue. The proposed framework provides a foundation to address the many gaps in knowledge of how laboratory measures of fatigue and fatigability impact real-world performance. PMID:27015386
Kalsen, Anders; Hostrup, Morten; Backer, Vibeke
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...
Jepsen, Jørgen Riis; Zhao, Zhiwei; van Leeuwen, Wessel M. A.
Background: The consequences of fatigue for the health and safety of seafarers has caused concern in the industry and among academics, and indicates the importance of further research into risk factors and preventive interventions at sea. This review gives an overview of the key issues relating...... to seafarer fatigue. Materials and methods: A literature study was conducted aiming to collect publications that address risk factors for fatigue, short-term and long-term consequences for health and safety, and options for fatigue mitigation at sea. Due to the limited number of publications that deals...... with seafarers, experiences from other populations sharing the same exposures (e.g. shift work) were also included when appropriate. Results: Work at sea involves multiple risk factors for fatigue, which in addition to acute effects (e.g., impaired cognition, accidents) contributes through autonomic, immunologic...
Background and Objectives: The Exstrophy Complex (EC) is a serious malformation of midline abdominal wall. Wide pubis prevents approximating the lateralized rectus muscle and leads to dehiscence and fi stula formation. Our aim was to recommend an easier method for abdominal wall closure in the Bladder Exstrophy ...
Dhar AM, Bhargava S, Bankata S. Isolated abdominal parietal cold abscess diagnosed on ultrasound. Indian J Radiol Imaging. 1999;9:157-8. 8. Dixit R, Dixit K, Shah H, Shah K. Tuberculous abscess of rectus abdominis muscle. Indian J Tuberc 2004;51:231-3. 9. Sharma N, Sharma S. Tuberculosis abscess of the abdominal ...
Kristensen, Michael; Albertsen, Janni; Rentsch, Maria
Lactic acid accumulation is generally believed to be involved in muscle fatigue. However, one study reported that in rat soleus muscle (in vitro), with force depressed by high external K+ concentrations a subsequent incubation with lactic acid restores force and thereby protects against fatigue...
Ray, C A; Hume, K M; Gracey, K H; Mahoney, E T
Elevation of muscle temperature has been shown to increase muscle sympathetic nerve activity (MSNA) during isometric exercise in humans. The purpose of the present study was to evaluate the effect of muscle cooling on MSNA responses during exercise. Eight subjects performed ischemic isometric handgrip at 30% of maximal voluntary contraction to fatigue followed by 2 min of postexercise muscle ischemia (PEMI), with and without local cooling of the forearm. Local cooling of the forearm decreased forearm muscle temperature from 31.8 +/- 0.4 to 23.1 +/- 0.8 degrees C (P = 0.001). Time to fatigue was not different during the control and cold trials (156 +/- 11 and 154 +/- 5 s, respectively). Arterial pressures and heart rate were not significantly affected by muscle cooling during exercise, although heart rate tended to be higher during the second minute of exercise (P = 0.053) during muscle cooling. Exercise-induced increases in MSNA were delayed during handgrip with local cooling compared with control. However, MSNA responses at fatigue and PEMI were not different between the two conditions. These findings suggest that muscle cooling delayed the activation of the muscle metaboreflex during ischemic isometric exercise but did not prevent its full expression during fatiguing contraction. These results support the concept that muscle temperature can play a role in the regulation of MSNA during exercise.
Ferris, Justine R; Tomlinson, Mary A; Ward, Tayler N; Pepin, Marie E; Malek, Moh H
Cognitive fatigue tasks performed prior to exercise may reduce exercise capacity. The electromyographic fatigue threshold (EMGFT) is the highest exercise intensity that can be maintained without significant increase in the EMG amplitude versus time relationship. To date, no studies have examined the effect of cognitive fatigue on the estimation of the EMGFT. The purpose of this study, therefore, was to determine whether or not cognitive fatigue prior to performing exercise reduces the estimated EMGFT. Eight healthy college-aged men were recruited from a university student population and visited the laboratory on multiple occasions. In a randomized order, subjects performed either the cognitive fatigue task (AX Continuous Performance Test; AX-CPT) for 60 min on one visit (experimental condition) or watched a video on trains for 60 min on the other visit (control condition). After each condition, subjects performed the incremental single-leg knee-extensor ergometry test while the EMG amplitude was recorded from the rectus femoris muscle and heart rate was monitored throughout. Thereafter, the EMGFT was calculated for each participant for each visit and compared using paired samples t-test. For exercise outcomes, there were no significant mean differences for maximal power output between the two conditions (control: 51 ± 5 vs. fatigue: 50 ± 3 W), but a significant decrease in EMGFT between the two conditions (control: 31 ± 3 vs. fatigue: 24 ± 2 W; p = 0.013). Moreover, maximal heart rate was significantly different between the two conditions (control: 151 ± 5 vs. fatigue: 132 ± 6; p = 0.027). These results suggest that performing the cognitive fatiguing task reduces the EMGFT with a corresponding reduction in maximal heart rate response.
