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Sample records for voluntary eccentric isokinetic

  1. Neuromuscular Changes and Damage after Isoload versus Isokinetic Eccentric Exercise.

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    Doguet, Valentin; Nosaka, Kazunori; Plautard, Mathieu; Gross, Raphaël; Guilhem, GaËL; Guével, Arnaud; Jubeau, Marc

    2016-12-01

    This study compared the effects of isoload (IL) and isokinetic (IK) knee extensor eccentric exercises on changes in muscle damage and neuromuscular parameters to test the hypothesis that the changes would be different after IL and IK exercises. Twenty-two young men were paired based on their strength and placed in the IL (N = 11) or the IK (N = 11) group. The IL group performed 15 sets of 10 eccentric contractions with a 150% of predetermined one-repetition maximum load. The IK group performed 15 sets of several maximal eccentric contractions matched set by set for the total amount of work and mean angular velocity with the IL group. Muscle damage markers (voluntary isometric peak torque, muscle soreness, and creatine kinase activity) and neuromuscular variables (e.g., voluntary activation, H-reflex, M-wave, and evoked torque) were measured before, immediately after, and 24, 48, 72, and 96 h postexercise. Voluntary isometric peak torque decreased to the same extent (P = 0.94) in both groups immediately after (IL = -40.6% ± 13.8% vs IK = -42.4% ± 10.2%) to 96 h after the exercise (IL = -21.8% ± 28.5% vs IK = -26.7% ± 23.5%). Neither peak muscle soreness (IL = 48.1 ± 28.2 mm vs IK = 54.7 ± 28.9 mm, P = 0.57) nor creatine kinase activity (IL = 12,811 ± 22,654 U·L vs IK = 15,304 ± 24,739 U·L, P = 0.59) significantly differed between groups. H-reflex (IL = -23% vs IK = -35%) and M-wave (IL = -10% vs IK = -17%) significantly decreased immediately postexercise similarly between groups. The changes in muscle damage and neuromuscular function after the exercise are similar between IL and IK, suggesting that resistance modality has little effects on acute muscle responses.

  2. Neuromuscular adaptations to isoload versus isokinetic eccentric resistance training.

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    Guilhem, Gaël; Cornu, Christophe; Maffiuletti, Nicola A; Guével, Arnaud

    2013-02-01

    The purpose of this study was to compare neuromuscular adaptations induced by work-matched isoload (IL) versus isokinetic (IK) eccentric resistance training. A total of 31 healthy subjects completed a 9-wk IL (n = 11) or IK (n = 10) training program for the knee extensors or did not train (control group; n = 10). The IL and IK programs consisted of 20 training sessions, which entailed three to five sets of eight repetitions in the respective modalities. The amount of work and the mean angular velocity were strictly matched between IL and IK conditions. Neuromuscular tests were performed before and after training and consisted of the assessment of quadriceps muscle strength, muscle architecture (vastus lateralis), EMG activity, and antagonist coactivation. IL, but not IK, eccentric resistance training enhanced eccentric strength at short muscle length (+20%), high-velocity eccentric strength (+15%), muscle thickness (+10%), and fascicle angle measured at rest (+11%; P eccentric movements (i.e., at short muscle lengths), which results in greater torque and angular velocities compared with IK actions, is the main determinant of strength and neuromuscular adaptations to eccentric training. These findings have important consequences for the optimization of IL and IK eccentric exercise for resistance training and rehabilitation purposes.

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

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    Rodrigo de Azevedo Franke

    2014-09-01

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

  4. Knee Extensor and Flexor Torque Development with Concentric and Eccentric Isokinetic Training

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    Miller, Larry E.; Pierson, Lee M.; Nickols-Richardson, Sharon M.; Wootten, David F.; Selmon, Serah E.; Ramp, Warren K.; Herbert, William G.

    2006-01-01

    This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training…

  5. Knee Extensor and Flexor Torque Development with Concentric and Eccentric Isokinetic Training

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    Miller, Larry E.; Pierson, Lee M.; Nickols-Richardson, Sharon M.; Wootten, David F.; Selmon, Serah E.; Ramp, Warren K.; Herbert, William G.

    2006-01-01

    This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training…

  6. Multiarticular isokinetic high-load eccentric training induces large increases in eccentric and concentric strength and jumping performance.

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    Papadopoulos, Christos; Theodosiou, Konstantinos; Bogdanis, Gregory C; Gkantiraga, Evangelia; Gissis, Ioannis; Sambanis, Michalis; Souglis, Athanasios; Sotiropoulos, Aristomenis

    2014-09-01

    This study investigated the effects of short-term eccentric exercise training using a custom-made isokinetic leg press device, on concentric and eccentric strength and explosiveness as well as jumping performance. Nineteen healthy males were divided into an eccentric (ECC, n = 10) and a control group (CG, n = 9). The ECC group trained twice per week for 8 weeks using an isokinetic hydraulic leg press machine against progressively increasing resistance ranging from 70 to 90% of maximal eccentric force. Jumping performance and maximal force generating capacity were measured before and after eccentric training. In the ECC group, drop jump (DJ) height and maximal power were increased by 13.6 ± 3.2% (p knee, and hip joint angles were also reduced by 33.9 ± 1.1%, 31.1 ± 1.0%, and 32.4 ± 1.6% (all p eccentric and concentric leg press force was increased by 64.9 ± 5.5% (p eccentric force, explosiveness, and DJ performance were markedly increased after only 16 training sessions, possibly because of the high eccentric load attained during the bilateral eccentric leg press exercise performed on this custom-made device.

  7. Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

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    Guilhem, G; Cornu, C; Guével, A

    2010-06-01

    To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

  8. A methodologic approach for normalizing angular work and velocity during isotonic and isokinetic eccentric training.

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    Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

    2012-01-01

    Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Controlled laboratory study. Controlled research laboratory. Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Angular work and angular velocity. The isotonic and isokinetic groups performed the same total amount of work (-185.2 ± 6.5 kJ and -184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury.

  9. Isokinetic eccentric resistance training prevents loss in mechanical muscle function after running

    DEFF Research Database (Denmark)

    Oliveira, Anderson S. C.; Caputo, Fabrizio; Aagaard, Per

    2013-01-01

    The aim of the study was to verify whether 8 weeks of resistance training employing maximal isokinetic eccentric (IERT) knee extensor actions would reduce the acute force loss observed after high-intensity treadmill running exercise. It was hypothesized that specific IERT would induce protective...... effects against muscle fatigue and ultrastructural damages, preventing or reducing the loss in mechanical muscle function after running. Subjects were tested before and after IERT protocol for maximal isometric, concentric and eccentric isokinetic knee extensor strength (60° and 180° s(-1)). In a second...... session, subjects performed treadmill running (~35 min) and the previously mentioned measurements were repeated immediately after running. Subsequently, subjects were randomized to training (n = 12) consisting of 24 sessions of maximal IERT knee extensors actions at 180° s(-1), or served as controls (n...

  10. Reliability of Concentric, Eccentric and Isometric Knee Extension and Flexion when using the REV9000 Isokinetic Dynamometer

    DEFF Research Database (Denmark)

    de Carvalho Froufe Andrade, Alberto César Pereira; Caserotti, Paolo; de Carvalho, Carlos Manuel Pereira

    2013-01-01

    The aim of this study was to assess the reliability of isokinetic and ISO knee extensor and flexor muscle strength when using the REV9000 (Technogym) isokinetic dynamometer. Moreover, the reliability of several strength imbalance indices and bilateral ratios were also examined. Twenty......). The results of this study showed a high reproducibility in eccentric (0.95-0.97), concentric (0.95-0.96) and isometric (0.93-0.96), isokinetic strength for knee extensor and flexor muscles, thus indicating that the REV9000 isokinetic dynamometer can be used in future sports performance studies. A low...

  11. Isokinetic eccentric resistance training prevents loss in mechanical muscle function after running.

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    Oliveira, Anderson Souza; Caputo, Fabrizio; Aagaard, Per; Corvino, Rogério Bulhões; Gonçalves, Mauro; Denadai, Benedito Sergio

    2013-09-01

    The aim of the study was to verify whether 8 weeks of resistance training employing maximal isokinetic eccentric (IERT) knee extensor actions would reduce the acute force loss observed after high-intensity treadmill running exercise. It was hypothesized that specific IERT would induce protective effects against muscle fatigue and ultrastructural damages, preventing or reducing the loss in mechanical muscle function after running. Subjects were tested before and after IERT protocol for maximal isometric, concentric and eccentric isokinetic knee extensor strength (60° and 180° s(-1)). In a second session, subjects performed treadmill running (~35 min) and the previously mentioned measurements were repeated immediately after running. Subsequently, subjects were randomized to training (n = 12) consisting of 24 sessions of maximal IERT knee extensors actions at 180° s(-1), or served as controls (n = 8). The effects of acute running-induced fatigue and training on isokinetic and isometric peak torque, and rate of force development (RFD) were investigated. Before IERT, running-induced eccentric torque loss at 180° s(-1) was -8 %, and RFD loss was -11 %. Longitudinal IERT led to reduced or absent acute running-induced losses in maximal IERT torque at 180° s(-1) (+2 %), being significantly reduced compared to before IERT (p 0.05). In conclusion, IERT yields a reduced strength loss after high-intensity running workouts, which may suggest a protective effect against fatigue and/or morphological damages. However, IERT may not avoid reductions in explosive muscle actions. In turn, this may allow more intense training sessions to be performed, facilitating the adaptive response to running training.

  12. Myocellular enzyme leakage, polymorphonuclear neutrophil activation and delayed onset muscle soreness induced by isokinetic eccentric exercise.

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    Croisier, J L; Camus, G; Deby-Dupont, G; Bertrand, F; Lhermerout, C; Crielaard, J M; Juchmès-Ferir, A; Deby, C; Albert, A; Lamy, M

    1996-01-01

    To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle

  13. Isokinetic eccentric exercise can induce skeletal muscle injury within the physiologic excursion of muscle-tendon unit: a rabbit model

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    Chen Pei-Yu

    2007-08-01

    Full Text Available Abstract Background and Purpose Intensive eccentric exercise can cause muscle damage. We simulated an animal model of isokinetic eccentric exercise by repetitively stretching stimulated triceps surae muscle-tendon units to determine if such exercise affects the mechanical properties of the unit within its physiologic excursion. Methods Biomechanical parameters of the muscle-tendon unit were monitored during isokinetic eccentric loading in 12 rabbits. In each animal, one limb (control group was stretched until failure. The other limb (study group was first subjected to isokinetic and eccentric cyclic loading at the rate of 10.0 cm/min to 112% (group I or 120% (group II of its initial length for 1 hour and then stretched to failure. Load-deformation curves and biomechanical parameters were compared between the study and control groups. Results When the muscle-tendon unit received eccentric cyclic loading to 112%, changes in all biomechanical parameters – except for the slope of the load-deformation curve – were not significant. In contrast, most parameters, including the slope of the load-deformation curve, peak load, deformation at peak load, total energy absorption, and energy absorption before peak load, significantly decreased after isokinetic eccentric cyclic loading to 120%. Conclusion We found a threshold for eccentrically induced injury of the rabbit triceps surae muscle at between 12% and 20% strain, which is within the physiologic excursion of the muscle-tendon units. Our study provided evidence that eccentric exercise may induce changes in the biomechanical properties of skeletal muscles, even within the physiologic range of the excursion of the muscle-tendon unit.

  14. Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

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    Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

    2017-06-01

    To evaluate the effects of exercise velocity (60, 150, 240deg∙s(-1)) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E). Significant differences of the t1/2 values were identified between 60 and 150deg∙s(-1). Significant differences in the t1/2 values were observed between V˙O2pulm and V˙CO2pulm and between V˙CO2pulm and V˙E. The time to attain the first avDO2-peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O2pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O2pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Unilateral eccentric resistance training: A direct comparison between isokinetic and dynamic constant external resistance modalities.

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    Coratella, Giuseppe; Milanese, Chiara; Schena, Federico

    2015-01-01

    Aim of the study was to compare the effects of unilateral eccentric-only training using constant velocity vs. constant external load. Forty-seven participants were randomized in isokinetic (IK), dynamic constant external resistance (DCER) unilateral eccentric training or control groups. Knee extension 1RM and isometric, eccentric and concentric knee extensors peak torque, as well as changes in vastus lateralis fascicle pennation angle, fascicle length, muscle thickness, and quadriceps fat-free mass were measured. Both IK and DCER training consisted in 5 × 8 eccentric-only repetitions, 2d/w, for 6 weeks. IK and DCER training sessions were matched for total volume. After training, both IK and DCER similarly increased 1RM (respectively, +4.4 kg, CI95% 1.8-7.0 and +5.5 kg, CI95% 3.3-7.9), isometric (respectively, +34.5 N/m, CI95% 23.0-45.9 and +15.8, CI95% 5.4-26.2) and concentric peak torque (respectively, +17.0 N/m, CI95% 6.6 to +27.4 and 12.2 CI95% 2.8-21.7). IK increased eccentric peak torque significantly more than DCER (respectively, +84.2 N/m, CI95% 66.3-102.1 and +38.2 N/m, CI95% 21.9-54.4). Both IK and DCER similarly increased fascicle length (respectively, +14.7 mm, CI95% 5.4-24.0 and +14.4 mm, CI95% 5.4-23.3) and muscle thickness (respectively, +3.3 mm, CI95% 1.5-5.1, and +4.1 mm, CI95% 2.5-5.7). Matching the training volume resulted in similar adaptations comparing eccentric-only IK or DCER resistance training. Both in rehabilitation and in training practice, the use of easily available gym devices can be a good substitute for expensive and often unavailable IK devices.

  16. Acute effects of static and dynamic stretching on hamstring eccentric isokinetic strength and unilateral hamstring to quadriceps strength ratios.

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    Ayala, Francisco; De Ste Croix, Mark; Sainz De Baranda, Pilar; Santonja, Fernando

    2013-01-01

    The main purposes of this study were to investigate the acute effects of static and dynamic lower limb stretching routines: (a) on peak torque, total external work and joint angle at peak torque of the hamstrings during maximal eccentric isokinetic leg flexion; (b) on unilateral hamstring to quadriceps (H/Q) strength ratios; as well as (c) to determine whether static and dynamic routines elicit similar responses. A total of 49 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching, and (c) dynamic stretching. After the stretching or control intervention, eccentric isokinetic peak torque, the angle of peak torque and total external work were assessed with participants prone at 1.04 and 3.14 rad · s(-1). Unilateral strength ratios of the knee were also recorded. Measures were compared via a fully-within-groups factorial analysis of variance (ANOVA). There were no main effects for eccentric isokinetic peak torque, angle of peak torque, total external work and unilateral H/Q strength ratios. The results suggest that dynamic and static stretching has no influence on eccentric strength profile and unilateral H/Q strength ratios and hence both forms of stretching do not reduce these two primary risk factors for muscle injury.

  17. Isokinetic eccentric exercise as a model to induce and reproduce pathophysiological alterations related to delayed onset muscle soreness

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    Lund, Henrik; Vestergaard-Poulsen, P; Kanstrup, I.L.

    1998-01-01

    Physiological alterations following unaccustomed eccentric exercise in an isokinetic dynamometer of the right m. quadriceps until exhaustion were studied, in order to create a model in which the physiological responses to physiotherapy could be measured. In experiment I (exp. I), seven selected...... parameters were measured bilaterally in 7 healthy subjects at day 0 as a control value. Then after a standardized bout of eccentric exercise the same parameters were measured daily for the following 7 d (test values). The measured parameters were: the ratio of phosphocreatine to inorganic phosphate (PCr...... (133Xenon washout technique). This was repeated in experiment II (exp. II) 6-12 months later in order to study reproducibility. In experiment III (exp. III), the normal fluctuations over 8 d of the seven parameters were measured, without intervention with eccentric exercise in 6 other subjects. All...

  18. Maximal force, voluntary activation and muscle soreness after eccentric damage to human elbow flexor muscles

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    Prasartwuth, O; Taylor, JL; Gandevia, SC

    2005-01-01

    Muscle damage reduces voluntary force after eccentric exercise but impaired neural drive to the muscle may also contribute. To determine whether the delayed-onset muscle soreness, which develops ∼1 day after exercise, reduces voluntary activation and to identify the possible site for any reduction, voluntary activation of elbow flexor muscles was examined with both motor cortex and motor nerve stimulation. We measured maximal voluntary isometric torque (MVC), twitch torque, muscle soreness and voluntary activation in eight subjects before, immediately after, 2 h after, 1, 2, 4 and 8 days after eccentric exercise. Motor nerve stimulation and motor cortex stimulation were used to derive twitch torques and measures of voluntary activation. Eccentric exercise immediately reduced the MVC by 38 ± 3% (mean ±s.d., n = 8). The resting twitch produced by motor nerve stimulation fell by 82 ± 6%, and the estimated resting twitch by cortical stimulation fell by 47 ± 15%. While voluntary torque recovered after 8 days, both measures of the resting twitch remained depressed. Muscle tenderness occurred 1–2 days after exercise, and pain during contractions on days 1–4, but changes in voluntary activation did not follow this time course. Voluntary activation assessed with nerve stimulation fell 19 ± 6% immediately after exercise but was not different from control values after 2 days. Voluntary activation assessed by motor cortex stimulation was unchanged by eccentric exercise. During MVCs, absolute increments in torque evoked by nerve and cortical stimulation behaved differently. Those to cortical stimulation decreased whereas those to nerve stimulation tended to increase. These findings suggest that reduced voluntary activation contributes to the early force loss after eccentric exercise, but that it is not due to muscle soreness. The impairment of voluntary activation to nerve stimulation but not motor cortical stimulation suggests that the activation deficit lies in the

  19. Piroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise

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    J-L. Croisier

    1996-01-01

    Full Text Available To test the hypothesis that delayed onset muscular soreness (DOMS following intense eccentric muscle contraction could be due to increased production of prostaglandin E2 (PGE2, ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene®. They were given one capsule containing either placebo or piroxicam (20 mg per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60°/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE2 measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05. However, statistical analysis (two-way ANOVA test revealed that exercise did not cause any significant change of mean plasma PGE2 over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001. By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1 oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2 the hypothetical role of increased PGE2 production in eccentric exercise-induced muscle damage, DOMS, and reduced

  20. Piroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise

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    Croisier, J-L.; Monfils, T.; Deby-Dupon, G.; Fafchamps, M.; Venneman, I.; Crielaard, J-M.; Juchmès-Ferir, A.; Lhermerout, C.; Lamy, M.; Deby, C.

    1996-01-01

    To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E2 (PGE2), ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene®). They were given one capsule containing either placebo or piroxicam (20 mg) per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60°/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE2 measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05). However, statistical analysis (two-way ANOVA test) revealed that exercise did not cause any significant change of mean plasma PGE2 over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001). By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1) oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2) the hypothetical role of increased PGE2 production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic

  1. The repeated bout effect of eccentric exercise is not associated with changes in voluntary activation.

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    Kamandulis, Sigitas; Skurvydas, Albertas; Brazaitis, Marius; Skikas, Laimutis; Duchateau, Jacques

    2010-04-01

    The aim of this study was to compare the possible changes in muscle activation level between a first and second bout of damaging eccentric exercise performed at 2 weeks interval (i.e. repeated bout effect). To that purpose, ten physically active males took part in this study. The eccentric exercise consisted of 10 sets of 12 maximal voluntary contractions (MVC) produced by the knee extensors during movements performed at a constant speed of 160 degrees s(-1). Changes in voluntary and electrically evoked torque in concentric and/or isometric conditions were assessed at the following time points: pre-exercise, and 2 min, 1 and 24 h after each eccentric exercise. At the same time points, voluntary activation was quantified by the superimposed electrical stimulation technique. Muscle soreness and plasma CK activity were measured within 48 h after the eccentric exercise. The results showed that the decrease in eccentric peak torque was linear throughout the exercise protocol. At the end of bouts 1 and 2, torque was significantly reduced by 27.7 +/- 9.1 and 23.4 +/- 11.2, respectively, with no difference between bouts (P > 0.05). At 24 h post-exercise, a lower reduction (P eccentric exercise appears to reduce muscle damage, but does not influence the level of voluntary activation.

  2. Effects of isokinetic eccentric training on knee extensor and flexor torque and on gait of individuals with long term ACL reconstruction: A controlled clinical trial

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    Heleodório Honorato dos Santos

    2014-12-01

    Full Text Available This study investigated the effects of the isokinetic eccentric training (IET on the knee extensor and flexor torque and kinematic gait parameters in individuals with ACL reconstruction. Sixteen men with ACL reconstructed (ACLr whose torque and the gait were evaluated, before and after 12 weeks of IET, was compared to a control group (14 individuals. Student t, MANOVA and ANOVA tests were performed with 5% of significance. The training increased the isometric, concentric at 30 and 120º/s (p < .05 and eccentric at 30º/s (p < .01 extensor torque on the affected limb (AL, and eccentric at 30 and 120º/s (p < .01, on the non-affected limb (NAL. In the flexors, there was an increase on the torque: isometric, concentric at 30º/s and eccentric at 30 and 120º/s (p < .01 in AL and in eccentric at 30 (p < .05 and 120º/s (p< .01 in NAL. With respect to the angular and spatio-temporal variables gait, there was no difference between pre-and post-training in LCAr group. Compared to control group, the cycle time, in two members, was lower in LCAr group, and stride length and cadence were higher in the AL of the LCAr (p < .05. Moreover, the knee flexion-extension angles (minimum and maximum remained lower in LCAr, pre- and post-training (p < .01. The torque gain associated with eccentric isokinetic training did not affect the kinematic parameters of gait in patients undergoing ACL reconstruction.

  3. Plyometric training improves voluntary activation and strength during isometric, concentric and eccentric contractions.

    Science.gov (United States)

    Behrens, Martin; Mau-Moeller, Anett; Mueller, Karoline; Heise, Sandra; Gube, Martin; Beuster, Nico; Herlyn, Philipp K E; Fischer, Dagmar-C; Bruhn, Sven

    2016-02-01

    This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. Twenty-seven participants were randomly assigned to the intervention or control group. Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  4. Comparison of acute responses to isotonic or isokinetic eccentric muscle action: differential outcomes in skeletal muscle damage and implications for rehabilitation.

    Science.gov (United States)

    Alemany, J A; Delgado-Díaz, D C; Mathews, H; Davis, J M; Kostek, M C

    2014-01-01

    Both isotonic and isokinetic eccentric muscle contractions are commonly used in muscle research laboratories to induce muscle damage, yet, the muscle damage outcomes between these 2 modes of eccentric contraction have not been compared. The purpose of this study was to compare modes of contraction for differences in muscle damage. 16 men were placed in the isotonic (IT: 110% of maximal isometric torque) or the isokinetic (IK: 120°/s) group, with each group performing 200 eccentric muscle actions of the knee extensors. Isometric peak torque, perceived soreness and CK activity were measured immediately pre and post exercise, and 48-h post exercise. Mean total work (~1700 J) and peak torque per set (~265 Nm) decreased over the 200 repetitions (ptorque (-13%), creatine kinase activity (+200%) and self-perceived muscular soreness (+4 unit change). Significant group×time interactions (ptorque was 22% lower, and creatine kinase and self-perceived muscular soreness were 330% and 3 unit difference higher in the IT as compared to the IK groups, 48-h post exercise. When equating for total work, skeletal muscle damage markers are higher during IT vs. IK modes. This reflects differences inherent in contraction type and suggests that this should be taken into account during physical rehabilitation.

  5. Inter-machine reliability of the Biodex and Cybex isokinetic dynamometers for knee flexor/extensor isometric, concentric and eccentric tests.

    Science.gov (United States)

    de Araujo Ribeiro Alvares, João Breno; Rodrigues, Rodrigo; de Azevedo Franke, Rodrigo; da Silva, Bruna Gonçalves Cordeiro; Pinto, Ronei Silveira; Vaz, Marco Aurélio; Baroni, Bruno Manfredini

    2015-02-01

    To assess the inter-machine reliability of the Biodex System 3 Pro and Cybex Humac Norm Model 770 dynamometers for knee extensor and knee flexor peak torque measurements in isometric, concentric and eccentric tests. Randomized/crossover. Exercise Research Laboratory, Federal University of Rio Grande do Sul (Brazil). 25 healthy male subjects. Isometric, concentric and eccentric knee extensor and knee flexor peak torques recorded in the same test procedure performed on both isokinetic dynamometers. One-way ANOVA, intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of variation (CV) were used to verify significant differences, relative and absolute reliability between devices. No significant differences were found between tests performed on Biodex and Cybex (p > 0.05). ICC values indicated a high to very high reproducibility for isometric, concentric and eccentric peak torques (0.88-0.92), and moderate to high reliability for agonist-antagonist strength ratios (0.62-0.73). Peak torque did not show great difference between dynamometers for SEM (3.72-11.27 Nm) and CV (5.27-7.77%). Strength ratios presented CV values of 8.57-10.72%. Maximal knee extensor and knee flexor tests performed in isometric (60° of knee flexion), concentric and eccentric modes at 60°/s in Biodex and Cybex dynamometers present similar values. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Brain Functional Connectivity is Different during VoluntaryConcentric and Eccentric Muscle Contraction

    Directory of Open Access Journals (Sweden)

    Wan X Yao

    2016-11-01

    Full Text Available Previous studies report greater activation in the cortical motor network in controlling eccentric contraction (EC than concentric contraction (CC of human skeletal muscles despite lower activation level of the muscle associated with EC. It is unknown, however, whether the strength of functional coupling between the primary motor cortex (M1 and other involved areas in the brain differs as voluntary movements are controlled by a network of regions in the primary, secondary and association cortices. Examining fMRI-based functional connectivity (FC offers an opportunity to measure strength of such coupling. To address the question, we examined functional MRI (fMRI data acquired during EC and CC (20 contractions each with similar movement distance and speed of the right first dorsal interosseous (FDI muscle in 11 young (20-32 years and healthy individuals and estimated FC between the M1 and a number of cortical regions in the motor control network. The major findings from the behavioral and fMRI-based FC analysis were that (1 no significant differences were seen in movement distance, speed and stability between the EC and CC; (2 significantly stronger mean FC was found for CC than EC. Our finding provides novel insights for a better understanding of the control mechanisms underlying voluntary movements produced by EC and CC. The finding is potentially helpful for guiding the development of targeted sport training and/or therapeutic programs for performance enhancement and injury prevention.

  7. An analysis of influence factors during isokinetic eccentric test of knee joint%影响膝关节等速离心收缩测试的相关因素探讨

    Institute of Scientific and Technical Information of China (English)

    成鹏; 毕霞; 郎海涛

    2001-01-01

    Objective: To analyze some influence factors during isokinetic eccentric test. Method: Twenty normal males were tested by Biodex isokinetic test and rehabilitation system. Their peak torque(PT) and peak torque to body weight (PT/BW) were analyzed under different conditions. Result: It was found that velocity and contraction mode influence the results significantly( P<0.01). Conclusion: Many factors must be considered during isokinetic eccentric test and training.%目的:探讨影响膝关节等速离心收缩测试和训练的因素,为进一步深入研究提供客观的依据。方法:利用Biodex等速测试及康复系统测试20健康男性的峰力矩及相对峰力矩,观察速度、惯用肢和功能运动对峰力矩和相对峰力矩的影响。结果:速度和功能运动对峰力矩和相对峰力矩影响显著,而对惯用肢的影响比较复杂。结论:离心等速测试和训练过程中,必须考虑速度、惯用肢和收缩方式等因素。

  8. Isokinetic and isometric muscle strength combined with transcutaneous electrical muscle stimulation in primary fibromyalgia syndrome

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Wildschiødtz, Gordon; Danneskiold-Samsøe, B

    1991-01-01

    Twenty women with primary fibromyalgia syndrome and 20 age matched healthy women were investigated. The subjects performed maximum voluntary isokinetic contractions of the right quadriceps in an isokinetic dynamometer. Maximum voluntary isometric contractions of the right quadriceps were performe...

  9. Combined effects of myofeedback and isokinetic training on hand ...

    African Journals Online (AJOL)

    Khaled A. Olama

    2012-04-25

    Apr 25, 2012 ... physical therapy program with isokinetic training for the triceps brachii muscle for 60 min, in addition group B ... The knee is extended. The foot is planter ..... movement with increased eccentric muscular control, and im-.

  10. Associated decrements in rate of force development and neural drive after maximal eccentric exercise.

    Science.gov (United States)

    Farup, J; Rahbek, S K; Bjerre, J; de Paoli, F; Vissing, K

    2016-05-01

    The present study investigated the changes in contractile rate of force development (RFD) and the neural drive following a single bout of eccentric exercise. Twenty-four subjects performed 15 × 10 maximal isokinetic eccentric knee extensor contractions. Prior to and at 24, 48, 72, 96, and 168 h during post-exercise recovery, isometric RFD (30, 50 100, and 200 ms), normalized RFD [1/6,1/2, and 2/3 of maximal voluntary contraction (MVC)] and rate of electromyography rise (RER; 30, 50, and 75 ms) were measured. RFD decreased by 28-42% peaking at 48 h (P eccentric exercise. This association suggests that exercise-induced decrements in RFD can, in part, be explained decrements in neural drive. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Low-intensity eccentric contractions attenuate muscle damage induced by subsequent maximal eccentric exercise of the knee extensors in the elderly.

    Science.gov (United States)

    Chen, Trevor C; Tseng, Wei-Chin; Huang, Guan-Ling; Chen, Hsin-Lian; Tseng, Kou-Wei; Nosaka, Kazunori

    2013-04-01

    This study investigated whether low-intensity eccentric contractions of the knee extensors would attenuate the magnitude of muscle damage induced by maximal eccentric exercise of the same muscle performed 7 days later using elderly individuals. Healthy older men (66.4 ± 4.6 years) were assigned to control or experimental (Exp) group (n = 13 per group). The control group performed six sets of ten maximal eccentric contractions (MaxECC) of the knee extensors of non-dominant leg. The Exp group performed six sets of ten low-intensity eccentric contractions of the knee extensors on a leg extension machine by lowering a weight of 10 % maximal voluntary isometric knee extension strength (10 %ECC) 7 days prior to MaxECC. Changes in maximal voluntary isokinetic concentric torque (MVC-CON), angle at peak torque, range of motion (ROM), upper thigh circumference, muscle soreness, plasma creatine kinase activity and myoglobin (Mb) concentration and B-mode ultrasound echo-intensity before and for 5 days after MaxECC were compared between groups by a mixed factor ANOVA. No significant changes in any variables were observed following 10 %ECC. Following MaxECC, all variables changed significantly, and changes in all variables except for angle at peak torque were significantly different between groups. MVC-CON and ROM decreased smaller and recovered faster (P eccentric contractions was effective for attenuating muscle damage induced by subsequent MaxECC of the knee extensors for elderly individuals.

  12. Attenuation of indirect markers of eccentric exercise-induced muscle damage by curcumin.

    Science.gov (United States)

    Tanabe, Yoko; Maeda, Seiji; Akazawa, Nobuhiko; Zempo-Miyaki, Asako; Choi, Youngju; Ra, Song-Gyu; Imaizumi, Atsushi; Otsuka, Yoshihiko; Nosaka, Kazunori

    2015-09-01

    Polyphenolic curcumin is known to have potent anti-inflammatory effects; thus the present study investigated the hypothesis that curcumin ingestion would attenuate muscle damage after eccentric exercise. Fourteen untrained young men (24 ± 1 years) performed 50 maximal isokinetic (120°/s) eccentric contractions of the elbow flexors of one arm on an isokinetic dynamometer and the same exercise with the other arm 4 weeks later. They took 150 mg of curcumin (theracurmin) or placebo (starch) orally before and 12 h after each eccentric exercise bout in a randomised, crossover design. Maximal voluntary contraction (MVC) torque of the elbow flexors, range of motion of the elbow joint, upper-arm circumference, muscle soreness, serum creatine kinase (CK) activity, and plasma interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentration were measured before, immediately after, and 24, 48, 72 and 96 h after each eccentric exercise. Changes in these variables over time were compared between curcumin and placebo conditions by two-way repeated measures ANOVA. MVC torque decreased smaller and recovered faster (e.g., 4 days post-exercise: -31 ± 13 % vs. -15 ± 15 %), and peak serum CK activity was smaller (peak: 7684 ± 8959 IU/L vs. 3398 ± 3562 IU/L) for curcumin than placebo condition (P exercise. It is concluded that theracurmin ingestion attenuates some aspects of muscle damage such as MVC loss and CK activity increase.

  13. EFFECT OF HEAT PRECONDITIONING BY MICROWAVE HYPERTHERMIA ON HUMAN SKELETAL MUSCLE AFTER ECCENTRIC EXERCISE

    Directory of Open Access Journals (Sweden)

    Norio Saga

    2008-03-01

    Full Text Available The purpose of this study was to clarify whether heat preconditioning results in less eccentric exercise-induced muscle damage and muscle soreness, and whether the repeated bout effect is enhanced by heat preconditioning prior to eccentric exercise. Nine untrained male volunteers aged 23 ± 3 years participated in this study. Heat preconditioning included treatment with a microwave hyperthermia unit (150 W, 20 min that was randomly applied to one of the subject's arms (MW; the other arm was used as a control (CON. One day after heat preconditioning, the subjects performed 24 maximal isokinetic eccentric contractions of the elbow flexors at 30°·s-1 (ECC1. One week after ECC1, the subjects repeated the procedure (ECC2. After each bout of exercise, maximal voluntary contraction (MVC, range of motion (ROM of the elbow joint, upper arm circumference, blood creatine kinase (CK activity and muscle soreness were measured. The subjects experienced both conditions at an interval of 3 weeks. MVC and ROM in the MW were significantly higher than those in the CON (p < 0.05 for ECC1; however, the heat preconditioning had no significant effect on upper arm circumference, blood CK activity, or muscle soreness following ECC1 and ECC2. Heat preconditioning may protect human skeletal muscle from eccentric exercise-induced muscle damage after a single bout of eccentric exercise but does not appear to promote the repeated bout effect after a second bout of eccentric exercise

  14. Greater strength gains after training with accentuated eccentric than traditional isoinertial loading loads in already strength-trained men

    Directory of Open Access Journals (Sweden)

    Simon eWalker

    2016-04-01

    Full Text Available As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength-trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading versus traditional isoinertial resistance training in strength-trained men. Young (22±3 y, 177±6 cm, 76±10 kg, n = 28 strength-trained men (2.6±2.2 y experience were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40% or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1 and three sets of 10-RM (session 2 bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle and isokinetic (concentric and eccentric 30°.s-1 knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasound and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18±10% vs. 1±5%, p<0.01, which was accompanied by an increase in voluntary activation (3.5±5%, p<0.05. Isokinetic eccentric torque increased significantly after accentuated eccentric load training only (10±9%, p<0.05, whereas concentric torque increased equally in both

  15. Whey protein isolate attenuates strength decline after eccentrically-induced muscle damage in healthy individuals

    Directory of Open Access Journals (Sweden)

    Cribb Paul J

    2010-09-01

    Full Text Available Abstract Background We examined the effects of short-term consumption of whey protein isolate on muscle proteins and force recovery after eccentrically-induced muscle damage in healthy individuals. Methods Seventeen untrained male participants (23 ± 5 yr, 180 ± 6 cm, 80 ± 11 kg were randomly separated into two supplement groups: i whey protein isolate (WPH; n = 9; or ii carbohydrate (CHO; n = 8. Participants consumed 1.5 g/kg.bw/day supplement (~30 g consumed immediately, and then once with breakfast, lunch, in the afternoon and after the evening meal for a period of 14 days following a unilateral eccentric contraction-based resistance exercise session, consisting of 4 sets of 10 repetitions at 120% of maximum voluntary contraction on the leg press, leg extension and leg flexion exercise machine. Plasma creatine kinase and lactate dehydrogenase (LDH levels were assessed as blood markers of muscle damage. Muscle strength was examined by voluntary isokinetic knee extension using a Cybex dynamometer. Data were analyzed using repeated measures ANOVA with an alpha of 0.05. Results Isometric knee extension strength was significantly higher following WPH supplementation 3 (P Conclusions The major finding of this investigation was that whey protein isolate supplementation attenuated the impairment in isometric and isokinetic muscle forces during recovery from exercise-induced muscle injury.

  16. Assessment of Muscle Pain Induced by Elbow-Flexor Eccentric Exercise.

    Science.gov (United States)

    Lau, Wing Yin; Blazevich, Anthony J; Newton, Michael J; Wu, Sam Shi Xuan; Nosaka, Kazunori

    2015-11-01

    Delayed-onset muscle soreness (DOMS) is a common muscle pain that many people experience and is often used as a model of acute muscle pain. Researchers have reported the effects of various interventions on DOMS, but different DOMS assessment protocols used in these studies make it difficult to compare the effects. To investigate DOMS characteristics after elbow-flexor eccentric exercise to establish a standardized DOMS assessment protocol. Descriptive laboratory study. Research laboratory. Ten healthy, untrained men (21-39 years). Participants performed 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors. Indirect muscle-damage markers were maximal voluntary isometric contraction torque, range of motion, and serum creatine kinase activity. Muscle pain was assessed before exercise, immediately postexercise, and 1 to 5 days postexercise using (1) a visual analog scale (VAS), (2) a category ratio-10 scale (CR-10) when applying static pressure and palpation at different sites (3, 9, and 15 cm above the elbow crease), and (3) pressure-pain thresholds (PPTs) at 50 sites (pain mapping). Maximal voluntary isometric contraction and range of motion decreased and creatine kinase activity increased postexercise, indicating muscle damage. Palpation induced greater pain than static pressure, and longitudinal and transverse palpations induced greater pain than circular palpation (P exercise, but the pain-sensitive regions shifted to the central and distal regions of the biceps brachii at 1 to 3 days postexercise (P eccentric exercise.

  17. Effect of Isokinetic Training Concentrically and Eccentrically on Knee Peak Torque and Hamstring/Quadricep Ratio%等速向心/离心训练对膝关节峰力矩和屈/伸肌峰力矩比影响的比较

    Institute of Scientific and Technical Information of China (English)

    柳华; 杨翼; 黄晓琳

    2015-01-01

    目的:分别进行4周膝关节的等速向心(c)/离心(e)训练后,比较屈膝肌(H)和伸膝肌(Q)在训练前后向心/离心收缩峰力矩(Hc、He、Qc、Qe)及其比值的变化及性别差异,为膝关节肌肉康复训练运动处方的制定提供参考。方法2014年5~6月本校无任何训练基础的28名大学生分为向心组(n=14)和离心组(n=14),分别在BIODEX等速肌力评估训练系统4上进行每周3次、共4周的右膝等速向心/离心训练。测量向心30°/s、60°/s、90°/s和离心60°/s、90°/s、120°/s训练前后峰力矩。结果向心组训练后60°/s、90°/s的Hc、He增加(P0.05)。向心组He/Qc在90°/s、Hc/Qc在30°/s均下降(P0.05)。向心组Qc/Qe在60º/s和90º/s,Hc/He在90º/s均提高(P0.05)。女性Hc、He、Qc、Qe、He/Qc与男性比较有显著性差异(P0.05). After concentric isokinet-ic training, the He/Qc ratio decreased at 90 °/s (P0.05). The Qc/Qe ratio increased at 60 °/s and 90 °/s (P0.05). There were significant differences in Hc, He, Qc, Qe and He/Qc ratio between different genders (P<0.05). Conclusion Concentric training and ec-centric training have different influences on the muscle strength after 4 weeks training. Eccentric training only can reduce the knee stability. Hc/He ratio and Qc/Qe ratio can be used to evaluate the knee muscle function. Gender should be considered into training.

  18. The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance.

    Science.gov (United States)

    Ratamess, Nicholas A; Beller, Noah A; Gonzalez, Adam M; Spatz, Gregory E; Hoffman, Jay R; Ross, Ryan E; Faigenbaum, Avery D; Kang, Jie

    2016-03-01

    The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM) strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT) or a non-exercising control group (CTL). The IRT group underwent 6 weeks of training (2 days per week) consisting of 5 sets of 6-10 repetitions at 75-85% of subjects' peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s(-1) [3-sec concentric (CON) and 3-sec eccentric (ECC) phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey's post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg), 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg), and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions) increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women. Key pointsMultiple-joint isokinetic resistance training increases dynamic maximal muscular strength, local muscular endurance, and maximal isokinetic strength in women.Multiple-joint isokinetic resistance training increased 1RM strength in the bench press (by

  19. Residual force enhancement following eccentric induced muscle damage.

    Science.gov (United States)

    Power, Geoffrey A; Rice, Charles L; Vandervoort, Anthony A

    2012-06-26

    During lengthening of an activated skeletal muscle, the force maintained following the stretch is greater than the isometric force at the same muscle length. This is termed residual force enhancement (RFE), but it is unknown how muscle damage following repeated eccentric contractions affects RFE. Using the dorsiflexors, we hypothesised muscle damage will impair the force generating sarcomeric structures leading to a reduction in RFE. Following reference maximal voluntary isometric contractions (MVC) in 8 young men (26.5±2.8y) a stretch was performed at 30°/s over a 30° ankle excursion ending at the same muscle length as the reference MVCs (30° plantar flexion). Surface electromyography (EMG) of the tibialis anterior and soleus muscles was recorded during all tasks. The damage protocol involved 4 sets of 25 isokinetic (30°/s) lengthening contractions. The same measures were collected at baseline and immediately post lengthening contractions, and for up to 10min recovery. Following the lengthening contraction task, there was a 30.3±6.4% decrease in eccentric torque (Pmuscle damage (Pmuscle function compared to isometric actions succeeding damage. Thus, active force of cross-bridges is decreased because of impaired excitation-contraction coupling but force generated during stretch remains intact because force contribution from stretched sarcomeric structures is less impaired.

  20. Peak torque and knee kinematics during gait after eccentric isokinetic training of quadriceps in healthy subjects O pico de torque e a cinemática do joelho durante a marcha após treino isocinético excêntrico do quadríceps em sujeitos saudáveis

    Directory of Open Access Journals (Sweden)

    PR Poletto

    2008-08-01

    Full Text Available OBJECTIVE: To evaluate the effects of eccentric isokinetic training on knee range of motion (ROM of healthy subjects. METHODS: The knee extensor and flexor isokinetic peak torques and ROM of flexion/extension and varus/valgus knee movements during gait of 18 healthy men (21.7±2.2 years; 1.73±0.10m; 68.7±9.4kg; body mass index: 22.6±2kg/m² were analyzed, before and after six weeks of bilateral eccentric isokinetic training of the knee extensors at 30º/s. RESULTS: The knee extensor torque increased in both limbs (right, from 229±54 to 304±53Nm; pOBJETIVO: Avaliar os efeitos do treino isocinético excêntrico sobre a amplitude de movimento (ADM do joelho em sujeitos saudáveis. MÉTODOS: Foram analisados os picos de torque isocinético dos extensores e flexores do joelho e a ADM de flexo/extensão e valgo/varo, durante a marcha, de 18 homens saudáveis (21,7±2,2 anos; 1,73±0,10m; 68,7±9,4kg; índice de massa corpórea: 22,6±2kg/m² antes e após seis semanas de treino isocinético excêntrico bilateral dos extensores do joelho a 30º/s. RESULTADOS: O torque extensor do joelho aumentou em ambos os membros, direito (de 229±54 para 304±53Nm; p<0,01 e esquerdo (de 228±59 para 311±63Nm; p<0,01 sem diferença de ganho de torque entre eles. O pico de torque flexor aumentou (de 114±30 para 123±22Nm; p<0,05, mas a razão isquiotibiais/quadríceps (I/Q diminuiu (de 0,5±0,08 para 0,39±0,07; p<0,01 após o treino. Não houve diferença para os movimentos de flexo/extensão e valgo/varo após o treino, exceto uma pequena mudança (4° no valgo para o joelho esquerdo. CONCLUSÕES: O treino isocinético excêntrico dos extensores do joelho aumentou o torque extensor e diminuiu a razão I/Q, entretanto o efeito sobre o padrão da marcha parece desprezível em sujeitos saudáveis. Um treino associado dos flexores, complementar ao treino dos extensores parece ser necessário para o equilíbrio entre agonistas e antagonistas do joelho.

  1. Eccentric training for shoulder abductors improves pain, function and isokinetic performance in subjects with shoulder impingement syndrome: a case series Treino excêntrico para abdutores do ombro melhora dor, função e desempenho isocinético em sujeitos com síndrome do impacto: série de casos

    Directory of Open Access Journals (Sweden)

    Paula R. Camargo

    2012-02-01

    Full Text Available BACKGROUND: Conservative treatments have been proposed for people with shoulder impingement syndrome (SIS, such as strengthening of the rotator cuff and scapular muscles and stretching of the soft tissues of the shoulder. However, there is a lack of studies analyzing the effectiveness of eccentric training in the treatment of SIS. OBJECTIVES: To evaluate the effects of eccentric training for shoulder abductors on pain, function, and isokinetic performance during concentric and eccentric abduction of the shoulder in subjects with SIS. METHODS: Twenty subjects (7 females, 34.2 SD 10.2 years, 1.7 SD 0.1 m, 78.0 SD 16.3 kg with unilateral SIS completed the study protocol. Bilateral isokinetic eccentric training at 60º/s for shoulder abductors was performed for six consecutive weeks, twice a week, on alternate days. For each training day, three sets of 10 repetitions were performed with a 3-minute rest period between the sets for each side. The range of motion trained was 60° (ranging from 80° to 20°. The Disabilities of the Arm, Shoulder and Hand (DASH questionnaire was used to evaluate functional status and symptoms of the upper limbs. Peak torque, total work and acceleration time were measured during concentric and eccentric abduction of the arm at 60º/s and 180º/s using an isokinetic dynamometer. RESULTS: DASH scores, peak torque, total work and acceleration time improved (pCONTEXTUALIZAÇÃO: Tratamentos conservadores têm sido propostos para pessoas com síndrome do impacto (SI do ombro, como fortalecimento do manguito rotador e dos músculos escapulares e alongamento dos tecidos moles do ombro. No entanto, são escassos os estudos que analisaram a eficácia do treinamento excêntrico no tratamento da SI. OBJETIVOS: Avaliar os efeitos do treinamento excêntrico para abdutores do ombro na dor, função e desempenho isocinético durante a abdução concêntrica e excêntrica do ombro em indivíduos com SI. MÉTODOS: Vinte indivíduos (sete

  2. Reduced susceptibility to eccentric exercise-induced muscle damage in resistance-trained men is not linked to resistance training-related neural adaptations

    Science.gov (United States)

    Beck, TW; Wages, NP

    2015-01-01

    The purpose of this study was to examine the acute effects of maximal concentric vs. eccentric exercise on the isometric strength of the elbow flexor, as well as the biceps brachii muscle electromyographic (EMG) responses in resistance-trained (RT) vs. untrained (UT) men. Thirteen RT men (age: 24 ± 4 years; height: 180.2 ± 7.7 cm; body weight: 92.2 ± 16.9 kg) and twelve UT men (age: 23 ± 4 years; height: 179.2 ± 5.0 cm; body weight: 81.5 ± 8.6 kg) performed six sets of ten maximal concentric isokinetic (CON) or eccentric isokinetic (ECC) elbow flexion exercise in two separate visits. Before and after the exercise interventions, maximal voluntary contractions (MVCs) were performed for testing isometric strength. In addition, bipolar surface EMG signals were detected from the biceps brachii muscle during the strength testing. Both CON and ECC caused isometric strength to decrease, regardless of the training status. However, ECC caused greater isometric strength decline than CON did for the UT group (p = 0.006), but not for the RT group. Both EMG amplitude and mean frequency significantly decreased and increased, respectively, regardless of the training status and exercise intervention. Resistance-trained men are less susceptible to eccentric exercise-induced muscle damage, but this advantage is not likely linked to the chronic resistance training-induced neural adaptations. PMID:26424922

  3. Two maximal isometric contractions attenuate the magnitude of eccentric exercise-induced muscle damage.

    Science.gov (United States)

    Chen, Hsin-Lian; Nosaka, Kazunori; Pearce, Alan J; Chen, Trevor C

    2012-08-01

    This study investigated whether maximal voluntary isometric contractions (MVC-ISO) would attenuate the magnitude of eccentric exercise-induced muscle damage. Young untrained men were placed into one of the two experimental groups or one control group (n = 13 per group). Subjects in the experimental groups performed either two or 10 MVC-ISO of the elbow flexors at a long muscle length (20° flexion) 2 days prior to 30 maximal isokinetic eccentric contractions of the elbow flexors. Subjects in the control group performed the eccentric contractions without MVC-ISO. No significant changes in maximal voluntary concentric contraction peak torque, peak torque angle, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and myoglobin concentration, muscle soreness, and ultrasound echo intensity were evident after MVC-ISO. Changes in the variables following eccentric contractions were smaller (P MVC-ISO group (e.g., peak torque loss at 5 days after exercise, 23% ± 3%; peak CK activity, 1964 ± 452 IU·L(-1); peak muscle soreness, 46 ± 4 mm) or the 10 MVC-ISO group (13% ± 3%, 877 ± 198 IU·L(-1), 30 ± 4 mm) compared with the control (34% ± 4%, 6192 ± 1747 IU·L(-1), 66 ± 5 mm). The 10 MVC-ISO group showed smaller (P MVC-ISO group. Therefore, two MVC-ISO conferred potent protective effects against muscle damage, whereas greater protective effect was induced by 10 MVC-ISO, which can be used as a strategy to minimize muscle damage.

  4. Changes in electrical pain threshold of fascia and muscle after initial and secondary bouts of elbow flexor eccentric exercise.

    Science.gov (United States)

    Lau, Wing Yin; Blazevich, Anthony J; Newton, Michael J; Wu, Sam Shi Xuan; Nosaka, Kazunori

    2015-05-01

    This study investigated changes in electrical pain threshold (EPT) after repeated eccentric exercise bouts to test the hypothesis that fascia would become more sensitive than muscle when greater delayed onset muscle soreness (DOMS) is induced. Ten young men performed two eccentric exercise bouts (ECC1, ECC2) consisting of ten sets of six maximal isokinetic eccentric contractions of the elbow flexors with the same arm separated by 4 weeks. Maximal voluntary isometric contraction torque, range of motion, muscle soreness assessed by a visual analogue scale (VAS) and pressure pain threshold (PPT) were measured before, immediately after and 1-5 days after exercise. EPT was assessed in the biceps brachii fascia (BBF), biceps brachii muscle, and brachialis fascia (BF) 1 day before, immediately after, and 1, 2 and 4 days after exercise. All measures showed smaller changes (P fascia becomes more sensitive than muscle to electrical stimulation after the initial eccentric exercise, suggesting that damage inflammation to fascia than muscle fibres is more associated with DOMS.