... Data Conducting Clinical Trials Statistical Tools and Data Terminology Resources NCI Data Catalog Cryo-EM NCI's Role ... Problems getting enough sleep. Being less active. Other medical conditions. Fatigue is common in people with advanced ...
Cejvanovic, S; Vissing, J
OBJECTIVE: Myasthenia gravis (MG) is characterized by fatigue and fluctuating muscle weakness as a result of impaired neuromuscular transmission (NMT). Although MG is a prototypic fatiguing disorder, little is known about how the condition affects fixed weakness, and if present, whether weakness...
Kent, Jane A; Ørtenblad, Niels; Hogan, Michael C
Muscle fatigue has been studied with a variety approaches, tools and technologies. The foci of these studies have ranged tremendously, from molecules to the entire organism. Single cell and animal models have been used to gain mechanistic insight into the fatigue process. The theme of this review...
Seo, Jung Wook [Inje Univ. Ilsan Paik Hospital, Goyang (Korea, Republic of)
To evaluate the imaging findings of abdominal wall endometriosis. In seven of 17 patients with surgically proven endometriosis of the abdominal wall, we retrospectively reviewed the findings of radiologic studies such as abdominal US (n=3), CT (n=4), and MRI (n=1). One patient under went more than one type of imaging, apparently. The surgical history of the seven, and their symptoms and preoperative diagnosis were reviewed, and the size, location, margin and nature of the mass, and the contrast enhancement patterns observed at radiologic studies, were assessed. The chief symptoms were palpable abdominal wall mass (n=5) and lower abdominal pain (n=2) around a surgical scar. Previous surgery included cesarean section (n=5), cesarean section with oophorectomy (n=1) and appendectomy (n=1). Masses were located in the subcutaneous fat layer (n=5) or rectus abdominis muscle (n=2), and their maximum diameter was 2.6 cm. Imaging findings, which correlated closely with the pathologic findings, included a well (n=5) or poorly marginated (n=2) solid mass, with a focal cystic area apparent in two cases. Although imaging findings of abdominal wall endometriosis may not be specific for diagnosis, the presence of a solid abdominal mass in female patients of reproductive age with a history of surgery is a diagnostic pointer.