  5. Creatine supplementation enhances muscle force recovery after eccentrically-induced muscle damage in healthy individuals

    Directory of Open Access Journals (Sweden)

    Cribb Paul J

    2009-06-01

    Full Text Available Abstract Background Eccentric exercise-induced damage leads to reductions in muscle force, increased soreness, and impaired muscle function. Creatine monohydrate's (Cr ergogenic potential is well established; however few studies have directly examined the effects of Cr supplementation on recovery after damage. We examined the effects of Cr supplementation on muscle proteins and force recovery after eccentrically-induced muscle damage in healthy individuals. Methods Fourteen untrained male participants (22.1 ± 2.3 yrs, 173 ± 7.7 cm, 76.2 ± 9.3 kg were randomly separated into 2 supplement groups: i Cr and carbohydrate (Cr-CHO; n = 7; or ii carbohydrate (CHO; n = 7. Participants consumed their supplement for a period of 5 days prior to, and 14 days following a resistance exercise session. Participants performed 4 sets of 10 eccentric-only repetitions at 120% of their maximum concentric 1-RM on the leg press, leg extension and leg flexion exercise machine. Plasma creatine kinase (CK and lactate dehydrogenase (LDH activity were assessed as relevant blood markers of muscle damage. Muscle strength was examined by voluntary isokinetic knee extension using a Cybex dynamometer. Data were analyzed using repeated measures ANOVA with an alpha of 0.05. Results The Cr-supplemented group had significantly greater isokinetic (10% higher and isometric (21% higher knee extension strength during recovery from exercise-induced muscle damage. Furthermore, plasma CK activity was significantly lower (by an average of 84% after 48 hrs (P Conclusion The major finding of this investigation was a significant improvement in the rate of recovery of knee extensor muscle function after Cr supplementation following injury.

  6. Acute effects of two different stretching techniques on isokinetic strength and power

    OpenAIRE

    Ayala, F.; De Ste Croix, M; Sainz de Baranda, P.; Santonja, F.

    2015-01-01

    Objectives: To examine and compare the acute effects of short duration static and dynamic lower-limb stretching routines on the knee flexor and extensor peak torque and mean power during maximal concentric and eccentric muscle actions. Method: Forty-nine active adults completed the following intervention protocols on separate days: non-stretching, static stretching and dynamic stretching. After the stretching or control intervention, concentric and eccentric isokinetic peak torque and mean...

  7. Proprioceptive isokinetic exercise test

    Science.gov (United States)

    Dempster, P. T.; Bernauer, E. M.; Bond, M.; Greenleaf, J. E.

    1993-01-01

    Proprioception, the reception of stimuli within the body that indicates position, is an important mechanism for optimal human performance. People exposed to prolonged bed rest, microgravity, or other deconditioning situations usually experience reduced proprioceptor and kinesthetic stimuli that compromise body balance, posture, and equilibrium. A new proprioceptive test is described that utilizes the computer-driven LIDO isokinetic ergometer. An overview of the computer logic, software, and testing procedure for this proprioceptive test, which can be performed with the arms or legs, is described.

  8. Isokinetic sampler; Amostrador isocinetico

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Luis Cesar C. de; Santos, Antonio Carlos dos [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Barrio, Lara B.A. del [AZ Armaturen do Brasil Ltda., Itatiba, SP (Brazil); Silva, Claudio B. da C. e; Silva, Ricardo R. da [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2005-07-01

    The Center of Research Leopoldo A. Miguez de Melo - CENPES - in association with AZ Armaturen Company do Brasil and TRANSPETRO developed and tested an Isokinetic sampler. This work presents the sampling principles and the results and performance of the tests realized in the 'Sitio de Testes de Atalaia' and in one of the terminals of bunker transfer of TRANSPETRO - 'Terminal Aquaviario da Baia de Guanabara'. In the 'Sitio de Testes' the products used were oil and water with BSW from 5% to 97% and in the terminal were tested samplings of bunker with ranges viscosities between (MF 180 to 380). (author)

  9. Isokinetic strength effects of FIFA'a "The 11+" injury prevention training programme

    DEFF Research Database (Denmark)

    Brito, João; Figueiredo, Pedro; Fernandes, Luís;

    2010-01-01

    times a week for 10 weeks. Isokinetic measurements were performed on the hamstrings and quadriceps muscles on both lower extremities at concentric 60 and 180°/s and eccentric 30°/s. The peak torque (PT) as well as conventional and dynamic control ratios (DCR) were calculated. Hamstrings PT in the non...

  10. Análise da resposta da freqüência cardíaca durante a realização de exercício isocinético excêntrico de grupamento extensor de joelho Analysis of heart rate response during eccentric isokinetic exercise of knee extensor muscle group

    Directory of Open Access Journals (Sweden)

    CA Malfatti

    2006-01-01

    Full Text Available Objetivo: Investigar a magnitude da resposta da freqüência cardíaca durante o exercício isocinético excêntrico do grupamento extensor do joelho, em diferentes velocidades angulares. Materiais e Métodos: Dez voluntários jovens, sadios e ativos foram submetidos a contração excêntrica máxima do grupo extensor do joelho dominante. Foi utilizado um dinamômetro isocinético, nas velocidades de 30º/s, 60º/s e 120º/s, ordenadas aleatoriamente. A FC foi obtida batimento a batimento, na derivação eletrocardiográfica MC5 modificada, durante 60s pré-exercício, durante o tempo de contração, sendo cinco repetições para cada velocidade, e por 120s após o esforço. Foram calculadas: FC média dos 60s pré-exercício, FC pico atingida ao final do esforço, e variação da FC (DFC, além dos valores do pico de torque. Também foram comparados valores da FC média dos 6 minutos pré-exercício com os 6 minutos de recuperação. Os resultados foram comparados pelo teste de Friedman com post hoc de Dunn. O nível de significância estabelecido foi de 5%. Resultados: Não foram observadas diferenças estatisticamente significantes entre os valores medianos da FC de repouso (68bpm para 30º/s e 60º/s, 70bpm para 120º/s, FC pico (107bpm para 30º/s, 103 em 60º/s e 100bpm em 120º/s e DFC (37bpm para 30º/s, 35bpmem 60º/s e 27bpm para 120ºs, além do pico de torque (209,5N/m para 30º/s, 217,2N/m em 60º/s e 210,6N/m para 120º/s. A mediana dos valores de FC anteriores ao esforço foi semelhante aos de recuperação (67bpm. Conclusão:A magnitude de resposta da FC foi semelhante, durante atividade muscular excêntrica, indicando uma mesma sobrecarga cardíaca, independente da velocidade angular realizada.Objective: To investigate heart rate response magnitudes during eccentric isokinetic exercise of the knee extensor muscles, at different angular velocities. Method: Ten healthy and active young volunteers underwent maximum eccentric

  11. Reduced muscle lengthening during eccentric contractions as a mechanism underpinning the repeated-bout effect.

    Science.gov (United States)

    Lau, Wing Yin; Blazevich, Anthony J; Newton, Michael J; Wu, Sam Shi Xuan; Nosaka, Kazunori

    2015-05-15

    This study investigated biceps brachii distal myotendinous junction (MTJ) displacement during maximal eccentric elbow flexor contractions to test the hypothesis that muscle length change would be smaller (less MTJ displacement) during the second than the first exercise bout. Ten untrained men performed two eccentric exercise bouts (ECC1 and ECC2) with the same arm consisting of 10 sets of six maximal isokinetic (60°/s) eccentric elbow flexor contractions separated by 4 wk. Biceps brachii distal MTJ displacement was assessed using B-mode ultrasonography, and changes in the displacement (muscle length change) from the start to the end of each contraction during each set and over 10 sets were compared between bouts by two-way repeated-measures ANOVA. Several indirect muscle damage markers were also measured and compared between bouts by two-way repeated-measures ANOVA. The magnitude of MTJ displacement (average of six contractions) increased from set 1 (8.2 ± 4.7 mm) to set 10 (16.4 ± 4.7 mm) during ECC1 (P < 0.05), but no significant changes over sets were evident during ECC2 (set 1: 8.5 ± 4.0 mm; set 10: 9.3 ± 3.1 mm). Changes in maximal voluntary isometric contraction strength, range of motion, muscle thickness, ultrasound echo intensity, serum creatine kinase activity, and muscle soreness (visual analog scale) were smaller (P < 0.05) following ECC2 than ECC1, showing less damage in the repeated bout. These results indicate that the magnitude of muscle lengthening was less during the second than the first eccentric exercise bout, which appears to be a mechanism underpinning the repeated-bout effect. Copyright © 2015 the American Physiological Society.

  12. The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance

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    Nicholas A. Ratamess, Noah A. Beller, Adam M. Gonzalez, Gregory E. Spatz, Jay R. Hoffman, Ryan E. Ross, Avery D. Faigenbaum, Jie Kang

    2016-03-01

    Full Text Available The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT or a non-exercising control group (CTL. The IRT group underwent 6 weeks of training (2 days per week consisting of 5 sets of 6-10 repetitions at 75-85% of subjects’ peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s-1 [3-sec concentric (CON and 3-sec eccentric (ECC phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey’s post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg, 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg, and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women.

  13. Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications.

    Science.gov (United States)

    Harris-Love, Michael O; Seamon, Bryant A; Gonzales, Tomas I; Hernandez, Haniel J; Pennington, Donte; Hoover, Brian M

    2017-01-01

    The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0-10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from -5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s(-1) while

  14. Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications

    Science.gov (United States)

    Harris-Love, Michael O.; Seamon, Bryant A.; Gonzales, Tomas I.; Hernandez, Haniel J.; Pennington, Donte; Hoover, Brian M.

    2017-01-01

    The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0–10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from −5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s−1

  15. Eccentric exercise

    DEFF Research Database (Denmark)

    Kjaer, Michael; Heinemeier, Katja Maria

    2014-01-01

    Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive...

  16. Kinesio Taping Does Not Alter Quadriceps Isokinetic Strength and Power in Healthy Nonathletic Men: A Prospective Crossover Study

    Directory of Open Access Journals (Sweden)

    Paweł Korman

    2015-01-01

    Full Text Available Objectives. The effects of Kinesio Taping (KT on muscular performance remain largely unclear. This study aimed to investigate the acute effects of KT on the maximum concentric and eccentric quadriceps isokinetic strength. Study Design. This is a single-blinded, placebo crossover, repeated measures study. Methods. Maximum isokinetic concentric/eccentric extension torque, work, and power were assessed by an isokinetic dynamometer without taping (NT and with KT or placebo taping (PT in 17 healthy young men. Repeated measures one-way analysis of variance (ANOVA was used for statistical analyses. Results. Testing concentric contractions at 60°/s or 180°/s isokinetic speed, no significant differences in peak torque (Nm, total work (J, or mean power (W were noted among the application modes under different conditions. Testing eccentric contractions at 30°/s or 60°/s isokinetic speed, no significant differences in mentioned parameters were noted, respectively. KT on the quadriceps neither decreased nor increased muscle strength in the participants. Conclusion. KT application onto the skin overlying the quadriceps muscle does not enhance the strength or power of knee extensors in healthy men.

  17. Concentrically trained cyclists are not more susceptible to eccentric exercise-induced muscle damage than are stretch-shortening exercise-trained runners.

    Science.gov (United States)

    Snieckus, Audrius; Kamandulis, Sigitas; Venckūnas, Tomas; Brazaitis, Marius; Volungevičius, Gintautas; Skurvydas, Albertas

    2013-03-01

    Here, we test the hypothesis that continuous concentric exercise training renders skeletal muscles more susceptible to damage in response to eccentric exercise. Elite road cyclists (CYC; n = 10, training experience 8.1 ± 2.0 years, age 22.9 ± 3.7 years), long-distance runners (LDR; n = 10, 9.9 ± 2.3 years, 24.4 ± 2.5 years), and healthy untrained (UT) men (n = 10; 22.4 ± 1.7 years) performed 100 submaximal eccentric contractions at constant angular velocity of 60° s(-1). Concentric isokinetic peak torque, isometric maximal voluntary contraction (MVC), and electrically induced knee extension torque were measured at baseline and immediately and 48 h after an eccentric exercise bout. Muscle soreness was assessed and plasma creatine kinase (CK) activity was measured at baseline and 48 h after exercise. Voluntary and electrically stimulated knee extension torque reduction were significantly greater (p exercise, MVC decreased by 32 % and 20 % in UT, 20 % and 5 % in LDR, and 25 % and 6 % in CYC. Electrically induced 20 Hz torque decreased at the same times by 61 and 29 % in UT, 40 and 17 % in LDR, and 26 and 14 % in CYC. Muscle soreness and plasma CK activity 48 h after exercise did not differ significantly between athletes and UT subjects. In conclusion, even though elite endurance athletes are more resistant to eccentric exercise-induced muscle damage than are UT people, stretch-shortening exercise-trained LDR have no advantage over concentrically trained CYC.

  18. Isokinetic leg strength and power in elite handball players.

    Science.gov (United States)

    González-Ravé, José M; Juárez, Daniel; Rubio-Arias, Jacobo A; Clemente-Suarez, Vicente J; Martinez-Valencia, María A; Abian-Vicen, Javier

    2014-06-28

    Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.

  19. Isokinetic muscle strength and running long jump performance in young jumpers

    Directory of Open Access Journals (Sweden)

    YIANNIS KOUTSIORAS; ATHANASIOS TSIOKANOS; DIMITRIOS TSAOPOULOS; PANAGIOTIS TSIMEAS

    2009-01-01

    Full Text Available The aim of this study was two-fold. Firstly we wanted to quantify the relationship of isokinetic muscle strength (IMS and long jump performance (LJP in young jumpers, and secondly to compare males and females in IMS. Our measurements in 7 males and 7 females showed that the LJP was correlated with the normalized peak joint moment of the concentric knee extensions and the concentric ankle plantar flexions. A low correlation was observed between the LJP and the eccentric knee extensions. The t-test showed significant gender differences in joint peak moment of concentric knee extensions and in normalized peak joint moment of concentric plantar flexions and eccentric plantar flexions at120 deg/sec. Although, our findings suggest that IMS is a major contributor to LJP, it is suggested that training intervention should not be based exclusively on isokinetic tests because of the differences in musculoskeletal function between the two movements.

  20. Acute effects of two different stretching techniques on isokinetic strength and power

    Directory of Open Access Journals (Sweden)

    F. Ayala

    2015-09-01

    Conclusions: Short pre-exercise static and dynamic lower-limb stretching routines did not elicit stretching-induce reductions or improvements in knee flexor and knee extensor isokinetic concentric and eccentric strength. In addition, the findings of the current study support the claim that dynamic stretching may be preferable to static stretching as part of a warm-up designed to prepare for physical activity.

  1. Isokinetic Strength Profile of Elite Female Handball Players

    Directory of Open Access Journals (Sweden)

    Xaverova Zuzana

    2015-12-01

    Full Text Available Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women’s Junior National Handball Team (JNT, n=8 or the Women’s National Handball Team (NT, n=9. The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric and 60°/s (eccentric. The Mann- Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02. However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

  2. Isokinetic Strength Profile of Elite Female Handball Players.

    Science.gov (United States)

    Xaverova, Zuzana; Dirnberger, Johannes; Lehnert, Michal; Belka, Jan; Wagner, Herbert; Orechovska, Karolina

    2015-12-22

    Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women's Junior National Handball Team (JNT, n=8) or the Women's National Handball Team (NT, n=9). The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric) and 60°/s (eccentric). The Mann-Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD) for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02). However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

  3. [Reliability and validity of the analysis of hand grip and pinch force in isometric and isokinetic conditions].

    Science.gov (United States)

    Benaglia, P G; Franchignoni, F; Ferriero, G; Zebellin, G; Sartorio, F

    1999-01-01

    Strength measurement of the hand grip is at the core of most protocols of functional assessment of the upper limb and in rehabilitation plays a major role in the analysis of treatment efficacy and patients' occupational ability. The aims of this study were to: a) verify the repeatability of strength measurements made during performance of the hand grip and three types of pinch, carried out under isometric and isokinetic conditions; b) compare maximal isometric strength with the corresponding isokinetic value for each of the manoeuvres studied; c) investigate the correlations between the strength expressed in the different manoeuvres, under both isometric and isokinetic conditions. We studied 14 voluntary subjects over three sessions conducted at 48-hr intervals, employing a computerized isokinetic dynamometer Lido WorkSet equipped with device N(o) 21 for the study of pinch (lateral pinch, pulp pinch, chuck pinch) and device N(o) 52 for the grip study. Isometric contractions resulted stronger than isokinetic ones, and the hand grip was found to be the manoeuvre able to produce most strength. The repeatability of each strength measurement test over the three days was high (Intraclass Correlation Coefficients: 0.89-0.93). Correlations between the isometric and isokinetic performance for each of the manoeuvres examined were always high (Pearson's r coefficients: 0.89-0.95) as were those between the different manoeuvres, whether performed in isometric or isokinetic modality (r: 0.60-0.94).

  4. Neuromuscular factors contributing to in vivo eccentric moment generation.

    Science.gov (United States)

    Webber, S; Kriellaars, D

    1997-07-01

    Muscle series elasticity and its contribution to eccentric moment generation was examined in humans. While subjects [male, n = 30; age 26.3 +/- 4.8 (SD) yr; body mass 78.8 +/- 13.1 kg] performed an isometric contraction of the knee extensors at 60 degrees of knee flexion, a quick stretch was imposed with a 12 degrees -step displacement at 100 degrees /s. The test was performed at 10 isometric activation levels ranging from 1.7 to 95.2% of maximal voluntary contraction (MVC). A strong linear relationship was observed between the peak imposed eccentric moment derived from quick stretch and the isometric activation level (y = 1.44x + 7.08; r = 0.99). This increase in the eccentric moment is consistent with an actomyosin-dependent elasticity located in series with the contractile element of muscle. By extrapolating the linear relationship to 100% MVC, the predicted maximum eccentric moment was found to be 151% MVC, consistent with in vitro data. A maximal voluntary, knee extensor strength test was also performed (5-95 degrees, 3 repetitions, +/-50, 100, 150, 200, and 250 degrees/s). The predicted maximum eccentric moment was 206% of the angle- and velocity-matched, maximal voluntary eccentric moments. This was attributed to a potent neural regulatory mechanism that limits the recruitment and/or discharge of motor units during maximal voluntary eccentric contractions.

  5. Functional and morphological changes in the quadriceps muscle induced by eccentric training after ACL reconstruction

    OpenAIRE

    Brasileiro,Jamilson S.; Pinto,Olga M. S. F.; Mariana A. Ávila; Tania F. Salvini

    2011-01-01

    OBJECTIVES: The purpose of this study was to investigate the contributions of functional and morphological factors in the recovery of the quadriceps muscle after anterior cruciate ligament (ACL) reconstruction. METHODS: Nine subjects (31.3±5.8 years) underwent eccentric exercise sessions twice a week for 12 weeks. Quadriceps muscle function was evaluated using an isokinetic dynamometer (isometric and eccentric peak torque) and electromyography (RMS). Morphological changes were measured using ...

  6. Isokinetic exercise: A review of the literature

    Science.gov (United States)

    Olree, H. D.; Corbin, B.; Smith, C.

    1978-01-01

    Isokinetic muscle training has all the advantages of isometrics and isotonics while minimizing their deficiencies. By holding the speed of movement constant throughout the full range of motion, isokinetic training devices respond with increased resistance rather than acceleration when the power output of the muscle is increased. Isokinetic training is superior to isometric and isotonic training with respect to increases in strength, specificity of training, desirable changes in motor performance tasks, lack of muscle soreness, and decreases in relative body fat.

  7. Influence of acute eccentric exercise on the H:Q ratio.

    Science.gov (United States)

    Thompson, B J; Smith, D B; Sobolewski, E J; Fiddler, R E; Everett, L; Klufa, J L; Ryan, E D

    2011-12-01

    The purpose of the present study was to examine the effects of an acute bout of eccentric exercise on maximal isokinetic concentric peak torque (PT) of the leg flexors and extensors and the hamstrings-to-quadriceps (H:Q) strength ratio. Sixteen male (mean±SD: age=20.9±2 years; stature=177.0±4.4 cm; mass=76.8±10.0 kg) volunteers performed maximal, concentric isokinetic leg extension and flexion muscle actions at 60°·sec - 1 before and after (24-72 h) a bout of eccentric exercise. The eccentric exercise protocol consisted of 4 sets of 10 repetitions for the leg press, leg extension, and leg curl exercises at 120% of the concentric one repetition maximum (1-RM). The results indicated that the acute eccentric exercise protocol resulted in a significant (Pexercise. However, the H:Q ratios were unaltered by the eccentric exercise protocol. These findings suggest that an acute bout of eccentric exercise utilizing both multi - and single - joint dynamic constant external resistance (DCER) exercises results in similar decreases in maximal isokinetic strength of the leg flexors and extensors, but does not alter the H:Q ratio. © Georg Thieme Verlag KG Stuttgart · New York.

  8. Knee Extensor Electromyographic Activity-to-Work Ratio is Greater With Isotonic Than Isokinetic Contractions.

    Science.gov (United States)

    Schmitz, Randy J.; Westwood, Kevin C.

    2001-12-01

    OBJECTIVE: To determine whether isotonic or isokinetic contractions produced greater electromyographic (EMG) activity per unit of work during isotonic and isokinetic knee-extension exercise. DESIGN AND SETTING: Subjects performed three 3-second maximal voluntary isometric contractions of the dominant knee extensors for EMG normalization. Exercise testing performed on the Biodex System 3 Dynamometer involved 10 isokinetic contractions at 180 degrees.s(-1) and 10 isotonic contractions with the resistance set at 50% of the previously recorded maximal voluntary isometric contraction. SUBJECTS: Recreationally active college students (10 men and 11 women). MEASUREMENTS: Surface EMG signals were collected from the vastus medialis and lateralis muscles and then integrated (IEMG) over the concentric phase of each repetition for both exercises. The IEMG was divided by the total work performed during the concentric phase for each exercise (IEMG/W). RESULTS: We analyzed the IEMG/W data using a 1-between (sex), 2-within (exercise and muscle) repeated-measures analysis of variance. There was a significant main effect for exercise, with the isotonic IEMG/W value being significantly greater than the isokinetic IEMG/W value. Additionally, the IEMG/W relationship did not appear to be affected by sex or individual muscle tested. CONCLUSIONS: Per unit of work performed, the isotonic contractions resulted in greater motor unit recruitment or an increased rate of firing, or both. This finding may have implications for the early phase of rehabilitation, when goals include complete motor unit recruitment of injured or atrophied muscles.

  9. Scaling lower-limb isokinetic strength for biological maturation and body size in adolescent basketball players.

    Science.gov (United States)

    Carvalho, Humberto Moreira; Coelho-e-Silva, Manuel; Valente-dos-Santos, João; Gonçalves, Rui Soles; Philippaerts, Renaat; Malina, Robert

    2012-08-01

    The relationships between knee joint isokinetic strength, biological maturity status and body size were examined in 14-16-year-old basketball players, considering proportional allometric modeling. Biological maturity status was assessed with maturity offset protocol. Stature, body mass, sitting height, and estimated thigh volume were measured by anthropometry. Maximal moments of force of concentric and eccentric muscular actions for the knee extensors and flexors were assessed by isokinetic dynamometry at 60° s(-1). Regression analysis revealed a linear relation between maximal moments of force of the knee extensors in both muscular actions and knee flexors in concentric actions were moderately high (0.55 ≤ r ≤ 0.64). As for knee flexors in eccentric actions, a squared term of maturity indicator was significant indicating that the relationship with maturity offset tended to plateau approximately 2 years after PHV. Incorporating maturity indicator term with body size term (body mass or thigh volume) in the allometric models revealed that the size exponents for both body mass and thigh volume were reduced compared with simple allometric modeling. The results indicate a significant inter-individual variation in lower-limb isokinetic strength performance at 60° s(-1) in concentric and eccentric muscular actions in late adolescent basketball players. The variability in performance is related to inter-individual variation in estimated time before or after peak height velocity, as well as differences in body size. Proportional allometric models indicate that the influence of estimated time from age at peak height velocity on isokinetic strength performance is mostly mediated by corresponding changes in overall body mass.

  10. The fatigue effect of a simulated futsal match protocol on isokinetic knee torque production.

    Science.gov (United States)

    Dal Pupo, Juliano; Detanico, Daniele; Santos, Saray Giovana Dos

    2014-11-01

    The objective of this study was to investigate the effects of a simulated futsal match protocol on isokinetic knee torque production. Twenty-one young futsal players participated in this study and performed a futsal-specific protocol comprising two blocks of 20-minute activities to simulate the match demands. At pre-protocol, half-time, and post-protocol, the concentric and eccentric isokinetic peak torque of the knee flexor and extensor muscles, the angle of peak torque, and the conventional and functional torque ratios were assessed. ANOVA was used to compare the variables (significance level p knee flexor and extensor eccentric torque and knee flexor concentric torque was found, in which the pre-protocol levels were higher than those at half-time, with both being larger than those at post-protocol. The knee extensor concentric torque reduced at half-time. The angle of eccentric torque of knee flexors increased, and the conventional and functional torque ratios decreased at post-protocol. In conclusion, the protocol produced a time-dependent reduction of knee flexor and extensor torque in both concentric and eccentric actions. These findings suggested a possible impairment of performance and the emergence of risk factors for hamstring strains during a futsal match.

  11. Unilateral eccentric exercise of the knee flexors affects muscle activation during gait.

    Science.gov (United States)

    Dover, Geoffrey C; Legge, Laura; St-Onge, Nancy

    2012-05-01

    Uni-lateral muscle soreness is common yet the effects on gait or electromyographic (EMG) activity are unknown. The purpose of our study was to induce delayed onset muscle soreness (DOMS) in the knee flexor group and measure the resultant change in EMG activity and knee motion during gait. Nine healthy subjects participated in the study. Measures of function, evoked tenderness of the biceps femoris, as well as knee angle, and EMG activity during gait were assessed prior and 48 h after an eccentric exercise protocol. DOMS was induced unilaterally in the knee flexors using an isokinetic dynamometer and subjects exercised until they could not generate 50% of their maximal voluntary isometric contraction (MVIC). There was a significant decrease in biceps femoris activity after DOMS during the last phase of gait. Moreover, there was a day × phase interaction for gastrocnemius activity with the last two phases displaying an increase in activity. There was no significant change in knee angle during gait. The decrease in biceps femoris activity as well as the increase in gastrocnemius activity could be evidence of a protective mechanism designed to decrease activity of the sore muscle while increasing the activity of a synergistic muscle. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Low-intensity eccentric contractions of the knee extensors and flexors protect against muscle damage.

    Science.gov (United States)

    Lin, Min-Ju; Chen, Trevor Chung-Ching; Chen, Hsin-Lian; Wu, Bo-Han; Nosaka, Kazunori

    2015-10-01

    This study investigated the magnitude and duration of the protective effect of low-intensity eccentric contractions (LowEC) against damage induced by maximal eccentric contractions (MaxEC) of the knee flexors (KF) and extensors (KE). Young men were assigned to 8 experimental groups and 2 control groups (n = 13/group); the experimental groups performed LowEC of KF or KE 2 days (2d), 1 week (1wk), 2 weeks (2wk), or 3 weeks (3wk) before MaxEC, while the control groups performed MaxEC of KF or KE without LowEC. The 2d, 1wk, 2wk, and 3wk groups performed 30 LowEC of KF or 60 LowEC of KE with a load of 10% of maximal voluntary isometric contraction strength on a resistance-training machine, and all groups performed 30 MaxEC of KF or 60 MaxEC of KE on an isokinetic dynamometer. Several muscle damage markers were measured from before to 2 days after exercise (LowEC) or from before to 5 days after exercise (MaxEC). No significant changes in any variables were evident after LowEC. The changes in all variables after MaxEC were smaller (P < 0.05) for the 2d and 1wk groups (e.g., peak creatine kinase activity: 1002 ± 501 IU/L; peak muscle soreness: 13 ± 5 mm) than for the control group (peak creatine kinase activity: 3005 ± 983 IU/L; peak muscle soreness 28 ± 6 mm) for both KE and KF. There were no significant differences between the 2d and 1wk groups or among the 2wk, 3wk, and control groups. These results show that LowEC provided 30%-66% protection against damage induced by MaxEC of KF and KE, and the protective effect lasted 1 week.

  13. Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

    Directory of Open Access Journals (Sweden)

    Natália Mariana Silva Luna

    2012-09-01

    Full Text Available OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5 years were divided into three groups: a triathlete group (n=26, a long-distance runner group (n = 23, and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180º/s was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60º/s was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners.

  14. Analysis of the association between isokinetic knee strength with offensive and defensive jumping capacity in high-level female volleyball athletes.

    Science.gov (United States)

    Sattler, Tine; Sekulic, Damir; Esco, Michael R; Mahmutovic, Ifet; Hadzic, Vedran

    2015-09-01

    Isokinetic-knee-strength was hypothesized to be an important factor related to jumping performance. However, studies examining this relation among elite female athletes and sport-specific jumps are lacking. This investigation determined the influence of isokinetic-knee flexor/extensor strength measures on spike-jump (offensive) and block-jump (defensive) performance among high-level female volleyball players. Cross-sectional laboratory study. Eighty-two female volleyball athletes (age = 21.3 ± 3.8 years, height = 175.4 ± 6.76 cm, and weight = 68.29 ± 8.53 kg) volunteered to participate in this study. The studied variables included spike-jump and block-jump performance and a set of isokinetic tests to evaluate the eccentric and concentric strength capacities of the knee extensors (quadriceps - Q), and flexors (hamstring - H) for both legs. Both jumping tests showed high intra-session reliability (ICC of 0.87 and 0.95 for spike-jump and block-jump, respectively). The athletes were clustered into three achievement-groups based on their spike-jump and block-jump performances. For the block-jump, ANOVA identified significant differences between achievement-groups for all isokinetic variables except the Right-Q-Eccentric-Strength. When observed for spike-jump, achievement-groups differed significantly in all tests but Right-H-Concentric-Strength. Discriminant canonical analysis showed that the isokinetic-strength variables were more associated with block-jump then spike-jump-performance. The eccentric isokinetic measures were relatively less important determinants of block-jump than for the spike-jump performance. Data support the hypothesis of the importance of isokinetic strength measures for the expression of rapid muscular performance in volleyball. The results point to the necessity of the differential approach in sport training for defensive and offensive duties. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Reliability of power output during eccentric sprint cycling.

    Science.gov (United States)

    Brughelli, Matt; Van Leemputte, Marc

    2013-01-01

    The purpose of this study was to determine the reliability of power outputs during maximal intensity eccentric cycling over short durations (i.e., eccentric sprint cycling) on a "motor-driven" isokinetic ergometer. Fourteen physically active male subjects performed isokinetic eccentric cycling sprints at 40, 60, 80, 100, and 120 revolutions per minute (rpm) on 4 separate occasions (T1-T4). Each sprint lasted for 6 seconds, and absolute measures of mean power (MP) and peak power (PP) per revolution were recorded. Significant increases in MP and PP were observed between T1 and subsequent trials, but no significant differences were identified between T2, T3, and T4. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated to reflect within-subject and between-session reliability of MP and PP at each cadence. The CV improved to below 10% for cadences of 60, 80, 100, and 120 rpm between T3 and T4, and the majority of ICC values improved to above 0.90. The remaining ICC values remained in the moderate range between T3 and T4 (i.e., 0.82-0.89). Coefficient of variation and ICC values for the 40 rpm cadence remained at unacceptable levels throughout the 4 trials and thus should be avoided in future investigations. The results of this study indicate that reliable power outputs may be obtained after 2 familiarization sessions during eccentric sprint cycling at cadences ranging from 60 to 120 rpm.

  16. Leg strength improvement in elderly fallers and non fallers after eigth week of isokinetic strengthening

    Directory of Open Access Journals (Sweden)

    SEMALTIANOU ELENI

    2012-01-01

    Full Text Available The purpose of the present study was to investigate the effects of an eight week strengthening program in an isokinetic dynamometer, in the knee joint muscles of healthy elderly people, with and with out a history of falls. In the study participated 59 elderly men and women all in good health aged 60 years and over. The elderly were assessed in five concentric, two eccentric speeds (60°, 90°, 120°, 180°, 240° and 60°, 120°/sec respectively and in four angular positions (75°, 60°, 45°, 30° of knee flexion, 0° = full extension in an Cybex Norm® isokinetic dynamometer. The experimental group of the study followed a strengthening program for quadriceps andhamstring muscles in the isokinetic dynamometer for eight weeks, in five concentric speeds. The results of the study indicated statistically significant differences (p _.05 in strength and power between initial and final assessment in the experimental group. The results indicated also statistically significant differences (p<0.05 in strength and power between fallers and non - fallers of the experimental group in the initial assessment. These differences were diminished after the intervention period with fallers achieving statistically significant improvement (p<0.05. The results of the study provide evidence that an eight week isokinetic strengthening program of lower extremities in elderly people is very efficient in fall prevention.

  17. Velocity-specific strength recovery after a second bout of eccentric exercise.

    Science.gov (United States)

    Barss, Trevor S; Magnus, Charlene R A; Clarke, Nick; Lanovaz, Joel L; Chilibeck, Philip D; Kontulainen, Saija A; Arnold, Bart E; Farthing, Jonathan P

    2014-02-01

    A bout of eccentric exercise (ECC) has the protective effect of reducing muscle damage during a subsequent bout of ECC known as the "repeated bout effect" (RBE). The purpose of this study was to determine if the RBE is greater when both bouts of ECC are performed using the same vs. different velocity of contraction. Thirty-one right-handed participants were randomly assigned to perform an initial bout of either fast (3.14 rad·s [180°·s]) or slow (0.52 rad·s [30°·s]) maximal isokinetic ECCs of the elbow flexors. Three weeks later, the participants completed another bout of ECC at the same velocity (n = 16), or at a different velocity (n = 15). Indirect muscle damage markers were measured before, immediately after, and at 24, 48, and 72 hours postexercise. Measures included maximal voluntary isometric contraction (MVC) strength (dynamometer), muscle thickness (MT; ultrasound), delayed onset muscle soreness (DOMS; visual analog scale), biceps and triceps muscle activation amplitude (electromyography), voluntary activation (interpolated twitch), and twitch torque. After the repeated bout, MVC strength recovered faster compared with the same time points after the initial bout for only the same velocity group (p = 0.017), with no differences for all the other variables. Irrespective of velocity, MT and DOMS were reduced after the repeated bout compared with that of the initial bout at 24, 48, and 72 hours with a corresponding increase in TT at 72 hours (p effects contribute to the RBE. The current findings support the idea of multiple mechanisms contributing to the RBE.

  18. THE EFFECT OF CREATINE SUPPLEMENTATION ON ATHLETE ISOKINETIC PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Erkan Faruk ŞİRİN

    2009-12-01

    Full Text Available The purpose of this study is to find the effects of Creatin Monohydrate (CrH2O on athlete performance (isokinetic power measured as a total workout used as an ergojenic aid in long-term (6 weeks supplementation. There are 38 participants willing to join to the study. Their ages are between 20 and 27. All of them are choosed from active athletes. From the findings of this study; all the participants’ in the creatin group have increased the total workout production in all cycles of isokinetic exercise. The difference between the values in the first and fifth cycles, (both before and after loading are statistically significant. In the creatin group the difference between before loading and 15th day values are statistically significant. But the difference between before loading and 50th day values does not have statistical difference. In placebo group, before and after values in all 5 cycles, there is no statistical difference between the total workout production values. There is also no statistical difference between the before loading and 15th day values. As the same there is no statistical difference between the before loading and the 50th day values. The most important finding in this study is that, there is no affect of long term creatin loading (50 days on maximal voluntary knee extansion, as a total muscle workout values. But the change in values before loading day and 15th day are significantly improved. And so we understand that, for getting better results in total workout production, we better use two weeks period loading instead of long term loading. Key Words: Ergogenic aid, creatine supplementation, isokinetic performance

  19. Time-Course of Neuromuscular Changes during and after Maximal Eccentric Contractions.

    Science.gov (United States)

    Doguet, Valentin; Jubeau, Marc; Dorel, Sylvain; Couturier, Antoine; Lacourpaille, Lilian; Guével, Arnaud; Guilhem, Gaël

    2016-01-01

    This study tested the relationship between the magnitude of muscle damage and both central and peripheral modulations during and after eccentric contractions of plantar flexors. Eleven participants performed 10 sets of 30 maximal eccentric contractions of the plantar flexors at 45°·s(-1). Maximal voluntary torque, evoked torque (peripheral component) and voluntary activation (central component) were assessed before, during, immediately after (POST) and 48 h after (48 h) the eccentric exercise. Voluntary eccentric torque progressively decreased (up to -36%) concomitantly to a significant alteration of evoked torque (up to -34%) and voluntary activation (up to -13%) during the exercise. Voluntary isometric torque (-48 ± 7%), evoked torque (-41 ± 14%) and voluntary activation (-13 ± 11%) decreased at POST, but only voluntary isometric torque (-19 ± 6%) and evoked torque (-10 ± 18%) remained depressed at 48 h. Neither changes in voluntary activation nor evoked torque during the exercise were related to the magnitude of muscle damage markers, but the evoked torque decrement at 48 h was significantly correlated with the changes in voluntary activation (r = -0.71) and evoked torque (r = 0.77) at POST. Our findings show that neuromuscular responses observed during eccentric contractions were not associated with muscle damage. Conversely, central and peripheral impairments observed immediately after the exercise reflect the long-lasting reduction in force-generating capacity.

  20. Inferring the eccentricity distribution

    CERN Document Server

    Hogg, David W; Bovy, Jo

    2010-01-01

    Standard maximum-likelihood estimators for binary-star and exoplanet eccentricities are biased high, in the sense that the estimated eccentricity tends to be larger than the true eccentricity. As with most non-trivial observables, a simple histogram of estimated eccentricities is not a good estimate of the true eccentricity distribution. Here we develop and test a hierarchical probabilistic method for performing the relevant meta-analysis, that is, inferring the true eccentricity distribution, taking as input the likelihood functions for the individual-star eccentricities, or samplings of the posterior probability distributions for the eccentricities (under a given, uninformative prior). The method is a simple implementation of a hierarchical Bayesian model; it can also be seen as a kind of heteroscedastic deconvolution. It can be applied to any quantity measured with finite precision--other orbital parameters, or indeed any astronomical measurements of any kind, including magnitudes, parallaxes, or photometr...

  1. Dissociated time course recovery between rate of force development and peak torque after eccentric exercise.

    Science.gov (United States)

    Molina, Renato; Denadai, Benedito S

    2012-05-01

    This study investigated the association between isokinetic peak torque (PT) of quadriceps and the corresponding peak rate of force development (peak RFD) during the recovery of eccentric exercise. Twelve untrained men (aged 21·7 ± 2·3 year) performed 100 maximal eccentric contractions for knee extensors (10 sets of 10 repetitions with a 2-min rest between each set) on isokinetic dynamometer. PT and peak RFD accessed by maximal isokinetic knee concentric contractions at 60° s(-1) were obtained before (baseline) and at 24 and 48 h after eccentric exercise. Indirect markers of muscle damage included delayed onset of muscle soreness (DOMS) and plasma creatine kinase (CK) activity. The eccentric exercise resulted in elevated DOMS and CK compared with baseline values. At 24 h, PT (-15·3%, P = 0·002) and peak RFD (-13·1%, P = 0·03) decreased significantly. At 48 h, PT (-7·9%, P = 0·002) was still decreased but peak RFD have returned to baseline values. Positive correlation was found between PT and peak RFD at baseline (r = 0·62, P = 0·02), 24 h (r = 0·99, P = 0·0001) and 48 h (r = 0·68, P = 0·01) after eccentric exercise. The magnitude of changes (%) in PT and peak RFD from baseline to 24 h (r = 0·68, P = 0·01) and from 24 to 48 h (r = 0·68, P = 0·01) were significantly correlated. It can be concluded that the muscle damage induced by the eccentric exercise affects differently the time course of PT and peak RFD recovery during isokinetic concentric contraction at 60° s(-1). During the recovery from exercise-induced muscle damage, PT and peak RFD are determined but not fully defined by shared putative physiological mechanisms. © 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

  2. Differential Effects of Unilateral Concentric Vs. Eccentric Exercise on the Dominant and Nondominant Forearm Flexors.

    Science.gov (United States)

    Beck, Travis W; Ye, Xin; Wages, Nathan P

    2016-03-01

    The purpose of this study was to compare the electromyographic (EMG) intensity patterns after unilateral concentric vs. eccentric exercise in the dominant (DOM) and nondominant (NONDOM) forearm flexors. Twenty-six men (mean ± SD: age, 24.0 ± 3.7 years) volunteered to perform a maximal isometric muscle action of the DOM and NONDOM forearm flexors before (PRE) and immediately after (POST) a series of maximal concentric isokinetic or maximal eccentric isokinetic muscle actions of the DOM forearm flexors. The concentric isokinetic and eccentric isokinetic muscle actions were performed on separate days that were randomly ordered. However, in both cases, the subjects performed 6 sets of 10 maximal muscle actions. A bipolar surface EMG signal was detected from the biceps brachii of the DOM and NONDOM limbs during the PRE and POST isometric muscle actions. The signals were then analyzed with a wavelet analysis, and the resulting intensity patterns were classified with a paired pattern classification procedure. The results indicated that the EMG intensity patterns could be correctly classified into their respective PRE vs. POST categories with an accuracy rate that was significantly better than random (20 of 26 patterns = 76.9% accuracy) but only for the DOM limb following the eccentric muscle actions. All other classifications were not significantly better than random. These findings indicated that eccentric exercise had a significant influence on the muscle activation pattern for the forearm flexors. It is possible that the muscle damage resulting from eccentric exercise affects muscle spindle or golgi tendon organ or both activity, thereby altering the muscle activation pattern.

  3. Shoulder isokinetic profile of male handball players of the Brazilian National Team

    Directory of Open Access Journals (Sweden)

    Marilia S. Andrade

    2013-12-01

    Full Text Available BACKGROUND: Data obtained on an isokinetic dynamometer are useful to characterize muscle status and have been reported in muscle imbalance studies in different types of sport. However, few studies have assessed elite handball players to establish reference values. OBJECTIVE: The purpose of this study was to compare, for the dominant (D and non-dominant (ND side, the isokinetic profile of shoulder rotator muscle strength between male handball players (H and asymptomatic non-athletes (NA. METHOD: Isokinetic concentric and eccentric strength tests for D upper limbs were performed by the H group (n=20 and the NA group (n=12. Internal and external rotator muscle peak torque in concentric action was assessed at 60°/s and 300°/s and in eccentric action at 300°/s. We also calculated conventional balance (the ratio of external rotator peak torque to internal rotator peak torque in concentric action and functional balance (the ratio of external rotator peak torque in eccentric action to internal rotator peak torque in concentric action. RESULTS: In the H group, dominant limbs were stronger in concentric action for external rotation at 60 and 300°/s. The conventional balance ratio for the D side was significantly lower at 60 and 300°/s for H compared to NA. The functional ratio for the D side was significantly lower at 300º/s for H compared to NA. CONCLUSIONS: Compared to asymptomatic non-athletes, handball players presented significant muscular imbalance resulting from daily sports practice, a known risk factor for shoulder injuries.

  4. Insights into the neural control of eccentric contractions.

    Science.gov (United States)

    Duchateau, Jacques; Baudry, Stéphane

    2014-06-01

    The purpose of this brief review is to examine our current knowledge of the neural control of eccentric contractions. The review focuses on three main issues. The first issue considers the ability of individuals to activate muscles maximally during eccentric contractions. Most studies indicate that, regardless of the experimental approach (surface EMG amplitude, twitch superimposition, and motor unit recordings), it is usually more difficult to achieve full activation of a muscle by voluntary command during eccentric contractions than during concentric and isometric contractions. The second issue is related to the specificity of the control strategy used by the central nervous system during submaximal eccentric contractions. This part underscores that although the central nervous system appears to employ a single size-related strategy to activate motoneurons during the different types of contractions, the discharge rate of motor units is less during eccentric contractions across different loading conditions. The last issue addresses the mechanisms that produce this specific neural activation. This section indicates that neural adjustments at both supraspinal and spinal levels contribute to the specific modulation of voluntary activation during eccentric contractions. Although the available information on the control of eccentric contractions has increased during the last two decades, this review indicates that the exact mechanisms underlying the unique neural modulation observed in this type of contraction at spinal and supraspinal levels remains unknown and their understanding represents, therefore, a major challenge for future research on this topic.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  6. Effect of low-level laser therapy on muscle adaptation to knee extensor eccentric training.

    Science.gov (United States)

    Baroni, Bruno Manfredini; Rodrigues, Rodrigo; Freire, Bruno Bolla; Franke, Rodrigo de Azevedo; Geremia, Jeam Marcel; Vaz, Marco Aurélio

    2015-03-01

    Eccentric training has been popularized for physical conditioning and prevention/rehabilitation of musculoskeletal disorders, especially due to the expressive responses in terms of muscular strength gain. In view of evidence that low-level laser therapy (LLLT) is able to increase exercise performance and accelerate post-exercise recovery, the aim of this study was to verify the effect of LLLT on hypertrophy and strengthening of knee extensor muscles submitted to eccentric training. Thirty healthy male subjects were randomized into three groups: Control Group (CG), Training Group (TG) and Training + LLLT Group (TLG). CG received no intervention, while TG and TLG were engaged on an 8-week knee extensor isokinetic eccentric training program. Only subjects from TLG were treated with LLLT (wavelength = 810 nm; power output = 200 mW; total dosage = 240 J) before each training session. Knee extensor muscle thickness and peak torque were assessed through ultrasonography and isokinetic dynamometry, respectively. CG presented no changes in any variable throughout the study, while eccentric training led to significant increases in muscle thickness and peak torque in TG and TLG. Subjects from TLG reached significantly higher percent changes compared to subjects from TG for sum of muscles' thicknesses (15.4 vs. 9.4%), isometric peak torque (20.5 vs. 13.7%), and eccentric peak torque (32.2 vs. 20.0%). LLLT applied before eccentric training sessions seems to improve the hypertrophic response and muscular strength gain in healthy subjects.

  7. Eccentric connectivity index

    CERN Document Server

    Ilić, Aleksandar

    2011-01-01

    The eccentric connectivity index $\\xi^c$ is a novel distance--based molecular structure descriptor that was recently used for mathematical modeling of biological activities of diverse nature. It is defined as $\\xi^c (G) = \\sum_{v \\in V (G)} deg (v) \\cdot \\epsilon (v)$\\,, where $deg (v)$ and $\\epsilon (v)$ denote the vertex degree and eccentricity of $v$\\,, respectively. We survey some mathematical properties of this index and furthermore support the use of eccentric connectivity index as topological structure descriptor. We present the extremal trees and unicyclic graphs with maximum and minimum eccentric connectivity index subject to the certain graph constraints. Sharp lower and asymptotic upper bound for all graphs are given and various connections with other important graph invariants are established. In addition, we present explicit formulae for the values of eccentric connectivity index for several families of composite graphs and designed a linear algorithm for calculating the eccentric connectivity in...

  8. On eccentric connectivity index

    CERN Document Server

    Zhou, Bo

    2010-01-01

    The eccentric connectivity index, proposed by Sharma, Goswami and Madan, has been employed successfully for the development of numerous mathematical models for the prediction of biological activities of diverse nature. We now report mathematical properties of the eccentric connectivity index. We establish various lower and upper bounds for the eccentric connectivity index in terms of other graph invariants including the number of vertices, the number of edges, the degree distance and the first Zagreb index. We determine the n-vertex trees of diameter with the minimum eccentric connectivity index, and the n-vertex trees of pendent vertices, with the maximum eccentric connectivity index. We also determine the n-vertex trees with respectively the minimum, second-minimum and third-minimum, and the maximum, second-maximum and third-maximum eccentric connectivity indices for

  9. EFFECTS OF BETWEEN-SET INTERVENTIONS ON NEUROMUSCULAR FUNCTION DURING ISOKINETIC MAXIMAL CONCENTRIC CONTRACTIONS OF THE KNEE EXTENSORS

    Directory of Open Access Journals (Sweden)

    Carole Cometti

    2011-12-01

    Full Text Available The presents study investigated the effects of between-set interventions on neuromuscular function of the knee extensors during six sets of 10 isokinetic (120°·s-1 maximal concentric contractions separated by three minutes. Twelve healthy men (age: 23.9 ± 2.4 yrs were tested for four different between-set recovery conditions applied during two minutes: passive recovery, active recovery (cycling, electromyostimulation and stretching, in a randomized, crossover design. Before, during and at the end of the isokinetic session, torque and thigh muscles electromyographic activity were measured during maximal voluntary contractions and electrically-evoked doublets. Activation level was calculated using the twitch interpolation technique. While quadriceps electromyographic activity and activation level were significantly decreased at the end of the isokinetic session (-5.5 ± 14.2 % and -2.7 ± 4.8 %; p < 0.05, significant decreases in maximal voluntary contractions and doublets were observed after the third set (respectively -0.8 ± 12.1% and -5.9 ± 9.9%; p < 0.05. Whatever the recovery modality applied, torque was back to initial values after each recovery period. The present results showed that fatigue appeared progressively during the isokinetic session with peripheral alterations occurring first followed by central ones. Recovery interventions between sets did not modify fatigue time course as compared with passive recovery. It appears that the interval between sets (3 min was long enough to provide recovery regardless of the interventions

  10. Agonist muscle activity and antagonist muscle co-activity levels during standardized isotonic and isokinetic knee extensions.

    Science.gov (United States)

    Remaud, Anthony; Cornu, Christophe; Guével, Arnaud

    2009-06-01

    This study aimed to analyze the effects of the contraction mode (isotonic vs. isokinetic concentric conditions), the joint angle and the investigated muscle on agonist muscle activity and antagonist muscle co-activity during standardized knee extensions. Twelve healthy adult subjects performed three sets of isotonic knee extensions at 40% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic knee extensions on an isokinetic dynamometer. For each set, the mean angular velocity and the total external amount of work performed were standardized during the two contraction modes. Surface electromyographic activity of vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), semitendinosus (ST) and biceps femoris (BF) muscles was recorded. Root mean square values were then calculated for each 10 degrees between 85 degrees and 45 degrees of knee extension (0 degrees =horizontal position). Results show that agonist muscle activity and antagonist muscle co-activity levels are significantly greater in isotonic mode compared to isokinetic mode. Quadriceps activity and hamstrings co-activity are significantly lower at knee extended position in both contraction modes. Considering agonist muscles, VL reveals a specific pattern of activity compared to VM and RF; whereas considering hamstring muscles, BF shows a significantly higher co-activity than ST in both contraction modes. Results of this study confirmed our hypothesis that higher quadriceps activity is required during isotonic movements compared to isokinetic movements leading to a higher hamstrings co-activity.

  11. Skeletal muscle collagen content in humans after high-force eccentric contractions

    DEFF Research Database (Denmark)

    Mackey, Abigail; Donnelly, Alan E; Turpeenniemi-Hujanen, Taina

    2004-01-01

    4) yr] each performed a bout of 100 maximum voluntary eccentric contractions of the knee extensors. Muscle biopsies were taken before exercise and on days 4 and 22 afterward. Image analysis of stained tissue sections was used to quantify endomysial collagen staining intensity. Maximum voluntary...

  12. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  13. Oscillations of Eccentric Pulsons

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Groenbech-Jensen, Niels; Lomdahl, Peter;

    1997-01-01

    Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct.......Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct....

  14. Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

    Science.gov (United States)

    Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M

    2016-01-01

    Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p knee extension torque was the only exercise tested that showed an interaction effect between age and muscle length (p torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

  15. Surface electromyographic amplitude-to-work ratios during isokinetic and isotonic muscle actions.

    Science.gov (United States)

    Purkayastha, Sushmita; Cramer, Joel T; Trowbridge, Cynthia A; Fincher, A Louise; Marek, Sarah M

    2006-01-01

    Isokinetic and isotonic resistance training exercises are commonly used to increase strength during musculoskeletal rehabilitation programs. Our study was designed to examine the efficacy of isokinetic and isotonic muscle actions using surface electromyographic (EMG) amplitude-to-work ratios (EMG/WK) and to extend previous findings to include a range of isokinetic velocities and isotonic loads. To examine work (WK), surface EMG amplitude, and EMG/WK during concentric-only maximal isokinetic muscle actions at 60, 120, 180, 240, and 300 degrees /s and isotonic muscle actions at 10%, 20%, 30%, 40%, and 50% of the maximal voluntary isometric contraction (MVIC) torque during leg extension exercises. A randomized, counterbalanced, cross-sectional, repeated-measures design. A university-based human muscle physiology research laboratory. Ten women (mean age = 22.0 +/- 2.6 years) and 10 men (mean age = 20.8 +/- 1.7 years) who were apparently healthy and recreationally active. Using the dominant leg, each participant performed 5 maximal voluntary concentric isokinetic leg extension exercises at randomly ordered angular velocities of 60, 120, 180, 240, and 300 degrees /s and 5 concentric isotonic leg extension exercises at randomly ordered loads of 10%, 20%, 30%, 40%, and 50% of the isometric MVIC. Work was recorded by a Biodex System 3 dynamometer, and surface EMG was recorded from the superficial quadriceps femoris muscles (vastus lateralis, rectus femoris, and vastus medialis) during the testing and was normalized to the MVIC. The EMG/WK ratios were calculated as the quotient of EMG amplitude (muVrms) and WK (J) during the concentric phase of each exercise. Isotonic EMG/WK remained unchanged ( P > .05) from 10% to 50% MVIC, but isokinetic EMG/WK increased ( P Isotonic EMG/WK was greater ( P .05) between 20% MVIC versus 240 degrees /s or 10% MVIC versus 300 degrees /s. An 18% decrease in active range of motion was seen for the isotonic muscle actions, from 10% to 50% MVIC

  16. Muscle fatigue experienced during maximal eccentric exercise is predictive of the plasma creatine kinase (CK) response.

    Science.gov (United States)

    Hody, S; Rogister, B; Leprince, P; Wang, F; Croisier, J-L

    2013-08-01

    Unaccustomed eccentric exercise may cause skeletal muscle damage with an increase in plasma creatine kinase (CK) activity. Although the wide variability among individuals in CK response to standardized lengthening contractions has been well described, the reasons underlying this phenomenon have not yet been understood. Therefore, this study investigated a possible correlation of the changes in muscle damage indirect markers after an eccentric exercise with the decline in muscle performance during the exercise. Twenty-seven healthy untrained male subjects performed three sets of 30 maximal isokinetic eccentric contractions of the knee extensors. The muscular work was recorded using an isokinetic dynamometer to assess muscle fatigue by means of various fatigue indices. Plasma CK activity, muscle soreness, and stiffness were measured before (pre) and one day after (post) exercise. The eccentric exercise bout induced significant changes of the three muscle damage indirect markers. Large inter-subject variability was observed for all criteria measured. More interestingly, the log (CK(post) /CK(pre)) and muscle stiffness appeared to be closely correlated with the relative work decrease (r = 0.84, r(2)  = 0.70 and r = 0.75, r(2)  = 0.56, respectively). This is the first study to propose that the muscle fatigue profile during maximal eccentric protocol could predict the magnitude of the symptoms associated with muscle damage in humans.

  17. Effect of Alcohol Consumption on Recovery From Eccentric Exercise Induced Muscle Damage in Females.

    Science.gov (United States)

    McLeay, Yanita; Stannard, Stephen R; Mundel, Toby; Foskett, Andrew; Barnes, Matthew

    2017-04-01

    This study was designed to investigate the effects of alcohol consumption on recovery of muscle force when consumed immediately postexercise in young females. Eight young women completed 300 maximal eccentric actions of the quadriceps femoris muscle on an isokinetic dynamometer on two occasions in a randomized, cross-over design after which an alcoholic beverage (0.88g ethanol/kg body weight) or an iso-caloric placebo was consumed. Maximal isokinetic (concentric and eccentric) torque and isometric tension produced across the knee were measured in both the exercised and control leg predamage, 36 hr post, and 60 hr post damage. Venous blood creatine kinase (CK) activity and muscle soreness ratings were taken before damage and once per day to 60 hr post damage. Significant differences were observed between the exercised and control leg for maximal concentric, and eccentric torque and isometric tension (p eccentric torque. No main effects of treatment (alcohol) or interactions with Time × Leg or Leg × Treatment were observed. Perceived muscle soreness during box stepping and squatting showed significant time effects (p eccentric exercise-induced muscle damage does not affect recovery in the days following damage in females.

  18. Voluntary Slavery

    Directory of Open Access Journals (Sweden)

    Danny Frederick

    2014-06-01

    Full Text Available The permissibility of actions depends upon facts about the flourishing and separateness of persons. Persons differ from other creatures in having the task of discovering for themselves, by conjecture and refutation, what sort of life will fulfil them. Compulsory slavery impermissibly prevents some persons from pursuing this task. However, many people may conjecture that they are natural slaves. Some of these conjectures may turn out to be correct. In consequence, voluntary slavery, in which one person welcomes the duty to fulfil all the commands of another, is permissible. Life-long voluntary slavery contracts are impermissible because of human fallibility; but fixed-term slavery contracts should be legally enforceable. Each person has the temporarily alienable moral right to direct her own life.

  19. Voluntary Slavery

    Directory of Open Access Journals (Sweden)

    Danny Frederick

    2014-06-01

    Full Text Available The permissibility of actions depends upon facts about the flourishing and separateness of persons. Persons differ from other creatures in having the task of discovering for themselves, by conjecture and refutation, what sort of life will fulfil them. Compulsory slavery impermissibly prevents some persons from pursuing this task. However, many people may conjecture that they are natural slaves. Some of these conjectures may turn out to be correct. In consequence, voluntary slavery, in which one person welcomes the duty to fulfil all the commands of another, is permissible. Life-long voluntary slavery contracts are impermissible because of human fallibility; but fixed-term slavery contracts should be legally enforceable. Each person has the temporarily alienable moral right to direct her own life.

  20. Hamstring Architectural and Functional Adaptations Following Long vs. Short Muscle Length Eccentric Training

    Science.gov (United States)

    Guex, Kenny; Degache, Francis; Morisod, Cynthia; Sailly, Matthieu; Millet, Gregoire P.

    2016-01-01

    Most common preventive eccentric-based exercises, such as Nordic hamstring do not include any hip flexion. So, the elongation stress reached is lower than during the late swing phase of sprinting. The aim of this study was to assess the evolution of hamstring architectural (fascicle length and pennation angle) and functional (concentric and eccentric optimum angles and concentric and eccentric peak torques) parameters following a 3-week eccentric resistance program performed at long (LML) vs. short muscle length (SML). Both groups performed eight sessions of 3–5 × 8 slow maximal eccentric knee extensions on an isokinetic dynamometer: the SML group at 0° and the LML group at 80° of hip flexion. Architectural parameters were measured using ultrasound imaging and functional parameters using the isokinetic dynamometer. The fascicle length increased by 4.9% (p torque did not change in the SML (p = 0.37) and the LML (p = 0.23) groups, whereas eccentric peak torque increased by 12.9% (p < 0.01, small effect size) and 17.9% (p < 0.001, small effect size) in the SML and the LML group, respectively. No group-by-time interaction was found for any parameters. A correlation was found between the training-induced change in fascicle length and the change in concentric optimum angle (r = −0.57, p < 0.01). These results suggest that performing eccentric exercises lead to several architectural and functional adaptations. However, further investigations are required to confirm the hypothesis that performing eccentric exercises at LML may lead to greater adaptations than a similar training performed at SML. PMID:27536252

  1. Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes: multiple regression approach.

    Science.gov (United States)

    Sattler, Tine; Sekulic, Damir; Spasic, Miodrag; Osmankac, Nedzad; Vicente João, Paulo; Dervisevic, Edvin; Hadzic, Vedran

    2016-01-01

    Previous investigations noted potential importance of isokinetic strength in rapid muscular performances, such as jumping. This study aimed to identify the influence of isokinetic-knee-strength on specific jumping performance in volleyball. The secondary aim of the study was to evaluate reliability and validity of the two volleyball-specific jumping tests. The sample comprised 67 female (21.96±3.79 years; 68.26±8.52 kg; 174.43±6.85 cm) and 99 male (23.62±5.27 years; 84.83±10.37 kg; 189.01±7.21 cm) high- volleyball players who competed in 1st and 2nd National Division. Subjects were randomly divided into validation (N.=55 and 33 for males and females, respectively) and cross-validation subsamples (N.=54 and 34 for males and females, respectively). Set of predictors included isokinetic tests, to evaluate the eccentric and concentric strength capacities of the knee extensors, and flexors for dominant and non-dominant leg. The main outcome measure for the isokinetic testing was peak torque (PT) which was later normalized for body mass and expressed as PT/Kg. Block-jump and spike-jump performances were measured over three trials, and observed as criteria. Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between and t-test differences between observed and predicted scores; and Bland Altman graphics. Jumping tests were found to be reliable (spike jump: ICC of 0.79 and 0.86; block-jump: ICC of 0.86 and 0.90; for males and females, respectively), and their validity was confirmed by significant t-test differences between 1st vs. 2nd division players. Isokinetic variables were found to be significant predictors of jumping performance in females, but not among males. In females, the isokinetic-knee measures were shown to be stronger and more valid predictors of the block-jump (42% and 64% of the explained variance for validation and cross-validation subsample, respectively

  2. Systemic cytokine response to three bouts of eccentric exercise

    Directory of Open Access Journals (Sweden)

    Stephen M. Cornish

    2014-01-01

    Full Text Available This research examined the changes in inflammatory cytokines interleukin 6 (IL-6, IL-1β, IL-10, as well as muscle force, muscle soreness, thigh circumference, and range of motion in response to 3 bouts of eccentric knee extension. Ten males were recruited to participate. The participants performed eccentric exercise on 3 consecutive days on the knee extensors on the right leg separated by 24 h. Participants performed 6 sets of 10 repetitions of isokinetic eccentric knee extension at 120° per second. Blood was sampled before and after each exercise bout and 24 h after the final exercise bout. Muscle isometric force, delayed onset muscle soreness (DOMS, thigh circumference, and range of motion were evaluated before and after each exercise bout and 24 h after the final exercise bout. There were no statistically significant differences noted for the changes in isometric strength, thigh circumference, and range of motion, or IL-6 over the 4 days (all p > 0.05. On the second day and third day there was a significant increase noted in DOMS as compared with baseline (p < 0.05. These results suggest that 3 consecutive days of eccentric exercise results in DOMS but does not produce a sustained systemic inflammatory reaction or changes in muscle function.

  3. Systemic cytokine response to three bouts of eccentric exercise

    Science.gov (United States)

    Cornish, Stephen M.; Johnson, Steven T.

    2014-01-01

    This research examined the changes in inflammatory cytokines interleukin 6 (IL-6), IL-1ß, IL-10, as well as muscle force, muscle soreness, thigh circumference, and range of motion in response to 3 bouts of eccentric knee extension. Ten males were recruited to participate. The participants performed eccentric exercise on 3 consecutive days on the knee extensors on the right leg separated by 24??h. Participants performed 6 sets of 10 repetitions of isokinetic eccentric knee extension at 120° per second. Blood was sampled before and after each exercise bout and 24?h after the final exercise bout. Muscle isometric force, delayed onset muscle soreness (DOMS), thigh circumference, and range of motion were evaluated before and after each exercise bout and 24?h after the final exercise bout. There were no statistically significant differences noted for the changes in isometric strength, thigh circumference, and range of motion, or IL-6 over the 4 days (all p > 0.05). On the second day and third day there was a significant increase noted in DOMS as compared with baseline (p eccentric exercise results in DOMS but does not produce a sustained systemic inflammatory reaction or changes in muscle function. PMID:24809007

  4. Feasibility of estimating isokinetic knee torque using a neural network model.

    Science.gov (United States)

    Hahn, Michael E

    2007-01-01

    Many studies have investigated the relationships between electromyography (EMG) and torque production. A few investigators have used adjusted learning algorithms and feed-forward artificial neural networks (ANNs) to estimate joint torque in the elbow. This study sought to estimate net isokinetic knee torque using ANN models. Isokinetic knee extensor and flexor torque data were measured simultaneously with agonist and antagonist EMG during concentric and eccentric contractions at joint velocities of 30 degrees /s and 60 degrees /s. Age, gender, height, body mass, agonist EMG, antagonist EMG, joint position and joint velocity were entered as predictive variables of net torque. A three-layer ANN model was developed and trained using an adjusted back-propagation algorithm. Accuracy results were compared against those of forward stepwise regression models. Stepwise regression models included body mass, body height and joint position as the most influential predictors, followed by agonist EMG for concentric and eccentric contractions. Estimation of eccentric torque included antagonist EMG following the agonist activation. ANN models resulted in more accurate torque estimation (R=0.96), compared to the stepwise regression models (R=0.71). ANN model accuracy increased greatly when the number of hidden units increased from 5 to 10, continuing to increase gradually with additional hidden units. The average number of training epochs necessary for solution convergence and the relative accuracy of the model indicate a strong ability for the ANN model to generalize these estimations to a broader sample. The ANN model appears to be a feasible technique for estimating joint torque in the knee.

  5. Effects of Static and Dynamic Stretching on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist Muscles.

    Science.gov (United States)

    Serefoglu, Abdullah; Sekir, Ufuk; Gür, Hakan; Akova, Bedrettin

    2017-03-01

    The aim of this study was to investigate if static and dynamic stretching exercises of the knee muscles (quadriceps and hamstring muscles) have any effects on concentric and eccentric isokinetic peak torques and electromyographic amplitudes (EMG) of the antagonist muscles. Twenty healthy male athletes (age between 18-30 years) voluntarily participated in this study. All of the subjects visited the laboratory to complete the following intervention in a randomized order on 5 separate days; (a) non-stretching (control), (b) static stretching of the quadriceps muscles, (c) static stretching of the hamstring muscles, (d) dynamic stretching of the quadriceps muscles, and (e) dynamic stretching of the hamstring muscles. Static stretching exercises either for the quadriceps or the hamstring muscles were carried out at the standing and sitting positions. Subjects performed four successive repetitions of each stretching exercises for 30 seconds in both stretching positions. Similar to static stretching exercises two different stretching modes were designed for dynamic stretching exercises. Concentric and eccentric isokinetic peak torque for the non-stretched antagonist quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities were measured before and immediately after the intervention. Isokinetic peak torques of the non-stretched agonist hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching of the antagonist quadriceps and hamstring muscles, respectively. Similarly, the EMG activities of the agonist muscles exhibited no significant alterations (p > 0.05) following both stretching exercises of the antagonist muscles. According to the results of the present study it is possible to state that antagonist stretching exercises either in the static or dynamic modes do not affect the isokinetic peak torques and the EMG activities

  6. Electromyographic analysis of upper limb muscles during standardized isotonic and isokinetic robotic exercise of spastic elbow in patients with stroke.

    Science.gov (United States)

    Sin, Minki; Kim, Won-Seok; Park, Daegeun; Min, Yu-Sun; Kim, Woo Jin; Cho, Kyujin; Paik, Nam-Jong

    2014-02-01

    Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods. Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis. The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0±17.0 (2nd), 87.8±14.4 (3rd) in isokinetic, 80.9±11.0 (2nd), 81.6±12.4 (3rd) in isotonic contraction, F[1,8]=11.168; P=0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Isokinetic Evaluation of Quadriceps Strength in Open and Closed Kinetic Chains in Patients with Anterior Cruciate Ligament Reconstruction

    Directory of Open Access Journals (Sweden)

    Ali Ashraf-Jamshidi

    2014-06-01

    Full Text Available Background: Strength of knee extension and squat were compared between anterior cruciate ligament reconstructed (ACLR patients and healthy subjects. Materials and Methods: Twenty ACLR and twenty control subjects were participated in this non-exprimental study. Isokinetic peak strength of knee extension and squat in involved and uninvolved side of the ACLR patient and control group were measured. Results: Concentric and eccentric knee extension strength of the involved leg was decreased but squat strength showed no difference. Conclusion: In spite of return to sport activity and normal squat strength weakness of knee extensor muscles in the involved side of the ACLR patient was existed.

  8. Intramuscular pressure and electromyography as indexes of force during isokinetic exercise

    Science.gov (United States)

    Aratow, M.; Ballard, R. E.; Grenshaw, A. G.; Styf, J.; Watenpaugh, D. E.; Kahan, N. J.; Hargens, A. R.

    1993-01-01

    A direct method for measuring force production of specific muscles during dynamic exercise is presently unavailable. Previous studies indicate that both intramuscular pressure (IMP) and electromyography (EMG) correlate linearly with muscle contraction force during isometric exercise. The objective of this study was to compare IMP and EMG as linear assessors of muscle contraction force during dynamic exercise. IMP and surface EMG activity were recorded during concentric and eccentric isokinetic plantarflexion and dorsiflexion of the ankle joint from the tibialis anterior (TA) and soleus (SOL) muscles of nine male volunteers. Ankle torque was measured using a dynamometer, and IMP was measured via catheterization. IMP exhibited better linear correlation than EMG with ankle joint torque during concentric contractions of the SOL and the TA, as well as during eccentric contractions. IMP provides a better index of muscle contraction force than EMG during concentric and eccentric exercise through the entire range of torque. IMP reflects intrinsic mechanical properties of individual muscles, such as length-tension relationships, which EMG is unable to assess.

  9. IS ENHANCED-ECCENTRIC RESISTANCE TRAINING SUPERIOR TO TRADITIONAL TRAINING FOR INCREASING ELBOW FLEXOR STRENGTH?

    Directory of Open Access Journals (Sweden)

    Thomas W. Kaminski

    2003-06-01

    Full Text Available Protocols for strengthening muscle are important for fitness, rehabilitation, and the prevention of myotendinous injuries. In trained individuals, the optimal method of increasing strength remains unclear. The purpose of this study was to compare the effects of a traditional method of strengthening with a method that allowed for enhanced-eccentric training, on changes in elbow flexor strength in trained subjects. Thirty-nine (8 male, 31 female trained subjects with normal elbow function participated in this study. Subjects were rank-ordered according to isometric force production and randomly assigned to one of three training groups: control (CONT, traditional concentric/eccentric (TRAD, and concentric/enhanced-eccentric (NEG. The training groups completed 24 training sessions. An evaluator blinded to training group performed all testing. Mixed model ANOVA techniques were used to determine if differences existed in concentric one repetition maximum strength, and isometric force production among groups. Changes in peak and average isokinetic force production were also compared. Type 1 error was maintained at 5%. While both groups improved concentric one repetition maximum (NEG = 15.5%, TRAD = 13.8% neither training group statistically differed from changes demonstrated by the CONT group. Nor did either training group show significant improvements in isometric or isokinetic force production over the CONT group. These results do not support the superiority of enhanced-eccentric training for increasing force production in trained subjects.

  10. A weekly bout of eccentric exercise is sufficient to induce health-promoting effects.

    Science.gov (United States)

    Paschalis, Vassilis; Nikolaidis, Michalis G; Theodorou, Anastasios A; Panayiotou, George; Fatouros, Ioannis G; Koutedakis, Yiannis; Jamurtas, Athanasios Z

    2011-01-01

    The effects of chronic eccentric-only versus concentric-only exercise on muscle physiology and blood biochemistry were investigated. Twenty women performed on an isokinetic dynamometer a concentric (n = 10;mean ± SEM: age = 21.0 ± 0.4 yr, body fat = 22.0% ± 0.9%) or an eccentric (n = 10, age = 20.0 ± 0.3 yr, body fat = 23.2% ± 0.7%) exercise session using the knee extensors of both lower limbs once a week for eight subsequent weeks. Muscle function (isometric, concentric, and eccentric peak torque, range of movement, and soreness) was evaluated before, immediately after, and 48 h postexercise in each one of the eight training weeks. Body fat, resting energy expenditure (REE), lipid, and carbohydrate oxidation rate as well as blood chemistry measurements (lipid, lipoprotein and apolipoprotein profile, glucose, insulin, glycosylated hemoglobin, and creatine kinase) were examined before and 48 h postexercise at the first and eighth week of training. Acute eccentric exercise increased REE and fat oxidation at week 1 (12.7% and 12.9%, respectively) and at week 8 (0.7% and 2.8%, respectively). Chronic eccentric exercise increased resting REE and fat oxidation at week 8 compared with week 1 (5.0% and 9.9%, respectively). Acute eccentric exercise improved blood lipid profile at week 1 and week 8. Chronic eccentric exercise improved resting blood lipid profile at week 8. Acute eccentric exercise increased insulin resistance at week 1 but not at week 8. Chronic eccentric exercise decreased resting insulin resistance at week 8. It is reported for the first time that only 30 min of eccentric exercise per week for 8 wk was sufficient to improve health risk factors.

  11. Eccentricity from transit photometry

    DEFF Research Database (Denmark)

    Van Eylen, Vincent; Albrecht, Simon

    2015-01-01

    Solar system planets move on almost circular orbits. In strong contrast, many massive gas giant exoplanets travel on highly elliptical orbits, whereas the shape of the orbits of smaller, more terrestrial, exoplanets remained largely elusive. Knowing the eccentricity distribution in systems of small...... and can be described by a Rayleigh distribution with $\\sigma$ = 0.049 $\\pm$ 0.013. This is in full agreement with solar system eccentricities, but in contrast to the eccentricity distributions previously derived for exoplanets from radial velocity studies. Our findings are helpful in identifying which...... (TTVs), and we present some previously unreported TTVs. Finally transit durations help distinguish between false positives and true planets and we use our measurements to confirm six new exoplanets....

  12. Acute hormonal responses following different velocities of eccentric exercise.

    Science.gov (United States)

    Libardi, Cleiton A; Nogueira, Felipe R D; Vechin, Felipe C; Conceição, Miguel S; Bonganha, Valéria; Chacon-Mikahil, Mara Patricia T

    2013-11-01

    The aim of this study was to compare the acute hormonal responses following two different eccentric exercise velocities. Seventeen healthy, untrained, young women were randomly placed into two groups to perform five sets of six maximal isokinetic eccentric actions at slow (30° s(-1) ) and fast (210° s(-1) ) velocities with 60-s rest between sets. Growth hormone, cortisol, free and total testosterone were assessed by blood samples collected at baseline, immediately postexercise, 5, 15 and 30 min following eccentric exercise. Changes in hormonal responses over time were compared between groups, using a mixed model followed by a Tukey's post hoc test. The main findings of the present study were that the slow group showed higher growth hormone values immediately (5·08 ± 2·85 ng ml(-1) , P = 0·011), 5 (5·54 ± 3·01 ng ml(-1) , P = 0·004) and 15 min (4·30 ± 2·87 ng ml(-1) , P = 0·021) posteccentric exercise compared with the fast group (1·39 ± 2·41 ng ml(-1) , 1·34 ± 1·97 ng ml(-1) and 1·24 ± 1·87 ng ml(-1) , respectively), and other hormonal responses were not different between groups (P>0·05). In conclusion, slow eccentric exercise velocity enhances more the growth hormone(GH) response than fast eccentric exercise velocity without cortisol and testosterone increases. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  13. Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise.

    Science.gov (United States)

    Barnes, Matthew J; Mündel, Toby; Stannard, Stephen R

    2010-01-01

    This study investigated the effects of acute moderate alcohol intake on muscular performance during recovery from eccentric exercise-induced muscle damage. Eleven healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed a beverage containing 1g/kg bodyweight ethanol (as vodka and orange juice) (ALC). On another occasion they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed an isocaloric quantity of orange juice (OJ). Measurement of maximal isokinetic (concentric and eccentric) and isometric torque produced across the knee, plasma creatine kinase (CK) concentrations and muscle soreness were made before and at 36 and 60h following each exercise bout. All measures of muscle performance were significantly reduced at 36 and 60h post-exercise compared to pre-exercise measures (all peccentric contractions, respectively. However, peak strength loss was significantly greater in ALC with the same performance measures decreasing by 34%, 40% and 34%, respectively. Post-exercise plasma creatine kinase activity and ratings of muscle soreness were not different between conditions (both p>0.05). These results indicate that consumption of even moderate amounts of alcohol following eccentric-based exercise magnifies the normally observed losses in dynamic and static strength. Therefore, to minimise exercise related losses in muscle function and expedite recovery, participants in sports involving eccentric muscle work should avoid alcohol-containing beverages in the post-event period. Copyright (c) 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  14. Is the subscapularis normal after the open Latarjet procedure? An isokinetic and magnetic resonance imaging evaluation.

    Science.gov (United States)

    Caubère, Alexandre; Lami, Damien; Boileau, Pascal; Parratte, Sébastien; Ollivier, Matthieu; Argenson, Jean-Noël

    2017-10-01

    The Latarjet procedure is considered to be a violation of the subscapularis muscle. This study evaluated the postoperative status of the subscapularis through isokinetic and magnetic resonance imaging analysis after splitting. We hypothesized that compared with a healthy contralateral shoulder, there would be satisfactory recovery of subscapularis strength at the cost of some fatigability and some mild fatty infiltration. This was a case-control retrospective study of patients who underwent a Latarjet procedure between January 2013 and January 2015. A total of 20 patients were reviewed at 1 year postoperatively. With the patient seated, strength testing of both shoulders was done (concentric, eccentric, and fatigability) with a dynamometer. Trophicity and fatty infiltration were analyzed by magnetic resonance imaging. Strength of the internal rotators (IRs) and external rotators (ERs) of the injured shoulder was significantly lower compared with the healthy shoulder in concentric testing at 180°/s and 60°/s (13% for IR and 20% for E, P Latarjet procedure, isokinetic testing showed a combined strength deficit in both internal and external rotation with a conserved muscle balance. Although no significant subscapularis fatty infiltration or atrophy was noted, there was a significant deficit in endurance compared with the healthy shoulder. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  15. Muscle damage and inflammation after eccentric exercise: can the repeated bout effect be removed?

    Science.gov (United States)

    Margaritelis, Nikos V; Theodorou, Anastasios A; Baltzopoulos, Vasilios; Maganaris, Constantinos N; Paschalis, Vassilis; Kyparos, Antonios; Nikolaidis, Michalis G

    2015-12-01

    The current consensus in exercise physiology is that the repeated bout effect always appears after few eccentric exercise sessions. This is the first attempt to challenge this tenet, by exploiting specificity in muscle plasticity. More specifically, we examined whether the opposing adaptations in muscle induced after concentric and eccentric exercise can attenuate and/or remove the repeated bout effect. Seventeen young men were randomly assigned into one of the following groups: (1) the alternating eccentric-concentric exercise group; and (2) the eccentric-only exercise group. Both groups performed 8 weeks of resistance exercise using the knee extensors of both legs on an isokinetic dynamometer. The alternating eccentric-concentric exercise group performed an alternating exercise protocol, switching between eccentric-only and concentric-only exercise every 4 weeks, while the eccentric-only group performed eccentric exercise. Evaluation of muscle damage using physiological (isometric torque, delayed onset muscle soreness, and range of movement) and biochemical (creatine kinase) markers and inflammation (C-reactive protein) was performed at weeks 1, 5, and 10. Baseline isometric peak torque was also evaluated at week 14 after another cycle (4 weeks) of alternating or eccentric-only exercise training. In the alternating eccentric-concentric exercise group, the concentric exercise training performed prior to eccentric exercise reduced dramatically the repeated bout effect by reversing muscle back to its unaccustomed state. On the contrary, the eccentric-only exercise group exhibited a typical manifestation of the repeated bout effect. Interestingly, muscle strength was elevated similarly for both alternating and eccentric-only exercise groups after 13 weeks of training. The alternating eccentric-concentric exercise scheme, implemented in the present study, has for the first time successfully overcame the repeated bout effect. The similarity in muscle strength

  16. Origin of Prometheus Eccentricity

    Science.gov (United States)

    Rappaport, N. J.; Longaretti, P.

    2006-12-01

    A number of Saturn's small satellites, from Atlas to the coorbital satellites Janus and Epimetheus, move on orbits just outside the main rings of the planet. These satellites undergo extremely rapid resonant interaction with the rings and outward motion, strongly suggesting that they originated in Saturn's A ring. However, their eccentricities, of the order of 1/1000 are several orders of magnitude larger than what could be expected if the small satellites formed in the ring. This paper represents a first step to providing an explanation for this phenomenon, by focusing on the dynamical processes that have affected the eccentricity of Prometheus. The explanation invokes past resonances with the coorbital satellites combined with chaos due to overlapping of these resonances.

  17. HAMSTRING ARCHITECTURAL AND FUNCTIONAL ADAPTATIONS FOLLOWING LONG VS. SHORT MUSCLE LENGTH ECCENTRIC TRAINING

    Directory of Open Access Journals (Sweden)

    Kenny Guex

    2016-08-01

    Full Text Available Most common preventive eccentric-based exercises, such as Nordic hamstring do not include any hip flexion. So, the elongation stress reached is lower than during the late swing phase of sprinting. The aim of this study was to assess the evolution of hamstring architectural (fascicle length and pennation angle and functional (concentric and eccentric optimum angles and concentric and eccentric peak torques parameters following a 3-week eccentric resistance program performed at long (LML versus short muscle length (SML. Both groups performed eight sessions of 3-5x8 slow maximal eccentric knee extensions on an isokinetic dynamometer: the SML group at 0° and the LML group at 80° of hip flexion. Architectural parameters were measured using ultrasound imaging and functional parameters using the isokinetic dynamometer. The fascicle length increased by 4.9% (p<0.01, medium effect size in the SML and by 9.3% (p<0.001, large effect size in the LML group. The pennation angle did not change (p=0.83 in the SML and tended to decrease by 0.7° (p=0.09, small effect size in the LML group. The concentric optimum angle tended to decrease by 8.8° (p=0.09, medium effect size in the SML and by 17.3° (p<0.01, large effect size in the LML group. The eccentric optimum angle did not change (p=0.19, small effect size in the SML and tended to decrease by 10.7° (p=0.06, medium effect size in the LML group. The concentric peak torque did not change in the SML (p=0.37 and the LML (p=0.23 groups, whereas eccentric peak torque increased by 12.9% (p<0.01, small effect size and 17.9% (p<0.001, small effect size in the SML and the LML group, respectively. No group-by-time interaction was found for any parameters. A correlation was found between the training-induced change in fascicle length and the change in concentric optimum angle (r=-0.57, p<0.01. These results suggest that performing eccentric exercises lead to several architectural and functional adaptations. However

  18. Functional changes of human quadriceps muscle injured by eccentric exercise

    Directory of Open Access Journals (Sweden)

    F.V. Serrão

    2003-06-01

    Full Text Available The present study evaluated functional changes of quadriceps muscle after injury induced by eccentric exercise. Maximal isometric torque of quadriceps and the surface electromyography (root mean square, RMS, and median frequency, MDF of the vastus medialis oblique (VMO and vastus lateralis (VL muscles were examined before, immediately after and during the first 7 days after injury. Serum creatine kinase (CK levels and magnetic resonance imaging (MRI were used to identify muscle injury. The subject was used as her own control and percent refers to pre-injury data. Experiments were carried out with a sedentary 23-year-old female. Injury was induced by 4 bouts of 15 maximal isokinetic eccentric contractions (angular velocity of 5º/s; range of motion from 40º to 110º of knee flexion. The isometric torque of the quadriceps (knee at 90º flexion decreased 52% immediately after eccentric exercise and recovered on the 5th day. The highest reduction of RMS occurred on the 2nd day after injury in both VL (63% and VMO (66% and only VL recovered to the pre-injury level on the 7th day. Immediately after injury, the MDF decreased by 5 and 3% (VMO and VL, respectively and recovered one day later. Serum CK levels increased by 109% on the 2nd day and were still increased by 32% on the 7th day. MRI showed large areas of injury especially in the deep region of quadriceps. In conclusion, eccentric exercise decreased the isometric torque and electromyographic signals of quadriceps muscle, which were recovered in one week, despite the muscle regeneration signals.

  19. Effects of Lumbosacral Manipulation on Isokinetic Strength of the Knee Extensors and Flexors in Healthy Subjects: A Randomized, Controlled, Single-Blind Crossover Trial

    Science.gov (United States)

    Sanders, Grant D.; Nitz, Arthur J.; Abel, Mark G.; Symons, T. Brock; Shapiro, Robert; Black, W. Scott; Yates, James W.

    2015-01-01

    Objective The purpose of this study was to investigate the effect of manual manipulations targeting the lumbar spine and/or sacroiliac joint on concentric knee extension and flexion forces. Torque production was measured during isometric and isokinetic contractions. Methods This was a randomized, controlled, single-blind crossover design with 21 asymptomatic, college-aged subjects who had never received spinal manipulation. During 2 separate sessions, subjects’ peak torques were recorded while performing maximal voluntary contractions on an isokinetic dynamometer. Isometric knee extension and flexion were recorded at 60° of knee flexion, in addition to isokinetic measurements obtained at 60°/s and 180°/s. Baseline measurements were acquired before either treatment form of lumbosacral manipulation or sham manipulation, followed by identical peak torque measurements within 5 and 20 minutes posttreatment. Data were analyzed with a repeated measures analysis of variance. Results A statistically significant difference did not occur between the effects of lumbosacral manipulation or the sham manipulation in the percentage changes of knee extension and flexion peak torques at 5 and 20 minutes posttreatment. Similar, nonsignificant results were observed in the overall percentage changes of isometric contractions (spinal manipulation 4.0 ± 9.5 vs sham 1.2 ± 6.3, P = .067), isokinetic contractions at 60°/s (spinal manipulation − 4.0 ± 14.2 vs sham − 0.3 ± 8.2, P = .34), and isokinetic contractions at 180°/s (spinal manipulation − 1.4 ± 13.9 vs sham − 5.5 ± 20.0, P = .18). Conclusion The results of the current study suggest that spinal manipulation does not yield an immediate strength-enhancing effect about the knee in healthy, college-aged subjects when measured with isokinetic dynamometry. PMID:26793035

  20. PEAK AND END RANGE ECCENTRIC EVERTOR/CONCENTRIC INVERTOR MUSCLE STRENGTH RATIOS IN CHRONICALLY UNSTABLE ANKLES: COMPARISON WITH HEALTHY INDIVIDUALS

    Directory of Open Access Journals (Sweden)

    Mahmut Komurcu

    2003-09-01

    Full Text Available The aim of this study was to evaluate the alterations in eccentric evertor/concentric invertor strength ratio and their importance in the chronically unstable ankle. Eight patients with chronic ankle instability (CAI and nine healthy individuals participated in this study. Isokinetic concentric and eccentric invertor and evertor muscle strength measurement was carried out at an angular velocity of 120°·sec-1 by measuring maximal force moments (torque during isokinetic ankle inversion and eversion movements. Functionally, evertor/invertor muscle strength ratios (E/I strength ratio were calculated separately based on peak moment and angle-specific moments obtained at 0°, 5°, 10°, 15°, 20° ankle joint angles. Peak and angle-specific eccentric evertor strength values at 0°, 5°, 10°, 15°, 20° were significantly lower in the chronic ankle instability (CAI group. In spite of this, no differences were obtained for peak and angle-specific concentric invertor torque values. Eccentric evertor/concentric invertor strength (Eecc/Icon ratios were also significantly lower in the CAI group, but only at 15° and 20°. Eccentric evertor muscle torque and end range (15°-20° Eecc/Icon strength ratio for the chronically unstable ankle were significantly different from those for the healthy ankle. For this reason, measurements of end range eccentric/concentric strength ratios are more valuable in monitoring chronic ankle injuries and rehabilitation should include not only concentric muscle strengthening but also eccentric muscle strengthening, particularly for the evertor muscles

  1. Isokinetic knee extension and vertical jumping: are they related?

    Science.gov (United States)

    Iossifidou, Anna; Baltzopoulos, Vasilios; Giakas, Giannis

    2005-10-01

    The aim of this study was to examine joint power generation during a concentric knee extension isokinetic test and a squat vertical jump. The isokinetic test joint power was calculated using four different methods. Five participants performed concentric knee extensions at 0.52, 1.57, 3.14 and 5.23 rad x s(-1) on a Lido isokinetic dynamometer. The squat vertical jump was performed on a Kistler force plate. Kinematic data from both tests were collected and analysed using an ELITE optoelectronic system. An inverse dynamics model was applied to measure knee joint moment in the vertical jump. Knee angular position data from the kinematic analysis in the isokinetic test were used to derive the actual knee angular velocity and acceleration, which, in turn, was used to correct the dynamometer moment for inertial effects. Power was measured as the product of angular velocity and moment at the knee joint in both tests. Significant differences (P knee joint power in the two tests (squat vertical jump: 2255 +/- 434 W; isokinetic knee extension: 771 +/- 81 W). Correlation analysis revealed that there is no relationship between the peak knee joint power during the vertical jump and the slow velocity isokinetic tests. Higher isokinetic velocity tests show better relationships with the vertical jump but only if the correct method for joint power calculation is used in the isokinetic test. These findings suggest that there are important differences in muscle activation and knee joint power development that must be taken into consideration when isokinetic tests are used to predict jumping performance.

  2. Eccentric exercise testing and training

    Science.gov (United States)

    Clarkson, Priscilla M.

    1994-01-01

    Some researchers and practitioners have touted the benefits of including eccentric exercise in strength training programs. However, others have challenged its use because they believe that eccentric actions are dangerous and lead to injuries. Much of the controversy may be based on a lack of understanding of the physiology of eccentric actions. This review will present data concerning eccentric exercise in strength training, the physiological characteristics of eccentric exercise, and the possible stimulus for strength development. Also a discussion of strength needs for extended exposure to microgravity will be presented. Not only is the use of eccentric exercise controversial, but the name itself is fraught with problems. The correct pronunciation is with a hard 'c' so that the word sounds like ekscentric. The confusion in pronunciation may have been prevented if the spelling that Asmussen used in 1953, excentric, had been adopted. Another problem concerns the expressions used to describe eccentric exercise. Commonly used expressions are negatives, eccentric contractions, lengthening contractions, resisted muscle lengthenings, muscle lengthening actions, and eccentric actions. Some of these terms are cumbersome (i.e., resisted muscle lengthenings), one is slang (negatives), and another is an oxymoron (lengthening contractions). Only eccentric action is appropriate and adoption of this term has been recommended by Cavanagh. Despite the controversy that surrounds eccentric exercise, it is important to note that these types of actions play an integral role in normal daily activities. Eccentric actions are used during most forms of movement, for example, in walking when the foot touches the ground and the center of mass is decelerated and in lowering objects, such as placing a bag of groceries in the car.

  3. Voluntary Environmental Governance Arrangements

    NARCIS (Netherlands)

    van der Heijden, J.

    2012-01-01

    Voluntary environmental governance arrangements have focal attention in studies on environmental policy, regulation and governance. The four major debates in the contemporary literature on voluntary environmental governance arrangements are studied. The literature falls short of sufficiently

  4. Voluntary Environmental Governance Arrangements

    NARCIS (Netherlands)

    van der Heijden, J.

    2012-01-01

    Voluntary environmental governance arrangements have focal attention in studies on environmental policy, regulation and governance. The four major debates in the contemporary literature on voluntary environmental governance arrangements are studied. The literature falls short of sufficiently specify

  5. Voluntary Service System (VSS)

    Data.gov (United States)

    Department of Veterans Affairs — Voluntary Service System (VSS) is a national-level application which replaced the site-based Voluntary Timekeeping System (VTK). VTK was used for many years at the...

  6. Eccentric wrist extensor contractions and the force velocity relationship in muscle.

    Science.gov (United States)

    Walmsley, R P; Pearson, N; Stymiest, P

    1986-01-01

    The torque produced by the wrist extensors during maximal isometric and isokinetic eccentric contractions has been investigated. The torque produced by eccentric contractions was measured at three different velocities: 0.36, 0.93, and 1.64 cmlsec. The speeds of contraction were generated by a specially designed apparatus, consisting of a gear drive and an electric motor that would maintain its speed irrespective of the load applied. Tenison produced by the wrist extensors was measured using a load cell. The results indicated that eccentric contractions of the wrist extensors exceed those produced by isometric contractions. The force-velocity relationship during eccentric contractions was determined to be different from that during concentric contractions. Force values were found to increase as the velocity of eccentric contraction increased. No signficant effect of wrist joint angle on torque values was found, nor was there an interaction effect of velocity and joint angle. The implications for rehabilitation of these findings are outlined. J Orthop Sports Phys Ther 1986;8(6):288-293.

  7. Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females.

    Directory of Open Access Journals (Sweden)

    K M Hicks

    Full Text Available To investigate whether there is a sex difference in exercise induced muscle damage.Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets, Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20-90°. Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage.Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (p0.05. Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (p<0.05, and remained higher when maximal voluntary eccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (p<0.05.Based on isometric torque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage.

  8. Eccentric exercise slows in vivo microvascular reactivity during brief contractions in human skeletal muscle.

    Science.gov (United States)

    Larsen, Ryan G; Hirata, Rogerio P; Madzak, Adnan; Frøkjær, Jens B; Graven-Nielsen, Thomas

    2015-12-01

    Unaccustomed exercise involving eccentric contractions results in muscle soreness and an overall decline in muscle function, however, little is known about the effects of eccentric exercise on microvascular reactivity in human skeletal muscle. Fourteen healthy men and women performed eccentric contractions of the dorsiflexor muscles in one leg, while the contralateral leg served as a control. At baseline, and 24 and 48 h after eccentric exercise, the following were acquired bilaterally in the tibialis anterior muscle: 1) transverse relaxation time (T2)-weighted magnetic resonance images to determine muscle cross-sectional area (mCSA) and T2; 2) blood oxygen level-dependent (BOLD) images during and following brief, maximal voluntary contractions (MVC) to monitor the hyperemic responses with participants positioned supine in a 3T magnet; 3) muscle strength; and 4) pain pressure threshold. Compared with the control leg, eccentric exercise resulted in soreness, decline in strength (∼20%), increased mCSA (∼7%), and prolonged T2 (∼7%) at 24 and 48 h (P eccentric exercise, such that time-to-peak (∼35%, P eccentric exercise may impede rapid adjustments in muscle blood flow at exercise onset and during activities involving brief bursts of muscle activation, which may impair O2 delivery and contribute to reduced muscle function after eccentric exercise. Copyright © 2015 the American Physiological Society.

  9. No reserve in isokinetic cycling power at intolerance during ramp incremental exercise in endurance-trained men.

    Science.gov (United States)

    Ferguson, Carrie; Wylde, Lindsey A; Benson, Alan P; Cannon, Daniel T; Rossiter, Harry B

    2016-01-01

    During whole body exercise in health, maximal oxygen uptake (V̇o2max) is typically attained at or immediately before the limit of tolerance (LoT). At the V̇o2max and LoT of incremental exercise, a fundamental, but unresolved, question is whether maximal evocable power can be increased above the task requirement, i.e., whether there is a "power reserve" at the LoT. Using an instantaneous switch from cadence-independent (hyperbolic) to isokinetic cycle ergometry, we determined maximal evocable power at the limit of ramp-incremental exercise. We hypothesized that in endurance-trained men at LoT, maximal (4 s) isokinetic power would not differ from the power required by the task. Baseline isokinetic power at 80 rpm (Piso; measured at the pedals) and summed integrated EMG from five leg muscles (ΣiEMG) were measured in 12 endurance-trained men (V̇o2max = 4.2 ± 1.0 l/min). Participants then completed a ramp incremental exercise test (20-25 W/min), with instantaneous measurement of Piso and ΣiEMG at the LoT. Piso decreased from 788 ± 103 W at baseline to 391 ± 72 W at LoT, which was not different from the required ramp-incremental flywheel power (352 ± 58 W; P > 0.05). At LoT, the relative reduction in Piso was greater than the relative reduction in the isokinetic ΣiEMG (50 ± 9 vs. 63 ± 10% of baseline; P power is not different from the power required by the task and is consequent to both central and peripheral limitations in evocable power. The absence of a power reserve suggests both the perceptual and physiological limits of maximum voluntary power production are not widely dissociated at LoT in this population.

  10. Validity and reliability of isometric, isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total knee arthroplasty.

    Science.gov (United States)

    Lienhard, K; Lauermann, S P; Schneider, D; Item-Glatthorn, J F; Casartelli, N C; Maffiuletti, N A

    2013-12-01

    Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947-0.966; standard error of measurement range: 5.1-9.3%). Involved quadriceps strength was significantly correlated to walking speed (r range: 0.641-0.710), step length (r range: 0.685-0.820) and WOMAC function (r range: 0.575-0.663), independent from the modality (P torque (P > 0.05). In conclusion, isometric, isokinetic, and isoinertial modalities ensure valid and reliable assessment of quadriceps muscle strength in TKA patients.

  11. Neuromuscular responses to mild-muscle damaging eccentric exercise in a low glycogen state.

    Science.gov (United States)

    Gavin, James P; Myers, Stephen D; Willems, Mark E T

    2015-02-01

    The aim of this study was to examine the effect of low muscle glycogen on the neuromuscular responses to maximal eccentric contractions. Fourteen healthy men (22 ± 3 years) performed single-leg cycling (20 min at ~75% maximal oxygen uptake (V̇O2 max); eight 90 s sprints at a 1:1 work-to-rest ratio (5% decrements from 90% to 55% V̇O2 max until exhaustion) the evening before 100 eccentric (1.57 rads(-1)) with reduced (RED) and normal glycogen (NORM). Neuromuscular responses were measured during and up to 48 h after with maximal voluntary and involuntary (twitch, 20 Hz and 50 Hz) isometric contractions. During eccentric contractions, peak torque decreased (RED: -16.1 ± 2.5%; NORM: -6.2 ± 5.1%) and EMG frequency increased according to muscle length. EMG activity decreased for RED only. After eccentric contractions, maximal isometric force was reduced up to 24h for NORM (-13.5 ± 5.8%) and 48 h for RED (-7.4 ± 10.9%). Twelve hours after eccentric contractions, twitch force and the 20:50 Hz ratio were decreased for RED but not for NORM. Immediate involuntary with prolonged voluntary force loss suggests that reduced glycogen is associated with increased susceptibility to mild muscle-damaging eccentric exercise with contributions of peripheral and central mechanisms to be different during recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Effects of Static and Dynamic Stretching on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist Muscles

    Science.gov (United States)

    Serefoglu, Abdullah; Sekir, Ufuk; Gür, Hakan; Akova, Bedrettin

    2017-01-01

    The aim of this study was to investigate if static and dynamic stretching exercises of the knee muscles (quadriceps and hamstring muscles) have any effects on concentric and eccentric isokinetic peak torques and electromyographic amplitudes (EMG) of the antagonist muscles. Twenty healthy male athletes (age between 18-30 years) voluntarily participated in this study. All of the subjects visited the laboratory to complete the following intervention in a randomized order on 5 separate days; (a) non-stretching (control), (b) static stretching of the quadriceps muscles, (c) static stretching of the hamstring muscles, (d) dynamic stretching of the quadriceps muscles, and (e) dynamic stretching of the hamstring muscles. Static stretching exercises either for the quadriceps or the hamstring muscles were carried out at the standing and sitting positions. Subjects performed four successive repetitions of each stretching exercises for 30 seconds in both stretching positions. Similar to static stretching exercises two different stretching modes were designed for dynamic stretching exercises. Concentric and eccentric isokinetic peak torque for the non-stretched antagonist quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities were measured before and immediately after the intervention. Isokinetic peak torques of the non-stretched agonist hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching of the antagonist quadriceps and hamstring muscles, respectively. Similarly, the EMG activities of the agonist muscles exhibited no significant alterations (p > 0.05) following both stretching exercises of the antagonist muscles. According to the results of the present study it is possible to state that antagonist stretching exercises either in the static or dynamic modes do not affect the isokinetic peak torques and the EMG activities

  13. [Isokinetic assessment of ankles in patients with rheumatoid arthritis].