Seo, Jung Wook
To evaluate the imaging findings of abdominal wall endometriosis. In seven of 17 patients with surgically proven endometriosis of the abdominal wall, we retrospectively reviewed the findings of radiologic studies such as abdominal US (n=3), CT (n=4), and MRI (n=1). One patient under went more than one type of imaging, apparently. The surgical history of the seven, and their symptoms and preoperative diagnosis were reviewed, and the size, location, margin and nature of the mass, and the contrast enhancement patterns observed at radiologic studies, were assessed. The chief symptoms were palpable abdominal wall mass (n=5) and lower abdominal pain (n=2) around a surgical scar. Previous surgery included cesarean section (n=5), cesarean section with oophorectomy (n=1) and appendectomy (n=1). Masses were located in the subcutaneous fat layer (n=5) or rectus abdominis muscle (n=2), and their maximum diameter was 2.6 cm. Imaging findings, which correlated closely with the pathologic findings, included a well (n=5) or poorly marginated (n=2) solid mass, with a focal cystic area apparent in two cases. Although imaging findings of abdominal wall endometriosis may not be specific for diagnosis, the presence of a solid abdominal mass in female patients of reproductive age with a history of surgery is a diagnostic pointer
In July 2010, at the Muscle Fatigue Meeting, I presented an overview of Chronic Fatigue Syndrome and Cancer Related Fatigue, emphasizing a critical interpretation of the potential association between Chronic Fatigue Syndrome and Cancer Related Fatigue and a newly discovered retrovirus: Xenotropic Murine Related Virus. Since this association was hotly debated at that time, I suggested at the Meeting that it was wrong and most likely due to the identification of the wrong virus culprit. Today, 20 months after the Meeting, the first part of our prediction has turned out to be correct, as Xenotropic Murine Related Virus was shown to be a laboratory-created artefact. Still, the potential association of fatigue-syndromes with an infection (most likely viral) is sustained by a plethora of evidence and this overview will initially summarize data suggesting prior viral infection(s). The principal hypothesized mechanisms for both peripheral and central Chronic Fatigue Syndrome/Cancer Related Fatigue will be then summarized, also indicating plausible associations and triggering factors. All evidence accrued so far suggests that further research work should be performed in this interesting area and in order to identify an infectious agent for Chronic Fatigue Syndrome/Cancer Related Fatigue. One candidate RNA virus, Micro-Foci inducing Virus, will be described in this overview. Copyright © 2012 Elsevier B.V. All rights reserved.
... Professions Site Index A-Z Abdominal Aortic Aneurysm (AAA) Abdominal aortic aneurysm (AAA) occurs when atherosclerosis or plaque buildup causes the ... weak and bulge outward like a balloon. An AAA develops slowly over time and has few noticeable ...
Vinge, O; Edvardsen, L; Jensen, F
In an experimental study, 13 patients undergoing major elective abdominal surgery were given postoperative transcutaneous electrical muscle stimulation (TEMS) to the quadriceps femoris muscle on one leg; the opposite leg served as control. Changes in cross-sectional area (CSA) and muscle protein ...... protein synthesis and muscle mass after abdominal surgery and should be evaluated in other catabolic states with muscle wasting.......In an experimental study, 13 patients undergoing major elective abdominal surgery were given postoperative transcutaneous electrical muscle stimulation (TEMS) to the quadriceps femoris muscle on one leg; the opposite leg served as control. Changes in cross-sectional area (CSA) and muscle protein...... synthesis were assessed by computed tomography and ribosome analysis of percutaneous muscle biopsies before surgery and on the sixth postoperative day. The percentage of polyribosomes in the ribosome suspension decreased significantly (P
Amyloidosis - abdominal wall fat pad biopsy; Abdominal wall biopsy; Biopsy - abdominal wall fat pad ... is the most common method of taking an abdominal wall fat pad biopsy . The health care provider cleans the ...
Cabieses Molina, Fernando
The concept of fatigue, stressing that this is a likely to be broken down into a series of links, the main process is first established in broad terms: fatigue of central synapses, fatigue neuromuscular plate and fatigue of the muscle fiber. The central synapses fatigue related to movement, is explained by the breakdown of some of the chemical equilibrium states that characterize the function of the neuron. It is located in the synapse and its essence is the inability to transmit nerve impuls...
Roussos, C S; Macklem, P T
The time required (tlim) to produce fatigue of the diaphragm was determined in three normal seated subjects, breathing through a variety of high alinear, inspiratory resistances. During each breath in all experimental runs the subject generated a transdiaphragmatic pressure (Pdi) which was a predetermined fraction of his maximum inspiratory Pdi (Pdimax) at functional residual capacity. The breathing test was performed until the subject was unable to generate this Pdi. The relationship between Pdi/Pdimax and tlim was curvilinear so that when Pdi/Pdimax was small tlim increased markedly for little changes in Pdi/Pdimax. The value of Pdi/Pdimax that could be generated indefinitely (Pdicrit) was around 0.4. Hypoxia appeared to have no influence on Pdicrit, but probably led to a reduction in tlim at Pdi greater than Pdicrit for equal rates of energy consumption. Insofar as the behavior of the diaphragm reflects that of other respiratory muscles it appears that quite high inspiratory loads can be tolerated indefinitely. However, when the energy consumption of the respiratory muscles exceeds a critical level, fatigue should develop. This may be a mechanism of respiratory failure in a variety in a variety of lung diseases.