    Science.gov (United States)

    Oliveira, Silvia Cristina Gutierrez; Oliveira, Leda Magalhaes; Jones, Anamaria; Natour, Jamil

    2015-01-01

    The foot and ankle in rheumatoid arthritis undergo highly destructive synovitis with loss of muscle strength. To evaluate the muscle strength of ankles in patients with rheumatoid arthritis based on isokinetic dynamometry parameters. Thirty patients with a diagnosis of rheumatoid arthritis involving the ankle(s) and 30 healthy subjects (control group) matched for age, gender, race, body mass index and lower limb dominance were studied. Dorsiflexion, plantarflexion, inversion and eversion were evaluated in all subjects on an isokinetic Cybex Norm dynamometer. The variables were compared between the rheumatoid arthritis and control groups and between the right and left ankles, and the dorsiflexor/plantar flexor and invertor/evertor muscle strength ratio was determined. Patients with rheumatoid arthritis performed statistically worse in the isokinetic dynamometry test for all ankle movements. The muscle strength ratio between dorsiflexors and plantar flexors was different in the two groups. No significant differences were observed in the invertor and evertor ratios. In the two groups the plantar flexor musculature was statistically stronger than dorsiflexors. We conclude that patients with rheumatoid arthritis perform worse in isokinetic dynamometry regarding all ankle movements than control subjects, with similar isokinetic test results being observed for the right and left side in both groups, with few exceptions. Isokinetic evaluation posed no additional risk such as important pain or inflammatory activity to patients with rheumatoid arthritis. Copyright © 2014 Elsevier Editora Ltda. All rights reserved.

  14. Isokinetic Testing in Evaluation Rehabilitation Outcome After ACL Reconstruction

    Science.gov (United States)

    Cvjetkovic, Dragana Dragicevic; Bijeljac, Sinisa; Palija, Stanislav; Talic, Goran; Radulovic, Tatjana Nozica; Kosanovic, Milkica Glogovac; Manojlovic, Slavko

    2015-01-01

    Introduction: Numerous rehab protocols have been used in rehabilitation after ACL reconstruction. Isokinetic testing is an objective way to evaluate dynamic stability of the knee joint that estimates the quality of rehabilitation outcome after ACL reconstruction. Our investigation goal was to show importance of isokinetic testing in evaluation thigh muscle strength in patients which underwent ACL reconstruction and rehabilitation protocol. Subjects and methods: In prospective study, we evaluated 40 subjects which were divided into two groups. Experimental group consisted of 20 recreational males which underwent ACL reconstruction with hamstring tendon and rehabilitation protocol 6 months before isokinetic testing. Control group (20 subjects) consisted of healthy recreational males. In all subjects knee muscle testing was performed on a Biodex System 4 Pro isokinetic dynamo-meter et velocities of 60°/s and 180°/s. We followed average peak torque to body weight (PT/BW) and classic H/Q ratio. In statistical analysis Student’s T test was used. Results: There were statistically significant differences between groups in all evaluated parameters except of the mean value of PT/BW of the quadriceps et velocity of 60°/s (p>0.05). Conclusion: Isokinetic testing of dynamic stabilizers of the knee is need in diagnostic and treatment thigh muscle imbalance. We believe that isokinetic testing is an objective parameter for return to sport activities after ACL reconstruction. PMID:25870471

  15. Position sense and reaction angle after eccentric exercise: the repeated bout effect.

    Science.gov (United States)

    Paschalis, V; Nikolaidis, M G; Giakas, G; Jamurtas, A Z; Owolabi, E O; Koutedakis, Y

    2008-05-01

    The purpose of the present investigation was to examine the effects of a repeated eccentric exercise on position sense and muscle reaction angle. Fourteen healthy women underwent an isokinetic exercise session on their knee flexors, which was repeated after 4 weeks. Muscle damage indices, position sense and joint reaction angle of the knee were examined before, immediately after, as well as at 1, 2, 3, 4 and 7 days after exercise. The second exercise bout induced significantly lesser effects in all muscle damage indices as well as lesser disturbances in position sense and reaction angle when compared to the first one. The main finding of this study is that position sense and joint reaction angle to release of the lower limbs may adapt in response to a repeated bout of eccentric exercise, leading to less disturbances in position sense and reaction angle after the second bout of exercise.

  16. Facilitation of quadriceps activation is impaired following eccentric exercise.

    Science.gov (United States)

    Hedayatpour, N; Arendt-Nielsen, L; Falla, D

    2014-04-01

    Contracting the knee flexor muscles immediately before a maximum voluntary contraction (MVC) of knee extension increases the maximal force that the extensor muscles can exert. It is hypothesized that this phenomenon can be impaired by muscle fiber damage following eccentric exercise [delayed onset muscle soreness (DOMS)]. This study investigates the effect of eccentric exercise and DOMS on knee extension MVC immediately following a reciprocal-resisted knee flexion contraction. Electromyography (EMG) was recorded from the knee extensors and flexors of 12 healthy men during knee extension MVCs performed in a reciprocal (maximal knee extension preceded by resisted knee flexion), and nonreciprocal condition (preceded by relaxation of the knee flexors). At baseline, knee extension MVC force was greater during the reciprocal condition (P eccentric exercise, the MVC force was not different between conditions. Similarly, at baseline, the EMG amplitude of the quadriceps during the MVC was larger for the reciprocal condition (P eccentric exercise abolished the facilitation of force production for the knee extensors, which normally occurs when maximum knee extension is preceded by activation of the knee flexors.

  17. Eccentric Binary Millisecond Pulsars

    CERN Document Server

    Freire, Paulo C C

    2009-01-01

    In this paper we review the recent discovery of several millisecond pulsars (MSPs) in eccentric binary systems. Timing these MSPs we were able to estimate (and in one case precisely measure) their masses. These results suggest that, as a class, MSPs have a much wider range of masses (1.3 to > 2 solar masses) than the normal and mildly recycled pulsars found in double neutron star (DNS) systems (1.25 < Mp < 1.44 solar masses). This is very likely to be due to the prolonged accretion episode that is thought to be required to form a MSP. The likely existence of massive MSPs makes them a powerful probe for understanding the behavior of matter at densities larger than that of the atomic nucleus; in particular, the precise measurement of the mass of PSR J1903+0327 ($1.67 +/- 0.01 solar masses) excludes several "soft" equations of state for dense matter.

  18. Eccentricity distribution of wide binaries

    CERN Document Server

    Tokovinin, Andrei

    2015-01-01

    A sample of 477 solar-type binaries within 67pc with projected separations larger than 50AU is studied by a new statistical method. Speed and direction of the relative motion are determined from the short observed arcs or known orbits, and their joint distribution is compared to the numerical simulations. By inverting the observed distribution with the help of simulations, we find that average eccentricity of wide binaries is 0.59+-0.02 and the eccentricity distribution can be modeled as f(e) ~= 1.2 e + 0.4. However, wide binaries containing inner subsystems, i.e. triple or higher-order multiples, have significantly smaller eccentricities with the average e = 0.52+-0.05 and the peak at e ~ 0.5. We find that the catalog of visual orbits is strongly biased against large eccentricities. A marginal evidence of eccentricity increasing with separation (or period) is found for this sample. Comparison with spectroscopic binaries proves the reality of the controversial period-eccentricity relation. The average eccentr...

  19. Greater Strength Gains after Training with Accentuated Eccentric than Traditional Isoinertial Loads in Already Strength-Trained Men.

    Science.gov (United States)

    Walker, Simon; Blazevich, Anthony J; Haff, G Gregory; Tufano, James J; Newton, Robert U; Häkkinen, Keijo

    2016-01-01

    As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading vs. traditional isoinertial resistance training in strength-trained men. Young (22 ± 3 years, 177 ± 6 cm, 76 ± 10 kg, n = 28) strength-trained men (2.6 ± 2.2 years experience) were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40%) or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1) and three sets of 10-RM (session 2) bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle) and isokinetic (concentric and eccentric 30°.s(-1)) knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasonography and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18 ± 10 vs. 1 ± 5%, p eccentric torque increased significantly after accentuated eccentric load training only (10 ± 9%, p eccentric load (10 ± 9%, p eccentric load group was significantly greater (p eccentric load group only (28%, p eccentric load training led

  20. Analysis of concentric and eccentric contractions in biceps brachii muscles using surface electromyography signals and multifractal analysis.

    Science.gov (United States)

    Marri, Kiran; Swaminathan, Ramakrishnan

    2016-06-23

    Muscle contractions can be categorized into isometric, isotonic (concentric and eccentric) and isokinetic contractions. The eccentric contractions are very effective for promoting muscle hypertrophy and produce larger forces when compared to the concentric or isometric contractions. Surface electromyography signals are widely used for analyzing muscle activities. These signals are nonstationary, nonlinear and exhibit self-similar multifractal behavior. The research on surface electromyography signals using multifractal analysis is not well established for concentric and eccentric contractions. In this study, an attempt has been made to analyze the concentric and eccentric contractions associated with biceps brachii muscles using surface electromyography signals and multifractal detrended moving average algorithm. Surface electromyography signals were recorded from 20 healthy individuals while performing a single curl exercise. The preprocessed signals were divided into concentric and eccentric cycles and in turn divided into phases based on range of motion: lower (0°-90°) and upper (>90°). The segments of surface electromyography signal were subjected to multifractal detrended moving average algorithm, and multifractal features such as strength of multifractality, peak exponent value, maximum exponent and exponent index were extracted in addition to conventional linear features such as root mean square and median frequency. The results show that surface electromyography signals exhibit multifractal behavior in both concentric and eccentric cycles. The mean strength of multifractality increased by 15% in eccentric contraction compared to concentric contraction. The lowest and highest exponent index values are observed in the upper concentric and lower eccentric contractions, respectively. The multifractal features are observed to be helpful in differentiating surface electromyography signals along the range of motion as compared to root mean square and median

  1. The effect of eccentric exercise on position sense and joint reaction angle of the lower limbs.

    Science.gov (United States)

    Paschalis, V; Nikolaidis, M G; Giakas, G; Jamurtas, A Z; Pappas, A; Koutedakis, Y

    2007-04-01

    Impaired position sense and impaired joint reaction angle of the lower limbs after muscle-damaging activities is a serious functional limitation that may lead to an increased risk of injury, particularly in older populations. The purpose of the present study was to examine whether position sense and joint reaction angle to release can be affected by eccentric exercise-induced muscle damage. Twelve women underwent an isokinetic exercise session of the lower limb. Isometric peak torque, delayed-onset muscle soreness, serum creatine kinase, position sense, and knee joint reaction angle to release were examined before, immediately after, and 24, 48, and 72 h post-exercise. Due to the effect of eccentric exercise, subjects persistently placed their lower limb at a more extended position, representing a shorter knee extensor muscle. Eccentric exercise increased the knee reaction angle of the lower limb after release from 0 degrees and 15 degrees but not from 30 degrees and 45 degrees . Position sense and joint reaction to release were similarly affected by eccentric exercise and independently of visual feedback. Position sense was impaired only immediately post-exercise (probably due to muscle fatigue), whereas impairment of the reaction angle to release persisted up to 3 days post-exercise (probably due to muscle damage). Attenuation of position sense and joint reaction angle of the lower limbs after damaging activities is a serious functional limitation that may lead to an increase risk of injury, particularly in older populations.

  2. Muscular hypertrophy and changes in cytokine production after eccentric training in the rat skeletal muscle.

    Science.gov (United States)

    Ochi, Eisuke; Nakazato, Koichi; Ishii, Naokata

    2011-08-01

    We investigated the time course effects of eccentric training on muscular size, strength, and growth factor/cytokine production by using an isokinetic-exercise system for rats. Male Wistar rats (n = 34) were randomly assigned into 4 groups: 5 session eccentric-training group (ECC5S, n = 10); 5 session sham-operated group (CON5S, n = 10); 10 session eccentric-training group (ECC10S, n = 7); 10 session sham-operated group (CON10S, n = 7). In each group, a session of either training or sham operation was performed every 2 days. The training consisted of 4 sets of forced dorsiflexion (5 repetitions) combined with electric stimulation of plantar flexors. The wet weight of medial gastrocnemius muscle did not increase significantly after 5 sessions of training, whereas that after 10 sessions of training significantly increased with a concomitant increase in the cross-sectional area (CSA) of muscle fibers (weight, p eccentric training for 20 days cause increases in muscular size and strength associated with increases in IL-6, follistatin, phospho-stat-3, and a decrease in myostatin. The delayed responses of IL-6, myostatin, phospho-stat-3, and follistatin would be due to the chronic effects of repeated training and possibly important for muscular hypertrophy.

  3. The influence of eccentric exercise on mRNA expression of skeletal muscle regulators.

    Science.gov (United States)

    Jensky, Nicole E; Sims, Jennifer K; Rice, Judd C; Dreyer, Hans C; Schroeder, E Todd

    2007-11-01

    To evaluate change in myostatin, follistatin, MyoD and SGT mRNA gene expression using eccentric exercise to study mechanisms of skeletal muscle hypertrophy. Young (28+/-5 years) and older (68+/-6 years) men participated in a bout of maximal single-leg eccentric knee extension on an isokinetic dynamometer at 60 degrees /s: six sets, 12-16 maximal eccentric repetitions. Muscle biopsies of the vastus lateralis were obtained from the dominant leg before exercise and 24 h after exercise. Paired t tests were used to compare change (pre versus post-exercise) for normalized gene expression in all variables. Independent t tests were performed to test group differences (young vs. older). A probability level of Peccentric exercise. Similarly, we did not observe significant change in myostatin (-3.83+/-8.8; P=0.23), follistatin (-2.66+/-5.2; P=0.17), MyoD (-0.13+/-3.1; P=0.90), or SGT (-1.6+/-3.5; P=0.19) mRNA expression in older subjects. Furthermore, the non-significant changes in mRNA expression were not different between young and older subjects, P>0.23 for all variables. Our data suggests that a single bout of maximal eccentric exercise does not alter myostatin, follistatin, MyoD or SGT mRNA gene expression in young or older subjects.

  4. Effects of fast-velocity eccentric resistance training on early and late rate of force development.

    Science.gov (United States)

    Oliveira, Anderson Souza; Corvino, Rogério Bulhões; Caputo, Fabrizio; Aagaard, Per; Denadai, Benedito Sérgio

    2016-01-01

    This study examined whether short-term maximal resistance training employing fast-velocity eccentric knee extensor actions would induce improvements in maximal isometric torque and rate of force development (RFD) at early (100 ms) of rising torque. Twenty healthy men were assigned to two experimental groups: eccentric resistance training (TG) or control (CG). Participants on the TG trained three days a week for a total of eight weeks. Training consisted of maximal unilateral eccentric knee extensors actions performed at 180 °s-1. Maximal isometric knee extensor torque (MVC) and incremental RFD in successive 50 ms time-windows from the onset contraction were analysed in absolute terms (RFDINC) or when normalised relative to MVC (RFDREL). After eight weeks, TG demonstrated increases in MVC (28%), RFDINC (0-50 ms: 30%; 50-100 ms: 31%) and RFDREL (0-50 ms: 29%; 50-100 ms: 32%). Moreover, no changes in the late phase of incremental RFD were observed in TG. No changes were found in the CG. In summary, we have demonstrated, in active individuals, that a short period of resistance training performed with eccentric fast-velocity isokinetic muscle contractions is able to enhance RFDINC and RFDREL obtained at the early phase of rising joint torque.

  5. Haptic control of a pneumatic muscle actuator to provide resistance for simulated isokinetic exercise; part II: control development and testing.

    Science.gov (United States)

    Hall, Kara L; Phillips, Chandler A; Reynolds, David B; Mohler, Stanley R; Rogers, Dana B; Neidhard-Doll, Amy T

    2015-01-01

    Pneumatic muscle actuators (PMAs) have a high power to weight ratio and possess unique characteristics which make them ideal actuators for applications involving human interaction. PMAs are difficult to control due to nonlinear dynamics, presenting challenges in system implementation. Despite these challenges, PMAs have great potential as a source of resistance for strength training and rehabilitation. The objective of this work was to control a PMA for use in isokinetic exercise, potentially benefiting anyone in need of optimal strength training through a joint's range of motion. The controller, based on an inverse three-element phenomenological model and adaptive nonlinear control, allows the system to operate as a type of haptic device. A human quadriceps dynamic simulator was developed (as described in Part I of this work) so that control effectiveness and accommodation could be tested prior to human implementation. Tracking error results indicate that the control system is effective at producing PMA displacement and resistance necessary for a scaled, simulated neuromuscular actuator to maintain low-velocity isokinetic movement during simulated concentric and eccentric knee extension.

  6. Progressive Resistance Exercise with Eccentric Loading for the Management of Knee Osteoarthritis.

    Science.gov (United States)

    Hernandez, Haniel J; McIntosh, Valerie; Leland, Azadeh; Harris-Love, Michael O

    2015-01-01

    The patient was a 58-year-old African-American male with radiographic evidence of bilateral knee osteoarthritis (OA). He participated in a standardized 12-week eccentric strengthening program within a Veterans Affairs (VA) medical center. The use of an eccentric training paradigm may prove to be beneficial for older adults with knee OA since eccentric muscle actions are involved in the energy absorption at the knee joint during gait and controlled movement during stair descent. Furthermore, in comparison to standard muscle actions, eccentric muscle actions result in higher torque generation and a lower rate of oxygen consumption at a given level of perceived exertion. Therefore, this mode of progressive resistance exercise may be ideal for older adults. The patient completed an eccentric strengthening regimen for the knee flexors and extensors twice per week without an exacerbation of knee pain. Muscle morphology measures of the rectus femoris were measured using diagnostic ultrasound. Isokinetic measures of muscle peak torque were obtained at 60°/s and 180°/s. Functional performance was assessed using a physical performance battery and stair-step performance was assessed from the linear displacement of the center of gravity trajectories obtained with a force plate. Visual analog scale pain ratings and self-reported global disease status were also documented. Post-exercise assessments revealed improvements in sonographic muscle size and tissue composition estimates, peak knee extensor torque (ranging from 60 to 253%), functional performance, and global disease status. The patient exhibited improvements in muscle morphology, muscle strength, functional performance, pain, and global disease status after 12 weeks of an eccentric strengthening regimen. The intervention and outcomes featured in this case were feasible to implement within a VA medical center and merit further investigation.

  7. Progressive Resistance Exercise with Eccentric Loading for the Management of Knee Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Michael O Harris-Love

    2015-07-01

    Full Text Available Introduction: The patient was a 58-year-old African-American male with radiographic evidence of knee osteoarthritis. He participated in a standardized 12-week eccentric strengthening program within a VA medical center. Background: The use of an eccentric training paradigm may prove to be beneficial for older adults with knee osteoarthritis since eccentric muscle actions are involved in the energy absorption at the knee joint during gait and controlled movement during stair descent. Furthermore, in comparison to standard muscle actions, eccentric muscle actions result in higher torque generation and a lower rate of oxygen consumption at a given level of perceived exertion. Therefore, this mode of progressive resistance exercise may be ideal for older adults. Discussion: The patient completed an eccentric strengthening regimen for the knee flexors and extensors twice per week without an exacerbation of knee pain. Muscle morphology measures of the rectus femoris were measured using diagnostic ultrasound. Isokinetic measures of muscle peak torque were be obtained at 60°/s and 180°/s. Functional performance was assessed using a physical performance battery and stair step performance was assessed from the linear displacement of the center of gravity trajectories obtained with a force plate. Visual analogue scale pain ratings and self-reported global disease status were also documented. Post-exercise assessments revealed improvements in sonographic muscle size and tissue composition estimates, peak knee extensor torque (ranging from 60% to 253%, functional performance, and global disease status. Concluding Remarks: The patient exhibited improvements in muscle morphology, muscle strength, functional performance, pain, and global disease status after 12 weeks of an eccentric strengthening regimen. The intervention and outcomes featured in this case were feasible to implement within a VA medical center and merit further investigation.

  8. The Relationships Among Isokinetic Endurance, Initial Strength Level, and Fiber Type.

    Science.gov (United States)

    Clarkson, Priscilla M.; And Others

    1982-01-01

    Knee extension isokinetic peak torque was assessed at four angular velocities, and isokinetic endurance was assessed in eight college age men. Muscle fiber type was determined and related to isokinetic strength and fatigability. Results indicate that factors other than fiber type and initial strength level must influence the rate of isokinetic…

  9. Effects of eccentric exercise on trapezius electromyography during computer work with active and passive pauses

    DEFF Research Database (Denmark)

    Samani, Afshin; Holtermann, Andreas; Søgaard, Karen

    2009-01-01

    BACKGROUND: The aim of this laboratory study was to investigate the effects of eccentric exercises on the trapezius muscle spatial electromyographic (EMG) activity during computer work with active and passive pauses. METHODS: Twelve healthy male subjects performed computer work with passive (relax......) and active (30% maximum voluntary contraction of shoulder elevation) pauses given every 40s over 2 days, before, immediately and 24h after eccentric exercise. Surface EMG signals were recorded from four parts of the trapezius during computer work. FINDINGS: EMG amplitude during computer work decreased...... immediately after exercise (Pactive pauses compared with passive ones (P

  10. Muscle-Tendon Unit Properties during Eccentric Exercise Correlate with the Creatine Kinase Response

    Directory of Open Access Journals (Sweden)

    Kirsty M. Hicks

    2017-09-01

    Full Text Available Aim: The aim of this paper was to determine whether; (1 patella tendon stiffness, (2 the magnitude of vastus lateralis fascicle lengthening, and (3 eccentric torque correlate with markers of exercise induced muscle damage.Method: Combining dynamometry and ultrasonography, patella tendon properties and vastus lateralis architectural properties were measured pre and during the first of six sets of 12 maximal voluntary eccentric knee extensions. Maximal isometric torque loss and creatine kinase activity were measured pre-damage (−48 h, 48, 96, and 168 h post-damage as markers of exercise-induced muscle damage.Results: A significant increase in creatine kinase (883 ± 667 UL and a significant reduction in maximal isometric torque loss (21% was reported post-eccentric contractions. Change in creatine kinase from pre to peak significantly correlated with the relative change in vastus lateralis fascicle length during eccentric contractions (r = 0.53, p = 0.02 and with eccentric torque (r = 0.50, p = 0.02. Additionally, creatine kinase tended to correlate with estimated patella tendon lengthening during eccentric contractions (p < 0.10. However, creatine kinase did not correlate with resting measures of patella tendon properties or vastus lateralis properties. Similarly, torque loss did not correlate with any patella tendon or vastus lateralis properties at rest or during eccentric contractions.Conclusion: The current study demonstrates that the extent of fascicle strain during eccentric contractions correlates with the magnitude of the creatine kinase response. Although at rest, there is no relationship between patella tendon properties and markers of muscle damage; during eccentric contractions however, the patella tendon may play a role in the creatine kinase response following EIMD.

  11. Eccentricity distribution in the main asteroid belt

    CERN Document Server

    Malhotra, Renu

    2016-01-01

    The observationally complete sample of the main belt asteroids now spans more than two orders of magnitude in size and numbers more than 64,000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that Plummer's (1916) conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution: there is a deficit of eccentricities smaller than $\\sim0.1$ and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance: the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modeled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Ra...

  12. Super-Eccentric Migrating Jupiters

    CERN Document Server

    Socrates, Aristotle; Dong, Subo; Tremaine, Scott

    2011-01-01

    An important class of formation theories for hot Jupiters involves the excitation of extreme orbital eccentricity (e=0.99 or even larger) followed by tidal dissipation at periastron passage that eventually circularizes the planetary orbit at a period less than 10 days. In a steady state, this mechanism requires the existence of a significant population of super-eccentric (e>0.9) migrating Jupiters with long orbital periods and periastron distances of only a few stellar radii. For these super-eccentric planets, the periastron is fixed due to conservation of orbital angular momentum and the energy dissipated per orbit is constant, implying that the rate of change in semi-major axis a is \\dot a \\propto a^0.5 and consequently the number distribution satisfies dN/dlog a\\propto a^0.5. If this formation process produces most hot Jupiters, Kepler should detect several super-eccentric migrating progenitors of hot Jupiters, allowing for a test of high-eccentricity migration scenarios.

  13. SUPER-ECCENTRIC MIGRATING JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Socrates, Aristotle; Katz, Boaz; Dong Subo; Tremaine, Scott [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2012-05-10

    An important class of formation theories for hot Jupiters involves the excitation of extreme orbital eccentricity (e = 0.99 or even larger) followed by tidal dissipation at periastron passage that eventually circularizes the planetary orbit at a period less than 10 days. In a steady state, this mechanism requires the existence of a significant population of super-eccentric (e > 0.9) migrating Jupiters with long orbital periods and periastron distances of only a few stellar radii. For these super-eccentric planets, the periastron is fixed due to conservation of orbital angular momentum and the energy dissipated per orbit is constant, implying that the rate of change in semi-major axis a is a-dot {proportional_to}a{sup 1/2} and consequently the number distribution satisfies dN/d log a{proportional_to}a{sup 1/2}. If this formation process produces most hot Jupiters, Kepler should detect several super-eccentric migrating progenitors of hot Jupiters, allowing for a test of high-eccentricity migration scenarios.

  14. Eccentricity evolution in hierarchical triple systems with eccentric outer binaries

    CERN Document Server

    Georgakarakos, Nikolaos

    2014-01-01

    We develop a technique for estimating the inner eccentricity in hierarchical triple systems, with the inner orbit being initially circular, while the outer one is eccentric. We consider coplanar systems with well separated components and comparable masses. The derivation of short period terms is based on an expansion of the rate of change of the Runge-Lenz vector. Then, the short period terms are combined with secular terms, obtained by means of canonical perturbation theory. The validity of the theoretical equations is tested by numerical integrations of the full equations of motion.

  15. The effect of gender on force, muscle activity, and frontal plane knee alignment during maximum eccentric leg-press exercise.

    Science.gov (United States)

    Liebensteiner, Michael C; Platzer, Hans-Peter; Burtscher, Martin; Hanser, Friedrich; Raschner, Christian

    2012-03-01

    To investigate for gender differences during eccentric leg-press exercise. Tears of the anterior cruciate ligament (ACL) are considered to be related to eccentric tasks, altered neuromuscular control (e.g., reduced co-contraction of hamstrings), and increased knee abduction (valgus alignment). Based on these observations and the fact that ACL tears are more common in women, it was hypothesized that men and women differ significantly with regard to key parameters of force, knee stabilization, and muscle activity when exposed to maximum eccentric leg extension. Thirteen women and thirteen men were matched for age and physical activity. They performed maximum isokinetic eccentric leg-pressing against footplates of varied stability. The latter was done because earlier studies had shown that perturbational test conditions might be relevant in respect of ACL injuries. Key parameters of force, frontal plane knee stabilization, and muscle recruitment of significant muscles crossing the knee were recorded. The 'force stabilization deficit' (difference between maximum forces under normal and perturbed leg-pressing) did not differ significantly between genders. Likewise, parameters of muscle activity and frontal plane leg stabilization revealed no significant differences between men and women. This study is novel, in that gender differences in parameters of force, muscle activity, and leg kinematic were investigated during functional conditions of eccentric leg-pressing. No gender differences were observed in the measured parameters. However, the conclusion should be viewed with caution because the findings concurred with, but also contrasted, previous research in this field. Diagnostic study, Level III.

  16. Effects of knee joint angle on the fascicle behavior of the gastrocnemius muscle during eccentric plantar flexions.

    Science.gov (United States)

    Wakahara, Taku; Kanehisa, Hiroaki; Kawakami, Yasuo; Fukunaga, Tetsuo

    2009-10-01

    The present study aimed to clarify the effects of knee joint angle on the behavior of the medial gastrocnemius muscle (MG) fascicles during eccentric plantar flexions. Eight male subjects performed maximal eccentric plantar flexions at two knee positions [fully extended (K0) and 90 degrees flexed (K90)]. The eccentric actions were preceded by static plantar flexion at a 30 degrees plantar flexed position and then the ankle joint was forcibly dorsiflexed to 15 degrees of dorsiflexion with an isokinetic dynamometer at 30 degrees /s and 150 degrees /s. Tendon force was calculated by dividing the plantar flexion torque by the estimated moment arm of the Achilles tendon. The MG fascicle length was determined with ultrasonography. The tendon forces during eccentric plantar flexions were influenced by the knee joint angle, but not by the angular velocity. The MG fascicle lengths were elongated as the ankle was dorsiflexed in K0, but in K90 they were almost constant despite the identical range of ankle joint motion. These results suggested that MG fascicle behavior during eccentric actions was markedly affected by the knee joint angle. The difference in the fascicle behavior between K0 and K90 could be attributed to the non-linear force-length relations and/or to the slackness of tendinous tissues.

  17. Plasma Actin, Gelsolin and Orosomucoid Levels after Eccentric Exercise.

    Science.gov (United States)

    Tékus, Éva; Váczi, Márk; Horváth-Szalai, Zoltán; Ludány, Andrea; Kőszegi, Tamás; Wilhelm, Márta

    2017-02-01

    The present study investigated the acute effect of eccentric exercise on blood plasma actin, gelsolin (GSN) and orosomucoid (AGP) levels in untrained and moderately trained individuals, and their correlation with exercise induced muscle damage (EIMD) markers (CK, intensity of muscle soreness and maximal voluntary contraction torque deficit). Healthy physical education students (6 untrained, 12 moderately trained) participated in this research. Actin, GSN, AGP and CK levels were measured in blood plasma at baseline, immediately, 1 h, 6 h and 24 h post-exercise comprising 90 eccentric quadriceps contractions performed on a dynamometer. There was significant time main effect for GSN, AGP, CK and significant difference was found between baseline and the lowest value of post-exercise GSN (p exercise AGP (p exercise and CK activity at 6 h, p exercise, p eccentric exercise do not seem sensitive to training status. The plasma actin level is used as an indicator of injury, however, our results suggest that it is not an accurate marker of EIMD, while plasma GSN concentrations show a better relationship with EIMD and the post-exercise inflammatory process. The elevated plasma AGP and the correlation between GSN and AGP seem to be promising for assessment of exercise-induced muscle injury.

  18. Effect of eccentric exercise-induced muscle damage on electromyographyic activity of quadriceps in untrained healthy females.

    Science.gov (United States)

    Rezaei, Mandana; Ebrahimi-Takamjani, Ismael; Jamshidi, Ali A; Vassaghi-Gharamaleki, Behnoush; Hedayatpour, Nosratollah; Havaei, Naser

    2014-01-01

    The aim of this study was to investigate muscle damage indicators and electromyography activities of quadriceps muscles at 25° of hip flexion in untrained healthy females after an eccentric exercise induced muscle fiber damage. A total of 14 healthy females participated in this pre-experimental study. The subjects performed maximal eccentric quadriceps contractions at 25˚ of hip flexion. Maximum voluntary extensor isometric and concentric moments, angle of maximum moment for concentric contractions, perceived pain intensity, and pain pressure threshold were examined before, immediately, 48 hours, 120 hours and 14 days after eccentric exercise. Additionally, electromyography of three parts of quadriceps muscle, knee flexion range of motion and thigh circumference were measured before and after eccentric exercise. Significant reductions in maximum isometric moment and maximum concentric moment were observed at angular velocity of 60˚ per sec immediately after eccentric exercise (peccentric exercise. Increased pain intensity and decreased knee joint range of motion manifested 48 hours after eccentric exercise. Pain pressure threshold for the quadriceps was higher 14 days after exercise as compared to 48 and 120 hours (p0.05). Eccentric exercise performed at 25˚ of hip flexion resulted in muscle fiber injuries within the quadriceps muscle. However, electromyography of quadriceps muscle was not significantly different than the baseline. The result indicates that hip joint position may modify the effect of eccentric exercise on muscle activation.

  19. Eccentric exercise in aging and diseased skeletal muscle: good or bad?

    Science.gov (United States)

    Lovering, Richard M; Brooks, Susan V

    2014-06-01

    Evidence is accumulating regarding the benefits of exercise in people who are more susceptible to injury, such as the elderly, or those with a neuromuscular disease, for example Duchenne muscular dystrophy (DMD). There appears to be a consensus that exercise can be safely performed in aging and diseased muscles, but the role of eccentric exercise is not as clear. Eccentric (lengthening) contractions have risks and benefits. Eccentric contractions are commonly performed on a daily basis, and high-force voluntary eccentric contractions are often employed in strength training paradigms with excellent results; however, high-force eccentric contractions are also linked to muscle damage. This minireview examines the benefits and safety issues of using eccentric exercise in at-risk populations. A common recommendation for all individuals is difficult to achieve, and guidelines are still being established. Some form of exercise is generally recommended with aging and even with diseased muscles, but the prescription (frequency, intensity, and duration) and type (resistance vs. aerobic) of exercise requires personal attention, as there is great diversity in the functional level and comorbidities in the elderly and those with neuromuscular disease. Copyright © 2014 the American Physiological Society.

  20. Titan's Eccentricity Tides

    Science.gov (United States)

    Iess, L.; Jacobson, R.; Ducci, M.; Stevenson, D. J.; Lunine, J. I.; Armstrong, J. W.; Asmar, S.; Racioppa, P.; Rappaport, N. J.; Tortora, P.

    2011-12-01

    The large eccentricity (e=0.03) of Titan's orbit causes significant variations in the tidal field from Saturn and induces periodic stresses in the satellite body at the orbital period (about 16 days). Peak-to-peak variations of the tidal field (from pericenter to apocenter) are about 18% (6e). If Titan hosts a liquid layer (such as an internal ocean), the gravity field would exhibit significant periodic variations. The response of the body to fast variations of the external, perturbing field is controlled by the Love numbers, defined for each spherical harmonic as the ratio between the perturbed and perturbing potential. For Titan the largest effect is by far on the quadrupole field, and the corresponding Love number is indicated by k2 (assumed to be identical for all degree 2 harmonics). Models of Titan's interior generally envisage a core made up of silicates, surrounded by a layer of high pressure ice, possibly a liquid water or water-ammonia ocean, and an ice-I outer shell, with variations associated with the dehydration state of the core or the presence of mixed rock-ice layers. Previous analysis of Titan's tidal response [1] shows that k2 depends crucially on the presence or absence of an internal ocean. k2 was found to vary from about 0.03 for a purely rocky interior to 0.48 for a rigid rocky core surrounded by an ocean and a thin (20 km) ice shell. A large k2 entails changes in the satellite's quadrupole coefficients by a few percent, enough to be detected by accurate range rate measurements of the Cassini spacecraft. So far, of the many Cassini's flybys of Titan, six were used for gravity measurements. During gravity flybys the spacecraft is tracked from the antennas of NASA's Deep Space Network using microwave links at X- and Ka-band frequencies. A state-of-the-art instrumentation enables range rate measurements accurate to 10-50 micron/s at integration times of 60 s. The first four flybys provided the static gravity field and the moment of inertia factor

  1. Aging is not a barrier to muscle and redox adaptations: applying the repeated eccentric exercise model.

    Science.gov (United States)

    Nikolaidis, Michalis G; Kyparos, Antonios; Spanou, Chrysa; Paschalis, Vassilis; Theodorou, Anastasios A; Panayiotou, George; Grivas, Gerasimos V; Zafeiridis, Andreas; Dipla, Konstantina; Vrabas, Ioannis S

    2013-08-01

    Despite the progress of analytic techniques and the refinement of study designs, striking disagreement exists among studies regarding the influence of exercise on muscle function and redox homeostasis in the elderly. The repeated eccentric exercise model was applied to produce long-lasting and extensive changes in redox biomarkers and to reveal more effectively the potential effects of aging on redox homeostasis. Ten young (20.6±0.5 years) and ten elderly men (64.6±1.1 years) underwent an isokinetic eccentric exercise session, which was repeated after three weeks. Muscle function/damage indices (torque, range of movement, muscle soreness and creatine kinase) and redox biomarkers (F2-isoprostanes, protein carbonyls, glutathione, catalase, superoxide dismutase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, uric acid, bilirubin and albumin) were assessed in plasma, erythrocytes or urine pre-exercise, immediately post-exercise and at 2 and 4 days post-exercise. As expected, the elderly group exhibited oxidative stress in baseline compared to the young group. Extensive muscle damage and extensive alterations in redox homeostasis appeared after the first bout of eccentric exercise. Noteworthy, the redox responses were similar between the age groups despite their differences in baseline values. Likewise, both age groups demonstrated blunted alterations in muscle damage and redox homeostasis after the second bout of eccentric exercise indicating adaptations from the first bout of exercise. Elderly individuals seem to be well fitted to participate in demanding physical activities without suffering detrimental effects on skeletal muscle and/or disturbances on redox homeostasis. The repeated eccentric exercise model may be a useful and practical physiological tool to study redox biology in humans. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. A new kinematical definition of orbital eccentricity

    Directory of Open Access Journals (Sweden)

    Ninković S.

    2009-01-01

    Full Text Available A new concept of orbital eccentricity is given. The dimensionless quantities proposed in the present paper to serve as orbital eccentricities have a kinematical nature. The purpose is to use them in describing the motion for the case of three-dimensional orbits. A comparison done for nearly planar orbits shows that the values of the eccentricities proposed here do not differ significantly from those corresponding to the eccentricities of geometric nature usually applied.

  3. Revisiting the Force-Joint Angle Relationship After Eccentric Exercise.

    Science.gov (United States)

    Welsh, Molly C; Allen, David L; Batliner, Matthew E; Byrnes, William C

    2015-12-01

    The purpose of this study was to evaluate force-angle curve fitting techniques pre-eccentric exercise, quantify changes in curve characteristics postexercise, and examine the relationship between curve changes and markers of muscle damage. Fourteen males unaccustomed to eccentric exercise performed 60 eccentric muscle actions of the elbow flexors. Maximal voluntary isometric force was measured throughout a range of angles pre- (Pre1 and Pre2), immediately post (IP), and 1, 2, 4, and 7 days postexercise. Force-angle curves for each visit were constructed using second-order polynomials. Changes in curve characteristics (optimal angle, peak force, curve height), range of motion, soreness, and creatine kinase activity were quantified. Optimal joint angle and force at optimal angle were significantly correlated from Pre1 to Pre2 (ICC = 0.821 and 0.979, respectively). Optimal angle was significantly right shifted (p = 0.035) by 10.4 ± 12.9° from Pre2 to IP and was restored by 1 day post exercise. Interestingly, the r value for curve fit was significantly decreased (p exercise (r = 0.750). Curve height was significantly decreased (39%) IP and restored to pre-exercise height by 4 days postexercise. There was no correlation between optimal angle or curve height and other damage markers. In conclusion, force-angle relationships can be accurately described using second-order polynomials. After eccentric exercise, the force-angle curve is flattened and shifted (downward and rightward), but these changes are not correlated to other markers of muscle damage. Changes in the force-angle relationship are multifaceted, but determining the physiological significance of these changes requires further investigation.

  4. ECCENTRIC JUPITERS VIA DISK–PLANET INTERACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Duffell, Paul C.; Chiang, Eugene, E-mail: duffell@berkeley.edu, E-mail: echiang@astro.berkeley.edu [Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley (United States)

    2015-10-20

    Numerical hydrodynamics calculations are performed to determine the conditions under which giant planet eccentricities can be excited by parent gas disks. Unlike in other studies, Jupiter-mass planets are found to have their eccentricities amplified—provided their orbits start off as eccentric. We disentangle the web of co-rotation, co-orbital, and external resonances to show that this finite-amplitude instability is consistent with that predicted analytically. Ellipticities can grow until they reach of order of the disk's aspect ratio, beyond which the external Lindblad resonances that excite eccentricity are weakened by the planet's increasingly supersonic epicyclic motion. Forcing the planet to still larger eccentricities causes catastrophic eccentricity damping as the planet collides into gap walls. For standard parameters, the range of eccentricities for instability is modest; the threshold eccentricity for growth (∼0.04) is not much smaller than the final eccentricity to which orbits grow (∼0.07). If this threshold eccentricity can be lowered (perhaps by non-barotropic effects), and if the eccentricity driving documented here survives in 3D, it may robustly explain the low-to-moderate eccentricities ≲0.1 exhibited by many giant planets (including Jupiter and Saturn), especially those without planetary or stellar companions.

  5. Reduced firing rates of high threshold motor units in response to eccentric overload.

    Science.gov (United States)

    Balshaw, Tom G; Pahar, Madhu; Chesham, Ross; Macgregor, Lewis J; Hunter, Angus M

    2017-01-01

    Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  6. Effects of flexibility training on eccentric exercise-induced muscle damage.

    Science.gov (United States)

    Chen, Che-Hsiu; Nosaka, Kazunori; Chen, Hsin-Lian; Lin, Ming-Ju; Tseng, Kuo-Wei; Chen, Trevor C

    2011-03-01

    This study investigated whether flexibility training would attenuate muscle damage induced by maximal eccentric exercise. Thirty untrained young men were allocated to static stretching (SS), proprioceptive neuromuscular facilitation (PNF), or control group (n = 10 per group). The SS consisted of 30 sets of a 30-s standard SS with a 30-s rest between sets, and the PNF included 5 sets of the 30-s standard SS followed by 3 sets of three "contract-relax-agonist-contract" procedures. These were performed three times a week for 8 wk, and all subjects performed six sets of 10 maximal isokinetic (30°·s) lengthening contractions of the knee flexors after the 8-wk training or 8 wk after the baseline measures (control). Changes in indirect markers of muscle damage before and for 5 d after the eccentric exercise were compared among the groups. The range of motion (ROM) of the hip joint increased by 25°, and the optimum angle of the knee flexors shifted (P knee flexor muscle strength and smaller changes in optimum angle, ROM, muscle soreness, and plasma creatine kinase activity and myoglobin concentration without significant differences between the groups. The preeccentric exercise ROM or optimum angle was significantly (P eccentric exercise-induced muscle damage and that flexible muscles are less susceptible to the damage.

  7. Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females.

    Science.gov (United States)

    Hicks, K M; Onambélé, G L; Winwood, K; Morse, C I

    2016-01-01

    To investigate whether there is a sex difference in exercise induced muscle damage. Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20-90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage. Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (pexercise induced muscle damage (p>0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (peccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (pexercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage.

  8. Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females

    Science.gov (United States)

    2016-01-01

    Aim To investigate whether there is a sex difference in exercise induced muscle damage. Materials and Method Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20–90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage. Results Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (ptorque loss and muscle soreness post exercise induced muscle damage (p>0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (pknee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (ptorque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage. PMID:26986066

  9. The susceptibility of the knee extensors to eccentric exercise-induced muscle damage is not affected by leg dominance but by exercise order.

    Science.gov (United States)

    Hody, S; Rogister, B; Leprince, P; Laglaine, T; Croisier, J-L

    2013-09-01

    The aims of this study were first to compare the response of dominant and non-dominant legs to eccentric exercise and second, to examine whether there is an effect of exercise order on the magnitude of symptoms associated with intense eccentric protocols. Eighteen young men performed three sets of 30 maximal eccentric isokinetic (60° s(-1)) contractions of the knee extensors (range of motion, ROM: 0°-100°, 0 = full extension) using either dominant or non-dominant leg. They repeated a similar eccentric bout using the contralateral leg 6 weeks later. The sequence of leg's use was allocated to create equally balanced groups. Four indirect markers of muscle damage including subjective pain intensity, maximal isometric strength, muscle stiffness and plasma creatine kinase (CK) activity were measured before and 24 h after exercise. All markers changed significantly following the eccentric bout performed either by dominant or non-dominant legs, but no significant difference was observed between legs. Interestingly, the comparison between the first and second eccentric bouts revealed that muscle soreness (-42%, Pexercise-induced muscle damage and supports for the first time the existence of a contralateral protection against exercise-induced muscle damage in the lower limbs.

  10. Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

    Science.gov (United States)

    English, K. L.; Ploutz-Snyder, R. J.; Cromwell, R. L.; Ploutz-Snyder, L. L.

    2010-01-01

    Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed rest

  11. Impairment of voluntary control of finger motion following stroke: role of inappropriate muscle coactivation.

    Science.gov (United States)

    Kamper, D G; Rymer, W Z

    2001-05-01

    Subjects with chronic hemiplegia following stroke attempted to perform voluntary isometric, isokinetic, and free contractions of the extensor muscles of the metacarpophalangeal (MCP) joints. We recorded torque, metacarpophalangeal joint angle and velocity, and electromyographic (EMG) activity of the extrinsic extensors and flexors and the first dorsal interosseous (FDI). We found that voluntary MCP joint extension in hemiparetic subjects was greatly impaired in comparison with control subjects: only two of the 11 stroke subjects were able to generate even 0.21 N-m of isometric extension torque, only two could produce positive finger extension with no load, and none could develop an isokinetic concentric extension. Deficits seemed to result from a combination of coactivation of the finger flexor and extensor muscles and decreased voluntary excitation of the extensors, as normalized flexor and FDI EMG activity were greater for stroke than for control subjects (P < 0.001), but normalized extensor activity was reduced (P < 0.001). Copyright 2001 John Wiley & Sons, Inc.

  12. Rethinking voluntary euthanasia.

    Science.gov (United States)

    Stoyles, Byron J; Costreie, Sorin

    2013-12-01

    Our goal in this article is to explicate the way, and the extent to which, euthanasia can be voluntary from both the perspective of the patient and the perspective of the health care providers involved in the patient's care. More significantly, we aim to challenge the way in which those engaged in ongoing philosophical debates regarding the morality of euthanasia draw distinctions between voluntary, involuntary, and nonvoluntary euthanasia on the grounds that drawing the distinctions in the traditional manner (1) fails to reflect what is important from the patient's perspective and (2) fails to reflect the significance of health care providers' interests, including their autonomy and integrity.

  13. Effects of eccentric exercise on toll-like receptor 4 signaling pathway in peripheral blood mononuclear cells.

    Science.gov (United States)

    Fernandez-Gonzalo, Rodrigo; De Paz, José A; Rodriguez-Miguelez, Paula; Cuevas, María J; González-Gallego, Javier

    2012-06-01

    This study aimed to investigate the response of the toll-like receptor 4 (TLR4) signaling pathway to an acute bout of eccentric exercise, and to assess whether eccentric training attenuated the effects induced by acute eccentric exercise. Twenty men (22.4 ± 0.5 yr) were divided into a control group (CG, n = 8) and a training group (TG, n = 12). Both groups performed two acute eccentric bouts on a squat machine in a 9-wk interval. During this time, TG followed a 6-wk eccentric training program (3 session/wk; 3-5 sets of 10 repetitions with loads ranging between the 40 and 50% of maximal isometric voluntary contraction). CD14, TLR4, and TNF-α mRNA levels, and CD14, TLR4, myeloid differentiation factor 88, tumor necrosis factor receptor-associated factor 6, TIR-domain-containing adapter-inducing interferon-β, phospho-IκB kinases, phospho-IκB, phospho-ERK-1/2, and TNF-α protein concentration were measured in peripheral blood mononuclear cells, before, immediately, and 2 h after each eccentric bout. The first acute eccentric bout triggered a proinflammatory response mediated by an upregulation of all of the factors measured within the TLR4 signaling pathway. Following the training period and after the second acute bout, CG showed a similar proinflammatory response than that seen after the first bout. However, the eccentric training intervention decreased significantly the protein concentration of all factors analyzed in TG compared with results obtained after the first bout. These results suggest that the TLR4-signaling pathway plays a critical role in the proinflammatory response seen after acute eccentric exercise. This response was attenuated after an eccentric training program through myeloid differentiation factor 88-dependent and -independent pathways.

  14. The Eccentric Behavior of Nearly Frozen Orbits

    Science.gov (United States)

    Sweetser, Theodore H.; Vincent, Mark A.

    2013-01-01

    Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

  15. Isokinetic evaluation of knee muscles in soccer players: discriminant analysis

    Directory of Open Access Journals (Sweden)

    Bruno Fles Mazuquin

    2015-10-01

    Full Text Available ABSTRACTIntroduction:Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance.Objectives:To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17 soccer category from the professional (PRO.Methods:Thirty four players were assessed (n=17 for each category. The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm, total work (J, average power (W, angle of peak torque (deg., agonist/ antagonist ratio (%, measured for three velocities (60°/s, 120°/s and 300°/s, with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories.Results:The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work.Conclusion:Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players.

  16. Assessment of isokinetic muscle function in Korea male volleyball athletes

    OpenAIRE

    Kim, Chang-Gyun; Jeoung, Bog Ja

    2016-01-01

    Volleyball players performed numerous repetitions of spike actions, which uses and requires strong and explosive force, and control of the muscles of the shoulder, lower back, and legs. Muscle imbalance is one of the main causes of sport injuries. The purpose of this study was to assess isokinetic muscle functions in male volleyball players. We thus aim to accurately evaluate their muscle functions, and identify the best training strategy to achieve optimal muscle strength balance in future t...

  17. Changes in H reflex and neuromechanical properties of the trapezius muscle after 5 weeks of eccentric training: a randomized controlled trial.

    Science.gov (United States)

    Vangsgaard, Steffen; Taylor, Janet L; Hansen, Ernst A; Madeleine, Pascal

    2014-06-15

    Trapezius muscle Hoffman (H) reflexes were obtained to investigate the neural adaptations induced by a 5-wk strength training regimen, based solely on eccentric contractions of the shoulder muscles. Twenty-nine healthy subjects were randomized into an eccentric training group (n = 15) and a reference group (n = 14). The eccentric training program consisted of nine training sessions of eccentric exercise performed over a 5-wk period. H-reflex recruitment curves, the maximal M wave (Mmax), maximal voluntary contraction (MVC) force, rate of force development (RFD), and electromyographic (EMG) voluntary activity were recorded before and after training. H reflexes were recorded from the middle part of the trapezius muscle by electrical stimulation of the C3/4 cervical nerves; Mmax was measured by electrical stimulation of the accessory nerve. Eccentric strength training resulted in significant increases in the maximal trapezius muscle H reflex (Hmax) (21.4% [5.5-37.3]; P = 0.01), MVC force (26.4% [15.0-37.7]; P training group (r = 0.57; P = 0.03). These results indicate that the net excitability of the trapezius muscle H-reflex pathway increased after 5 wk of eccentric training. This is the first study to investigate and document changes in the trapezius muscle H reflex following eccentric strength training.

  18. Voluntary Public Unemployment Insurance

    DEFF Research Database (Denmark)

    O. Parsons, Donald; Tranæs, Torben; Bie Lilleør, Helene

    Denmark has drawn much attention for its active labor market policies, but is almost unique in offering a voluntary public unemployment insurance program requiring a significant premium payment. A safety net program – a less generous, means-tested social assistance plan – completes the system...

  19. LONG-TERM ASSESSMENT OF ECCENTRIC, ISOMETRIC, CONCENTRIC MUSCLE STRENGTH AND FUNCTIONAL CAPACITY AFTER SEVERELY BURNED ADULT

    Directory of Open Access Journals (Sweden)

    Anwar Abdelgayed Ebid

    2015-06-01

    Full Text Available Background: Severe burn leads to marked and prolonged skeletal muscle catabolism and weakness. Objective: The aim of this study was to investigate the long term effect of severe burn injury on eccentric, concentric, isometric muscle torque, average power, lean body mass, six minute walk and 8-foot walk. Design: Eccentric, isometric and concentric muscle torque and average power were assessed at 24 months in burned adult with 40%-50% total body surface area (TBSA at 150 o/s by using isokinetic dynamometry, Total lean body mass (TLBM and lower limb mass (LLM measurements were assessed for both groups using dual energy X-ray absorptiometry. Functional capacity was assessed using six minute walk test (6MWT and 8-Feet walk test. Lean body mass (LBM was determined via dual energy X-ray absorptiometry. Nonburned adult was assessed similarly, and served as controls. Results: severely burned adult (n=35, relative to nonburned adult (n=42 had significantly lower peak torque of eccentric, isometric, concentric muscle strength, average power and functional capacity. The most affected type of muscle strength after burn was concentric, isometric then eccentric. Conclusions: Our results serve as an objective data for assessing the three modes of muscle strength and functional capacity in severely burned adult population.

  20. A contralateral repeated bout effect attenuates induction of NF-κB DNA binding following eccentric exercise.

    Science.gov (United States)

    Xin, Ling; Hyldahl, Robert D; Chipkin, Stuart R; Clarkson, Priscilla M

    2014-06-01

    We investigated the existence of contralateral repeated bout effect and tested if the attenuation of nuclear factor-kappa B (NF-κB; an important regulator of muscle inflammation) induction following eccentric exercise is a potential mechanism. Thirty-one healthy men performed two bouts of knee extension eccentric exercise, initially with one leg and then with the opposite leg 4 wk later. Vastus lateralis muscle biopsies of both exercised and control legs were taken 3 h postexercise. Knee extension isometric and isokinetic strength (60°/sec and 180°/sec) were measured at baseline, pre-exercise, immediately postexercise, and 1/day for 5 days postexercise. Serum creatine kinase (CK) activity and muscle soreness were assessed at baseline and 1/day for 5 days postexercise. NF-κB (p65) DNA-binding activity was measured in the muscle biopsies. Isometric strength loss was lower in bout 2 than in bout 1 at 24, 72, and 96 h postexercise (P eccentric exercise (compared with the control leg) in bout 1 (122.9% ± 2.6%; P eccentric exercise results in a contralateral repeated bout effect, which could be due to the attenuated increase in NF-κB activity postexercise. Copyright © 2014 the American Physiological Society.

  1. Introducing the Moon's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2014-11-01

    I present a novel way to introduce the lunar orbital eccentricity in introductory astronomy courses. The Moon is perhaps the clearest illustration of the general orbital elements such as inclination, ascending node, eccentricity, perigee, and so on. Furthermore, I like the students to discover astronomical phenomena for themselves, by means of a guided exercise, rather than just telling them the facts.1 The inclination and nodes may be found by direct observation, monitoring carefully the position of the Moon among the stars. Even the regression of the nodes may be discovered in this way2 To find the eccentricity from students' observations is also possible,3 but that requires considerable time and effort. if a whole class should discover it in a short time, here is a method more suitable for a one-day class or home assignment. The level I aim at is, more or less, advanced high school or first-year college students. I assume them to be acquainted with celestial coordinates and the lunar phases, and to be able to use algebra and trigonometry.

  2. Reduced short-interval intracortical inhibition after eccentric muscle damage in human elbow flexor muscles.

    Science.gov (United States)

    Pitman, Bradley M; Semmler, John G

    2012-09-01

    The purpose of this study was to use paired-pulse transcranial magnetic stimulation (TMS) to examine the effect of eccentric exercise on short-interval intracortical inhibition (SICI) after damage to elbow flexor muscles. Nine young (22.5 ± 0.6 yr; mean ± SD) male subjects performed maximal eccentric exercise of the elbow flexor muscles until maximal voluntary contraction (MVC) force was reduced by ∼40%. TMS was performed before, 2 h after, and 2 days after exercise under Rest and Active (5% MVC) conditions with motor-evoked potentials (MEPs) recorded from the biceps brachii (BB) muscle. Peripheral electrical stimulation of the brachial plexus was used to assess maximal M-waves, and paired-pulse TMS with a 3-ms interstimulus interval was used to assess changes in SICI at each time point. The eccentric exercise resulted in a 34% decline in strength (P muscle strength (27%, P muscle soreness (P muscle damage. When the test MEP amplitudes were matched between sessions, we found that SICI was reduced by 27% in resting and 23% in active BB muscle 2 h after exercise. SICI recovered 2 days after exercise when muscle pain and soreness were present, suggesting that delayed onset muscle soreness from eccentric exercise does not influence SICI. The change in SICI observed 2 h after exercise suggests that eccentric muscle damage has widespread effects throughout the motor system that likely includes changes in motor cortex.

  3. Electromyographic analysis of an eccentric calf muscle exercise in persons with and without Achilles tendinopathy.

    Science.gov (United States)

    Reid, Duncan; McNair, Peter J; Johnson, Shelley; Potts, Geoff; Witvrouw, Erik; Mahieu, Nele

    2012-08-01

    To compare surface electromyographic (EMG) activity of the gastrocnemius and soleus muscles between persons with and without Achilles tendinopathy (AT) during an eccentric muscle exercise in different knee joint positions. Repeated measures design. Research laboratory. Participants (n = 18) diagnosed with AT and 18 control subjects were recruited. Gastrocnemius and soleus muscle activity was examined by surface (EMG) during extended and flexed knee joint conditions while performing the eccentric training technique. The EMG data were expressed as a percentage of a maximum voluntary contraction (MVC). EMG activity was notably higher (mean difference: 10%, effect size: 0.59) in those subjects with AT. Irrespective of the presence of AT, there was a significant interaction effect between muscle and joint position. The gastrocnemius muscle was significantly more active in the extended knee condition and soleus muscle activity was unchanged across joint positions. The results indicated that the presence of AT influenced calf muscle activity levels during performance of the eccentric exercise. There were differences in muscle activity during the extended and flexed knee conditions. This result does support performing Alfredson, Pietila, Jonsson, and Lorentzon (1998) eccentric exercise in an extended knee position but the specific effects of the knee flexed position on the Achilles tendon during eccentric exercise have yet to be determined, particularly in those with AT. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Gender differences in fascicular lengthening during eccentric contractions: the role of the patella tendon stiffness.

    Science.gov (United States)

    Hicks, K M; Onambele-Pearson, G L; Winwood, K; Morse, C I

    2013-11-01

    Elastic tendons have been suggested to attenuate fascicle lengthening during eccentric contractions; however, there is no in vivo evidence to support this hypothesis. Therefore, the aim of this study was to determine whether patella tendon stiffness modulates vastus lateralis (VL) fascicle lengthening during eccentric contractions in males and females. Vastus lateralis and patella tendon properties were measured in males and females owing to previously reported intrinsic gender differences in tendon properties. During maximal voluntary eccentric knee extensions, VL fascicle lengthening and torque were recorded at every 10° (range of motion 20-90°). A significant correlation between maximal patella tendon stiffness and change in fascicle length (r=0.476, P=0.023) was observed. Similarly, there was a significant correlation between maximal Young's modulus and change in fascicle length (r=0.470, P=0.049). As expected, patella tendon stiffness and Young's modulus were significantly higher in males compared with females (Pmuscle-tendon unit elongation was estimated to be significantly greater in males compared with females (5.24 and 4.84 cm respectively). The significant difference in fascicle lengthening during eccentric contractions may be partly explained by the significantly higher patella tendon moment arm, patella tendon stiffness and Young's modulus found in males compared with females. The current study provides in vivo evidence to support the hypothesis that the tendon acts as a 'mechanical buffer' during eccentric contractions. © 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  5. EFFICACY OF ISOKINETIC STRENGTH TRAINING AND BALANCE EXERCISES ON LOWER LIMB MUSCLES IN SUBJECTS WITH STROKE

    OpenAIRE

    Dr.P.Keerthi Chandra Sekhar; Dr K. Madhavi; Dr. V.Srikumari; Dr. Patchava Appa Rao; Dr. A.Chathurvedi .P

    2013-01-01

    Background:To evaluate the efficacy of isokinetic strength training and balance exercises on lower limb musclesamong the subjects suffering with stroke.Materials and Methods:40 subjects who are suffering from strokewere divided into two groups, Experimental group received Isokinetic strength training and balance exercises(n=20) and Control group received conventional physiotherapy, results were measured withIsokinetic deviceand Berg balance scale for peak torque of knee extensors on paretic l...

  6. Chronic Eccentric Exercise and the Older Adult.

    Science.gov (United States)

    Gluchowski, Ashley; Harris, Nigel; Dulson, Deborah; Cronin, John

    2015-10-01

    Eccentric exercise has gained increasing attention as a suitable and promising intervention to delay or mitigate the known physical and physiological declines associated with aging. Determining the relative efficacy of eccentric exercise when compared with the more conventionally prescribed traditional resistance exercise will support evidence-based prescribing for the aging population. Thus, original research studies incorporating chronic eccentric exercise interventions in the older adult population were included in this review. The effects of a range of eccentric exercise modalities on muscular strength, functional capacity, body composition, muscle architecture, markers of muscle damage, the immune system, cardiovascular system, endocrine system, and rating of perceived exertion were all reviewed as outcomes of particular interest in the older adult. Muscular strength was found to increase most consistently compared with results from traditional resistance exercise. Functional capacity and body composition showed significant improvements with eccentric endurance protocols, especially in older, frail or sedentary cohorts. Muscle damage was avoided with the gradual progression of novel eccentric exercise, while muscle damage from intense acute bouts was significantly attenuated with repeated sessions. Eccentric exercise causes little cardiovascular stress; thus, it may not generate the overload required to elicit cardiovascular adaptations. An anabolic state may be achievable following eccentric exercise, while improvements to insulin sensitivity have not been found. Finally, rating of perceived exertion during eccentric exercise was often significantly lower than during traditional resistance exercise. Overall, evidence supports the prescription of eccentric exercise for the majority of outcomes of interest in the diverse cohorts of the older adult population.

  7. Unilateral eccentric contraction of the plantarflexors leads to bilateral alterations in leg dexterity

    Directory of Open Access Journals (Sweden)

    Akira Nagamori

    2016-11-01

    Full Text Available Eccentric contractions can affect musculotendon mechanical properties and disrupt muscle proprioception, but their behavioral consequences are poorly understood. We tested whether repeated eccentric contractions of plantarflexor muscles of one leg affected the dexterity of either leg. Twenty healthy male subjects (27.3+/-4.0 yrs compressed a compliant and slender spring prone to buckling with each isolated leg. The maximal instability they could control (i.e., the maximal average sustained compression force, or lower extremity dexterity force, LEDForce quantified the dexterity of each leg. We found that eccentric contractions did not affect LEDForce, but reduced force variability (LEDSD. Surprisingly, LEDForce increased in the non-exposed, contralateral leg. These effects were specific to exposure to eccentric contractions because an effort-matched exposure to walking did not affect leg dexterity. In the exposed leg, eccentric contractions (i reduced voluntary error corrections during spring compressions (i.e., reduced 0.5-4 Hz power of LEDForce; (ii did not change spinal excitability (i.e., unaffected H-reflexes; and (iii changed the structure of the neural drive to the alpha-motoneuron pool (i.e., reduced EMG power within the 4-8 Hz physiological tremor band. These results suggest that repeated eccentric contractions alter the feedback control for dexterity in the exposed leg by reducing muscle spindle sensitivity. Moreover, the unexpected improvement in LEDForce in the non-exposed contralateral leg was likely a consequence of crossed-effects on its spinal and supraspinal feedback control. We discuss the implications of these bilateral effects of unilateral eccentric contractions, their effect on spinal and supraspinal control of dynamic foot-ground interactions, and their potential to facilitate rehabilitation from musculoskeletal and neuromotor impairments.

  8. The Eccentric Torque Production Capacity of the Ankle, Knee, and Hip Muscle Groups in Patients with Unilateral Chronic Ankle Instability

    Science.gov (United States)

    Negahban, Hossein; Moradi-Bousari, Aida; Naghibi, Saeed; Sarrafzadeh, Javad; Shaterzadeh-Yazdi, Mohammad-Jafar; Goharpey, Shahin; Etemadi, Malihe; Mazaheri, Masood; Feizi, Awat

    2013-01-01

    Purpose The aim of this study was to investigate eccentric torque production capacity of the ankle, knee and hip muscle groups in patients with unilateral chronic ankle instability (CAI) as compared to healthy matched controls. Methods In this case-control study, 40 participants (20 with CAI and 20 controls) were recruited based on convenient non-probability sampling. The average peak torque to body weight (APT/BW) ratio of reciprocal eccentric contraction of ankle dorsi flexor/plantar flexor, ankle evertor/invertor, knee flexor/extensor, hip flexor/extensor and hip abductor/adductor was determined using an isokinetic dynamometer. All subjects participated in two separate sessions with a rest interval of 48 to 72 hours. In each testing session, the torque production capacity of the ankle, knee, and hip muscle groups of only one lower limb was measured. At first, 3 repetitions of maximal eccentric-eccentric contraction were performed for the reciprocal muscles of a joint in a given movement direction. Then, the same procedure of practice and testing trials was repeated for the next randomly-ordered muscle group or joint of the same limb. Results There was no significant interaction of group (CAI and healthy controls) by limb (injured and non-injured) for any muscle groups. Main effect of limb was not significant. Main effect of group was only significant for eccentric torque production capacity of ankle dorsi flexor and hip flexor muscle groups. The APT/BW ratio of these muscles was significantly lower in the CAI group than the healthy controls (P<0.05). Conclusion CAI is associated with eccentric strength deficit of ankle dorsi flexor and hip flexor muscles as indicated by reduction in torque production capacity of these muscles compared to healthy controls. This strength deficit appeared to exist in both the injured and non-injured limbs of the patients. PMID:23802057

  9. Comparison in eccentric exercise-induced muscle damage among four limb muscles.

    Science.gov (United States)

    Chen, Trevor C; Lin, Kun-Yi; Chen, Hsin-Lian; Lin, Ming-Ju; Nosaka, Kazunori

    2011-02-01

    This study tested the hypothesis that changes in indirect markers of muscle damage following maximal eccentric exercise would be smaller for the knee extensors (KE) and flexors (KF) compared with the elbow flexors (EF) and extensors (EE). A total of 17 sedentary men performed five sets of six maximal isokinetic (90° s(-1)) eccentric contractions of EF (range of motion, ROM: 90°-0°, 0 = full extension), EE (55°-145°), KF (90°-0°), and KE (30°-120°) using a different limb with a 4-5-week interval in a counterbalanced order. Changes in maximal isometric and concentric isokinetic strength, optimum angle, limb circumference, ROM, plasma creatine kinase activity and myoglobin concentration, muscle soreness, and echo-intensity of B-mode ultrasound images before and for 5 days following exercise were compared amongst the four exercises using two-way repeated-measures ANOVA. All variables changed significantly following EF, EE, and KF exercises, but KE exercise did not change the optimum angle, limb circumference, and echo-intensity. Compared with KF and KE, EF and EE showed significantly greater changes in all variables, without significant differences between EF and EE. Changes in all variables were significantly greater for KF than KE. For the same subjects, the magnitude of change in the dependent variables following exercise varied among the exercises. These results suggest that the two arm muscles are equally more susceptible to muscle damage than leg muscles, but KF is more susceptible to muscle damage than KE. The difference in the susceptibility to muscle damage seems to be associated with the use of muscles in daily activities.

  10. Decline eccentric squats increases patellar tendon loading compared to standard eccentric squats

    DEFF Research Database (Denmark)

    Kongsgaard, M; Aagaard, P; Roikjaer, S

    2006-01-01

    Recent studies have shown excellent clinical results using eccentric squat training on a 25 degrees decline board to treat patellar tendinopathy. It remains unknown why therapeutic management of patellar tendinopathy using decline eccentric squats offer superior clinical efficacy compared...

  11. Changes in passive tension after stretch of unexercised and eccentrically exercised human plantarflexor muscles.

    Science.gov (United States)

    Reisman, Simone; Allen, Trevor J; Proske, Uwe

    2009-03-01

    The study measured the effect of stretch on passive mechanical properties in unexercised and eccentrically exercised plantarflexor muscles, to obtain insight into how stretch might serve athletes as a warm-up strategy. Passive torque, voluntary contraction strength and muscle soreness were measured before and after a large amplitude stretch given before and after a period of eccentric exercise and at 0, 1, 2 and 24 h later. Stretch of the unexercised muscle led to a 20% fall in passive torque which recovered within an hour. About 40% of the fall could be recovered immediately with a voluntary contraction. After eccentric exercise there was a rise in passive torque by 20% at 2 h post-exercise. This rise was postulated to result from an injury contracture in muscle fibres damaged by the exercise. It was accompanied by a fall in maximum voluntary torque and the development of muscle soreness at 24 h. Stretch of the exercised muscle led to a fall in passive torque and rise in pain threshold. It is proposed that in response to a stretch there is a fall in passive tension in the muscle due to stable cross-bridges in sarcomeres which could be recovered with a voluntary contraction and an additional component attributable to the elastic filament, titin. The size of the fall was not significantly different between exercised and unexercised muscle. These observations provide a physiological basis for the effects of passive stretches on skeletal muscle and help to explain why they are used as a popular warm-up strategy.

  12. Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males.

    Science.gov (United States)

    Clarke, David H.; Manning, James M.

    1985-01-01

    Eighteen male subjects, aged 20 to 28 years, engaged in three fatigue bouts using an isokinetic dynamometer to measure knee extension contractions. Peak torque varied inversely with movement speed, and the pattern of decrement was independent of speed. Time to peak torque did not change significantly across trials in isokinetic fatigue. (Author/MT)

  13. Eccentric Exercise: Physiological Characteristics and Acute Responses.

    Science.gov (United States)

    Douglas, Jamie; Pearson, Simon; Ross, Angus; McGuigan, Mike

    2017-04-01

    An eccentric contraction involves the active lengthening of muscle under an external load. The molecular and neural mechanisms underpinning eccentric contractions differ from those of concentric and isometric contractions and remain less understood. A number of molecular theories have been put forth to explain the unexplained observations during eccentric contractions that deviate from the predictions of the established theories of muscle contraction. Postulated mechanisms include a strain-induced modulation of actin-myosin interactions at the level of the cross-bridge, the activation of the structural protein titin, and the winding of titin on actin. Accordingly, neural strategies controlling eccentric contractions also differ with a greater, and possibly distinct, cortical activation observed despite an apparently lower activation at the level of the motor unit. The characteristics of eccentric contractions are associated with several acute physiological responses to eccentrically-emphasised exercise. Differences in neuromuscular, metabolic, hormonal and anabolic signalling responses during, and following, an eccentric exercise bout have frequently been observed in comparison to concentric exercise. Subsequently, the high levels of muscular strain with such exercise can induce muscle damage which is rarely observed with other contraction types. The net result of these eccentric contraction characteristics and responses appears to be a novel adaptive signal within the neuromuscular system.

  14. Combination of eccentric exercise and neuromuscular electrical stimulation to improve quadriceps function post-ACL reconstruction.

    Science.gov (United States)

    Lepley, Lindsey K; Wojtys, Edward M; Palmieri-Smith, Riann M

    2015-06-01

    Neuromuscular electrical stimulation (NMES) has been shown to reduce quadriceps activation failure (QAF), and eccentric exercise has been shown to lessen muscle atrophy post-ACL reconstruction. Given that these are two critical components of quadriceps strength, intervention combining these therapies may be effective at reinstituting quadriceps function post-reconstruction. Thus, the aim of this study was to evaluate the effectiveness of a combined NMES and eccentric exercise intervention to improve the recovery of quadriceps activation and strength post-reconstruction. Thirty-six individuals post-injury were placed into four treatment groups (N&E, NMES and eccentrics; E-only, eccentrics only; N-only, NMES-only; and STND, standard of care) and ten healthy controls participated. N&E and N-only received the NMES protocol 2× per week for the first 6 weeks post-reconstruction. N&E and E-only received the eccentric exercise protocol 2× per week beginning 6 weeks post-reconstruction. Quadriceps activation was assessed via the superimposed burst technique and quantified via the central activation ratio. Quadriceps strength was assessed via maximal voluntary isomeric contractions (Nm/kg). Data was gathered on three occasions: pre-operative, 12-weeks-post-surgery and at return-to-play. No differences in pre-operative measures existed (P>0.05). E-only recovered quadriceps activation better than N-only or STND (P0.05). Eccentric exercise was capable of restoring levels of quadriceps activation and strength that were similar to those of healthy adults and better than NMES alone. Level 3, Parallel longitudinal study. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Re-evaluation of sarcolemma injury and muscle swelling in human skeletal muscles after eccentric exercise.

    Science.gov (United States)

    Yu, Ji-Guo; Liu, Jing-Xia; Carlsson, Lena; Thornell, Lars-Eric; Stål, Per S

    2013-01-01

    The results regarding the effects of unaccustomed eccentric exercise on muscle tissue are often conflicting and the aetiology of delayed onset muscle soreness (DOMS) induced by eccentric exercise is still unclear. This study aimed to re-evaluate the paradigm of muscular alterations with regard to muscle sarcolemma integrity and fibre swelling in human muscles after voluntary eccentric exercise leading to DOMS. Ten young males performed eccentric exercise by downstairs running. Biopsies from the soleus muscle were obtained from 6 non-exercising controls, 4 exercised subjects within 1 hour and 6 exercised subjects at 2-3 days and 7-8 days after the exercise. Muscle fibre sarcolemma integrity, infiltration of inflammatory cells and changes in fibre size and fibre phenotype composition as well as capillary supply were examined with specific antibodies using enzyme histochemistry and immunohistochemistry. Although all exercised subjects experienced DOMS which peaked between 1.5 to 2.5 days post exercise, no significant sarcolemma injury or inflammation was detected in any post exercise group. The results do not support the prevailing hypothesis that eccentric exercise causes an initial sarcolemma injury which leads to subsequent inflammation after eccentric exercise. The fibre size was 24% larger at 7-8 days than at 2-3 days post exercise (pexercise (lower in 5 of the 6 subjects at 7-8 days than at 2-3 days; pexercise was interpreted to reflect fibre swelling. Because the fibre swelling did not appear at the time that DOMS peaked (between 1.5 to 2.5 days post exercise), we concluded that fibre swelling in the soleus muscle is not directly associated with the symptom of DOMS.

  16. Modelling the maximum voluntary joint torque/angular velocity relationship in human movement.

    Science.gov (United States)

    Yeadon, Maurice R; King, Mark A; Wilson, Cassie

    2006-01-01

    The force exerted by a muscle is a function of the activation level and the maximum (tetanic) muscle force. In "maximum" voluntary knee extensions muscle activation is lower for eccentric muscle velocities than for concentric velocities. The aim of this study was to model this "differential activation" in order to calculate the maximum voluntary knee extensor torque as a function of knee angular velocity. Torque data were collected on two subjects during maximal eccentric-concentric knee extensions using an isovelocity dynamometer with crank angular velocities ranging from 50 to 450 degrees s(-1). The theoretical tetanic torque/angular velocity relationship was modelled using a four parameter function comprising two rectangular hyperbolas while the activation/angular velocity relationship was modelled using a three parameter function that rose from submaximal activation for eccentric velocities to full activation for high concentric velocities. The product of these two functions gave a seven parameter function which was fitted to the joint torque/angular velocity data, giving unbiased root mean square differences of 1.9% and 3.3% of the maximum torques achieved. Differential activation accounts for the non-hyperbolic behaviour of the torque/angular velocity data for low concentric velocities. The maximum voluntary knee extensor torque that can be exerted may be modelled accurately as the product of functions defining the maximum torque and the maximum voluntary activation level. Failure to include differential activation considerations when modelling maximal movements will lead to errors in the estimation of joint torque in the eccentric phase and low velocity concentric phase.

  17. The time course of short-term hypertrophy in the absence of eccentric muscle damage.

    Science.gov (United States)

    Stock, Matt S; Mota, Jacob A; DeFranco, Ryan N; Grue, Katherine A; Jacobo, A Unique; Chung, Eunhee; Moon, Jordan R; DeFreitas, Jason M; Beck, Travis W

    2017-05-01

    It has been proposed that the increase in skeletal muscle mass observed during the initial weeks of initiating a resistance training program is concomitant with eccentric muscle damage and edema. We examined the time course of muscle hypertrophy during 4 weeks of concentric-only resistance training. Thirteen untrained men performed unilateral concentric-only dumbbell curls and shoulder presses twice per week for 4 weeks. Sets of 8-12 repetitions were performed to failure, and training loads were increased during each session. Subjects consumed 500 ml of whole milk during training. Assessments of soreness, lean mass, echo intensity, muscle thickness, relaxed and flexed arm circumference, and isokinetic strength were performed every 72 or 96 h. Soreness, echo intensity, relaxed circumference, and peak torque data did not significantly change. Significant increases in lean mass, muscle thickness, and flexed circumference were observed within seven training sessions. Lean mass was elevated at tests #7 (+109.3 g, p = .002) and #8 (+116.1 g, p = .035), with eight different subjects showing changes above the minimal difference of 139.1 g. Muscle thickness was elevated at tests #6 (+0.23 cm, p = .004), #7 (+0.31 cm, p hypertrophy may occur in the absence of eccentric muscle damage within seven training sessions.

  18. Eccentricity distribution in the main asteroid belt

    Science.gov (United States)

    Malhotra, Renu; Wang, Xianyu

    2017-03-01

    The observationally complete sample of the main belt asteroids now spans more than two orders of magnitude in size and numbers more than 64 000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that a century old conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution; there is a deficit of eccentricities smaller than ∼0.1 and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance; the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modelled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Rayleigh distribution of parameter ∼0.06, and an excitation of random phase and magnitude ∼0.13. These results imply that when a late dynamical excitation of the asteroids occurred, it was independent of asteroid size and was stronger in the inner belt than in the outer belt. We discuss implications for the primordial asteroid belt and suggest that the observationally complete sample size of main belt asteroids is large enough that more sophisticated model-fitting of the eccentricities is warranted and could serve to test alternative theoretical models of the dynamical excitation history of asteroids and its links to the migration history of the giant planets.

  19. Assessment of isokinetic muscle function in Korea male volleyball athletes

    Science.gov (United States)

    Kim, Chang-Gyun; Jeoung, Bog Ja

    2016-01-01

    Volleyball players performed numerous repetitions of spike actions, which uses and requires strong and explosive force, and control of the muscles of the shoulder, lower back, and legs. Muscle imbalance is one of the main causes of sport injuries. The purpose of this study was to assess isokinetic muscle functions in male volleyball players. We thus aim to accurately evaluate their muscle functions, and identify the best training strategy to achieve optimal muscle strength balance in future training programs. The participants in this study consisted of 14 male volleyball players. Muscle strength was measured using the isokinetic dynamometer. Muscle strength was evaluated in terms of peak torque and average power, calculated from five repeated measurements at an angular speed of 60°/sec. Three players who were left attackers showed shoulder imbalance, four players showed trunk joint imbalance, nine players had knee joint of extension/flexion imbalance and four players showed left/right imbalance. The results showed that the number of volleyball players with differences between the strength of the bilateral knee muscles, and between the strength of the hamstrings and quadriceps muscles was higher than the number of players with differences between the strength of the shoulder internal and external rotation muscles, and higher than the number of players with differences between the strength of the lower back extension and flexion muscles. PMID:27807521

  20. A COX-2 inhibitor reduces muscle soreness, but does not influence recovery and adaptation after eccentric exercise

    DEFF Research Database (Denmark)

    Paulsen, G; Egner, I M; Drange, M

    2010-01-01

    The aim of this study was to investigate the effect of a cyclooxygenase (COX)-2 inhibitor on the recovery of muscle function, inflammation, regeneration after, and adaptation to, unaccustomed eccentric exercise. Thirty-three young males and females participated in a double-blind, placebo...... by celecoxib. In summary, celecoxib, a COX-2 inhibitor, did not detectably affect recovery of muscle function or markers of inflammation and regeneration after unaccustomed eccentric exercise, nor did the drug influence the repeated-bout effect. However, it alleviated muscle soreness.......-controlled experiment. Seventy unilateral, voluntary, maximal eccentric actions with the elbow flexors were performed twice (bouts 1 and 2) with the same arm, separated by 3 weeks. The test group participants were administered 400 mg/day of celecoxib for 9 days after bout 1. After both bouts 1 and 2, concentric...

  1. Effects of set-repetition configuration in eccentric exercise on muscle damage and the repeated bout effect.

    Science.gov (United States)

    Chan, R; Newton, M; Nosaka, K

    2012-07-01

    The number of eccentric contractions is a factor affecting the magnitude of muscle damage; however, it is unknown whether set-repetition configurations for the same total number of eccentric contractions affect the muscle damage. The present study investigated whether different set-repetition configurations would result in different force output during eccentric exercise and different magnitude of muscle damage following the first and second exercise bouts. Ten non-resistance-trained men (26.1 ± 4.1 years) performed two bouts of eccentric exercise of the elbow flexors of each arm (4 bouts in total). One arm performed 3 sets of 10 maximal eccentric contractions (3 × 10) and the contralateral arm performed 10 sets of 3 maximal eccentric contractions (10 × 3), and each arm performed 20 sets of 3 maximal eccentric contractions (20 × 3) 4 weeks after the first bout. The order of the exercise (3 × 10, 10 × 3) and the use of arm (dominant, non-dominant) were counterbalanced amongst subjects. The torque produced over 30 eccentric contractions was similar between 3 × 10 and 10 × 3, and the changes in torque during 20 × 3 were similar between arms. Maximal voluntary contraction strength, range of motion, biceps brachii cross-sectional area and muscle soreness changed significantly (P exercise without significant differences between 3 × 10 and 10 × 3, and changes in the measures following 20 × 3 were similar between arms, except for range of motion (ROM). No significant difference in the changes in any measures except ROM was evident when compared between the first and second bouts. These results showed that changing the set-repetition configuration had little effect on muscle damage.

  2. Muscle fascicle behavior during eccentric cycling and its relation to muscle soreness.

    Science.gov (United States)

    Peñailillo, Luis; Blazevich, Anthony J; Nosaka, Kazunori

    2015-04-01

    A single bout of eccentric exercise confers a protective effect against muscle damage and soreness in subsequent eccentric exercise bouts, but the mechanisms underpinning this effect are unclear. This study compared vastus lateralis (VL) muscle-tendon behavior between two eccentric cycling bouts to test the hypothesis that muscle-tendon behavior would be different between bouts and would be associated with the protective effect. Eleven untrained men (27.1 ± 7.0 yr) performed two bouts of eccentric cycling (ECC1 and ECC2) separated by 2 wk for 10 min at 65% of maximal concentric workload (191.9 ± 44.2 W) each. Muscle soreness (by visual analog scale) and maximal voluntary isometric contraction (MVC) torque of the knee extensors were assessed before and 1-2 d after exercise. Using ultrasonography, VL fascicle length and angle changes during cycling were assessed, and tendinous tissue (TT) length changes were estimated. VL EMG amplitude, crank torque, and knee joint angles were measured during cycling. Soreness was greater (P knee angles were evident between bouts. However, fascicle elongation was 16% less during ECC2 than ECC1 (P knee joint angle during ECC2 than ECC1 (P = 0.055). These results suggest that a lesser fascicle elongation and earlier TT elongation were associated with reduced muscle soreness after ECC2 than ECC1; thus, changes in muscle-tendon behavior may be an important mechanism underpinning the protective effect.

  3. Flywheel resistance training calls for greater eccentric muscle activation than weight training.

    Science.gov (United States)

    Norrbrand, Lena; Pozzo, Marco; Tesch, Per A

    2010-11-01

    Changes in muscle activation and performance were studied in healthy men in response to 5 weeks of resistance training with or without "eccentric overload". Subjects, assigned to either weight stack (grp WS; n = 8) or iso-inertial "eccentric overload" flywheel (grp FW; n = 9) knee extensor resistance training, completed 12 sessions of four sets of seven concentric-eccentric actions. Pre- and post-measurements comprised maximal voluntary contraction (MVC), rate of force development (RFD) and training mode-specific force. Root mean square electromyographic (EMG(RMS)) activity of mm. vastus lateralis and medialis was assessed during MVC and used to normalize EMG(RMS) for training mode-specific concentric (EMG(CON)) and eccentric (EMG(ECC)) actions at 90°, 120° and 150° knee joint angles. Grp FW showed greater (p  0.05), MVC and training-specific strength increased (p exercise compared to standard weight lifting could be attributed to its unique iso-inertial loading features. Hence, the resulting greater mechanical stress may explain the robust muscle hypertrophy reported earlier in response to flywheel resistance training.

  4. Chronic Eccentric Exercise and Antioxidant Supplementation: Effects on Lipid Profile and Insulin Sensitivity.

    Science.gov (United States)

    Yfanti, Christina; Tsiokanos, Athanasios; Fatouros, Ioannis G; Theodorou, Anastasios A; Deli, Chariklia K; Koutedakis, Yiannis; Jamurtas, Athanasios Z

    2017-09-01

    Eccentric exercise has been shown to exert beneficial effects in both lipid profile and insulin sensitivity. Antioxidant supplementation during chronic exercise is controversial as it may prevent the physiological training-induced adaptations. The aim of this study was to investigate: 1) the minimum duration of the eccentric exercise training required before changes on metabolic parameters are observed and 2) whether antioxidant supplementation during training would interfere with these adaptations. Sixteen young healthy men were randomized into the Vit group (1 g of vitamin C and 400 IU vitamin E daily) and the placebo (PL) group. Subjects received the supplementation for 9 weeks. During weeks 5-9 all participants went through an eccentric exercise training protocol consisting of two exercise sessions (5 sets of 15 eccentric maximal voluntary contractions) per week. Plasma triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), apolipoproteins (Apo A1, Apo B and Lpa) and insulin sensitivity (HOMA) were assessed before the supplementation (week 0), at weeks 5, 6, 7, 8 and 9. TG, TC and LDL were significantly lower compared to pre supplementation at both weeks 8 and 9 (Peccentric exercise training is required before beneficial effects in lipid profile can be observed in healthy young men. Concomitant antioxidant supplementation does not interfere with the training-induced adaptations.

  5. Effects of repeated concentric and eccentric contractions on tendon blood circulation.

    Science.gov (United States)

    Kubo, K

    2015-06-01

    Previous studies demonstrated that treatment involving eccentric training was effective in the conservative management of chronic tendinosis. However, the mechanisms for these phenomena are unknown. The purpose of this study was to compare changes in blood circulation of the tendons after the repeated concentric and eccentric contractions. 11 healthy males volunteered for this study. Subjects performed the repeated concentric (CON) and eccentric (ECC) contractions (5 sets of 10 maximal voluntary contractions) of the plantar flexors. During and after repeated contractions, oxyhemoglobin (Oxy), deoxyhemoglobin (Deoxy), total hemoglobin (THb), and oxygen saturation (StO2) of the Achilles tendons were measured using red laser lights. Oxy and THb increased during and after ECC, but not CON. Deoxy decreased during both CON and ECC. Increase in StO2 during and after ECC was greater than that during and after CON. These results suggested that changes in blood circulation of the Achilles tendon during and after repeated eccentric contractions were more remarkable than those during and after repeated concentric contractions.

  6. Thoracic posture, shoulder muscle activation patterns and isokinetic ...

    African Journals Online (AJOL)

    determined at 60°/sec by measuring the concentric and eccentric forces during internal rotation (IR) and ... muscle was observed prior to impact, compared with the pectoralis major ... tight shoulder internal rotators and adductors, high body mass and ..... EMG analysis of rugby players' scapulothoracic muscles is limited, but.

  7. Post-exercise muscle soreness after eccentric exercise: psychophysical effects and implications on mean arterial pressure.

    Science.gov (United States)

    Bajaj, P; Graven-Nielsen, T; Arendt-Nielsen, L

    2001-10-01

    The aim of the study was to examine the time course of changes in pressure pain threshold (PPT), visual analogue scale (VAS) pain and tenderness scores, McGill Pain Questionnaire (MPQ) descriptors, pain areas, skin temperature and mean arterial pressure (MAP) following intensive eccentric exercise. In 11 healthy male subjects, eccentric exercise of the first dorsal interosseous muscle (FDI) of the right hand with 114% maximum voluntary contraction weight (MVC) was used to induce post-exercise muscle soreness (PEMS) in the right hand, while the left hand served as a control. At 24 h to 48 h all the pain profiles indicated the presence of PEMS in the right hand when compared to before exercise (Prole of central mechanisms in the PEMS, thereby giving further insight into clinical aspects of muscle pain.

  8. Algorithms and novel applications based on the isokinetic ensemble. I. Biophysical and path integral molecular dynamics

    Science.gov (United States)

    Minary, Peter; Martyna, Glenn J.; Tuckerman, Mark E.

    2003-02-01

    In this paper (Paper I) and a companion paper (Paper II), novel new algorithms and applications of the isokinetic ensemble as generated by Gauss' principle of least constraint, pioneered for use with molecular dynamics 20 years ago, are presented for biophysical, path integral, and Car-Parrinello based ab initio molecular dynamics. In Paper I, a new "extended system" version of the isokinetic equations of motion that overcomes the ergodicity problems inherent in the standard approach, is developed using a new theory of non-Hamiltonian phase space analysis [M. E. Tuckerman et al., Europhys. Lett. 45, 149 (1999); J. Chem. Phys. 115, 1678 (2001)]. Reversible multiple time step integrations schemes for the isokinetic methods, first presented by Zhang [J. Chem. Phys. 106, 6102 (1997)] are reviewed. Next, holonomic constraints are incorporated into the isokinetic methodology for use in fast efficient biomolecular simulation studies. Model and realistic examples are presented in order to evaluate, critically, the performance of the new isokinetic molecular dynamic schemes. Comparisons are made to the, now standard, canonical dynamics method, Nosé-Hoover chain dynamics [G. J. Martyna et al., J. Chem. Phys. 97, 2635 (1992)]. The new isokinetic techniques are found to yield more efficient sampling than the Nosé-Hoover chain method in both path integral molecular dynamics and biophysical molecular dynamics calculations. In Paper II, the use of isokinetic methods in Car-Parrinello based ab initio molecular dynamics calculations is presented.

  9. Increased residual force enhancement in older adults is associated with a maintenance of eccentric strength.

    Directory of Open Access Journals (Sweden)

    Geoffrey A Power

    Full Text Available Despite an age-related loss of voluntary isometric and concentric strength, muscle strength is well maintained during lengthening muscle actions (i.e., eccentric strength in old age. Additionally, in younger adults during lengthening of an activated skeletal muscle, the force level observed following the stretch is greater than the isometric force at the same muscle length. This feature is termed residual force enhancement (RFE and is believed to be a combination of active and passive components of the contractile apparatus. The purpose of this study was to provide an initial assessment of RFE in older adults and utilize aging as a muscle model to explore RFE in a system in which isometric force production is compromised, but structural mechanisms of eccentric strength are well-maintained. Therefore, we hypothesised that older adults will experience greater RFE compared with young adults. Following a reference maximal voluntary isometric contraction (MVC of the dorsiflexors in 10 young (26.1 ± 2.7 y and 10 old (76.0 ± 6.5 y men, an active stretch was performed at 15°/s over a 30° ankle joint excursion ending at the same muscle length as the reference MVCs (40° of plantar flexion. Any additional torque compared with the reference MVC therefore represented RFE. In older men RFE was ~2.5 times greater compared to young. The passive component of force enhancement contributed ~37% and ~20% to total force enhancement, in old and young respectively. The positive association (R(2 = 0.57 between maintained eccentric strength in old age and RFE indicates age-related mechanisms responsible for the maintenance of eccentric strength likely contributed to the observed elevated RFE. Additionally, as indicated by the greater passive force enhancement, these mechanisms may be related to increased muscle series elastic stiffness in old age.

  10. The acute effects of flotation restricted environmental stimulation technique on recovery from maximal eccentric exercise.

    Science.gov (United States)

    Morgan, Paul M; Salacinski, Amanda J; Stults-Kolehmainen, Matthew A

    2013-12-01

    Flotation restricted environmental stimulation technique (REST) involves compromising senses of sound, sight, and touch by creating a quiet dark environment. The individual lies supine in a tank of Epsom salt and water heated to roughly skin temperature (34-35° C). This study was performed to determine if a 1-hour flotation REST session would aid in the recovery process after maximal eccentric knee extensions and flexions. Twenty-four untrained male students (23.29 ± 2.1 years, 184.17 ± 6.85 cm, 85.16 ± 11.54 kg) participated in a randomized, repeated measures crossover study. The participants completed 2 exercise and recovery protocols: a 1-hour flotation REST session and a 1-hour seated control (passive recovery). After isometric muscle strength testing, participants were fatigued with eccentric isokinetic muscle contractions (50 repetitions at 60°·s) of the nondominant knee extensors and flexors. Blood lactate, blood glucose, heart rate, OMNI-rating of perceived exertion for resistance exercise (OMNI-RPE), perceived pain, muscle soreness, and isometric strength were collected before exercise, after treatment, and 24 and 48 hours later. A multivariate analysis of covariance found that treatment had a significant main effect on blood lactate, whereas subsequent univariate analyses of variance found statistical significance with the immediate posttreatment blood lactate measures. The results indicate that flotation REST appears to have a significant impact on blood lactate and perceived pain compared with a 1-hour passive recovery session in untrained healthy men. No difference was found between conditions for muscle strength, blood glucose, muscle soreness, heart rate, or OMNI-RPE. Flotation REST may be used for recreational and professional athletes to help reduce blood lactate levels after eccentric exercise.

  11. Voluntary Simplicity: A Lifestyle Option.

    Science.gov (United States)

    Pestle, Ruth E.

    This guide provides practical ideas for incorporating the concept of voluntary simplicity into home economics classes. Discussed in the first chapter are the need to study voluntary simplicity, its potential contributions to home economics, and techniques and a questionnaire for measuring student attitudes toward the concept. The remaining…

  12. Operant Variability and Voluntary Action

    Science.gov (United States)

    Neuringer, Allen; Jensen, Greg

    2010-01-01

    A behavior-based theory identified 2 characteristics of voluntary acts. The first, extensively explored in operant-conditioning experiments, is that voluntary responses produce the reinforcers that control them. This bidirectional relationship--in which reinforcer depends on response and response on reinforcer--demonstrates the functional nature…

  13. Toward voluntary parenthood.

    Science.gov (United States)

    Scarr, S

    2000-06-01

    David Lykken's proposal to license married parents for child rearing, and to deny the same opportunity to single and inept parents, springs from his deep concern for millions of youngsters cruelly subjected to abusive and neglectful rearing circumstances. Children from such inadequate homes grow up to have high rates of school failure, criminality, and drug addiction. The problem is clear, but Lykken's remedies of mandated marriage and parental licensure are unacceptable in U.S. society, where our reproductive rights are fortunately protected by our Constitution. As a devoted proponent of reproductive rights, I propose a legally and morally acceptable proposal to the same end. Increasing women's effective control of reproduction and moving toward entirely voluntary parenthood will accomplish the same goals without compromising our civil liberties.

  14. Modulation in voluntary neural drive in relation to muscle soreness

    Science.gov (United States)

    Bringard, A.; Puchaux, K.; Noakes, T. D.; Perrey, S.

    2007-01-01

    The aim of this study was to investigate whether (1) spinal modulation would change after non-exhausting eccentric exercise of the plantar flexor muscles that produced muscle soreness and (2) central modulation of the motor command would be linked to the development of muscle soreness. Ten healthy subjects volunteered to perform a single bout of backward downhill walking exercise (duration 30 min, velocity 1 ms−1, negative grade −25%, load 12% of body weight). Neuromuscular test sessions [H-reflex, M-wave, maximal voluntary torque (MVT)] were performed before, immediately after, as well as 1–3 days after the exercise bout. Immediately after exercise there was a −15% decrease in MVT of the plantar flexors partly attributable to an alteration in contractile properties (−23% in electrically evoked mechanical twitch). However, MVT failed to recover before the third day whereas the contractile properties had significantly recovered within the first day. This delayed recovery of MVT was likely related to a decrement in voluntary muscle drive. The decrease in voluntary activation occurred in the absence of any variation in spinal modulation estimated from the H-reflex. Our findings suggest the development of a supraspinal modulation perhaps linked to the presence of muscle soreness. PMID:17978834

  15. Isokinetic profile of subjects with the ruptured anterior cruciated ligament

    Directory of Open Access Journals (Sweden)

    Drapšin Miodrag

    2016-01-01

    Full Text Available Background/Aim. All changes in the knee that appear after anterior cruciate ligament (ACL lesion lead to difficulties in walking, running, jumping especially during sudden changes of the line of movement. This significantly impairs quality of life of these subjects and leads to decrease in physical activity. Knee injuries make 5% of all most severe acute sport injuries. The aim of the study was to determine strength of the thigh muscles in persons with unilateral rupture of the ACL and to evaluate potential bilateral differences between healthy and injured leg. Methods. This study involved 114 male athletes of different sport specialities with the clinical diagnosis of ACL rupture. Each subject had unilateral ACL rupture and the other leg was actually the control for this research. An isokinetic device was used to evaluate the muscle strength of thigh muscles. Testing was performed for two testing speeds, 60º/s and 180º/s. Results. Data analysis showed a statistically significant difference (p < 0.01 between the ACL and the healthy leg in the following parameters: peak torque for thigh extensors (Ptrq_E, angle to peak torque during extension (Ang_E, power of extension (Pow_E and work during extension (Work_E. Analysing hamstrings to quadriceps (H/Q ratio we found the unilateral disbalance of thigh muscle strength in ACL leg. Conclusion. A high level of validity makes isokinetic dynamometry the method for evaluation of thigh muscles strength and leaves this field of research open for new studies in order to improve both diagnostic and rehabilitation of patients with the insufficient ACL.

  16. Eccentric exercise in treatment of Achilles tendinopathy

    DEFF Research Database (Denmark)

    Nørregaard, J; Larsen, C C; Bieler, T

    2007-01-01

    Prognosis and treatment of Achilles tendon pain (achillodynia) has been insufficiently studied. The purpose of the present study was to examine the long-term effect of eccentric exercises compared with stretching exercises on patients with achillodynia.......Prognosis and treatment of Achilles tendon pain (achillodynia) has been insufficiently studied. The purpose of the present study was to examine the long-term effect of eccentric exercises compared with stretching exercises on patients with achillodynia....

  17. Blood flow after contraction and cuff occlusion is reduced in subjects with muscle soreness after eccentric exercise.

    Science.gov (United States)

    Souza-Silva, E; Christensen, S W; Hirata, R P; Larsen, R G; Graven-Nielsen, T

    2017-04-28

    Delayed onset muscle soreness (DOMS) occurs within 1-2 days after eccentric exercise, but the mechanism mediating hypersensitivity is unclear. This study hypothesized that eccentric exercise reduces the blood flow response following muscle contractions and cuff occlusion, which may result in accumulated algesic substances being a part of the sensitization in DOMS. Twelve healthy subjects (five women) performed dorsiflexion exercise (five sets of 10 repeated eccentric contractions) in one leg, while the contralateral leg was the control. The maximal voluntary contraction (MVC) of the tibialis anterior muscle was recorded. Blood flow was assessed by ultrasound Doppler on the anterior tibialis artery (ATA) and within the anterior tibialis muscle tissue before and immediately after 1-second MVC, 5-seconds MVC, and 5-minutes thigh cuff occlusion. Pressure pain thresholds (PPTs) were recorded on the tibialis anterior muscle. All measures were done bilaterally at day 0 (pre-exercise), day 2, and day 6 (post-exercise). Subjects scored the muscle soreness on a Likert scale for 6 days. Eccentric exercise increased Likert scores at day 1 and day 2 compared with day 0 (Pexercise (day 0), reduced PPT (~25%, Peccentric contractions decreased vessel diameter, impaired the blood flow response, and promoted hyperalgesia. Thus, the results suggest that the blood flow reduction may be involved in the increased pain response after eccentric exercise. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

    National Research Council Canada - National Science Library

    Luna, Natália Mariana Silva; Alonso, Angelica Castilho; Brech, Guilherme Carlos; Mochizuki, Luis; Nakano, Eduardo Yoshio; Greve, Júlia Maria D'Andrea

    2012-01-01

    OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. METHODS...

  19. Analyzing voluntary medical incident reports.

    Science.gov (United States)

    Gong, Yang; Richardson, James; Zhijian, Luan; Alafaireet, Patricia; Yoo, Illhoi

    2008-11-06

    Voluntary medical incident reports lacking consistency and accuracy impede the ultimate use of the reports for patient safety research. To improve this, two coders examined harm score usage in a voluntary medical incident reporting system where the harm scores were selected from a predefined list by different reporters. The two coders inter-rater agreement percent was 82%. The major categories and reviewed harm score jointly demonstrate that this process is critical and necessary in preparing the voluntary reports for further content and semantics analysis.

  20. Effects of elastic taping, non-elastic taping and static stretching on recovery after intensive eccentric exercise.

    Science.gov (United States)

    Boobphachart, Disaphon; Manimmanakorn, Nuttaset; Manimmanakorn, Apiwan; Thuwakum, Worrawut; Hamlin, Michael J

    2017-01-25

    The purpose of this study was to compare the effect of elastic tape (Kinesio tape) to placebo tape or static stretching on delayed onset muscle soreness. Fifty-one untrained female healthy volunteers were randomly assigned into three groups (n = 17/group), elastic tape, placebo tape and stretching group. Muscle soreness was induced by 4 sets of 25 maximal isokinetic (60°.s(-1)) eccentric contractions of dominant quadriceps on an isokinetic dynamometer. Compared with placebo tape, the elastic tape participants had less muscle soreness at 72 h post-exercise (p = 0.01). The elastic tape also increased isometric strength at 72 h post-exercise compared with the placebo (p = 0.03) and stretching group (p = 0.02). However, there was little effect between groups for changes in thigh circumference, jumping, pressure pain threshold, rate of perceived exertion, creatine kinase activity and joint motion. Elastic taping increased muscle strength recovery and reduced muscle soreness after intensive exercise.

  1. Effects of a shoulder injury prevention strength training program on eccentric external rotator muscle strength and glenohumeral joint imbalance in female overhead activity athletes.