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to β-hydroxy β-methylbutyrate monohydrate (HMB) alone or in combination with α-ketoisocaproic acid (KIC) and reduction of muscle tissue damage during exercise (ID 1577, , 1584), increase in lean body mass (ID 1579, 1582, 1583), increase in muscle strength (ID 1578, 1583, 1587), increase in endurance performance (ID 1580, 1581), skeletal muscle tissue repair (ID 1586) and faster recovery from muscle fatigue after exercise (ID 1576, 1585) pursuant to Article 13
Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of health...... and faster recovery from muscle fatigue after exercise. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member States or directly from stakeholders. The food constituent...
Métodos de avaliação da fadigabilidade muscular periférica e seus determinantes energético-metabólicos na DPOC Methods for the assessment of peripheral muscle fatigue and its energy and metabolic determinants in COPD
Rafaella Rezende Rondelli
Full Text Available Está bem estabelecido que, além do acometimento pulmonar, a DPOC apresenta consequências sistêmicas que podem convergir para a disfunção muscular periférica, com maior fadigabilidade muscular, menor tolerância ao exercício e menor sobrevida nesses pacientes. Tendo em vista as repercussões negativas da fadiga muscular precoce na DPOC, esta revisão teve como objetivo discutir os principais achados da literatura relacionados aos seus determinantes metabólicos e bioenergéticos e suas repercussões funcionais, bem como seus métodos de identificação e de quantificação. O substrato anatomofuncional da maior fadigabilidade muscular na DPOC parece incluir a redução dos níveis de fosfatos de alta energia, a redução da densidade mitocondrial, a lactacidemia precoce, o aumento da amônia sérica e a perfusão muscular reduzida. Essas alterações podem ser evidenciadas por falência de contração, redução da taxa de disparo das unidades motoras e maior recrutamento de unidades motoras numa dada atividade, exteriorizando-se funcionalmente por redução da força, potência e resistência musculares. Esta revisão mostra também que diversos tipos de regimes contráteis e protocolos têm sido utilizados com o intuito de detectar fadiga nessa população. A partir de tais conhecimentos, estratégias reabilitadoras podem ser traçadas visando o aumento da resistência à fadiga muscular nessa população.It has been well established that, in addition to the pulmonary involvement, COPD has systemic consequences that can lead to peripheral muscle dysfunction, with greater muscle fatigue, lower exercise tolerance and lower survival in these patients. In view of the negative repercussions of early muscle fatigue in COPD, the objective of this review was to discuss the principal findings in the literature on the metabolic and bioenergy determinants of muscle fatigue, its functional repercussions, as well as the methods for its
Noha Abdel Kader Abdel Kader Hasan
Conclusion: The study shows that the BMI of children had a positive correlation with the muscle strength of quadriceps, triceps, and abdominal muscles while a negative correlation with the endurance time of these muscles.
Full Text Available CONTEXTUALIZAÇÃO: A estimulação elétrica neuromuscular (EENM é uma técnica bastante utilizada na área da reabilitação em fisioterapia, porém a instalação da fadiga ocorre de maneira mais rápida se comparada à contração voluntária. Na prática clínica, torna-se necessário monitorar a fadiga muscular em protocolos de EENM, visando adequar os parâmetros da corrente elétrica e prolongar o tempo de estimulação. OBJETIVOS: O objetivo deste estudo foi utilizar a mecanomiografia como meio de avaliação da fadiga muscular periférica durante a aplicação de um protocolo de EENM. MÉTODOS: Um sistema de aquisição de sinais mecanomiográficos (MMG e um protocolo experimental foram desenvolvidos. Durante os ensaios in vivo com 10 voluntários, foram realizados testes de contração voluntária máxima (CVM para extensão do joelho. Realizou-se uma fase de potencialização com contrações dinâmicas produzidas por EENM a 10% da CVM (100 Hz, 400 µm no músculo quadríceps femoral, e o protocolo de EENM propriamente dito ocorreu a 30% da CVM (50 Hz, 400 µm. Simultaneamente, foram adquiridos os sinais de MMG RMS (amplitude e MMG MPF (frequência do músculo reto femoral e de torque (amplitude para a extensão do joelho. RESULTADOS: A linha de tendência da MMG RMS foi descendente, indicando que a MMG RMS relaciona-se à amplitude do torque. Porém, a MMG MPF não teve uma boa correlação com o torque para este protocolo de EENM. CONCLUSÕES: A MMG pode ser aplicada simultaneamente à EENM, pois não ocorre interferência elétrica, e pode ser utilizada na realização de movimentos funcionais na contração muscular gerada por EENM. Artigo registrado no Australian New Zealand Clinical Trials Registry (ANZCTR sob o número ACTRN12609000866202.BACKGROUND: Neuromuscular electrical stimulation (NMES is a widely used technique for rehabilitation in physical therapy, however it causes muscle fatigue more rapidly than does voluntary