    Science.gov (United States)

    Niederbracht, Yvonne; Shim, Andrew L; Sloniger, Mark A; Paternostro-Bayles, Madeline; Short, Thomas H

    2008-01-01

    Imbalance of the eccentrically-activated external rotator cuff muscles versus the concentrically-activated internal rotator cuff muscles is a primary risk factor for glenohumeral joint injuries in overhead activity athletes. Nonisokinetic dynamometer based strength training studies, however, have focused exclusively on resulting concentric instead of applicable eccentric strength gains of the external rotator cuff muscles. Furthermore, previous strength training studies did not result in a reduction in glenoumeral joint muscle imbalance, thereby suggesting that currently used shoulder strength training programs do not effectively reduce the risk of shoulder injury to the overhead activity athlete. Two collegiate women tennis teams, consisting of 12 women, participated in this study throughout their preseason training. One team (n = 6) participated in a 5-week, 4 times a week, external shoulder rotator muscle strength training program next to their preseason tennis training. The other team (n = 6) participated in a comparable preseason tennis training program, but did not conduct any upper body strength training. Effects of this strength training program were evaluated by comparing pre- and posttraining data of 5 maximal eccentric external immediately followed by concentric internal contractions on a Kin-Com isokinetic dynamometer (Chattecx Corp., Hixson, Tennessee). Overall, the shoulder strength training program significantly increased eccentric external total work without significant effects on concentric internal total work, concentric internal mean peak force, or eccentric external mean peak force. In conclusion, by increasing the eccentric external total exercise capacity without a subsequent increase in the concentric internal total exercise capacity, this strength training program potentially decreases shoulder rotator muscle imbalances and the risk for shoulder injuries to overhead activity athletes.

  2. A study of isokinetic strength and laxity with and without anterior cruciate ligament injury

    OpenAIRE

    Kim, Kewwan; Jeon, Kyoungkyu; Mullineaux, David R.; Cho, Eunok

    2016-01-01

    [Purpose] The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non...

  3. A study of isokinetic strength and laxity with and without anterior cruciate ligament injury

    OpenAIRE

    Kim, Kewwan; Jeon, Kyoungkyu; Mullineaux, David R.; Cho, Eunok

    2016-01-01

    The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non-involved ...

  4. Understanding the effect of speed of exertion on isokinetic strength using a multiaxial dynamometer.

    Science.gov (United States)

    Nimbarte, Ashish D; Aghazadeh, Fereydoun; Bogolu, Sai Chaitanya R; Rajulu, Sudhakar L

    2009-01-01

    In this study a multiaxial isokinetic dynamometer was used to measure strength during various upper-body isokinetic exertions. Ten male participants performed 7 different upper-body isokinetic exertions. In addition, to evaluate the effect of speed on strength, each participant performed sitting pull exertions at the speed of 0.026, 0.130, and 0.260 m/s. Average isokinetic strength increased from 236.6 +/- 39.1 to 291.8 +/- 65.8 N with the initial increase in speed from 0.026 to 0.130 m/s. The average isokinetic strength decreased to 276.7 +/- 87.2 N with a further increase in speed to 0.260 m/s. The curve between isokinetic strength and speed followed a bell-shaped curve (fitted with the Gaussian function, R(2) = .9). The results of this study could be useful in deciding on the work pace of various manual material handling tasks requiring maximal and/or near maximal exertions.

  5. The Notion of Voluntary Unemployment.

    Science.gov (United States)

    Standing, Guy

    1981-01-01

    Considers the distinction between voluntary and involuntary unemployment by analyzing six behavioral characteristics attributed to groups of workers suspected of indulging in the former, and the labor market mechanisms supposedly encouraging them. (Author/CT)

  6. Orbital eccentricities in primordial black hole binaries

    Science.gov (United States)

    Cholis, Ilias; Kovetz, Ely D.; Ali-Haïmoud, Yacine; Bird, Simeon; Kamionkowski, Marc; Muñoz, Julian B.; Raccanelli, Alvise

    2016-10-01

    It was recently suggested that the merger of ˜30 M⊙ primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on time scales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO and the Einstein Telescope to such effects. We show that if PBHs make up the dark matter, then roughly one event should have a detectable eccentricity given LIGO's expected sensitivity and observing time of six years. The Einstein Telescope should see O (10 ) such events after ten years.

  7. Aging, Functional Capacity and Eccentric Exercise Training

    Science.gov (United States)

    Gault, Mandy L.; Willems, Mark E.T.

    2013-01-01

    Aging is a multi-factorial process that ultimately induces a decline in our physiological functioning, causing a decreased health-span, quality of life and independence for older adults. Exercise participation is seen as a way to reduce the impact of aging through maintenance of physiological parameters. Eccentric exercise is a model that can be employed with older adults, due to the muscle’s ability to combine high muscle force production with a low energy cost. There may however be a risk of muscle damage before the muscle is able to adapt. The first part of this review describes the process of aging and how it reduces aerobic capacity, muscle strength and therefore functional mobility. The second part highlights eccentric exercise and the associated muscle damage, in addition to the repeated bout effect. The final section reviews eccentric exercise interventions that have been completed by older adults with a focus on the changes in functional mobility. In conclusion, eccentric endurance exercise is a potential training modality that can be applied to older adults for improving muscle strength, aerobic capacity and functional ability. However, further research is needed to assess the effects on aerobic capacity and the ideal prescription for eccentric endurance exercise. PMID:24307968

  8. Eccentric Exercise to Enhance Neuromuscular Control.

    Science.gov (United States)

    Lepley, Lindsey K; Lepley, Adam S; Onate, James A; Grooms, Dustin R

    Neuromuscular alterations are a major causal factor of primary and secondary injuries. Though injury prevention programs have experienced some success, rates of injuries have not declined, and after injury, individuals often return to activity with functionality below clinical recommendations. Considering alternative therapies to the conventional concentric exercise approach, such as one that can target neuromuscular injury risk and postinjury alterations, may provide for more effective injury prevention and rehabilitation protocols. Peer-reviewed sources available on the Web of Science and MEDLINE databases from 2000 through 2016 were gathered using searches associated with the keywords eccentric exercise, injury prevention, and neuromuscular control. Eccentric exercise will reduce injury risk by targeting specific neural and morphologic alterations that precipitate neuromuscular dysfunction. Clinical review. Level 4. Neuromuscular control is influenced by alterations in muscle morphology and neural activity. Eccentric exercise beneficially modifies several underlying factors of muscle morphology (fiber typing, cross-sectional area, working range, and pennation angle), and emerging evidence indicates that eccentric exercise is also beneficial to peripheral and central neural activity (alpha motorneuron recruitment/firing, sarcolemma activity, corticospinal excitability, and brain activation). There is mounting evidence that eccentric exercise is not only a therapeutic intervention influencing muscle morphology but also targets unique alterations in neuromuscular control, influencing injury risk.

  9. Collisional evolution of eccentric planetesimal swarms

    CERN Document Server

    Wyatt, M C; Payne, M J; Churcher, L J

    2009-01-01

    Models for the steady state collisional evolution of low eccentricity planetesimal belts identify debris disks with hot dust at 1AU, like eta Corvi and HD69830, as anomalous since collisional processing should have removed most of the planetesimal mass over their >1 Gyr lifetimes. This paper looks at the effect of large planetesimal eccentricities (e>>0.3) on their collisional lifetime and the amount of mass that can remain at late times M_{late}. For an axisymmetric planetesimal disk with common pericentres and eccentricities e, we find that M_{late} \\propto e^{-5/3}(1+e)^{4/3}(1-e)^{-3}. For a scattered disk-like population (i.e., common pericentres), in the absence of dynamical evolution, the mass evolution at late times would be as if only planetesimals with the largest eccentricity were present. Despite the increased remaining mass, higher eccentricities do not increase the hot emission from the collisional cascade until e>0.99, partly because most collisions occur near pericentre thus increasing the dus...

  10. Behavior of fascicles and the myotendinous junction of human medial gastrocnemius following eccentric strength training.

    Science.gov (United States)

    Duclay, Julien; Martin, Alain; Duclay, Alice; Cometti, Gilles; Pousson, Michel

    2009-06-01

    This study is the first in which measurements of thickness, fascicle angle and length, and tendon elongation were combined to examine the impact of eccentric strength training on both muscle architecture and tendinous structures. Eighteen healthy male subjects were divided into an eccentric strength training group (n = 10) and a control group (n = 8). The training program consisted of 18 sessions of eccentric exercises over a 7-week period. All subjects were tested at baseline and after the last training session. Using ultrasound imaging, the fascicle angle and length and thickness of the medial gastrocnemius (MG) were analyzed at rest (i.e., theta(p), Fl(p), and t(p), respectively), at 50% of maximal voluntary contraction (MVC) (i.e., theta(50), Fl(50), and t(50), respectively), and during MVC (i.e., theta(100), Fl(100), and t(100), respectively). Tendon elongation (TE) was measured by tracking the proximal displacement of the myotendinous junction of the MG during ramp isometric contraction. During ramp isometric contraction, the slope of the load-deformation relationship of the gastrocnemius tendon above 50% MVC was defined as an index of stiffness. After training, muscle thickness and fascicle angle increased significantly at rest and during contraction, whereas fascicle length increased at rest and did not change during contraction. Furthermore, the stiffness of the gastrocnemius tendon increased significantly. The results suggest that the behavior of muscle architecture and tendon mechanical properties are affected differently by strength training.

  11. Delayed recovery of velocity-dependent power loss following eccentric actions of the ankle dorsiflexors

    Science.gov (United States)

    Power, Geoffrey A.; Dalton, Brian H.; Rice, Charles L.

    2010-01-01

    Unaccustomed eccentric exercise has been shown to impair muscle function, although little is known regarding this impairment on muscle power. The purpose of this study was to investigate changes in neuromuscular properties of the ankle dorsiflexors during and after an eccentric contraction task and throughout recovery in 21 (10 men, 11 women) recreationally active young adults (25.8 ± 2.3 yr). All subjects performed 5 sets of 30 eccentric contractions at 80% of maximum isometric voluntary contraction (MVC) torque. Data were recorded at baseline, during the fatigue task, and for 30 min of recovery. There were no significant sex differences for all fatigue measures; thus data were pooled. After the fatigue task, MVC torque declined by 28% (P 99%) during and after the fatigue task (P > 0.05). Peak twitch torque was reduced by 21% at 2 min of recovery and progressively decreased to 35% by 30 min (P concentric power was reduced by 8% immediately after task termination and did not recover fully within 30 min (P contraction coupling and cross-bridge kinetics and reduced the number of functional sarcomeres in series, ultimately leading to velocity-dependent power loss. PMID:20576845

  12. Whey protein supplementation accelerates satellite cell proliferation during recovery from eccentric exercise.

    Science.gov (United States)

    Farup, Jean; Rahbek, Stine Klejs; Knudsen, Inge Skovgaard; de Paoli, Frank; Mackey, Abigail L; Vissing, Kristian

    2014-11-01

    Human skeletal muscle satellite cells (SCs) are essential for muscle regeneration and remodeling processes in healthy and clinical conditions involving muscle breakdown. However, the potential influence of protein supplementation on post-exercise SC regulation in human skeletal muscle has not been well investigated. In a comparative human study, we investigated the effect of hydrolyzed whey protein supplementation following eccentric exercise on fiber type-specific SC accumulation. Twenty-four young healthy subjects received either hydrolyzed whey protein + carbohydrate (whey, n = 12) or iso-caloric carbohydrate (placebo, n = 12) during post-exercise recovery from 150 maximal unilateral eccentric contractions. Prior to and 24, 48 and 168 h post-exercise, muscle biopsies were obtained from the exercise leg and analyzed for fiber type-specific SC content. Maximal voluntary contraction (MVC) and serum creatine kinase (CK) were evaluated as indices of recovery from muscle damage. In type II fiber-associated SCs, the whey group increased SCs/fiber from 0.05 [0.02; 0.07] to 0.09 [0.06; 0.12] (p eccentric exercise.

  13. Gravitational waves from spinning eccentric binaries

    CERN Document Server

    Csizmadia, Péter; Rácz, István; Vasúth, Mátyás

    2012-01-01

    This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity. In addition, by investigating the validity of the energy balance relat...

  14. [Sincerity of effort: isokinetic evaluation of knee extension].

    Science.gov (United States)

    Colombo, R; Demaiti, G; Sartorio, F; Orlandini, D; Vercelli, S; Ferriero, G

    2008-01-01

    The aim of this study was to find a reliable method to evaluate the sincerity of the muscular maximal effort performed in a dynamometric isokinetic test of knee flexion-extension. The coefficient of variation of the peak torque (CV) and 3 new indices were analysed: (1) the average coefficient of variation calculated on the complete peak torque curve (CVM); (2) the slope of the regression line in an endurance test (PRR); (3) the correlation coefficient of the peak torques in the same endurance test (CCR). Twenty healthy subjects underwent assessment in two different trials, maximal (MX) and 50% submaximal (SMX), with 20 minutes of rest between trials. Each trial consisted of 4 tests, each of 3 repetitions, at angular speed of 30, 180, 30, and 180 degrees/s, respectively, and 1 test of 15 repetitions at 240 degrees/s. Our findings confirmed the ability of CV to detect a high percentage of sincere efforts: at 30 degrees/s Sensibility (Sns)=100% and Specificity (Spc)=70%; at 180 degrees/s Sns=75%, Spc=95%. The 3 new indices here proposed showed high characteristics of Sns and Spc, generally better than those of CV. CVM showed at 180 degrees/s Sns=90% and Spc=100%, while at 30 degrees/s Sns=90%, Spc=75%. PRR was the best index identifying all the efforts, except one (Sns=100%, Spc=95%). The CCR coefficient showed Sns and Spc values both of 90%.

  15. Isokinetic knee joint evaluation in track and field events.

    Science.gov (United States)

    Deli, Chariklia K; Paschalis, Vassilis; Theodorou, Anastasios A; Nikolaidis, Michalis G; Jamurtas, Athanasios Z; Koutedakis, Yiannis

    2011-09-01

    The purpose of this study was to evaluate maximal torque of the knee flexors and extensors, flexor/extensor ratios, and maximal torque differences between the 2 lower extremities in young track and field athletes. Forty male track and field athletes 13-17 years old and 20 male nonathletes of the same age participated in the study. Athletes were divided into 4 groups according to their age and event (12 runners and 10 jumpers 13-15 years old, 12 runners and 6 jumpers 16-17 years old) and nonathletes into 2 groups of the same age. Maximal torque evaluation of knee flexors and extensors was performed on an isokinetic dynamometer at 60°·s(-1). At the age of 16-17 years, jumpers exhibited higher strength values at extension than did runners and nonathletes, whereas at the age of 13-15 years, no significant differences were found between events. Younger athletes were weaker than older athletes at flexion. Runners and jumpers were stronger than nonathletes in all relative peak torque parameters. Nonathletes exhibited a higher flexor/extensor ratio compared with runners and jumpers. Strength imbalance in athletes was found between the 2 lower extremities in knee flexors and extensors and also at flexor/extensor ratio of the same extremity. Young track and field athletes exhibit strength imbalances that could reduce their athletic performance, and specific strength training for the weak extremity may be needed.

  16. Hamstrings to quadriceps peak torque ratios diverge between sexes with increasing isokinetic angular velocity.

    Science.gov (United States)

    Hewett, Timothy E; Myer, Gregory D; Zazulak, Bohdanna T

    2008-09-01

    Our purpose was to determine if females demonstrate decreased hamstrings to quadriceps peak torque (H/Q) ratios compared to males and if H/Q ratios increase with increased isokinetic velocity in both sexes. Maturation disproportionately increases hamstrings peak torque at high velocity in males, but not females. Therefore, we hypothesised that mature females would demonstrate decreased H/Q ratios compared to males and the difference in H/Q ratio between sexes would increase as isokinetic velocity increased. Studies that analysed the H/Q ratio with gravity corrected isokinetic strength testing reported between 1967 and 2004 were included in our review and analysis. Keywords were hamstrings/quadriceps, isokinetics, peak torque and gravity corrected. Medline and Smart databases were searched combined with cross-checked bibliographic reference lists of the publications to determine studies to be included. Twenty-two studies were included with a total of 1568 subjects (1145 male, 423 female). Males demonstrated a significant correlation between H/Q ratio and isokinetic velocity (R=0.634, pratio at the lowest angular velocity (47.8+/-2.2% at 30 degrees /s) compared to the highest velocity (81.4+/-1.1% at 360 degrees /s, pratio and isokinetic velocity (R=0.065, p=0.77) or a change in relative hamstrings strength as the speed increased (49.5+/-8.8% at 30 degrees /s; 51.0+/-5.7% at 360 degrees /s, p=0.84). Gender differences in isokinetic H/Q ratios were not observed at slower angular velocities. However, at high knee flexion/extension angular velocities, approaching those that occur during sports activities, significant gender differences were observed in the H/Q ratio. Females, unlike males, do not increase hamstrings to quadriceps torque ratios at velocities that approach those of functional activities.

  17. Fiber-type susceptibility to eccentric contraction-induced damage of hindlimb-unloaded rat AL muscles

    Science.gov (United States)

    Vijayan, K.; Thompson, J. L.; Norenberg, K. M.; Fitts, R. H.; Riley, D. A.

    2001-01-01

    Slow oxidative (SO) fibers of the adductor longus (AL) were predominantly damaged during voluntary reloading of hindlimb unloaded (HU) rats and appeared explainable by preferential SO fiber recruitment. The present study assessed damage after eliminating the variable of voluntary recruitment by tetanically activating all fibers in situ through the motor nerve while applying eccentric (lengthening) or isometric contractions. Muscles were aldehyde fixed and resin embedded, and semithin sections were cut. Sarcomere lesions were quantified in toluidine blue-stained sections. Fibers were typed in serial sections immunostained with antifast myosin and antitotal myosin (which highlights slow fibers). Both isometric and eccentric paradigms caused fatigue. Lesions occurred only in eccentrically contracted control and HU muscles. Fatigue did not cause lesions. HU increased damage because lesioned- fiber percentages within fiber types and lesion sizes were greater than control. Fast oxidative glycolytic (FOG) fibers were predominantly damaged. In no case did damaged SO fibers predominate. Thus, when FOG, SO, and hybrid fibers are actively lengthened in chronically unloaded muscle, FOG fibers are intrinsically more susceptible to damage than SO fibers. Damaged hybrid-fiber proportions ranged between these extremes.

  18. Unstable force analysis for induction motor eccentricity

    Science.gov (United States)

    Han, Xu; Palazzolo, Alan

    2016-05-01

    The increasing popularity of motors in machinery trains has led to an intensified interest in the forces they produce that may influence machinery vibration. Motor design typically assumes a uniform air gap, however in practice all motors operate with the rotor slightly displaced from the motor centerline in what is referred to as an eccentric position. Rotor center eccentricity can cause a radially unbalanced magnetic field when the motor is operating. This will results in both a radial force pulling the motor further away from the center, and a tangential force which can induce a vibration stability problem. In this paper, a magnetic equivalent circuit MEC modeling method is proposed to calculate both the radial and tangential motor eccentric force. The treatment of tangential force determination is rarely addressed, but it is very important for rotordynamic vibration stability evaluation. The proposed model is also coupled with the motor electric circuit model to provide capability for transient vibration simulations. FEM is used to verify the MEC model. A parametric study is performed on the motor radial and tangential eccentric forces. Also a Jeffcott rotor model is used to study the influence of the motor eccentric force on mechanical vibration stability and nonlinear behavior. Furthermore, a stability criteria for the bearing damping is provided. The motor radial and tangential eccentric forces are both curved fitted to include their nonlinearity in time domain transient simulation for both a Jeffcott rotor model and a geared machinery train with coupled torsional-lateral motion. Nonlinear motions are observed, including limit cycles and bifurcation induced vibration amplitude jumps.

  19. Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA

    CERN Document Server

    Vos, Joris; Marchant, Pablo; Van Winckel, Hans

    2015-01-01

    Hot subdwarf-B stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts those objects to be circularised before the onset of Roche-lobe overflow (RLOF). We aim to find binary-evolution mechanisms that can explain these eccentric long-period orbits, and reproduce the currently observed period-eccentricity diagram. Three different processes are considered; tidally-enhanced wind mass-loss, phase-dependent RLOF on eccentric orbits and the interaction between a circumbinary disk and the binary. The binary module of the stellar-evolution code MESA (Modules for Experiments in Stellar Astrophysics) is extended to include the eccentricity-pumping processes. The effects of different input parameters on the final period and eccentricity of a binary-evolution model are tested with MESA. The end products of models with only tidally-enhanced wind mass-loss can indeed be eccentric, but these models need to lose too much mass, and invariably end up with a helium ...

  20. Eccentric connectivity index and eccentric distance sum of some graph operations

    Directory of Open Access Journals (Sweden)

    Buzohragul Eskender

    2013-03-01

    Full Text Available Let $G=(V,E$ be a connected graph. The eccentric connectivity index of $G$, $xi^{c}(G$, is defined as $xi^{c}(G=sum_{vin V(G}deg(vec(v$, where $deg(v$ is the degree of a vertex $v$ and $ec(v$ is its eccentricity. The eccentric distance sum of $G$ is defined as $xi^{d}(G=sum_{vin V(G}ec(vD(v$, where $D(v=sum_{uin V(G}d_{G}(u,v$ and $d_{G}(u,v$ is the distance between $u$ and $v$ in $G$. In this paper, we calculate the eccentric connectivity index and eccentric distance sum of generalized hierarchical product of graphs. Moreover, we present explicit formulae for the eccentric connectivity index of $F$-sum graphs in terms of some invariants of the factors. As applications, we present exact formulae for the values of the eccentric connectivity index of some graphs of chemical interest such as $C_{4}$ nanotubes, $C_{4}$ nanotoris and hexagonal chains.

  1. Comparing Voluntary and Mandatory Gameplay

    Directory of Open Access Journals (Sweden)

    Esther Kuindersma

    2016-09-01

    Full Text Available Gameplay is commonly considered to be a voluntary activity. Game designers generally believe that voluntary gameplay is essentially different from mandatory gameplay. Such a belief may be a challenge for serious games, as instruction is usually mandatory. The article describes the outcomes of two experiments on the impact of voluntariness on the learning effect and enjoyment of a serious game. In the first experiment freedom of choosing to play a serious game was studied, with participants who had volunteered to participate. The results suggested that, contrary to the opinion of many game designers, being required to play a serious game does not automatically take the fun out of the game. The second experiment had voluntary participants and mandatory participants, who had to participate as part of a homework assignment. The outcomes show that mandatory participants enjoyed the game as much as the voluntary participants, even if they had to play the game for a minimum required time. These studies indicate that mandatory gameplay does not reduce enjoyment and learning effect.

  2. Voluntary organisation and adult education

    Directory of Open Access Journals (Sweden)

    Konrad Elsdon

    1998-12-01

    Full Text Available The author starts by offering a definition of voluntary organisations. He then discusses their importance and role, focusing on the issue of adult education wi­ thin these organisations. He also wells upon learning and change of voluntary organisation members, making use of the results of a study he conducted together with his collaborators. One of their fin­dings has been that voluntary organisati­ons, due to their organisational targets li­ke painting, singing or caring for people in need, lead their members to learning, i.e. essentially content learning. Moreo­ver, voluntary organisations offer a fair number of opportunities for social lear­ning and change. ln spite of the fact that the respondents were mostly not aware of the outcomes of their learning and change, careful listeners conducting the interview made them understand the im­portance of the learning they had gone through. The author concludes by poin­ ting out that formal education of adults can get its inspiration in learning in voluntary organisations. On the other hand, such learning would benefit greatly from findings and methods of formal education of adults.

  3. Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

    Science.gov (United States)

    Ebenbichler, Gerold R.; Unterlerchner, Lena; Habenicht, Richard; Bonato, Paolo; Kollmitzer, Josef; Mair, Patrick; Riegler, Sara; Kienbacher, Thomas

    2017-01-01

    Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG) data. Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's), an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG) and the instantaneous median frequency (IMDF-SEMG) estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise. Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise. Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior. PMID:28559851

  4. Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

    Directory of Open Access Journals (Sweden)

    Gerold R. Ebenbichler

    2017-05-01

    Full Text Available Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG data.Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's, an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG and the instantaneous median frequency (IMDF-SEMG estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise.Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise.Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

  5. Isokinetic Evaluation of Knee Extensor/Flexor Muscle Strength in Behcet’s Patients

    Directory of Open Access Journals (Sweden)

    Bekir Durmus

    2015-10-01

    Full Text Available Background: Behçet’s disease (BD is an idiopathic, multisystemic, progressive disease. The purpose of this study is to compare the knee flexor and extensor isokinetic muscle strengths of Behcet’s patients with that of healthy subjects. Methods: Twenty-five (13 male and 12 female patients with BD and 25 (15 male and 10 female healthy individuals were included in the study. Velocities of 90°/sec, 120°/sec, and 150°/sec were used for the isokinetic muscle strength testing. Patients with active inflammatory knee arthritis were excluded. Peak torque (Nm and peak torque adjusted to body weight (% were taken into consideration for comparison between study groups. Results: Compared to healthy controls, there was a statistically significant decrease in both the bilateral knee extensor and flexor muscle isokinetic peak torques(Nm as well as the peak torques adjusted to body weight (% at velocities of 90°/sec, 120°/sec and 150°/sec in patients with BD (p < 0.05. However, there was no significant difference in the agonist-antagonist ratio of the isokinetic peak torques of knee muscles between the two groups. Conclusion: In light of these findings, we have concluded that both knee flexor and extensor isokinetic muscle strengths are lower in BD. We therefore recommend careful monitoring of patients with BD in terms of muscle strength.

  6. An adequate interset rest period for strength recovery during a common isokinetic test.

    Science.gov (United States)

    Blazquez, Ivan N; Warren, Barbara L; O'Hanlon, Ann M; Silvestri, Lynette R

    2013-07-01

    Isokinetic testing is used in rehabilitation settings on a regular basis; yet, there is a lack of consistency in rest period usage among protocols. Furthermore, the allotment of rest periods has been arbitrary (e.g., 30, 60, 90 seconds or more). This investigation examines the work:rest ratio as an effective method of standardizing rest periods in isokinetic testing. The purpose of this study was to establish an adequate rest period that would allow reproducibility of strength during a common isokinetic strength test. Twenty-seven healthy college-aged men (age, 23 ± 3.8 years; body weight, 79.54 ± 11.09 kg) were tested on 5 separate occasions: 2 familiarization sessions and 3 experimental sessions. Each subject performed a knee extension/flexion isokinetic strength protocol (Cybex NORM; Lumex, Inc., Ronkonkoma, NY, USA) to determine peak torque by performing 5 maximal reciprocal repetitions at each ascending velocity of 60, 180, and 300°·s. Work:rest ratios of 1:3, 1:8, and 1:12 were counterbalanced between sets. A 3 × 3 repeated measures analysis of variance was used to analyze the data. A significance level of α ≤ 0.05 was used for all tests. There was no significant difference in either knee extension or knee flexion peak torque when comparing work:rest ratios. These findings suggest that a 1:3 work:rest ratio is sufficient during a common isokinetic strength test.

  7. Effects of different stretching techniques on the outcomes of isokinetic exercise in patients with knee osteoarthritis.

    Science.gov (United States)

    Weng, Ming-Cheng; Lee, Chia-Ling; Chen, Chia-Hsin; Hsu, Jui-Jen; Lee, Wei-Der; Huang, Mao-Hsiung; Chen, Tien-Wen

    2009-06-01

    We recruited 132 subjects with bilateral knee osteoarthritis (Altman Grade II) to compare the effects of different stretching techniques on the outcomes of isokinetic muscle strengthening exercises. Patients were randomly divided into four groups (I-IV). The patients in Group I received isokinetic muscular strengthening exercises, Group II received bilateral knee static stretching and isokinetic exercises, Group III received proprioceptive neuromuscular facilitation (PNF) stretching and isokinetic exercises, and Group IV acted as controls. Outcomes were measured by changes in Lequesne's index, range of knee motion, visual analog pain scale, and peak muscle torques during knee flexion and extension. Patients in all the treated groups experienced significant reductions in knee pain and disability, and increased peak muscle torques after treatment and at follow-up. However, only patients in Groups II and III had significant improvements in range of motion and muscle strength gain during 60 degrees/second angular velocity peak torques. Group III demonstrated the greatest increase in muscle strength gain during 180 degrees/second angular velocity peak torques. In conclusion, stretching therapy could increase the effectiveness of isokinetic exercise in terms of functional improvement in patients with knee osteoarthritis. PNF techniques were more effective than static stretching.

  8. Relation between isokinetic muscle strength and functional capacity in recreational athletes with chondromalacia patellae

    Science.gov (United States)

    Yildiz, Y; Aydin, T; Sekir, U; Cetin, C; Ors, F; Alp, K

    2003-01-01

    Objectives: To investigate the effects of isokinetic exercise on pain and functional test scores of recreational athletes with chondromalacia patellae (CMP) and to examine the correlation between isokinetic parameters and functional tests or pain score. Methods: The functional ability of 30 recreational athletes with unilateral CMP was evaluated using six different tests. Pain scores were assessed during daily activities before and after the treatment protocol. Isokinetic exercise sessions were carried out at angular velocities of 60°/s (25–90° range of flexion) and 180°/s (full range). These sessions were repeated three times a week for six weeks. Results: Quadriceps and hamstring peak torque, total work, and endurance ratios had improved significantly after the treatment, as did the functional parameters and pain scores. There was a poor correlation between the extensor endurance ratio and one leg standing test. A moderate correlation between the visual analogue scale and the extensor endurance ratio or flexion endurance ratio was also found. Conclusions: The isokinetic exercise programme used in this study had a positive effect on muscle strength, pain score, and functional ability of knees with CMP. The improvement in the functional capacity did not correlate with the isokinetic parameters. PMID:14665581

  9. Isokinetic assessment of the hip muscles in patients with osteoarthritis of the knee

    Directory of Open Access Journals (Sweden)

    Renata Alqualo Costa

    2010-01-01

    Full Text Available OBJECTIVES: To evaluate the difference in isokinetic strength of hip muscles between patients with knee osteoarthritis (OA and matched healthy controls, and to establish the correlation between this isokinetic strength and pain and function in patients with knee OA. METHODS: 25 patients with a diagnosis of unilateral knee OA, 25 patients with bilateral knee OA, and 50 matched controls were evaluated using the visual analog scale for pain, knee Lequesne index, Western Ontario and McMaster Universities questionnaire and an isokinetic test. RESULTS: The groups were matched for age, gender and body mass index. The results of the isokinetic test revealed lower peak torque of the hip in patients with OA of the knee than in the control group for all movements studied. Strong correlations were found between the peak torque, visual analog scale and function. CONCLUSIONS: Patients with OA of the knee exhibit lower isokinetic strength in the hip muscles than healthy control subjects. Strengthening the muscles surrounding the hip joint may help to decrease pain in people with knee OA. Some correlations between pain/function and peak torque were found.

  10. Muscular performance characterization in athletes: a new perspective on isokinetic variables

    Directory of Open Access Journals (Sweden)

    Giovanna M. Amaral

    2014-12-01

    Full Text Available Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development. Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments.

  11. Orbital eccentricities in primordial black holes binaries

    CERN Document Server

    Cholis, Ilias; Ali-Haïmoud, Yacine; Bird, Simeon; Kamionkowski, Marc; Muñoz, Julian B; Raccanelli, Alvise

    2016-01-01

    It was recently suggested that the merger of $\\sim30\\,M_\\odot$ primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on timescales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO a...

  12. Density and Eccentricity of Kepler Planets

    CERN Document Server

    Wu, Yanqin

    2012-01-01

    We analyze the transit timing variations obtained by the Kepler mission for 22 sub-jovian planet pairs (17 published, 5 new) that lie close to mean motion resonances. We find that the TTV phases for most of these pairs lie close to zero, consistent with an eccentricity distribution that has a very low RMS value of e ~ 0.01; but about a quarter of the pairs possess much higher eccentricities, up to 0.1 - 0.4. For the low-eccentricity pairs, we are able to statistically remove the effect of eccentricity to obtain planet masses from TTV data. These masses, together with those measured by radial velocity, yield a best fit mass-radius relation M~3 M_E (R/R_E). This corresponds to a constant surface escape velocity of 20km/s. We separate the planets into two distinct groups, "mid-sized" (those greater than 3 R_E), and "compact" (those smaller). All mid-sized planets are found to be less dense than water and therefore contain extensive H/He envelopes, likely comparable in mass to that of their cores. We argue that t...

  13. Vibration of an eccentrically clamped annular plate

    Science.gov (United States)

    Tseng, J.-G.; Wickert, J. A.

    1994-04-01

    Small amplitude vibration of an eccentric annular plate, which is free along its outer edge and clamped along the interior, is investigated through experimental and analytical methods. A disk with this geometry, or a stacked array in which the clamping and symmetry axes of each disk are nominally coincident, is common in data storage and brake systems applications. In the present case, the geometric imperfections on the boundary can have important implications for the disk's dynamic response. Changes that occur in the natural frequency spectrum, the mode shapes, and the free response under eccentric mounting are studied through laboratory measurements and an approximate discrete model of the plate. The natural frequencies and modes are found through global discretization of the Kamke quotient for a classical thin plate. For the axisymmetric geometry, the natural frequencies of the sine and cosine vibration modes for a specified number of nodal diameters are repeated. With increasing eccentricity, on the other hand, each pair of repeated frequencies splits at a rate that depends on the number of nodal diameters. Over a range of clamping and eccentricity ratios, the model's predictions are compared to the measured results.

  14. Chain hexagonal cacti with the extremal eccentric distance sum.

    Science.gov (United States)

    Qu, Hui; Yu, Guihai

    2014-01-01

    Eccentric distance sum (EDS), which can predict biological and physical properties, is a topological index based on the eccentricity of a graph. In this paper we characterize the chain hexagonal cactus with the minimal and the maximal eccentric distance sum among all chain hexagonal cacti of length n, respectively. Moreover, we present exact formulas for EDS of two types of hexagonal cacti.

  15. Effects of Eccentric Strength Training on Different Maximal Strength and Speed-Strength Parameters of the Lower Extremity.

    Science.gov (United States)

    Wirth, Klaus; Keiner, Michael; Szilvas, Elena; Hartmann, Hagen; Sander, Andre

    2015-07-01

    The aim of this investigation was to analyze the effects of an eccentric strength training protocol using supramaximal loads (>1 repetition maximum [1RM]) on different maximal and explosive strength parameters of the lower extremity. The eccentric maximal strength (EX max), maximal isometric strength ("maximal voluntary contraction" [MVC]), 1RM, explosive strength ("rate of force development" [RFD]), countermovement jump, and squat jump height were tested before and after a training period of 6 weeks. The training group was composed of 15 individuals with low-weight training experience and a control group of 13 subjects, also with a low-weight training experience. The lower extremities were trained 3 days per week using a 45° leg press. Each training session comprised 5 sets of 3 repetitions with a 6-minute rest between each set. The training weights were adjusted continuously during each training session and between training sessions. In each case, a load was chosen that could be lowered unilaterally in a controlled manner by the subjects. For the concentric part of the exercise, 2 investigators lifted the weight to the starting position. After 6 weeks, strength training with supramaximal loads showed a significant increase in EX max (28.2%, p strength training in the leg press generates equal and significant improvements in unilateral eccentric and bilateral eccentric-concentric maximal strength, with a nonsignificant transfer to vertical jump performances and unilateral isometric force production.

  16. Effect of eccentric exercise with reduced muscle glycogen on plasma interleukin-6 and neuromuscular responses of musculus quadriceps femoris.

    Science.gov (United States)

    Gavin, James P; Myers, Stephen D; Willems, Mark E T

    2016-07-01

    Eccentric exercise can result in muscle damage and interleukin-6 (IL-6) secretion. Glycogen availability is a potent stimulator of IL-6 secretion. We examined effects of eccentric exercise in a low-glycogen state on neuromuscular function and plasma IL-6 secretion. Twelve active men (23 ± 4 yr, 179 ± 5 cm, 77 ± 10 kg, means ± SD) completed two downhill treadmill runs (gradient, -12%, 5 × 8 min; speed, 12.1 ± 1.1 km/h) with normal (NG) and reduced muscle glycogen (RG) in randomized order and at least 6 wk apart. Muscle glycogen was reduced using an established cycling protocol until exhaustion and dietary manipulation the evening before the morning run. Physiological responses were measured up to 48 h after the downhill runs. During recovery, force deficits of musculus quadriceps femoris by maximal isometric contractions were similar. Changes in low-frequency fatigue were larger with RG. Voluntary activation and plasma IL-6 levels were similar in recovery between conditions. It is concluded that unaccustomed, damaging eccentric exercise with low muscle glycogen of the m. quadriceps femoris 1) exacerbated low-frequency fatigue but 2) had no additional effect on IL-6 secretion. Neuromuscular impairment after eccentric exercise with low muscle glycogen appears to have a greater peripheral component in early recovery.

  17. Comparison of nutritional intake, body composition, bone mineral density, and isokinetic strength in collegiate female dancers.

    Science.gov (United States)

    Lim, Se-Na; Chai, Joo-Hee; Song, Jong Kook; Seo, Myong-Won; Kim, Hyun-Bae

    2015-12-01

    This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at Pcontemporary and ballet dancers had lower body fat percentages than controls (Pdance type and more scientific methods of dance training are needed.

  18. Using Evolved Fuzzy Neural Networks for Injury Detection from Isokinetic Curves

    Science.gov (United States)

    Couchet, Jorge; Font, José María; Manrique, Daniel

    In this paper we propose an evolutionary fuzzy neural networks system for extracting knowledge from a set of time series containing medical information. The series represent isokinetic curves obtained from a group of patients exercising the knee joint on an isokinetic dynamometer. The system has two parts: i) it analyses the time series input in order generate a simplified model of an isokinetic curve; ii) it applies a grammar-guided genetic program to obtain a knowledge base represented by a fuzzy neural network. Once the knowledge base has been generated, the system is able to perform knee injuries detection. The results suggest that evolved fuzzy neural networks perform better than non-evolutionary approaches and have a high accuracy rate during both the training and testing phases. Additionally, they are robust, as the system is able to self-adapt to changes in the problem without human intervention.

  19. Voluntary euthanasia: a utilitarian perspective.

    Science.gov (United States)

    Singer, Peter

    2003-10-01

    Belgium legalised voluntary euthanasia in 2002, thus ending the long isolation of the Netherlands as the only country in which doctors could openly give lethal injections to patients who have requested help in dying. Meanwhile in Oregon, in the United States, doctors may prescribe drugs for terminally ill patients, who can use them to end their life--if they are able to swallow and digest them. But despite President Bush's oft-repeated statements that his philosophy is to 'trust individuals to make the right decisions' and his opposition to 'distant bureaucracies', his administration is doing its best to prevent Oregonians acting in accordance with a law that its voters have twice ratified. The situation regarding voluntary euthanasia around the world is therefore very much in flux. This essay reviews ethical arguments regarding voluntary euthanasia and physician-assisted suicide from a utilitarian perspective. I shall begin by asking why it is normally wrong to kill an innocent person, and whether these reasons apply to aiding a person who, when rational and competent, asks to be killed or given the means to commit suicide. Then I shall consider more specific utilitarian arguments for and against permitting voluntary euthanasia.

  20. Social Cohesion and Voluntary Associations

    Science.gov (United States)

    Heuser, Brian L.

    2005-01-01

    Voluntary organizations exert great influence over how social norms and ethical codes are guided into action. As such, they have a significant impact on societal levels of social cohesion. Although social capital involves generalized trust becoming manifest as spontaneous sociability, social cohesion is determined by how that sociability is…

  1. Voluntary Incentive Early Retirement Programs.

    Science.gov (United States)

    Research Dialogues, 1988

    1988-01-01

    Arrangements in educational institutions for voluntary early retirement programs are discussed. Retirement at any age can be a profound and stressful lifetime change; and it can also represent a welcome transition into newly satisfying and rewarding opportunities. The focus is on: mandatory retirement (exceptions and the new meaning of "early");…

  2. Voluntary disclosure: Evidence from UK

    NARCIS (Netherlands)

    N.S. Zourarakis (Nicolaos)

    2009-01-01

    textabstractThis paper investigates the voluntary disclosure of Intellectual Capital (IC) of British firms and provides some evidence on an unexplored area of the literature; that of the association of Corporate Governance (CG) with IC disclosure. Inconsistent with expectations, the results show tha

  3. 陕西省优秀跆拳道运动员髋关节屈伸肌群等速测试与研究%Isokinetic test and research of hip flexion and extension muscles of Shaanxi elite taekwondo athletes

    Institute of Scientific and Technical Information of China (English)

    石新燕

    2011-01-01

    Abstract:The paper aimed to obtain the biomechanical characteristics of isokinetic contraction by using ISOMED2000 system to test the hip joints of Shaanxi elite taekwondo athletes. The joint angle was between 133.7° and 140.2° when the isokinetic eccentric contraction of right hip flexors reached peak torque and between 121. 2° and 106.3° when that of right hip extensors reached peak torque. It is when the concentric and eccentric contraction speed of hip flexors and extensors was at 240°/s that the relative torque gradient reached the maximum.%采用ISOMED2000获得陕西省优秀跆拳道运动员髋关节等速收缩的生物力学特征。右髋关节屈肌群等速离心收缩峰值力矩出现时的关节角度在133.7°-140.20之间,伸肌群等速离心收缩峰值力矩出现时的关节角度在121.2°-106.30之间;髋关节屈伸肌群向心收缩、离心收缩速度在240°/s时相对力矩梯度达到最大。

  4. Voluntary sterilization in Serbia: Unmet need?

    OpenAIRE

    Rašević Mirjana M.

    2002-01-01

    Is voluntary sterilization as a birth control method accepted in Serbia? This is certainly a question that is being imposed for research, regardless of the fact that voluntary sterilization is neither accessible nor promoted. Most importantly because there is no understanding in the social nor political sphere for legalization of voluntary sterilization as a form of birth control, apart from the clear necessity for this, first, step. They are: the recognition that voluntary sterilization is a...

  5. 22 CFR 513.210 - Voluntary exclusion.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Voluntary exclusion. 513.210 Section 513.210... GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (GRANTS) Effect of Action § 513.210 Voluntary exclusion. Persons who accept voluntary exclusions under § 513.315 are excluded in accordance with the terms of...

  6. Eccentricity Pumping Through Circumbinary Disks in Hot Subdwarf Binaries

    Science.gov (United States)

    Vos, J.

    2015-12-01

    Hot subdwarf-B stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts these objects to be circularized before the onset of Roche-lobe overflow (RLOF). We have tested three different eccentricity pumping processes on their viability to reproduce the observed wide sdB population; tidally-enhanced wind mass-loss, phase-dependent RLOF on eccentric orbits and the interaction between a circumbinary (CB) disk and the binary. The binary module of the stellar-evolution code Modules for Experiments in Stellar Astrophysics (MESA) is extended to include the eccentricity-pumping processes, and a parameter study is carried out. We find that models including phase-dependent RLOF or a CB disk can reach the observed periods and eccentricities. However, the models cannot explain the observed correlation between period and eccentricity. Nor can circular short period systems be formed when eccentricity pumping mechanisms are active.

  7. Effects of Retinal Eccentricity on Human Manual Control

    Science.gov (United States)

    Popovici, Alexandru; Zaal, Peter M. T.

    2017-01-01

    This study investigated the effects of viewing a primary flight display at different retinal eccentricities on human manual control behavior and performance. Ten participants performed a pitch tracking task while looking at a simplified primary flight display at different horizontal and vertical retinal eccentricities, and with two different controlled dynamics. Tracking performance declined at higher eccentricity angles and participants behaved more nonlinearly. The visual error rate gain increased with eccentricity for single-integrator-like controlled dynamics, but decreased for double-integrator-like dynamics. Participants' visual time delay was up to 100 ms higher at the highest horizontal eccentricity compared to foveal viewing. Overall, vertical eccentricity had a larger impact than horizontal eccentricity on most of the human manual control parameters and performance. Results might be useful in the design of displays and procedures for critical flight conditions such as in an aerodynamic stall.

  8. International Voluntary Renewable Energy Markets (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Heeter, J.

    2012-06-01

    This presentation provides an overview of international voluntary renewable energy markets, with a focus on the United States and Europe. The voluntary renewable energy market is the market in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. In 2010, the U.S. voluntary market was estimated at 35 terawatt-hours (TWh) compared to 300 TWh in the European market, though key differences exist. On a customer basis, Australia has historically had the largest number of customers, pricing for voluntary certificates remains low, at less than $1 megawatt-hour, though prices depend on technology.

  9. Eccentric Connectivity Index of Chemical Trees

    CERN Document Server

    c, Aleksandar Ili\\'

    2011-01-01

    The eccentric connectivity index $\\xi^c$ is a distance--based molecular structure descriptor that was recently used for mathematical modeling of biological activities of diverse nature. We prove that the broom has maximum $\\xi^c$ among trees with a fixed maximum vertex degree, and characterize such trees with minimum $\\xi^c$\\,. In addition, we propose a simple linear algorithm for calculating $\\xi^c$ of trees.

  10. Habitable Climates: The Influence of Eccentricity

    CERN Document Server

    Dressing, Courtney D; Scharf, Caleb A; Raymond, Sean N

    2010-01-01

    Radiative equilibrium studies that place Earth-like exoplanets on different circular orbits from the parent star do not fully sample the range of plausible habitability conditions in planetary systems. In the outer regions of the habitable zone, the risk of transitioning into a globally frozen "snowball" state poses a threat to the habitability. Here, we use a one-dimensional energy balance climate model (EBM) to examine how obliquity, spin rate, orbital eccentricity, and the fraction of the surface covered by ocean might influence the onset of such a snowball state. Since, for constant semimajor axis, the annual mean stellar irradiation scales with (1-e^2)^(-1/2), one might expect the greatest habitable semimajor axis to scale as (1-e^2)^(-1/4). We find that this standard simple ansatz provides a reasonable lower bound on the outer boundary of the habitable zone, but the influence of both obliquity and ocean fraction can be profound in the context of planets on eccentric orbits. For planets with eccentricity...

  11. Eccentric Contraction-Induced Muscle Fibre Adaptation

    Directory of Open Access Journals (Sweden)

    Arabadzhiev T. I.

    2009-12-01

    Full Text Available Hard-strength training induces strength increasing and muscle damage, especially after eccentric contractions. Eccentric contractions also lead to muscle adaptation. Symptoms of damage after repeated bout of the same or similar eccentrically biased exercises are markedly reduced. The mechanism of this repeated bout effect is unknown. Since electromyographic (EMG power spectra scale to lower frequencies, the adaptation is related to neural adaptation of the central nervous system (CNS presuming activation of slow-non-fatigable motor units or synchronization of motor unit firing. However, the repeated bout effect is also observed under repeated stimulation, i.e. without participation of the CNS. The aim of this study was to compare the possible effects of changes in intracellular action potential shape and in synchronization of motor units firing on EMG power spectra. To estimate possible degree of the effects of central and peripheral changes, interferent EMG was simulated under different intracellular action potential shapes and different degrees of synchronization of motor unit firing. It was shown that the effect of changes in intracellular action potential shape and muscle fibre propagation velocity (i.e. peripheral factors on spectral characteristics of EMG signals could be stronger than the effect of synchronization of firing of different motor units (i.e. central factors.

  12. Roll Eccentricity Control Using Identified Eccentricity of Top/Bottom Rolls by Roll Force

    Science.gov (United States)

    Imanari, Hiroyuki; Koshinuma, Kazuyoshi

    Roll eccentricity is a periodic disturbance caused by a structure of back up rolls in rolling mills, and it affects product thickness accuracy. It cannot be measured directly by sensors, so it should be identified by measured thickness or measured roll force. When there is a large difference of diameters between top and bottom back up roll, the performance of roll eccentricity control using feedback signals of roll force or thickness has not been so good. Also it has been difficult for the control to be applied from the most head end because it is necessary to identify the roll eccentricity during rolling. A new roll eccentricity control has been developed to improve these disadvantages and to get better performance. The method identifies top and bottom roll eccentricity respectively from one signal of roll force and it can start the control from head end. In this paper the new control method is introduced and actual application results to a hot strip mill are shown.

  13. Low-Frequency Fatigue Assessed as Double to Single Twitch Ratio after Two Bouts of Eccentric Exercise of the Elbow Flexors

    Directory of Open Access Journals (Sweden)

    Damian Janecki, Anna Jaskólska, Jarosław Marusiak, Artur Jaskólski

    2016-12-01

    Full Text Available The aim of this study was to assess low-frequency fatigue as a double to single twitch ratio after repeated eccentric exercise of the elbow flexors. Maximal isometric torque, single and double twitch responses and low-frequency fatigue were assessed on the elbow flexors in 16 untrained male volunteers before, immediately after, 24 and 48 hours following two bouts of eccentric exercise consisted of 30 repetitions of lowering a dumbbell adjusted to ~75% of each individual’s maximal isometric torque. Maximal isometric torque and electrically evoked responses decreased significantly in all measurements after the first bout of eccentric exercise (p < 0.05. In measurements performed at 24 and 48 hours after the second bout both maximal voluntary isometric torque and electrically evoked contractions were significantly higher than in measurements performed after the first bout (p < 0.05. Although low-frequency fatigue significantly increased up to 48 hours after each bout of eccentric exercise, its values at 24 and 48 hours after the second bout were significantly lower than at respective time points after the first bout (p < 0.05. Double to single twitch ratio could be used as a sensitive tool in the evaluation of muscle recovery and adaptation to repeated eccentric exercise.

  14. Isokinetic strength of the trunk Xexor muscles after surgical repair for incisional hernia

    NARCIS (Netherlands)

    D. den Hartog (Dennis); H.H. Eker (Hasan); W.E. Tuinebreijer (Wim); G.J. Kleinrensink (Gert Jan); H.J. Stam (Henk); J.F. Lange (Johan)

    2010-01-01

    textabstractPurpose The repair of incisional hernias can be accomplished by open or laparoscopic techniques. The Biodex® dynamometer measures muscle strength during isokinetic movement. The objectives of this study are to compare the strength of the trunk Xexors between patients who underwent repair

  15. Establishing isokinetic flow for a plasma torch exhaust gas diagnostic for a plasma hearth furnace

    Energy Technology Data Exchange (ETDEWEB)

    Pollack, B.R.