Comparação da fadiga eletromiográfica dos músculos paraespinhais e da cinemática angular da coluna entre indivíduos com e sem dor lombar Comparison of electromyographic fatigue of erector spinae muscles and angular kinematic of spine between individuals with and without low back pain
Marcio Massao Kawano
Full Text Available Indivíduos com dor lombar têm redução na força e na resistência dos músculos paraespinhais. A avaliação da fadiga e da resistência dos músculos paraespinhais é importante, uma vez que tem sido reportado que indivíduos com lombalgia desenvolvem um déficit no condicionamento físico que influencia na força e na função do tronco. Além disso, ainda é incerto a relação da fadiga dos paraespinhais e o ângulo de flexão anterior de tronco. Os objetivos deste estudo foram comparar a fadiga em indivíduos com e sem dor lombar e correlacionar a fadiga com o ângulo de flexão anterior de tronco. O grupo lombalgia foi composto por dez indivíduos com diagnóstico médico exclusivo de lombalgia. O grupo controle foi composto por dez indivíduos que possuíam características físicas semelhantes. Inicialmente avaliou-se a flexão anterior de tronco dos indivíduos pelo método angular de Whistance. A fadiga dos músculos paraespinhais foi avaliada nas alturas de L1 e L5 por meio da eletromiografia de superfície em duas cargas: 50 e 75% da contração isométrica voluntária máxima. Os resultados do estudo indicaram que o grupo lombalgia apresentou menor força durante os testes de contração isométrica voluntária máxima (P Subjects with low back pain have reduction in strength and endurance of the erector spinae muscles. The assessment of the fatigue and the endurance of these muscles is important, once it has been reported that individuals with low back pain develop a deficit in physical conditioning which influences on trunk strength and function. Moreover, the relationship between back muscles fatigue and trunk forward flexion is still unclear. The aims of this study were to compare fatigue between individuals with and without low back pain and to correlate the muscles fatigue with the angle of trunk forward flexion. The low back pain group consisted of ten low back pain subjects. The control group was composed by ten subjects
Pline, Kevin M; Madigan, Michael L; Nussbaum, Maury A
The purpose of this study was to investigate the influence of fatigue time and fatigue level on the increases in postural sway during quiet standing. Centre of pressure-based measures of postural sway were collected both before and after fatiguing participants using three different fatigue levels and two different fatigue times. Results showed increasing fatigue time increased sway velocity and sway area, and increasing fatigue level increased sway velocity. Fatigue time effects are important to consider when applying laboratory-based findings to the field given that the fatigue time can differ substantially between the two. Fatigue level effects imply a dose - response relationship between localized muscle fatigue and risk of falling that can have important implications in work/rest cycle scheduling for occupations at risk of injurious falls.
EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to citrulline-malate and faster recovery from muscle fatigue after exercise pursuant to Article 13(5) of Regulation (EC) No 1924/2006
Following an application from Biocodex, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Belgium, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scienti......Following an application from Biocodex, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Belgium, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion...... on the scientific substantiation of a health claim related to citrulline-malate and faster recovery from muscle fatigue after exercise. The Panel considers that citrulline-malate is sufficiently characterised. The claimed effect proposed by the applicant is “improved recovery from muscle fatigue”. Faster recovery...... function. The evidence provided by the applicant did not establish that a faster reduction of blood lactate concentrations through a dietary intervention leads to faster recovery from muscle fatigue by contributing to the restoration of muscle function after exercise. No conclusions cou