    1996-05-01

    Real time monitoring of toxic metallic effluents in confined gas streams can be accomplished through use of Microwave Induced Plasmas to perform atomic emission spectroscopy, For this diagnostic to be viable it is necessary that it sample from the flowstream of interest in an isokinetic manner. A method of isokinetic sampling was established for this device for use in the exhaust system of a plasma hearth vitrification furnace. The flow and entrained particulate environment were simulated in the laboratory setting using a variable flow duct of the same dimensions (8-inch diameter, schedule 40) as that in the field and was loaded with similar particulate (less than 10 {mu}m in diameter) of lake bed soil typically used in the vitrification process. The flow from the furnace was assumed to be straight flow. To reproduce this effect a flow straightener was installed in the device. An isokinetic sampling train was designed to include the plasma torch, with microwave power input operating at 2.45 GHz, to match local freestream velocities between 800 and 2400 ft/sec. The isokinetic sampling system worked as planned and the plasma torch had no difficulty operating at the required flowrates. Simulation of the particulate suspension was also successful. Steady particle feeds were maintained over long periods of time and the plasma diagnostic responded as expected.

  16. EFFICACY OF ISOKINETIC STRENGTH TRAINING AND BALANCE EXERCISES ON LOWER LIMB MUSCLES IN SUBJECTS WITH STROKE

    Directory of Open Access Journals (Sweden)

    Dr.P.Keerthi Chandra Sekhar

    2013-06-01

    Full Text Available Background:To evaluate the efficacy of isokinetic strength training and balance exercises on lower limb musclesamong the subjects suffering with stroke.Materials and Methods:40 subjects who are suffering from strokewere divided into two groups, Experimental group received Isokinetic strength training and balance exercises(n=20 and Control group received conventional physiotherapy, results were measured withIsokinetic deviceand Berg balance scale for peak torque of knee extensors on paretic leg and balance respectively.Results:obtained results were analyzed with the use ofPaired T-test, which has been carried out to observe the treat-ment impact between the groups before and after the treatment. After a 6 week treatment period, thesub-jects in the Group I (strength training and balance exercise compared with the subjects in the Group II (con-ventional physiotherapy had shown a statistically significant improvement with the outcome measuresat 0.05level.Conclusion:Isokinetic strength training and balance exercise was found much effective in improving strengthof quadriceps lower limb and balance in subjects with stroke.

  17. Establishing isokinetic flow for a plasma torch exhaust gas diagnostic for a plasma hearth furnace

    Energy Technology Data Exchange (ETDEWEB)

    Pollack, Brian R. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    1996-05-01

    Real time monitoring of toxic metallic effluents in confined gas streams can be accomplished through use of Microwave Induced Plasmas to perform atomic emission spectroscopy, For this diagnostic to be viable it is necessary that it sample from the flowstream of interest in an isokinetic manner. A method of isokinetic sampling was established for this device for use in the exhaust system of a plasma hearth vitrification furnace. The flow and entrained particulate environment were simulated in the laboratory setting using a variable flow duct of the same dimensions (8-inch diameter, schedule 40) as that in the field and was loaded with similar particulate (less than 10 μm in diameter) of lake bed soil typically used in the vitrification process. The flow from the furnace was assumed to be straight flow. To reproduce this effect a flow straightener was installed in the device. An isokinetic sampling train was designed to include the plasma torch, with microwave power input operating at 2.45 GHz, to match local freestream velocities between 800 and 2400 ft/sec. The isokinetic sampling system worked as planned and the plasma torch had no difficulty operating at the required flowrates. Simulation of the particulate suspension was also successful. Steady particle feeds were maintained over long periods of time and the plasma diagnostic responded as expected.

  18. Lower-extremity isokinetic strength profiling in professional rugby league and rugby union.

    Science.gov (United States)

    Brown, Scott R; Brughelli, Matt; Griffiths, Peter C; Cronin, John B

    2014-03-01

    While several studies have documented isokinetic knee strength in junior and senior rugby league players, investigations of isokinetic knee and hip strength in professional rugby union players are limited. The purpose of this study was to provide lower-extremity strength profiles and compare isokinetic knee and hip strength of professional rugby league and rugby union players. 32 professional rugby league and 25 professional rugby union players. Cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque and strength ratios of the dominant and nondominant legs during seated knee-extension/ flexion and supine hip-extension/flexion actions at 60°/s. Forwards from both codes were taller and heavier and had a higher body-mass index than the backs of each code. Rugby union forwards produced significantly (P rugby league forwards. Rugby league backs produced significantly greater hip-extension peak torque in the dominant and nondominant legs (ES = 0.83 and 0.77) compared with rugby union backs. There were no significant differences in hamstring-to-quadriceps ratios between code, position, or leg. Rugby union forwards and backs produced significantly greater knee-flexion-to-hip-extension ratios in the dominant and nondominant legs (ES = 1.49-2.26) than rugby union players. It seems that the joint torque profiles of players from rugby league and union codes differ, which may be attributed to the different demands of each code.

  19. Comparitive Assessment of Isokinetic and Pneumatic Lower Limb Strength in Functionally-Limited Elderly Subjects

    Science.gov (United States)

    The purpose of this study was to investigate the relationship between isokinetic and pneumatic knee extensor strength in functionally-limited elders and to compare the respective changes in knee extensor peak torque and one repetition maximum strength (1RM) after a randomized controlled progressive ...

  20. A study of isokinetic strength and laxity with and without anterior cruciate ligament injury

    Science.gov (United States)

    Kim, Kewwan; Jeon, Kyoungkyu; Mullineaux, David R.; Cho, Eunok

    2016-01-01

    [Purpose] The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non-involved and involved sides, classified on the basis of the severity of anterior cruciate ligament injury, were assessed. [Results] A comparison of isokinetic muscle strength measured from the non-involved and involved sides showed a significant difference in the maximum strength and knee flexor muscle strength. For laxity, a significant difference was observed in the anterior drawer test results obtained with a force of 88 N. [Conclusion] In conclusion, this study has shown that the assessment of isokinetic muscle strength and ligament laxity from athletes with anterior cruciate ligament injury should be utilized to provide baseline data for prevention and prediction of injury. PMID:28174432

  1. An Analysis of Isotonic and Isokinetic Strength-Training Methods and Techniques.

    Science.gov (United States)

    Metcalfe, Randall E.

    This annotated bibliography documents traditional isotonic strength training and nontraditional isotonic strength training (isokinetics) to aid the athletic coach in deciding which type and scheme of training will best develop strength. A glossary of terms is provided. Appendices include muscle action charts and tables, body position charts, a…

  2. Isokinetic Leg Flexion and Extension Strength of Elite Adolescent Female Track and Field Athletes.

    Science.gov (United States)

    Housh, Terry J.; And Others

    1984-01-01

    Adolescent female track-and-field athletes were measured to compare isokinetic strength of leg flexion and extension movements. Throwers, jumpers, middle-distance runners, and sprinters participated in the study. Throwers were found to be stronger in absolute strength, but there were no significant differences in relative strength. Results are…

  3. Use of isokinetic muscle strength as a measure of severity of rheumatoid arthritis

    DEFF Research Database (Denmark)

    Schiøttz-Christensen, Berit; Lyngberg, K; Keiding, N

    2001-01-01

    The aim of this study was to study the association between isokinetic muscle strength (IMS) and other clinical indicators of disability and disease activity in patients with rheumatoid arthritis (RA). A cohort of 36 RA patients was followed over a 1-year period with five measurements of disease a...

  4. Effects of eccentric cycle ergometry in alpine skiers.

    Science.gov (United States)

    Gross, M; Lüthy, F; Kroell, J; Müller, E; Hoppeler, H; Vogt, M

    2010-08-01

    Eccentric cycling, where the goal is to resist the pedals, which are driven by a motor, increases muscle strength and size in untrained subjects. We hypothesized that it could also be beneficial for athletes, particularly in alpine skiing, which involves predominantly eccentric contractions at longer muscle lengths. We investigated the effects of replacing part of regular weight training with eccentric cycling in junior male alpine skiers using a matched-pair design. Control subjects ( N=7) executed 1-h weight sessions 3 times per week, which included 4-5 sets of 4 leg exercises. The eccentric group ( N=8) performed only 3 sets, followed by continuous sessions on the eccentric ergometer for the remaining 20 min. After 6 weeks, lean thigh mass increased significantly only in the eccentric group. There was a groupxtime effect on squat-jump height favouring the eccentric group, which also experienced a 6.5% improvement in countermovement-jump height. The ability to finely modulate muscle force during variable eccentric cycling improved 50% (p=0.004) only in the eccentric group. Although eccentric cycling did not significantly enhance isometric leg strength, we believe it is beneficial for alpine skiers because it provides an efficient means for hypertrophy while closely mimicking the type of muscle actions encountered while skiing.

  5. Orbital evolution of eccentric planets in radiative discs

    Science.gov (United States)

    Bitsch, B.; Kley, W.

    2010-11-01

    Context. With an average eccentricity of about 0.29, the eccentricity distribution of extrasolar planets is markedly different from the solar system. Among other scenarios considered, it has been proposed that eccentricity may grow through planet-disc interaction. Recently, it has been noticed that the thermodynamical state of the disc can significantly influence the migration properties of growing protoplanets. However, the evolution of planetary eccentricity in radiative discs has not been considered yet. Aims: In this paper we study the evolution of planets on eccentric orbits that are embedded in a three-dimensional viscous disc and analyse the disc's effect on the orbital evolution of the planet. Methods: We use the three-dimensional hydrodynamical code NIRVANA that includes full tensor viscosity and implicit radiation transport in the flux-limited diffusion approximation. The code uses the FARGO-algorithm to speed up the simulations. First we measure the torque and power exerted on the planet by the disc for fixed orbits, and then we let the planet start with initial eccentricity and evolve it in the disc. Results: For locally isothermal discs we confirm previous results and find eccentricity damping and inward migration for planetary cores. For low eccentricity (e ⪉ 2 H/r) the damping is exponential, while for higher e it follows dot{e} ∝ e-2. In the case of radiative discs, the planets experience an inward migration as long as its eccentricity lies above a certain threshold. After the damping of eccentricity cores with masses below 33 MEarth begin to migrate outward in radiative discs, while higher mass cores always migrate inward. For all planetary masses studied (up to 200 MEarth) we find eccentricity damping. Conclusions: In viscous discs the orbital eccentricity of embedded planets is damped during the evolution independent of the mass. Hence, planet-disc interaction does not seem to be a viable mechanism to explain the observed high eccentricity of

  6. Relevance of ellipse eccentricity for camera calibration

    Science.gov (United States)

    Mordwinzew, W.; Tietz, B.; Boochs, F.; Paulus, D.

    2015-05-01

    Plane circular targets are widely used within calibrations of optical sensors through photogrammetric set-ups. Due to this popularity, their advantages and disadvantages are also well studied in the scientific community. One main disadvantage occurs when the projected target is not parallel to the image plane. In this geometric constellation, the target has an elliptic geometry with an offset between its geometric and its projected center. This difference is referred to as ellipse eccentricity and is a systematic error which, if not treated accordingly, has a negative impact on the overall achievable accuracy. The magnitude and direction of eccentricity errors are dependent on various factors. The most important one is the target size. The bigger an ellipse in the image is, the bigger the error will be. Although correction models dealing with eccentricity have been available for decades, it is mostly seen as a planning task in which the aim is to choose the target size small enough so that the resulting eccentricity error remains negligible. Besides the fact that advanced mathematical models are available and that the influence of this error on camera calibration results is still not completely investigated, there are various additional reasons why bigger targets can or should not be avoided. One of them is the growing image resolution as a by-product from advancements in the sensor development. Here, smaller pixels have a lower S/N ratio, necessitating more pixels to assure geometric quality. Another scenario might need bigger targets due to larger scale differences whereas distant targets should still contain enough information in the image. In general, bigger ellipses contain more contour pixels and therefore more information. This supports the target-detection algorithms to perform better even at non-optimal conditions such as data from sensors with a high noise level. In contrast to rather simple measuring situations in a stereo or multi-image mode, the impact

  7. Normative values of eccentric hip abduction strength in novice runners

    DEFF Research Database (Denmark)

    Ramskov, D; Pedersen, M B; Kastrup, K

    2014-01-01

    .354) Nm/kg. CONCLUSION: Normative values for maximal eccentric hip abduction strength in novice runners can be calculated by taking into account the differences in strength across genders and the decline in strength that occurs with increasing age. Age and gender were associated with maximal eccentric hip......PURPOSE: Low eccentric strength of the hip abductors, might increase the risk of patellofemoral pain syndrome and iliotibial band syndrome in runners. No normative values for maximal eccentric hip abduction strength have been established. Therefore the purpose of this study was to establish...... normative values of maximal eccentric hip abduction strength in novice runners. METHODS: Novice healthy runners (n = 831) were recruited through advertisements at a hospital and a university. Maximal eccentric hip abduction strength was measured with a hand-held dynamometer. The demographic variables...

  8. Changes in the number of circulating CD34+cells after eccentric exercise of the elbow flexors in relation to muscle damage

    Institute of Scientific and Technical Information of China (English)

    Ho Seong Lee; Makii Muthalib; Takayuki Akimoto; Kazunori Nosaka

    2015-01-01

    Background:It has been reported that strenuous exercise increases the number of bone marrow-derived progenitor cells such as CD34+cells in the blood, but no previous studies have investigated the changes in circulating CD34+cells following resistance exercise. This study tested the hypothesis that the number of CD34+cells in the blood would increase after eccentric exercise of the elbow flexors, but decrease in recovery, and the magnitude of the changes would be dependent on the magnitude of muscle damage. Methods:Nine men (28.0 ± 6.6 years) performed exercises consisting of 10 sets of six maximal voluntary eccentric contractions of the elbow flexors with their non-dominant arm. Six of them performed the same exercise with the same arm 4 weeks later. Changes in indirect markers of muscle damage were measured before, within 10 min after, and at 24, 48, 72, and 96 h after eccentric exercise. Differential leukocyte counts (total leukocytes, neutrophils, lymphocytes, monocytes) and CD34+cells in the blood were measured before, immediately after, and at 2, 24, 48, 72, and 96 h following the exercises. Results:After eccentric exercise, significant ( p<0.05) decreases in maximal voluntary isometric contraction torque and increases in delayed onset muscle soreness and plasma creatine kinase activity were observed. However, no significant changes in leukocytes and CD34+cells were evident. The changes in muscle damage markers were significantly ( p<0.05) smaller following the second exercise session as compared with the first exercise session, but the changes in leukocytes and CD34+cells were not significantly different between sessions. Conclusion:These results did not support the hypothesis, and showed that eccentric exercise-induced muscle damage to the elbow flexors did not influence the number of circulating CD34+cells.

  9. Fish oil supplementation reduces markers of oxidative stress but not muscle soreness after eccentric exercise.

    Science.gov (United States)

    Gray, Patrick; Chappell, Andrew; Jenkinson, Alison McE; Thies, Frank; Gray, Stuart R

    2014-04-01

    Due to the potential anti-inflammatory properties of fish-derived long chain n-3 fatty acids, it has been suggested that athletes should regularly consume fish oils-although evidence in support of this recommendation is not clear. While fish oils can positively modulate immune function, it remains possible that, due to their high number of double bonds, there may be concurrent increases in lipid peroxidation. The current study aims to investigate the effect of fish oil supplementation on exercise-induced markers of oxidative stress and muscle damage. Twenty males underwent a 6-week double-blind randomized placebo-controlled supplementation trial involving two groups (fish oil or placebo). After supplementation, participants undertook 200 repetitions of eccentric knee contractions. Blood samples were taken presupplementation, postsupplementation, immediately, 24, 48, and 72 hr postexercise and muscle soreness/maximal voluntary contraction (MVC) assessed. There were no differences in creatine kinase, protein carbonyls, endogenous DNA damage, muscle soreness or MVC between groups. Plasma thiobarbituric acid reactive substances (TBARS) were lower (p < .05) at 48 and 72 hr post exercise and H2O2 stimulated DNA damage was lower (p < .05) immediately postexercise in the fish oil, compared with the control group. The current study demonstrates that fish oil supplementation reduces selected markers of oxidative stress after a single bout of eccentric exercise.

  10. Influence of vibration on delayed onset of muscle soreness following eccentric exercise

    Science.gov (United States)

    Bakhtiary, Amir H; Safavi‐Farokhi, Ziaeddin; Aminian‐Far, Atefeh

    2007-01-01

    Delayed onset muscle soreness (DOMS), which may occur after eccentric exercise, may cause some reduction in ability in sport activities. For this reason, several studies have been designed on preventing and controlling DOMS. As vibration training (VT) may improve muscle performance, we designed this study to investigate the effect of VT on controlling and preventing DOMS after eccentric exercise. Methods Fifty healthy non‐athletic volunteers were assigned randomly into two experimental, VT (n = 25) and non‐VT (n = 25) groups. A vibrator was used to apply 50 Hz vibration on the left and right quadriceps, hamstring and calf muscles for 1 min in the VT group, while no vibration was applied in the non‐VT group. Then, both groups walked downhill on a 10° declined treadmill at a speed of 4 km/hour. The measurements included the isometric maximum voluntary contraction force (IMVC) of left and right quadriceps muscles, pressure pain threshold (PPT) 5, 10 and 15 cm above the patella and mid‐line of the calf muscles of both lower limbs before and the day after treadmill walking. After 24 hours, the serum levels of creatine‐kinase (CK), and DOMS level by visual analogue scale were measured. Results The results showed decreased IMVC force (P = 0.006), reduced PPT (P = 0.0001) and significantly increased mean of DOMS and CK levels in the non‐VT group, compared to the VT group (P = 0.001). Conclusion A comparison by experimental groups indicates that VT before eccentric exercise may prevent and control DOMS. Further studies should be undertaken to ascertain the stability and effectiveness of VT in athletics. PMID:17138635

  11. Flow Mode Magnetorheological Dampers with an Eccentric Gap

    OpenAIRE

    Choi, Young-Tai; Norman M. Wereley

    2014-01-01

    This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and dam...

  12. Isometric and isokinetic muscle strength in patients with fibrositis syndrome. New characteristics for a difficult definable category of patients

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Danneskiold-Samsøe, B

    1987-01-01

    A common complaint among patients with fibrositis syndrome is exhaustion and fatique. It was therefore felt desirable to evaluate the muscle strength of these patients compared with normal subjects. Maximum isometric and isokinetic strength of knee extension was measured in 15 patients and 15...... healthy matched subjects, using an isokinetic dynamometer (Cybex II). Maximum isometric strength at various knee extension angles (90 degrees, 60 degrees and 30 degrees degrees) was significantly (p less than 0.001) lower in the fibrositis group than in controls, a reduction of approximately 58......-66%. Maximum isokinetic strength at various knee extension velocities (30-240 degrees per second) was also significantly (p less than 0.01) lower in the fibrositis group than in controls, the reduction being approximately 41-51%. In conclusion, isometric and isokinetic muscle strength is found to be lower...

  13. Test-retest reliability of lower limb isokinetic endurance in COPD: a comparison of angular velocities

    Directory of Open Access Journals (Sweden)

    Ribeiro F

    2015-06-01

    Full Text Available Fernanda Ribeiro,* Pierre-Alexis Lépine,* Corine Garceau-Bolduc, Valérie Coats, Étienne Allard, François Maltais, Didier Saey Centre de recherche de l’Institut Universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada *These authors contributed equally to this workBackground: The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD. Methods: After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1 55%±18% predicted performed two quadriceps isokinetic endurance tests on two separate occasions within a 5–7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. Results: High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Conclusion: Despite a limited sample size, our findings su pport the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index

  14. Isokinetic performance capacity of trunk muscles. Part II: Coefficient of variation in isokinetic measurement in maximal effort and in submaximal effort.

    Science.gov (United States)

    Luoto, S; Hupli, M; Alaranta, H; Hurri, H

    1996-12-01

    It has been claimed that with the aid of isokinetic trunk strength measuring devices it is possible to distinguish true muscular weakness from submaximal effort in the test. This proposition is based on the presumption that in the isokinetic trunk strength test identical performances can only be reproduced by maximal effort. The purpose of this study was to investigate whether it is possible to distinguish maximal effort from submaximal with the aid of the coefficient of variation (CV) in an isokinetic trunk muscle strength test. The study group included 35 (21 male and 14 female) subjects of whom 12 were healthy, 10 had a mild low-back pain and 13 had a more severe chronic low-back pain. The subjects performed five consecutive bendings both with maximal (100%) and submaximal (50%) efforts at a speed of 90 degrees/second. In maximal effort only healthy subjects reached an average level of CV close to 10% both in extension and in flexion. In the chronic low-back pain group the average CV was close to 20%. The difference in CV was statistically significant (p < 0.05-0.02) between the healthy and the chronic low-back pain subjects. In the submaximal effort all health groups had a CV of approximately 20% or more and no significant differences were found. The group of slightly variable measurements (CV = 11-20%) was remarkably large in both the maximal and submaximal effort. The results suggest that an effort with a CV of 11-20% cannot be classified as definitely submaximal or maximal. When the CV is less than 10% the effort can be fairly certainly classified as maximal.

  15. 78 FR 49382 - Voluntary Education Programs

    Science.gov (United States)

    2013-08-14

    ... English, reading, writing, speaking, mathematics, and computer skills that are essential to successful job... education advisor: Education Services Specialist, Education Services Officer (ESO), Voluntary...

  16. Dynamics of Voluntary Cough Maneuvers

    Science.gov (United States)

    Naire, Shailesh

    2008-11-01

    Voluntary cough maneuvers are characterized by transient peak expiratory flows (PEF) exceeding the maximum expiratory flow-volume (MEFV) curve. In some cases, these flows can be well in excess of the MEFV, generally referred to as supramaximal flows. Understanding the flow-structure interaction involved in these maneuvers is the main goal of this work. We present a simple theoretical model for investigating the dynamics of voluntary cough and forced expiratory maneuvers. The core modeling idea is based on a 1-D model of high Reynolds number flow through flexible-walled tubes. The model incorporates key ingredients involved in these maneuvers: the expiratory effort generated by the abdominal and expiratory muscles, the glottis and the flexibility and compliance of the lung airways. Variations in these allow investigation of the expiratory flows generated by a variety of single cough maneuvers. The model successfully reproduces PEF which is shown to depend on the cough generation protocol, the glottis reopening time and the compliance of the airways. The particular highlight is in simulating supramaximal PEF for very compliant tubes. The flow-structure interaction mechanisms behind these are discussed. The wave speed theory of flow limitation is used to characterize the PEF. Existing hypotheses of the origin of PEF, from cough and forced expiration experiments, are also tested using this model.

  17. Moderate Load Eccentric Exercise; A Distinct Novel Training Modality.

    Science.gov (United States)

    Hoppeler, Hans

    2016-01-01

    Over the last 20 years a number of studies have been published using progressive eccentric exercise protocols on motorized ergometers or similar devices that allow for controlled application of eccentric loads. Exercise protocols ramp eccentric loads over an initial 3 weeks period in order to prevent muscle damage and delayed onset muscle soreness. Final training loads reach 400-500 W in rehabilitative settings and over 1200 W in elite athletes. Training is typically carried out three times per week for durations of 20-30 min. This type of training has been characterizes as moderate load eccentric exercise. It has also been denoted RENEW (Resistance Exercise via Negative Eccentric Work by LaStayo et al., 2014). It is distinct from plyometric exercises (i.e., drop jumps) that impose muscle loads of several thousand Watts on muscles and tendons. It is also distinct from eccentric overload training whereby loads in a conventional strength training setting are increased in the eccentric phase of the movement to match concentric loads. Moderate load eccentric exercise (or RENEW) has been shown to be similarly effective as conventional strength training in increasing muscle strength and muscle volume. However, as carried out at higher angular velocities of joint movement, it reduces joint loads. A hallmark of moderate load eccentric exercise is the fact that the energy requirements are typically 4-fold smaller than in concentric exercise of the same load. This makes moderate load eccentric exercise training the tool of choice in medical conditions with limitations in muscle energy supply. The use and effectiveness of moderate load eccentric exercise has been demonstrated mostly in small scale studies for cardiorespiratory conditions, sarcopenia of old age, cancer, diabetes type 2, and neurological conditions. It has also been used effectively in the prevention and rehabilitation of injuries of the locomotor system in particular the rehabilitation after anterior cruciate

  18. Short-term effects of kinesio tape on joint position sense, isokinetic measurements, and clinical parameters in patellofemoral pain syndrome

    OpenAIRE

    Kurt, Emine Eda; Büyükturan, Öznur; Erdem, Hatice Rana; Tuncay, Figen; Sezgin, Hicabi

    2016-01-01

    [Purpose] To evaluate the short-term effects of kinesio tape on joint position sense, isokinetic measurements, kinesiophobia, symptoms, and functional limitations in patients with patellofemoral pain syndrome. [Subjects and Methods] A total of 90 patients (112 knees) with patellofemoral pain syndrome were randomized into a kinesio tape group (n=45) or placebo kinesio tape group (n=45). Baseline isokinetic quadriceps muscle tests and measurements of joint position sense were performed in both ...

  19. Asymmetric transition disks: Vorticity or eccentricity?

    CERN Document Server

    Zsom, A; Ghanbari, J

    2013-01-01

    Context. Transition disks typically appear in resolved millimeter observations as giant dust rings surrounding their young host stars. More accurate observations with ALMA have shown several of these rings to be in fact asymmetric: they have lopsided shapes. It has been speculated that these rings act as dust traps, which would make them important laboratories for studying planet formation. It has been shown that an elongated giant vortex produced in a disk with a strong viscosity jump strikingly resembles the observed asymmetric rings. Aims. We aim to study a similar behavior for a disk in which a giant planet is embedded. However, a giant planet can induce two kinds of asymmetries: (1) a giant vortex, and (2) an eccentric disk. We studied under which conditions each of these can appear, and how one can observationally distinguish between them. This is important because only a vortex can trap particles both radially and azimuthally, while the eccentric ring can only trap particles in radial direction. Method...

  20. Comparative assessment of knee extensor and flexor muscle strength measured using a hand-held vs. isokinetic dynamometer.

    Science.gov (United States)

    Muff, Guillaume; Dufour, Stéphane; Meyer, Alain; Severac, François; Favret, Fabrice; Geny, Bernard; Lecocq, Jehan; Isner-Horobeti, Marie-Eve

    2016-09-01

    [Purpose] To compare measurements of knee extensor and flexor muscle strength performed using a hand-held dynamometer and an isokinetic dynamometer in apparently healthy subjects. [Subjects and Methods] Thirty adult volunteers underwent knee muscle strength evaluation using an isokinetic or a hand-held dynamometer. [Results] Strong positive correlations were found between the 2 methods, with correlation coefficients r ranging from 0.72 (95% confidence interval [CI], 0.48-0.86) to 0.87 (95% CI, 0.75-0.94), depending on the muscle group and the isokinetic evaluation mode. The reproducibility of the hand-held dynamometer findings was good, judged by a coefficient of variation of 3.2-4.2%. However, the correlation between the 2 methods for the assessment of flexor/extensor ratios ranged from -0.04 to 0.46. [Conclusion] Knee extensor and flexor muscle strength recorded with a hand-held dynamometer is reproducible and significantly correlated with the isokinetic values, indicating that this method may in some cases be a useful replacement for isokinetic strength measurement. However, for strength ratio assessment, and when judged against the isokinetic standard, a hand-held dynamometer is not a valid option.

  1. Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training.

    Science.gov (United States)

    Matta, Thiago Torres; Nascimento, Francisco Xavier; Trajano, Gabriel S; Simão, Roberto; Willardson, Jeffrey Michael; Oliveira, Liliam Fernandes

    2017-03-01

    One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  2. The Retrogressive movement of eccentric vortex in the Column Vessel

    OpenAIRE

    赤澤, 孝; Akazawa, Takashi

    2012-01-01

    Our experiment found that the center of an eccentric vortex retrogrades and move nutationally when modeled using an eccentric vortex of water in the column vessel. This paper reports that this retrogressive movement is established and caused by the propagation of only one wave. This result is in line with the findings of previous experiments.

  3. Response of electrostatic probes to eccentric charge distributions

    DEFF Research Database (Denmark)

    Johansson, Torben; McAllister, Iain Wilson

    2001-01-01

    The response of an electrostatic probe mounted in an electrode is examined with reference to eccentric charge distributions. The study involves using the probe λ function to derive a characteristic parameter. This parameter enables the response of the probe to different degrees of eccentricity...

  4. Introducing the Moon's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2014-01-01

    I present a novel way to introduce the lunar orbital eccentricity in introductory astronomy courses. The Moon is perhaps the clearest illustration of the general orbital elements such as inclination, ascending node, eccentricity, perigee, and so on. Furthermore, I like the students to discover astronomical phenomena for themselves, by means of a…

  5. Accurate and efficient waveforms for compact binaries on eccentric orbits

    CERN Document Server

    Huerta, E A; McWilliams, Sean T; O'Shaughnessy, Richard; Yunes, Nicolas

    2014-01-01

    Compact binaries that emit gravitational waves in the sensitivity band of ground-based detectors can have non-negligible eccentricities just prior to merger, depending on the formation scenario. We develop a purely analytic, frequency-domain model for gravitational waves emitted by compact binaries on orbits with small eccentricity, which reduces to the quasi-circular post-Newtonian approximant TaylorF2 at zero eccentricity and to the post-circular approximation of Yunes et al. (2009) at small eccentricity. Our model uses a spectral approximation to the (post-Newtonian) Kepler problem to model the orbital phase as a function of frequency, accounting for eccentricity effects up to ${\\cal{O}}(e^8)$ at each post-Newtonian order. Our approach accurately reproduces an alternative time-domain eccentric waveform model for eccentricities $e\\in [0, 0.4]$ and binaries with total mass less than 12 solar masses. As an application, we evaluate the signal amplitude that eccentric binaries produce in different networks of e...

  6. Isokinetic Strength Changes Following Long-Duration Spaceflight on the ISS.

    Science.gov (United States)

    English, Kirk L; Lee, Stuart M C; Loehr, James A; Ploutz-Snyder, Robert J; Ploutz-Snyder, Lori L

    2015-12-01

    Long-duration spaceflight results in a loss of muscle strength that poses both operational and medical risks, particularly during emergency egress, upon return to Earth, and during future extraterrestrial exploration. Isokinetic testing of the knee, ankle, and trunk quantifies movement-specific strength changes following spaceflight and offers insight into the effectiveness of in-flight exercise countermeasures. We retrospectively evaluated changes in isokinetic strength for 37 ISS crewmembers (Expeditions 1-25) following 163 ± 38 d (mean ± SD) of spaceflight. Gender, in-flight resistance exercise hardware, and preflight strength were examined as potential modifiers of spaceflight-induced strength changes. Mean isokinetic strength declined 8-17% following spaceflight. One month after return to Earth, strength had improved, but small deficits of 1-9% persisted. Spaceflight-induced strength losses were not different between men and women. Mean strength losses were as much as 7% less in crewmembers who flew after the Advanced Resistive Exercise Device (ARED) replaced the interim Resistive Exercise Device (iRED) as the primary in-flight resistance exercise hardware, although these differences were not statistically significant. Absolute and relative preflight strength were moderately correlated (r = -0.47 and -0.54, respectively) with postflight strength changes. In-flight resistance exercise did not prevent decreased isokinetic strength after long-duration spaceflight. However, continued utilization of ARED, a more robust resistance exercise device providing higher loads than iRED, may result in greater benefits as exercise prescriptions are optimized. With reconditioning upon return to Earth, strength is largely recovered within 30 d.

  7. Effect of isokinetic cycling versus weight training on maximal power output and endurance performance in cycling.

    Science.gov (United States)

    Koninckx, Erwin; Van Leemputte, Marc; Hespel, Peter

    2010-07-01

    The aim of this study was to compare the effects of a weight training program for the leg extensors with isokinetic cycling training (80 rpm) on maximal power output and endurance performance. Both strength training interventions were incorporated twice a week in a similar endurance training program of 12 weeks. Eighteen trained male cyclists (VO(2peak) 60 +/- 1 ml kg(-1) min(-1)) were grouped into the weight training (WT n = 9) or the isokinetic training group (IT n = 9) matched for training background and sprint power (P (max)), assessed from five maximal sprints (5 s) on an isokinetic bicycle ergometer at cadences between 40 and 120 rpm. Crank torque was measured (1 kHz) to determine the torque distribution during pedaling. Endurance performance was evaluated by measuring power, heart rate and lactate during a graded exercise test to exhaustion and a 30-min performance test. All tests were performed on subjects' individual race bicycle. Knee extension torque was evaluated isometrically at 115 degrees knee angle and dynamically at 200 degrees s(-1) using an isokinetic dynamometer. P (max) at 40 rpm increased in both the groups (~15%; P < 0.05). At 120 rpm, no improvement of P (max) was found in the IT training group, which was possibly related to an observed change in crank torque at high cadences (P < 0.05). Both groups improved their power output in the 30-min performance test (P < 0.05). Isometric knee extension torque increased only in WT (P < 0.05). In conclusion, at low cadences, P (max) improved in both training groups. However, in the IT training group, a disturbed pedaling technique compromises an improvement of P (max) at high cadences.

  8. THE INFLUENCE OF BODY POSITION ON LOAD RANGE DURING ISOKINETIC KNEE EXTENSION/FLEXION

    Directory of Open Access Journals (Sweden)

    Brian W. Findley

    2006-09-01

    Full Text Available Isokinetic range of motion (ROM has three distinct phases: rate of velocity development (RVD, load range (LR, and deceleration (DCC. The purpose of this study was to determine if differences in isokinetic knee extension/flexion LR exist between body positions. Ten subjects (4 males and 6 females, age 29.3 ± 5.4 yrs, ht 1.71 ± 0.10 m, wt 71.9 ± 12.9 kg volunteered to participate in the seated vs. prone investigation and nine different subjects (4 males and 5 females, age 29.5 ± 6.9 yrs, ht 1.72 ± 0.09 m, wt 69.0 ± 13.8 kg volunteered to participate in the seated vs. supine study. Each subject completed 3 maximal reciprocal concentric/concentric repetitions of dominant knee extension/flexion on a Biodex System 2 isokinetic dynamometer at 60, 120, 180, 240 and 360 deg·sec-1 in the supine or prone and seated positions. Repeated measures ANOVA revealed that only seated flexion at 360 deg·sec-1 (57.6 ± 1.7 degrees elicited significantly (p < 0.05 greater LR than prone (49.2 ± 2.8 degrees. No significant differences in LR extension or flexion existed at any velocity between the supine vs. seated positions. ANOVA also demonstrated differences between seated vs. prone torque, work and power at most velocities while there was no difference between seated vs. supine. LR is the only phase of an isokinetic repetition where quantifiable resistance is maintained and this data appears to support that it may not be position-dependent but position may alter traditional performance variables

  9. Eccentric exercise decreases maximal insulin action in humans

    DEFF Research Database (Denmark)

    Asp, Svend; Daugaard, J R; Kristiansen, S

    1996-01-01

    1. Unaccustomed eccentric exercise decreases whole-body insulin action in humans. To study the effects of one-legged eccentric exercise on insulin action in muscle and systemically, the euglycaemic clamp technique combined with arterial and bilateral femoral venous catheterization was used. Seven...... subjects participated in two euglycaemic clamps, performed in random order. One clamp was preceded 2 days earlier by one-legged eccentric exercise (post-eccentric exercise clamp (PEC)) and one was without the prior exercise (control clamp (CC)). 2. During PEC the maximal insulin-stimulated glucose uptake......) necessary to maintain euglycaemia during maximal insulin stimulation was lower during PEC compared with CC (15.7%, 81.3 +/- 3.2 vs. 96.4 +/- 8.8 mumol kg-1 min-1, P eccentric exercise, muscle and whole-body insulin action is impaired at maximal...

  10. Normative values of eccentric hip abduction strength in novice runners

    DEFF Research Database (Denmark)

    Jørgensen, Daniel Ramskov; Pedersen, Mette Broen; Kastrup, Kristrian

    2014-01-01

    normative values of maximal eccentric hip abduction strength in novice runners. METHODS: Novice healthy runners (n = 831) were recruited through advertisements at a hospital and a university. Maximal eccentric hip abduction strength was measured with a hand-held dynamometer. The demographic variables......PURPOSE: Low eccentric strength of the hip abductors, might increase the risk of patellofemoral pain syndrome and iliotibial band syndrome in runners. No normative values for maximal eccentric hip abduction strength have been established. Therefore the purpose of this study was to establish...... associated with maximal eccentric hip abduction strength from a univariate analysis were included in a multivariate linear regression model. Based on the results from the regression model, a regression equation for normative hip abduction strength is presented. RESULTS: A SIGNIFICANT DIFFERENCE IN MAXIMAL...

  11. Local and global dynamics of eccentric astrophysical discs

    CERN Document Server

    Ogilvie, Gordon I

    2014-01-01

    We formulate a local dynamical model of an eccentric disc in which the dominant motion consists of elliptical Keplerian orbits. The model is a generalization of the well known shearing sheet, and is suitable for both analytical and computational studies of the local dynamics of eccentric discs. It is spatially homogeneous in the horizontal dimensions but has a time-dependent geometry that oscillates at the orbital frequency. We show how certain averages of the stress tensor in the local model determine the large-scale evolution of the shape and mass distribution of the disc. The simplest solutions of the local model are laminar flows consisting of a (generally nonlinear) vertical oscillation of the disc. Eccentric discs lack vertical hydrostatic equilibrium because of the variation of the vertical gravitational acceleration around the eccentric orbit, and in some cases because of the divergence of the orbital velocity field associated with an eccentricity gradient. We discuss the properties of the laminar sol...

  12. Eccentric double white dwarfs as LISA sources in globular clusters

    CERN Document Server

    Willems, B; Vecchio, A; Ivanova, N; Rasio, F A; Fregeau, J M; Belczynski, K

    2007-01-01

    We consider the formation of double white dwarfs (DWDs) through dynamical interactions in globular clusters. Such interactions can readily give rise to eccentric DWDs, in contrast to the exclusively circular population that is expected to form in the Galactic disk. We show that for a 5-year Laser Interferometer Space Antenna (LISA) mission and distances as far as the Large Magellanic Cloud, multiple harmonics from eccentric DWDs can be detected at a signal-to-noise ratio higher than 8 for at least a handful of eccentric DWDs, given their formation rate and typical merger lifetimes estimated from current cluster simulations. Consequently the association of eccentricity with stellar-mass LISA sources does not uniquely involve neutron stars, as is usually assumed. Due to the difficulty of detecting these systems with present and planned electromagnetic observatories, LISA could provide unique dynamical identifications of eccentric DWDs in globular clusters.

  13. Preconditioning by light-load eccentric exercise is equally effective as low-level laser therapy in attenuating exercise-induced muscle damage in collegiate men

    Directory of Open Access Journals (Sweden)

    Nausheen S

    2017-09-01

    Full Text Available Samar Nausheen,1 Jamal Ali Moiz,1 Shahid Raza,1 Mohammad Yakub Shareef,2 Shahnawaz Anwer,3,4 Ahmad H Alghadir3 1Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, New Delhi, India; 2Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India; 3Rehabilitation Research Chair, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; 4Dr. D. Y. Patil College of Physiotherapy, Dr. D. Y. Patil Vidyapeeth, Pune, India Background/objective: Previous studies have already reported an independent effect of light-load eccentric exercise (10% eccentric exercise contraction [EEC] and low-level laser therapy (LLLT as a protective measure against more strenuous eccentric exercise. However, the difference between these two interventions is largely unknown. Therefore, the present study aimed to compare the preconditioning effect of 10% EEC vs. LLLT on subjective, physiological, and biochemical markers of muscle damage in elbow flexors in collegiate men.Methods: All 36 enrolled subjects were randomly assigned to either 10% EEC or LLLT group. Subjects in 10% EEC group performed 30 repetitions of an eccentric exercise with 10% maximal voluntary contraction strength 2 days prior to maximal eccentric exercise bout, whereas subjects in LLLT group were given LLLT. All the indirect markers of muscle damage were measured pre-exercise and at 24, 48, and 72 hours after the exercise-induced muscle damage protocol.Results: The muscle soreness was reduced in both groups (p = 0.024; however, soreness was attenuated more in LLLT group at 48 hours (33.5 vs. 42.7, p = 0.004. There was no significant difference between the effect of 10% EEC and LLLT groups on other markers of muscle damage like a maximum voluntary isometric contraction (p = 0.47, range of motion (p = 0.16, upper arm circumference (p = 0.70, creatine kinase (p = 0.42, and lactate dehydrogenase (p = 0.08. Within-group analysis showed both interventions provided

  14. 75 FR 47504 - Voluntary Education Programs

    Science.gov (United States)

    2010-08-06

    ... America. TTT helps relieve teacher shortages, especially in math, science, special education, and other... of the Secretary 32 CFR Part 68 RIN 0790-AI50 Voluntary Education Programs AGENCY: Office of the... for the operation of voluntary education programs within DoD. Included are: Procedures for Service...

  15. Pedagogical Aspects of Voluntary School Work

    Science.gov (United States)

    Mária Jármai, Erzsébet; Palányi, Ildikó Zsupanekné

    2015-01-01

    The economic importance of voluntary work has been exceedingly appreciated in the last few decades. This is not surprising at all, because it is highly profitable according to the related estimated data. There are 115,9 million people doing voluntary work only in Europe, which means that they would create the world's 7th biggest economy with EUR…

  16. 14 CFR 234.7 - Voluntary reporting.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Voluntary reporting. 234.7 Section 234.7 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS AIRLINE SERVICE QUALITY PERFORMANCE REPORTS § 234.7 Voluntary reporting. (a) In addition to the...

  17. Changing Dynamics in the Voluntary Market (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Heeter, J.

    2014-12-01

    Voluntary green power markets are those in which consumers and institutions voluntarily purchase renewable energy to match their electricity needs. This presentation, presented at the Renewable Energy Markets Conference in December 2014, outlines the voluntary market in 2013, including community choice aggregation and community solar.

  18. 12 CFR 546.4 - Voluntary dissolution.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Voluntary dissolution. 546.4 Section 546.4... ASSOCIATIONS-MERGER, DISSOLUTION, REORGANIZATION, AND CONVERSION § 546.4 Voluntary dissolution. A Federal savings association's board of directors may propose a plan for dissolution of the association. The plan...

  19. Effect of isokinetic training on muscle strength and postural balance in children with Down's syndrome.

    Science.gov (United States)

    Eid, Mohamed A; Aly, Sobhy M; Huneif, Mohamed A; Ismail, Dina K

    2017-06-01

    Children with Down's syndrome (DS) often have greater postural sway and delay in motor development. Muscle weakness and hypotonia, particularly of the lower extremities, are theorized to impair their overall physical health and ability to perform daily activities. Therefore, the aim of this study was to investigate the effects of isokinetic training on muscle strength and postural balance in children with DS. Thirty-one children with DS ranging in age from 9 to 12 years were assigned randomly into two groups. The control group received the conventional physical therapy, whereas the study group received the same therapy as the control group in addition to the isokinetic training 3 days a week for 12 weeks. Measurement of stability indices using the Biodex Stability System as well as peak torque of knee flexors and extensors of both sides using the isokinetic dynamometer was performed before and after 12 weeks of the treatment program. Each group showed significant improvements in postural balance and peak torque of knee flexors and extensors (Ptraining program induced greater improvements in muscle strength and postural balance in children with DS.

  20. Reliability of isokinetic normalized peak torque assessments for knee muscles in post-stroke hemiparesis.

    Science.gov (United States)

    Noorizadeh Dehkordi, Shohreh; Talebian, Saeed; Olyaei, Gholamreza; Montazeri, Ali

    2008-05-01

    The purpose of this study was to establish test-retest reliability of measurement procedures for quantifying isokinetic concentric peak torque (PT) at the knee using normalization methods post-stroke. A second aim was to estimate the change required to show clinically significant improvements in knee muscles strength. The isokinetic normalized PT (NPT) values for the knee extensors and flexors were measured in each participant at two different angular velocities during two sessions 1 day apart. Thirty participants with mild to moderate hemiparesis after stroke who were able to walk were tested. The normalized PT measures for the knee muscles of the affected lower extremity were highly reliable (intraclass correlation coefficients ranged from 0.85 to 0.98; pknee flexors had more random variation than the knee extensors. This study supports the use of isokinetic dynamometers for the assessment of knee muscle strength in participants with chronic mild to moderate post-stroke hemiparesis and to measure clinical improvements. Established measurement error and smallest real differences in normalized PT will aid interpretation of real changes in muscle strength in this clinical population.

  1. Effect of unilateral exercise on spinal and pelvic deformities, and isokinetic trunk muscle strength.

    Science.gov (United States)

    Jeon, Kyoungkyu; Kim, Soonyoung

    2016-03-01

    [Purpose] The purpose of this study was to collect basic data regarding the prevention of spinal and pelvic deformities by investigating the spinal shape and muscular function characteristics of imbalance reduction and functional improvement following asymmetric activities. [Subjects and Methods] The subjects were 14 archery athletes who mostly perform unilateral motion with spinal and pelvic pain, and 19 healthy subjects. All the participants were evaluated using spinal structure analysis and for 60°/sec isokinetic muscular strength of the trunk. [Results] Between the two groups, there were significant differences in the interaction effect of trunk inclination deformities, and flexor and extensor 60°/sec isokinetic muscular strength of the trunk. Also, the main effects of gender comparison showed significant differences in the trunk inclination deformities, pelvic rotation deformities, lordosis angles, and flexor and extensor 60 ˚/sec isokinetic muscular strengths of the trunk. [Conclusion] The basic data obtained in this study can be used to help develop a strategic exercise program for improving unilateral movement and malalignment of the spine and pelvis.

  2. Comparison of knee laxity and isokinetic muscle strength in patients with a posterior cruciate ligament injury.

    Science.gov (United States)

    Jeon, Kyoungkyu

    2016-03-01

    [Purpose] The aim of this study was to compare knee laxity and isokinetic muscle strength in patients with an isolated posterior cruciate ligament injury. [Subjects and Methods] Twenty high school rugby players with a previous posterior cruciate ligament injury and abnormal findings higher than surgical grade I were included. Laxity with 132 N of pressure was measured using Kneelax 3 to assess the stability of the posterior cruciate ligament, and flexor and extensor torques were measured at 60°/sec, 180°/sec, and 240°/sec to measure the isokinetic muscle strength of the knee joint. The average and standard deviation values were extracted from all data to assess the measured data. [Results] Regarding the ipsilateral and contralateral laxity, the deviation value at the peak force and maximum manual drawer was statistically significant. The peak torque and peak torque per body weight in isokinetic measurements were significantly different only for knee extensor torque at 60°/sec, 180°/sec, and 240°/sec. [Conclusion] Return to normal activities post injury is important. Thus base data gathered by comparing patients' ipsilateral and contralateral sides will serve as essential criteria for structuring future rehabilitation programs to facilitate functional improvements.

  3. Comparison of knee laxity and isokinetic muscle strength in patients with a posterior cruciate ligament injury

    Science.gov (United States)

    Jeon, Kyoungkyu

    2016-01-01

    [Purpose] The aim of this study was to compare knee laxity and isokinetic muscle strength in patients with an isolated posterior cruciate ligament injury. [Subjects and Methods] Twenty high school rugby players with a previous posterior cruciate ligament injury and abnormal findings higher than surgical grade I were included. Laxity with 132 N of pressure was measured using Kneelax 3 to assess the stability of the posterior cruciate ligament, and flexor and extensor torques were measured at 60°/sec, 180°/sec, and 240°/sec to measure the isokinetic muscle strength of the knee joint. The average and standard deviation values were extracted from all data to assess the measured data. [Results] Regarding the ipsilateral and contralateral laxity, the deviation value at the peak force and maximum manual drawer was statistically significant. The peak torque and peak torque per body weight in isokinetic measurements were significantly different only for knee extensor torque at 60°/sec, 180°/sec, and 240°/sec. [Conclusion] Return to normal activities post injury is important. Thus base data gathered by comparing patients’ ipsilateral and contralateral sides will serve as essential criteria for structuring future rehabilitation programs to facilitate functional improvements. PMID:27134367

  4. Low level laser therapy before eccentric exercise reduces muscle damage markers in humans.

    Science.gov (United States)

    Baroni, Bruno Manfredini; Leal Junior, Ernesto Cesar Pinto; De Marchi, Thiago; Lopes, André Luiz; Salvador, Mirian; Vaz, Marco Aurélio

    2010-11-01

    The purpose of the present study was to determine the effect of low level laser therapy (LLLT) treatment before knee extensor eccentric exercise on indirect markers of muscle damage. Thirty-six healthy men were randomized in LLLT group (n = 18) and placebo group (n = 18). After LLLT or placebo treatment, subjects performed 75 maximal knee extensors eccentric contractions (five sets of 15 repetitions; velocity = 60° seg(-1); range of motion = 60°). Muscle soreness (visual analogue scale--VAS), lactate dehydrogenase (LDH) and creatine kinase (CK) levels were measured prior to exercise, and 24 and 48 h after exercise. Muscle function (maximal voluntary contraction--MVC) was measured before exercise, immediately after, and 24 and 48 h post-exercise. Groups had no difference on kineanthropometric characteristics and on eccentric exercise performance. They also presented similar baseline values of VAS (0.00 mm for LLLT and placebo groups), LDH (LLLT = 186 IU/l; placebo = 183 IU/l), CK (LLLT = 145 IU/l; placebo = 155 IU/l) and MVC (LLLT = 293 Nm; placebo = 284 Nm). VAS data did not show group by time interaction (P = 0.066). In the other outcomes, LLLT group presented (1) smaller increase on LDH values 48 h post-exercise (LLLT = 366 IU/l; placebo = 484 IU/l; P = 0.017); (2) smaller increase on CK values 24 h (LLLT = 272 IU/l; placebo = 498 IU/l; P = 0.020) and 48 h (LLLT = 436 IU/l; placebo = 1328 IU/l; P exercise; (3) smaller decrease on MVC immediately after exercise (LLLT = 189 Nm; placebo = 154 Nm; P = 0.011), and 24 h (LLLT = 249 Nm; placebo = 205 Nm; P = 0.004) and 48 h (LLLT = 267 Nm; placebo = 216 Nm; P = 0.001) post-exercise compared with the placebo group. In conclusion, LLLT treatment before eccentric exercise was effective in terms of attenuating the increase of muscle proteins in the blood serum and the decrease in muscle force.

  5. Effects of specific resistance training program on force-velocity relationship, power consumption and work production of quadrics muscle during eccentric actions in elite athletes

    Directory of Open Access Journals (Sweden)

    KONSTANTINOS FLESSAS, MARIA KOUMPOULA, DESPINA TSOPANI, CHRALAMBOS OIKONOMOU

    2008-01-01

    Full Text Available Aim: Resistance training is the most famous method for the prevention, rehabilitation of myotendinous injuries and especially for the development of muscle’s ability in competitive and recreational sports. The purpose of the present study was to examine the average exerted force ( , the mean power consumption (Pmean and the work production on Quadriceps Femoris Muscle of elite athletes, in accordance with joint’s knee movement velocity, during eccentric contractions, before and after the application of a specific resistance training program. Methods: 14 elite athletes participated in this study. Seven of them (training group performed isometric and eccentric contractions on isokinetic dynamometer before and after the application of specific resistance training program. The other seven athletes (control group followed the training program of their team and they have participated only to the procedure of measurements. Results: The results showed, that after the application of the specific training program, the subjects improved significantly (P<.05 , Pmean (P<.05 at high angular velocities of joint’s knee movement and maximal isometric exerted force ( , P<.05. Conlusion: This study suggests that the application of the specific training program creates adaptations to the subject muscles’ which concerns the power consumption ability and the maximal effort activation.

  6. Cross-education strength and activation after eccentric exercise.

    Science.gov (United States)

    Lepley, Lindsey K; Palmieri-Smith, Riann M

    2014-01-01

    After injury, eccentric exercise of the injured limb is often contraindicated. Cross-education training, whereby the uninvolved limb is exercised, is an alternative that may improve quadriceps muscle strength and activation in the unexercised limb. To determine the effect of eccentric exercise on quadriceps strength and activation gains in the unexercised limb. Eighteen healthy individuals were randomly assigned to an eccentric training group or a control group. Quadriceps strength and activation measures were collected at preintervention, midintervention, and postintervention. Eccentric training participants exercised their dominant limb with a dynamometer in eccentric mode at 60°/s, 3 times per week for 8 weeks. Quadriceps strength was quantified at 30° and 60°/s in concentric and eccentric modes. Quadriceps activation was assessed using the burst superimposition technique and quantified via the central activation ratio. A 2 × 3 repeated-measures analysis of variance was used to detect the effects of group and testing session on quadriceps strength and activation. Where appropriate, post hoc Bonferroni multiple-comparisons procedures were used. We found greater eccentric strength in the unexercised limbs of eccentric training participants between preintervention and midintervention and between preintervention and postintervention (preintervention to midintervention: 30°/s P = .05; preintervention to postintervention: 30°/s P = .02, 60°/s P = .02). No differences were noted in concentric strength (P > .05). An overall trend toward greater quadriceps activation in the unexercised knee was detected between preintervention and postintervention (P = .063), with the eccentric training group demonstrating a strong effect (Cohen d = 0.83). Control strength did not change (P > .05). Exercising with eccentric actions resulted in mode-specific and velocity-specific gains in quadriceps strength in the unexercised limb. A trend toward greater quadriceps activation in

  7. Between voluntary agreement and legislation

    DEFF Research Database (Denmark)

    Gwozdz, Wencke; Hedegaard, Liselotte; Reisch, Lucia

    2009-01-01

    Voluntary agreements and self-imposed standards are broadly applied to restrict the influence food advertising exerts on children’s food choices – yet their effects are unknown. The current project will therefore investigate whether and, if yes, how the Danish Code for Responsible Food Marketing...... Communication towards Children (hereafter: CODE) – with its dependence on a supportive institutional environment and acceptance of as well as dynamics between involved key stakeholders like consumers, political actors and firms – contributes to fighting the obesity pandemic.Thus, we explore within this article...... what information about the process of implementing the CODE as well as about the evolved dynamics between key stakeholders is already available. Here, the recently published report of the PolMark project sheds light on the dynamics between the key stakeholders in relation to the current Danish...

  8. Eccentric muscle damage has variable effects on motor unit recruitment thresholds and discharge patterns in elbow flexor muscles.

    Science.gov (United States)

    Dartnall, Tamara J; Rogasch, Nigel C; Nordstrom, Michael A; Semmler, John G

    2009-07-01

    The purpose of this study was to determine the effect of eccentric muscle damage on recruitment threshold force and repetitive discharge properties of low-threshold motor units. Ten subjects performed four tasks involving isometric contraction of elbow flexors while electromyographic (EMG) data were recorded from human biceps brachii and brachialis muscles. Tasks were 1) maximum voluntary contraction (MVC); 2) constant-force contraction at various submaximal targets; 3) motor unit recruitment threshold task; and 4) minimum motor unit discharge rate task. These tasks were performed on three separate days before, immediately after, and 24 h after eccentric exercise of elbow flexor muscles. MVC force declined (42%) immediately after exercise and remained depressed (29%) 24 h later, indicative of muscle damage. Mean motor unit recruitment threshold for biceps brachii was 8.4+/-4.2% MVC, (n=34) before eccentric exercise, and was reduced by 41% (5.0+/-3.0% MVC, n=34) immediately after and by 39% (5.2+/-2.5% MVC, n=34) 24 h after exercise. No significant changes in motor unit recruitment threshold were observed in the brachialis muscle. However, for the minimum tonic discharge rate task, motor units in both muscles discharged 11% faster (10.8+/-2.0 vs. 9.7+/-1.7 Hz) immediately after (n=29) exercise compared with that before (n=32). The minimum discharge rate variability was greater in brachialis muscle immediately after exercise (13.8+/-3.1%) compared with that before (11.9+/-3.1%) and 24 h after exercise (11.7+/-2.4%). No significant changes in minimum discharge rate variability were observed in the biceps brachii motor units after exercise. These results indicate that muscle damage from eccentric exercise alters motor unit recruitment thresholds for >or=24 h, but the effect is not the same in the different elbow flexor muscles.

  9. No Differences Between Alter G-Trainer And Active And Passive Recovery Strategies On Isokinetic Strength, Systemic Oxidative Stress And Perceived Muscle Soreness After Exercise-Induced Muscle Damage.

    Science.gov (United States)

    Cooke, Matthew B; Nix, Carrie; Greenwood, Lori; Greenwood, Mike

    2016-11-28

    The incidence of muscle injuries is prevalent in elite sport athletes as well as weekend warriors and strategies that safely and effectively hasten recovery are highly desirable. The purpose of this study was to examine the differences between three recovery methods after eliciting muscle damage in recreationally active men relative to maximal isokinetic contractions, perceived muscle soreness and psychological mood states. Twenty-five recreationally active men (22.15±3.53yrs, 75.75±11.91kg, 180.52±7.3cm) were randomly matched by VO2 peak (53.86±6.65ml·kg·min) and assigned to one of three recovery methods: Anti-gravity Treadmill (G-Trainer) (N = 8), Conventional Treadmill (N = 8) or Static Stretching (N = 9). Recovery methods were performed 30 minutes, 24, 48 and 72 hours following a 45 minute downhill run. Following eccentrically-biased running, no significant differences were noted in isokinetic knee flexion and extension peak torque, systemic markers of muscle damage, oxidative stress and lipid peroxidation such as serum creatine kinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA), respectively, and subjective ratings of perceived muscle soreness between recovery methods. The G-Trainer group did however display a higher mood state as indicated by the Profile of Mood State global scores at 24 hours post-exercise when compared to the conventional treadmill recovery group (p=0.035). The improved mood state following the use of the anti-gravity treadmill may provide clinical relevance to other populations.

  10. Red-giant stars in eccentric binaries

    Directory of Open Access Journals (Sweden)

    Beck P. G.

    2015-01-01

    Full Text Available The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs.

  11. FUZZY ECCENTRICITY AND GROSS ERROR IDENTIFICATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The dominant and recessive effect made by exceptional interferer is analyzed in measurement system based on responsive character, and the gross error model of fuzzy clustering based on fuzzy relation and fuzzy equipollence relation is built. The concept and calculate formula of fuzzy eccentricity are defined to deduce the evaluation rule and function of gross error, on the base of them, a fuzzy clustering method of separating and discriminating the gross error is found. Utilized in the dynamic circular division measurement system, the method can identify and eliminate gross error in measured data, and reduce measured data dispersity. Experimental results indicate that the use of the method and model enables repetitive precision of the system to improve 80% higher than the foregoing system, to reach 3.5 s, and angle measurement error is less than 7 s.

  12. Highly eccentric inspirals into a black hole

    Science.gov (United States)

    Osburn, Thomas; Warburton, Niels; Evans, Charles R.

    2016-03-01

    We model the inspiral of a compact stellar-mass object into a massive nonrotating black hole including all dissipative and conservative first-order-in-the-mass-ratio effects on the orbital motion. The techniques we develop allow inspirals with initial eccentricities as high as e ˜0.8 and initial separations as large as p ˜50 to be evolved through many thousands of orbits up to the onset of the plunge into the black hole. The inspiral is computed using an osculating elements scheme driven by a hybridized self-force model, which combines Lorenz-gauge self-force results with highly accurate flux data from a Regge-Wheeler-Zerilli code. The high accuracy of our hybrid self-force model allows the orbital phase of the inspirals to be tracked to within ˜0.1 radians or better. The difference between self-force models and inspirals computed in the radiative approximation is quantified.

  13. THE INFLUENCE OF VELOCITY OVERSHOOT MOVEMENT ARTIFACT ON ISOKINETIC KNEE EXTENSION TESTS

    Directory of Open Access Journals (Sweden)

    Fabiano Peruzzo Schwartz

    2010-03-01

    Full Text Available Exercise on an isokinetic device involves three distinct movement phases: acceleration, constant velocity, and deceleration. Inherent in these phases are unique occurrences that may confound test data and, thereby, test interpretation. Standard methods of data reduction like windowing and other techniques consist of removing the acceleration and deceleration phases in order to assure analysis under constant velocity conditions. However, none of these techniques adequately quantify the velocity overshoot (VO movement artifact which is a result of the devices resistance imposed to the limb. This study tested the influence of VO on isokinetic data interpretation. A computational algorithm was developed to accurately identify each movement phase and to delineate the VO segment. Therefore, the VO was then treated as a fourth and independent phase. A total of sixteen healthy men (26.8 ± 4.7 yrs, 1.76 ± 0.05 m, and 79.2 ± 9.4 kg performed two sets of ten maximal concentric extension repetitions of their dominant knee (at 60º·s-1 and 180º·s-1, on separate days and in a counterbalanced order, on a Biodex System 3 Pro dynamometer. All the phases of the isokinetic exercise were measured in terms of their biomechanical descriptors and according to the developed algorithm, the windowing method, and a data reduction technique that eliminates the first and last 10º of the total range of motion. Results showed significant differences (p < 0.05 between the constant velocity phases found by each method: the largest segment was obtained with the windowing method; the second one, with the algorithm; and the smallest, with data reduction technique. The point of peak torque was not affected by none of the techniques, but significant differences (p < 0.05 were found between the data including and not including the VO phase, concerning total work, time interval, and average length of load range: VO represents more than 10% of the amount calculated in constant

  14. Eccentric Exercise Versus Eccentric Exercise and Soft Tissue Treatment (Astym) in the Management of Insertional Achilles Tendinopathy.

    Science.gov (United States)

    McCormack, Joshua R; Underwood, Frank B; Slaven, Emily J; Cappaert, Thomas A

    Eccentric exercise is commonly used in the management of Achilles tendinopathy (AT) but its effectiveness for insertional AT has been questioned. Soft tissue treatment (Astym) combined with eccentric exercise could result in better outcomes than eccentric exercise alone. Soft tissue treatment (Astym) plus eccentric exercise will be more effective than eccentric exercise alone for subjects with insertional AT. Prospective randomized controlled trial. Level 2. Sixteen subjects were randomly assigned to either a soft tissue treatment (Astym) and eccentric exercise group or an eccentric exercise-only group. Intervention was completed over a 12-week period, with outcomes assessed at baseline, 4, 8, 12, 26, and 52 weeks. Outcomes included the Victorian Institute of Sport Assessment Achilles-Specific Questionnaire (VISA-A), the numeric pain rating scale (NPRS), and the global rating of change (GROC). Significantly greater improvements on the VISA-A were noted in the soft tissue treatment (Astym) group over the 12-week intervention period, and these differences were maintained at the 26- and 52-week follow-ups. Both groups experienced a similar statistically significant improvement in pain over the short and long term. A significantly greater number of subjects in the soft tissue treatment (Astym) group achieved a successful outcome at 12 weeks. Soft tissue treatment (Astym) plus eccentric exercise was more effective than eccentric exercise only at improving function during both short- and long-term follow-up periods. Soft tissue treatment (Astym) plus eccentric exercise appears to be a beneficial treatment program that clinicians should consider incorporating into the management of their patients with insertional AT.

  15. Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two dimensions: validation of secular theory

    CERN Document Server

    Barker, Adrian J

    2016-01-01

    We perform global two-dimensional hydrodynamical simulations of Keplerian discs with free eccentricity over thousands of orbital periods. Our aim is to determine the validity of secular theory in describing the evolution of eccentric discs, and to explore their nonlinear evolution for moderate eccentricities. Linear secular theory is found to correctly predict the structure and precession rates of discs with small eccentricities. However, discs with larger eccentricities (and eccentricity gradients) are observed to precess faster (retrograde relative to the orbital motion), at a rate that depends on their eccentricities (and eccentricity gradients). We derive analytically a nonlinear secular theory for eccentric gas discs, which explains this result as a modification of the pressure forces whenever eccentric orbits in a disc nearly intersect. This effect could be particularly important for highly eccentric discs produced in tidal disruption events, or for narrow gaseous rings; it might also play a role in cau...

  16. Thermal hydraulics of rod bundles: The effect of eccentricity

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Amit K., E-mail: amit_fmlab@yahoo.co.in [Fluid Mechanics Laboratory, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036 (India); Prasad, B.V.S.S.S., E-mail: prasad@iitm.ac.in [Thermal Turbomachines Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Patnaik, B.S.V., E-mail: bsvp@iitm.ac.in [Fluid Mechanics Laboratory, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2013-10-15

    Highlights: • Present CFD investigation explores, whole bundle eccentricity for the first time. • Fluid flow and thermal characteristics in various subchannels are analyzed. • Mass flux distribution is particularly analyzed to study eccentricity effect. • Higher eccentricity resulted in a shoot up in rod surface temperature distribution. • Both tangential and radial flow in rod bundles has resulted due to eccentricity. -- Abstract: The effect of eccentricity on the fluid flow and heat transfer through a 19-rod bundle is numerically carried out. When the whole bundle shifts downwards with respect to the outer (pressure) tube, flow redistribution happens. This in turn is responsible for changes in mass flux, pressure and differential flow development in various subchannels. The heat flux imposed on the surface of the fuel rods and the mass flux through the subchannels determines the coolant outlet temperatures. The simulations are performed for a coolant flow Reynolds number of 4 × 10{sup 5}. For an eccentricity value of 0.7, the mass flux in the bottom most subchannel (l) was found to decrease by 10%, while the surface temperature of the fuel rod in the vicinity of this subchannel increased by 250% at the outlet section. Parameters of engineering interest including skin friction coefficient, Nusselt number, etc., have been systematically explored to study the effect of eccentricity on the rod bundle.

  17. Eccentricity effect of micropatterned surface on contact angle.

    Science.gov (United States)

    Kashaninejad, Navid; Chan, Weng Kong; Nguyen, Nam-Trung

    2012-03-13

    This article experimentally shows that the wetting property of a micropatterned surface is a function of the center-to-center offset distance between successive pillars in a column, referred to here as eccentricity. Studies were conducted on square micropatterns which were fabricated on a silicon wafer with pillar eccentricity ranging from 0 to 6 μm for two different pillar diameters and spacing. Measurement results of the static as well as the dynamic contact angles on these surfaces revealed that the contact angle decreases with increasing eccentricity and increasing relative spacing between the pillars. Furthermore, quantification of the contact angle hysteresis (CAH) shows that, for the case of lower pillar spacing, CAH could increase up to 41%, whereas for the case of higher pillar spacing, this increment was up to 35%, both corresponding to the maximum eccentricity of 6 μm. In general, the maximum obtainable hydrophobicity corresponds to micropillars with zero eccentricity. As the pillar relative spacing decreases, the effect of eccentricity on hydrophobicity becomes more pronounced. The dependence of the wettability conditions of the micropatterned surface on the pillar eccentricity is attributed to the contact line deformation resulting from the changed orientation of the pillars. This finding provides additional insights in design and fabrication of efficient micropatterned surfaces with controlled wetting properties.

  18. Voluntary muscle activation improves with power training and is associated with changes in gait speed in mobility-limited older adults - A randomized controlled trial.

    Science.gov (United States)

    Hvid, Lars G; Strotmeyer, Elsa S; Skjødt, Mathias; Magnussen, Line V; Andersen, Marianne; Caserotti, Paolo

    2016-07-01

    Incomplete voluntary muscle activation may contribute to impaired muscle mechanical function and physical function in older adults. Exercise interventions have been shown to increase voluntary muscle activation, although the evidence is sparse for mobility-limited older adults, particularly in association with physical function. This study examined the effects of 12weeks of power training on outcomes of voluntary muscle activation and gait speed in mobility-limited older adults from the Healthy Ageing Network of Competence (HANC) study. We included 37 older men and women with a usual gait speed of analysis: n=16 in the training group (TG: 12weeks of progressive high-load power training, 2 sessions per week; age: 82.3±1.3years, 56% women) and n=21 in the control group (CG: no interventions; age: 81.6±1.1years, 67% women). Knee extensor muscle thickness (ultrasonography), strength (isokinetic dynamometry), voluntary activation (interpolated twitch technique), and gait speed (2-min maximal walking test) were assessed at baseline and post-intervention. At baseline, TG and CG were comparable for all measures. Post-intervention, significant between-group changes (TG vs. CG; pgait speed (+0.12m/s), whereas the between-group change in muscle thickness was non-significant (+0.08cm). Improvements in voluntary muscle activation were associated with improvements in gait speed in TG (r=0.67, ppower training, and is associated with improved maximal gait speed. Incomplete voluntary muscle activation should be considered one of the key mechanisms influencing muscle mechanical function and gait speed in older adults.

  19. AN ECONOMETRIC APPROACH ABOUT VOLUNTARY TURNOVER

    Directory of Open Access Journals (Sweden)

    ADALET EREN

    2013-06-01

    Full Text Available This study analyzes individual and organizational variables that affect voluntary turnover are determined in the special defence and security companies. A binomial logistic regression model is used to estimate voluntary turnover.  Binomial Logistic regression, reliability test (scale alfa, variance (ANOVA, Post-hoc/Tukey, correlation (Pearson and other basic statistical techniques  with SPSS 13 statistical packet program was used in the analyzes ofresearch data. The study finds that; situation of suppose working, number of child, number of death child, number of home’s moving, support of rent, total monthly income of household, last work’s region, number of prizes, affect voluntary turnover are determined.

  20. Rehabilitative effectiveness of isokinetic training on chondromalacia patellae at early-middle stage%等速训练对早中期髌骨软骨病的康复疗效研究

    Institute of Scientific and Technical Information of China (English)

    徐卫华; 赵彦; 王鸿; 王家祥; 孙强

    2016-01-01

    目的::在超短波和温针治疗的基础上,观察等速训练对早中期髌骨软骨病患者进行康复的效果。方法:将58例早中期髌骨软骨病单膝自愿患者随机分成等速组30例和常规组28例。2组均采用超短波、温针进行治疗;在此基础上,等速组用等速测力仪器进行康复训练,常规组进行常规的运动疗法康复;检测比较2组患者治疗前后大腿围度和角速度为60°/s 时等速肌力测试峰力矩等指标,同时进行 Lysholm 膝关节评分和治疗后临床疗效比较。结果:治疗8周后,2组患膝屈伸肌 PT、伸肌 PT 患/健侧比值及患侧 PT 屈/伸比均较治疗前有明显改善(P <0.01),同时等速组在患膝伸肌 PT 和伸肌 PT 患/健侧比值上较常规组提高更显著(P <0.05)。2组患膝大腿腿围和 Lysholm 膝关节功能评分均较治疗前明显提高(P <0.01),等速组更高于常规组(P <0.05)。治疗后,等速组总有效率明显高于常规组(P <0.05)。结论:等速训练在早中期髌骨软骨病的康复中疗效显著。%Objective:On the basis of remedy by ultrashort wave and acupuncture with warmed needle,to observe the curative effect of isokinetic training on chondromalacia patellae (CP)at early-middle stage.Methods:Fifty-eight voluntary sole knee patients with CP at early-middle stage were randomly divided into isokinetic group (n=30)and control group (n=28).Both two groups were treated with ultrashort wave and acupuncture with warmed needle. The isokinetic group was given rehabilitation training with isokinetic dynamometer,and control group was given conventional kinesiatrics.The indexes including thigh circumference,peak torque which were measured at 60°/sec with isokinetic dynamometer before and after the treatment were detected.Simultaneously,the knee Lysholm scores and the curative effectiveness after the treatment were compared.Results:After 8-week treatment,PT of extensor and flexor,the peak torque ratios for

  1. Effect of Eccentricity and Radius Ratio on Fluid Flow and Heat Transfer Inside and Eccentric Semicircular Enclosure

    Institute of Scientific and Technical Information of China (English)

    ProdipKumarDas; ShohelMahmud

    2000-01-01

    The problem of laminar natural convective heat transfer inside an eccentric semicircular enclosure of different radius ratio and eccentricity is investigated numerically,At the same time,combined effect of the radius ratio and eccentricity on fluid flow is also observed with isothermal upper and lower surface.Here laminar,steady nuatural convection heat transfer are predicted for radius ratio R*=1.75,2.0,2.25,2.5.Simulation was carried out for a range of eccentricity,ε=0.0 to 0.6.Governing equations are solved using finite volume method with a body fitted grid with collocated variable arrangement for a range of Grashof numer 101-107 based on R0.Results are presented in the form of constant stream function,isothermal lines,local Nusselt number and average Nusselt number at different angular position.Eccentricity has little dominance on heat transfer rate.But significant effect of eccentricity is observed on flow field.Radius ratio has significant effect on natural convection heat transfer as well as on flow field.At higher eccentricity,bi-cellular flow is observed with one crescent-shape vortex at narrower coross section.This crescent shaped vortex is broken down into two cells with the increase of radius ratio that means transition Grashof number for bi-cellular flow to tri-cellular flow is decreased with the increase of radius ratio.Eccentricity also has the same effect of flow field.Eccentricity has little effect on heat transfer but with the increase of radius ratio.average heat trasfer rate increases.

  2. On Some Bounds and Exact Formulae for Connective Eccentric Indices of Graphs under Some Graph Operations

    Directory of Open Access Journals (Sweden)

    Nilanjan De

    2014-01-01

    Full Text Available The connective eccentric index of a graph is a topological index involving degrees and eccentricities of vertices of the graph. In this paper, we have studied the connective eccentric index for double graph and double cover. Also we give the connective eccentric index for some graph operations such as joins, symmetric difference, disjunction, and splice of graphs.

  3. Anticipatory signatures of voluntary memory suppression.

    Science.gov (United States)

    Hanslmayr, Simon; Leipold, Philipp; Pastötter, Bernhard; Bäuml, Karl-Heinz

    2009-03-04

    Voluntary memory suppression can keep unwanted memories from entering consciousness, inducing later forgetting of the information. In the present study, we searched for the existence of anticipatory processes, mediating such voluntary memory suppression. Using the think/no-think paradigm, subjects received a cue whether to prepare to think of a previously studied cue-target pair or whether to not let a previously studied cue-target pair enter consciousness. Examining event-related potentials, we identified two electrophysiological processes of voluntary memory suppression: (1) an early anticipatory process operating before the memory cue for a to-be-suppressed memory was provided, and (2) a later process operating after memory cue presentation. Both ERP effects were due to a decreased right frontal and left parietal positivity. They were positively related and predicted later forgetting. The results point to the existence of anticipatory processes, mediating voluntary memory suppression.

  4. Pedagogical Aspects of Voluntary School Work

    Directory of Open Access Journals (Sweden)

    Mária Jármai Erzsébet

    2015-03-01

    Full Text Available The economic importance of voluntary work has been exceedingly appreciated in the last few decades. This is not surprising at all, because it is highly profitable according to the related estimated data. There are 115,9 million people doing voluntary work only in Europe, which means that they would create the world's 7th biggest economy with EUR 282 billion value creation if they formed an individual state. The organizations know that voluntary work has several advantages apart from the economic benefits. It is profitable both for the society and for the individuals as well. Several researches have proven that voluntary work positively influences the development of the personality, because the key-competencies - such as: co-operation, empathy, solidarity, conflict handling, problem solving, etc. - expected in the labor market can be improved.

  5. Managing voluntary turnover through challenging assignments

    NARCIS (Netherlands)

    Preenen, P.T.Y.; Pater, I.E. de; Vianen, A.E.M. van; Keijzer, L.

    2011-01-01

    This study examines employees' challenging assignments as manageable means to reduce turnover intentions, job search behaviors, and voluntary turnover. Results indicate that challenging assignments are negatively related to turnover intentions and job search behaviors and that these relationships

  6. Corticospinal excitability in human voluntary movement

    NARCIS (Netherlands)

    Elswijk, G.A.F. van

    2008-01-01

    The research described in this thesis addressed the neurophysiologic changes in the human corticospinal system during preparation and execution of voluntary hand movements. The experiments involved transcranial magnetic stimulation (TMS) of the motor cortex combined with electromyography (EMG) and e

  7. Contemplated Suicide Among Voluntary and Involuntary Retirees

    Science.gov (United States)

    Peretti, Peter O.; Wilson, Cedric

    1978-01-01

    This study explored anomic and egoistic dimensions of contemplated suicide among voluntary and involuntary retired males. Results indicated a direct relationship between anomie and egoism on the one hand, and contemplation of suicide on the other. (Author)

  8. A Free Market Requires Voluntary Actions

    DEFF Research Database (Denmark)

    Sløk-Madsen, Stefan Kirkegaard

    are essential to the construct of consumer sovereignty. Understanding the degree of voluntary actions in a given commercial setting has implications for both business strategy and policy making. This paper thus aims to contribute to explain why restricted markets become crony capitalism.......This paper draws attention to the importance of the understanding of voluntary actions in the free market construct. Failing to understand the role of voluntary actions in the free market construct will often result in discussions of capitalism versus socialism focusing on asset ownership...... and not consumer sovereignty. I argue that asset ownership is less important than true consumer sovereignty, which again is the essential argument for why capitalism is the superior mode of resource allocation and social organization. The paper analyzes how our understanding of markets and voluntary actions...

  9. Contemplated Suicide Among Voluntary and Involuntary Retirees

    Science.gov (United States)

    Peretti, Peter O.; Wilson, Cedric

    1978-01-01

    This study explored anomic and egoistic dimensions of contemplated suicide among voluntary and involuntary retired males. Results indicated a direct relationship between anomie and egoism on the one hand, and contemplation of suicide on the other. (Author)

  10. Effects of recovery modes after knee extensor muscles eccentric contractions

    National Research Council Canada - National Science Library

    Martin, Vincent; Millet, Guillaume Y; Lattier, Grégory; Perrod, Loïc

    2004-01-01

    ...) to hasten the recovery process from eccentric-contraction-induced injury. Before and 30 min, 24 h, 48 h, and 96 h after a one-legged downhill run, electrical stimulations were applied to the femoral nerve of healthy volunteers...

  11. Characterizing Spinning Black Hole Binaries in Eccentric Orbits with LISA

    CERN Document Server

    Key, Joey Shapiro

    2010-01-01

    The Laser Interferometer Space Antenna (LISA) is designed to detect gravitational wave signals from astrophysical sources, including those from coalescing binary systems of compact objects such as black holes. Colliding galaxies have central black holes that sink to the center of the merged galaxy and begin to orbit one another and emit gravitational waves. Some galaxy evolution models predict that the binary black hole system will enter the LISA band with significant orbital eccentricity, while other models suggest that the orbits will already have circularized. Using a full seventeen parameter waveform model that includes the effects of orbital eccentricity, spin precession and higher harmonics, we investigate how well the source parameters can be inferred from simulated LISA data. Defining the reference eccentricity as the value one year before merger, we find that for typical LISA sources, it will be possible to measure the eccentricity to an accuracy of parts in a thousand. The accuracy with which the ec...

  12. FOREVER ALONE? TESTING SINGLE ECCENTRIC PLANETARY SYSTEMS FOR MULTIPLE COMPANIONS

    Energy Technology Data Exchange (ETDEWEB)

    Wittenmyer, Robert A.; Horner, Jonathan; Tinney, C. G.; Bailey, J.; Salter, G. S.; Wright, D. [Department of Astrophysics, School of Physics, Faculty of Science, The University of New South Wales, Sydney, NSW 2052 (Australia); Wang Songhu; Zhou Jilin [Department of Astronomy and Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210093 (China); Butler, R. P. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States); Jones, H. R. A. [University of Hertfordshire, Centre for Astrophysics Research, Science and Technology Research Institute, College Lane, AL10 9AB Hatfield (United Kingdom); O' Toole, S. J. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Carter, B. D., E-mail: rob@phys.unsw.edu.au [Faculty of Sciences, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia)

    2013-09-15

    Determining the orbital eccentricity of an extrasolar planet is critically important for understanding the system's dynamical environment and history. However, eccentricity is often poorly determined or entirely mischaracterized due to poor observational sampling, low signal-to-noise, and/or degeneracies with other planetary signals. Some systems previously thought to contain a single, moderate-eccentricity planet have been shown, after further monitoring, to host two planets on nearly circular orbits. We investigate published apparent single-planet systems to see if the available data can be better fit by two lower-eccentricity planets. We identify nine promising candidate systems and perform detailed dynamical tests to confirm the stability of the potential new multiple-planet systems. Finally, we compare the expected orbits of the single- and double-planet scenarios to better inform future observations of these interesting systems.

  13. Forever alone? Testing single eccentric planetary systems for multiple companions

    CERN Document Server

    Wittenmyer, Robert A; Horner, Jonathan; Tinney, C G; Butler, R P; Jones, H R A; O'Toole, S J; Bailey, J; Carter, B D; Salter, G S; Wright, D

    2013-01-01

    Determining the orbital eccentricity of an extrasolar planet is critically important for understanding the system's dynamical environment and history. However, eccentricity is often poorly determined or entirely mischaracterized due to poor observational sampling, low signal-to-noise, and/or degeneracies with other planetary signals. Some systems previously thought to contain a single, moderate-eccentricity planet have been shown, after further monitoring, to host two planets on nearly-circular orbits. We investigate published apparent single-planet systems to see if the available data can be better fit by two lower-eccentricity planets. We identify nine promising candidate systems and perform detailed dynamical tests to confirm the stability of the potential new multiple-planet systems. Finally, we compare the expected orbits of the single- and double-planet scenarios to better inform future observations of these interesting systems.

  14. Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis

    CERN Document Server

    Xie, Ji-Wei; Zhu, Zhaohuan; Huber, Daniel; Zheng, Zheng; De Cat, P; Fu, J N; Liu, Hui-Gen; Luo, Ali; Wu, Yue; Zhang, Haotong; Zhang, Hui; Zhou, Ji-Lin; Cao, Zihuang; Hou, Yonghui; Wang, Yuefei; Zhang, Yong

    2016-01-01

    The nearly circular (mean eccentricity ~0.06) and coplanar (mean mutual inclination ~3 deg) orbits of the Solar System planets motivated Kant and Laplace to put forth the hypothesis that planets are formed in disks, which has developed into the widely accepted theory of planet formation. Surprisingly, the first several hundred extrasolar planets (mostly Jovian) discovered using the Radial Velocity (RV) technique are commonly on eccentric orbits ( ~ 0.3). This raises a fundamental question: Are the Solar System and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown. By using the precise spectroscopic host star parameters from the LAMOST observations, we measure the eccentricity distributions for a large (698) and homogeneous Kepler planet sample with transit duration statistics. Nearly half of the planets are in systems with single transiting planets (singles), while the other half are multiple-t...

  15. Near- and Far-Field Optical Response of Eccentric Nanoshells.

    Science.gov (United States)

    Peña-Rodríguez, Ovidio; Díaz-Núñez, Pablo; Rodríguez-Iglesias, Vladimir; Montaño-Priede, Luis; Rivera, Antonio; Pal, Umapada

    2017-12-01

    We study the optical response of eccentric nanoshells (i.e., spherical nanoparticles with an eccentric spherical inclusion) in the near and the far field through finite-difference time-domain simulations. Plasmon hybridization theory is used to explain the obtained results. The eccentricity generates a far-field optical spectrum with various plasmon peaks. The number, position, and width of the peaks depend on the core offset. Near-field enhancements in the surroundings of these structures are significantly larger than those obtained for equivalent concentric nanoshells and, more importantly, they are almost independent of the illumination conditions. This opens up the door for using eccentric nanoshells in applications requiring intense near-field enhancements.

  16. Kepler Planet Masses and Eccentricities from TTV Analysis

    CERN Document Server

    Hadden, Sam

    2016-01-01

    We conduct a uniform analysis of the transit timing variations (TTVs) of 145 planets from 55 Kepler multiplanet systems to infer planet masses and eccentricities. Eighty of these planets do not have previously reported mass and eccentricity measurements. We employ two complementary methods to fit TTVs: Markov chain Monte Carlo simulations based on N-body integration and an analytic fitting approach. Mass measurements of 49 planets, including 12 without previously reported masses, meet our criterion for classification as robust. Using mass and radius measurements, we infer the masses of planets' gaseous envelopes for both our TTV sample as well as transiting planets with radial velocity observations. Insight from analytic TTV formulae allows us to partially circumvent degeneracies inherent to inferring eccentricities from TTV observations. We find that planet eccentricities are generally small, typically a few percent, but in many instances are non-zero.

  17. Growth of eccentric modes in disc-planet interactions

    CERN Document Server

    Teyssandier, Jean

    2016-01-01

    We formulate a set of linear equations that describe the behaviour of small eccentricities in a protoplanetary system consisting of a gaseous disc and a planet. Eccentricity propagates through the disc by means of pressure and self-gravity, and is exchanged with the planet via secular interactions. Excitation and damping of eccentricity can occur through Lindblad and corotation resonances, as well as viscosity. We compute normal modes of the coupled disc-planet system in the case of short-period giant planets orbiting inside an inner cavity, possibly carved by the stellar magnetosphere. Three-dimensional effects allow for a mode to be trapped in the inner parts of the disc. This mode can easily grow within the disc's lifetime. An eccentric mode dominated by the planet can also grow, although less rapidly. We compute the structure and growth rates of these modes and their dependence on the assumed properties of the disc.

  18. Pull factors of Finland and voluntary work

    OpenAIRE

    Jurvakainen, Janika

    2016-01-01

    This thesis studies pull factors of Finland and voluntary work. The aim of this study is to understand the pull factors of Finland from the perspective of young travelers. Which pull factors attract to choose Finland as their destination? In addition, which pull factors attract young travelers to participate in international voluntary work? The commissioner of this thesis is Allianssi Youth Exchange. The thesis is research-based and includes a quantitative Webropol survey and some qualit...

  19. Achilles tendinopathy modulates force frequency characteristics of eccentric exercise.

    Science.gov (United States)

    Grigg, Nicole L; Wearing, Scott C; O'Toole, John M; Smeathers, James E

    2013-03-01

    Previous research has demonstrated that ground reaction force (GRF) recorded during eccentric ankle exercise is characterized by greater power in the 8- to 12-Hz bandwidth when compared with that recorded during concentric ankle exercise. Subsequently, it was suggested that vibrations in this bandwidth may underpin the beneficial effect of eccentric loading in tendon repair. However, this observation has been made only in individuals without Achilles tendinopathy. This research compared the force frequency characteristics of eccentric and concentric exercises in individuals with and without Achilles tendinopathy. Eleven male adults with unilateral midportion Achilles tendinopathy and nine control male adults without tendinopathy participated in the research. Kinematics and GRF were recorded while the participants performed a common eccentric rehabilitation exercise protocol and a concentric equivalent. Ankle joint kinematics and the frequency power spectrum of the resultant GRF were calculated. Eccentric exercise was characterized by a significantly greater proportion of spectral power between 4.5 and 11.5 Hz when compared with concentric exercise. There were no significant differences between limbs in the force frequency characteristics of concentric exercise. Eccentric exercise, in contrast, was defined by a shift in the power spectrum of the symptomatic limb, resulting in a second spectral peak at 9 Hz, rather than 10 Hz in the control limb. Compared with healthy tendon, Achilles tendinopathy was characterized by lower frequency vibrations during eccentric rehabilitation exercises. This finding may be associated with changes in neuromuscular activation and tendon stiffness that have been shown to occur with tendinopathy and provides a possible rationale for the previous observation of a different biochemical response to eccentric exercise in healthy and injured Achilles tendons.

  20. TTVFaster: First order eccentricity transit timing variations (TTVs)

    Science.gov (United States)

    Agol, Eric; Deck, Katherine

    2016-04-01

    TTVFaster implements analytic formulae for transit time variations (TTVs) that are accurate to first order in the planet-star mass ratios and in the orbital eccentricities; the implementations are available in several languages, including IDL, Julia, Python and C. These formulae compare well with more computationally expensive N-body integrations in the low-eccentricity, low mass-ratio regime when applied to simulated and to actual multi-transiting Kepler planet systems.

  1. Eccentric hamstring strength and hamstring injury risk in Australian footballers.

    Science.gov (United States)

    Opar, David A; Williams, Morgan D; Timmins, Ryan G; Hickey, Jack; Duhig, Steven J; Shield, Anthony J

    2015-04-01

    Are eccentric hamstring strength and between-limb imbalance in eccentric strength, measured during the Nordic hamstring exercise, risk factors for hamstring strain injury (HSI)? Elite Australian footballers (n = 210) from five different teams participated. Eccentric hamstring strength during the Nordic exercise was obtained at the commencement and conclusion of preseason training and at the midpoint of the season. Injury history and demographic data were also collected. Reports on prospectively occurring HSI were completed by the team medical staff. Relative risk (RR) was determined for univariate data, and logistic regression was employed for multivariate data. Twenty-eight new HSI were recorded. Eccentric hamstring strength below 256 N at the start of the preseason and 279 N at the end of the preseason increased the risk of future HSI 2.7-fold (RR, 2.7; 95% confidence interval, 1.3 to 5.5; P = 0.006) and 4.3-fold (RR, 4.3; 95% confidence interval, 1.7 to 11.0; P = 0.002), respectively. Between-limb imbalance in strength of greater than 10% did not increase the risk of future HSI. Univariate analysis did not reveal a significantly greater RR for future HSI in athletes who had sustained a lower limb injury of any kind within the last 12 months. Logistic regression revealed interactions between both athlete age and history of HSI with eccentric hamstring strength, whereby the likelihood of future HSI in older athletes or athletes with a history of HSI was reduced if an athlete had high levels of eccentric strength. Low levels of eccentric hamstring strength increased the risk of future HSI. Interaction effects suggest that the additional risk of future HSI associated with advancing age or previous injury was mitigated by higher levels of eccentric hamstring strength.

  2. Flow of viscoplastic fluids in eccentric annular geometries

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1992-01-01

    A classification of flowfields for the flow of a Bingham fluid in general eccentric annular geometries is presented. Simple arguments show that a singularity can exist in the stress gradient on boundaries between zones with yielded and un-yielded fluid respectively. A Finite Element code is used...... to verify this property of the Bingham fluid. An analytical solution for the flowfield in case of small eccentricities is derived....

  3. Chronic Adaptations to Eccentric Training: A Systematic Review.

    Science.gov (United States)

    Douglas, Jamie; Pearson, Simon; Ross, Angus; McGuigan, Mike

    2017-05-01

    Resistance training is an integral component of physical preparation for athletes. A growing body of evidence indicates that eccentric strength training methods induce novel stimuli for neuromuscular adaptations. The purpose of this systematic review was to determine the effects of eccentric training in comparison to concentric-only or traditional (i.e. constrained by concentric strength) resistance training. Searches were performed using the electronic databases MEDLINE via EBSCO, PubMed and SPORTDiscus via EBSCO. Full journal articles investigating the long-term (≥4 weeks) effects of eccentric training in healthy (absence of injury or illness during the 4 weeks preceding the training intervention), adult (17-35 years), human participants were selected for the systematic review. A total of 40 studies conformed to these criteria. Eccentric training elicits greater improvements in muscle strength, although in a largely mode-specific manner. Superior enhancements in power and stretch-shortening cycle (SSC) function have also been reported. Eccentric training is at least as effective as other modalities in increasing muscle cross-sectional area (CSA), while the pattern of hypertrophy appears nuanced and increased CSA may occur longitudinally within muscle (i.e. the addition of sarcomeres in series). There appears to be a preferential increase in the size of type II muscle fibres and the potential to exert a unique effect upon fibre type transitions. Qualitative and quantitative changes in tendon tissue that may be related to the magnitude of strain imposed have also been reported with eccentric training. Eccentric training is a potent stimulus for enhancements in muscle mechanical function, and muscle-tendon unit (MTU) morphological and architectural adaptations. The inclusion of eccentric loads not constrained by concentric strength appears to be superior to traditional resistance training in improving variables associated with strength, power and speed

  4. Exoplanet orbital eccentricity: multiplicity relation and the Solar System.

    Science.gov (United States)

    Limbach, Mary Anne; Turner, Edwin L

    2015-01-06

    The known population of exoplanets exhibits a much wider range of orbital eccentricities than Solar System planets and has a much higher average eccentricity. These facts have been widely interpreted to indicate that the Solar System is an atypical member of the overall population of planetary systems. We report here on a strong anticorrelation of orbital eccentricity with multiplicity (number of planets in the system) among cataloged radial velocity (RV) systems. The mean, median, and rough distribution of eccentricities of Solar System planets fits an extrapolation of this anticorrelation to the eight-planet case rather precisely despite the fact that no more than two Solar System planets would be detectable with RV data comparable to that in the exoplanet sample. Moreover, even if regarded as a single or double planetary system, the Solar System lies in a reasonably heavily populated region of eccentricity-multiplicity space. Thus, the Solar System is not anomalous among known exoplanetary systems with respect to eccentricities when its multiplicity is taken into account. Specifically, as the multiplicity of a system increases, the eccentricity decreases roughly as a power law of index -1.20. A simple and plausible but ad hoc and model-dependent interpretation of this relationship implies that ∼ 80% of the one-planet and 25% of the two-planet systems in our sample have additional, as yet undiscovered, members but that systems of higher observed multiplicity are largely complete (i.e., relatively rarely contain additional undiscovered planets). If low eccentricities indeed favor high multiplicities, habitability may be more common in systems with a larger number of planets.

  5. Eccentricity in Zone Routing Protocol for MANET

    Directory of Open Access Journals (Sweden)

    Mrs Komal Nair

    2012-06-01

    Full Text Available A Mobile Ad-Hoc Network (MANET is a decentralized network of autonomous mobile nodes, able to communicate with each other over wireless links. Due to the mobility of the nodes, the topology ofthe network changes spontaneously, therefore use of conventional routing tables maintained at fixed points (routers is not suggested. Such a network may operate in a standalone fashion. There are variousrouting protocols available for MANETs. The most popular ones are DSR, DSDV and ZRP .The zone routing protocol (ZRP is a hybrid routing protocol that proactively maintains routes within a localregion of the network. ZRP can be configured for a particular network through adjustment of a single parameter, the routing zone radius. In this paper, we address the issue of configuring the ZRP to providethe best performance for a particular network at any time with the concept of eccentricity. The results illustrate the important characteristics of different protocols based on their performance and thus suggest some improvements in the respective protocol. The tools used for the simulation are NS2 which is the main simulator, NAM (Network Animator and Tracegraph which is used for preparing the graphs from the trace files.

  6. Highly eccentric inspirals into a black hole

    CERN Document Server

    Osburn, Thomas; Evans, Charles R

    2015-01-01

    We model the inspiral of a compact stellar-mass object into a massive non-rotating black hole including all dissipative and conservative first-order-in-the-mass-ratio effects on the orbital motion. The techniques we develop allow inspirals with initial eccentricities as high as $e\\sim0.8$ and initial separations as large as $\\sim 100M$ to be evolved through many thousands of orbits up to the onset of the plunge into the black hole. The inspiral is computed using an osculating elements scheme driven by a hybridized self-force model, which combines Lorenz-gauge self-force results with highly accurate flux data from a Regge-Wheeler-Zerilli code. The high accuracy of our hybrid self-force model allows the orbital phase of the inspirals to be tracked to within $\\sim0.1$ radians or better. The difference between self-force models and inspirals computed in the radiative approximation is quantified.

  7. Comparative study on isokinetic capacity of knee and ankle joints by functional injury.

    Science.gov (United States)

    Jeon, Kyoungkyu; Seo, Byoung-Do; Lee, Sang-Ho

    2016-01-01

    [Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability.

  8. Strength deficits of the shoulder complex during isokinetic testing in people with chronic stroke

    Directory of Open Access Journals (Sweden)

    Lucas R. Nascimento

    2014-07-01

    Full Text Available OBJECTIVES: To examine the strength deficits of the shoulder complex after stroke and to characterize the pattern of weakness according to type of movement and type of isokinetic parameter. METHOD: Twelve chronic stroke survivors and 12 age-matched healthy controls had their shoulder strength measured using a Biodex isokinetic dynamometer. Concentric measures of peak torque and work during shoulder movements were obtained in random order at speeds of 60°/s for both groups and sides. Type of movement was defined as scapulothoracic (protraction and retraction, glenohumeral (shoulder internal and external rotation or combined (shoulder flexion and extension. Type of isokinetic parameter was defined as maximum (peak torque or sustained (work. Strength deficits were calculated using the control group as reference. RESULTS: The average strength deficit for the paretic upper limb was 52% for peak torque and 56% for work. Decreases observed in the non-paretic shoulder were 21% and 22%, respectively. Strength deficit of the scapulothoracic muscles was similar to the glenohumeral muscles, with a mean difference of 6% (95% CI -5 to 17. Ability to sustain torque throughout a given range of motion was decreased as much as the peak torque, with a mean difference of 4% (95% CI -2 to 10. CONCLUSIONS: The findings suggest that people after stroke might benefit from strengthening exercises directed at the paretic scapulothoracic muscles in addition to exercises of arm elevation. Clinicians should also prescribe different exercises to improve the ability to generate force and the ability to sustain the torque during a specific range of motion.

  9. 47 CFR 80.310 - Watch required by voluntary vessels.

    Science.gov (United States)

    2010-10-01

    ... Watches § 80.310 Watch required by voluntary vessels. Voluntary vessels not equipped with DSC must.... Voluntary vessels equipped with VHF-DSC equipment must maintain a watch on 2182 kHz and on either 156.525... used to communicate. Voluntary vessels equipped with MF-HF DSC equipment must have the radio turned...

  10. The Effect of Concentric Isokinetic Strength Training of the Quadriceps Femoris on Electromyography and Muscle Strength in the Trained and Untrained Limb.

    Science.gov (United States)

    Evetovich, Tammy K.; Housh, Terry J.; Housh, Dona J.; Johnson, Glen O.; Smith, Douglas B.; Ebersole, Kyle T.

    2001-01-01

    Examined the effects of unilateral concentric isokinetic leg extension training on peak torque and electromyographic (EMG) responses in trained and untrained limbs. Adult men participated in training and control groups. Overall, unilateral concentric isokinetic strength training induced strength increases in trained as well as untrained limbs.…

  11. The bilateral leg strength deficit is present in old, young and adolescent females during isokinetic knee extension and flexion.

    Science.gov (United States)

    Kuruganti, Usha; Seaman, Kenneth

    2006-06-01

    The bilateral limb deficit (BLD) describes the difference in maximal or near maximal force generating capacity of muscles when they are contracted alone or in combination with the contralateral muscles. A deficit occurs when the summed unilateral force is greater than the bilateral force. This study examined the presence of the BLD during isokinetic knee extensions and flexions in a group of adolescent females (n=8, mean of 15+/-1 years) and compared with previously reported data by this researcher of adult and older females. Data were collected from subjects during slow (45 deg/s) isokinetic knee extensions and flexions and it was found that a BLD exists during both extension and flexion regardless of age. Furthermore, this study is the first to examine the presence of the deficit in an adolescent population. Myoelectric signal (MES) data showed that there is no difference between bilateral and unilateral isokinetic knee extensions and flexions regardless of age group.

  12. The Solar System and the Exoplanet Orbital Eccentricity - Multiplicity Relation

    CERN Document Server

    Limbach, Mary Anne

    2014-01-01

    The known population of exoplanets exhibits a much wider range of orbital eccentricities than Solar System planets and has a much higher average eccentricity. These facts have been widely interpreted to indicate that the Solar System is an atypical member of the overall population of planetary systems. We report here on a strong anti-correlation of orbital eccentricity with multiplicity (number of planets in the system) among catalogued RV systems. The mean, median and rough distribution of eccentricities of Solar System planets fits an extrapolation of this anti-correlation to the eight planet case rather precisely. Thus, the Solar System is not anomalous among known exoplanetary systems with respect to eccentricities when its multiplicity is taken into account. Specifically, as the multiplicity of a system increases the eccentricity decreases roughly as a power law of index -1.20. A simple and plausible but ad hoc model of this relationship implies that approximately 80% of the one planet and 25% of the two...

  13. Exoplanet orbital eccentricities derived from LAMOST-Kepler analysis.

    Science.gov (United States)

    Xie, Ji-Wei; Dong, Subo; Zhu, Zhaohuan; Huber, Daniel; Zheng, Zheng; De Cat, Peter; Fu, Jianning; Liu, Hui-Gen; Luo, Ali; Wu, Yue; Zhang, Haotong; Zhang, Hui; Zhou, Ji-Lin; Cao, Zihuang; Hou, Yonghui; Wang, Yuefei; Zhang, Yong

    2016-10-11

    The nearly circular (mean eccentricity [Formula: see text]) and coplanar (mean mutual inclination [Formula: see text]) orbits of the solar system planets motivated Kant and Laplace to hypothesize that planets are formed in disks, which has developed into the widely accepted theory of planet formation. The first several hundred extrasolar planets (mostly Jovian) discovered using the radial velocity (RV) technique are commonly on eccentric orbits ([Formula: see text]). This raises a fundamental question: Are the solar system and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown. By using the precise spectroscopic host star parameters from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) observations, we measure the eccentricity distributions for a large (698) and homogeneous Kepler planet sample with transit duration statistics. Nearly half of the planets are in systems with single transiting planets (singles), whereas the other half are multiple transiting planets (multiples). We find an eccentricity dichotomy: on average, Kepler singles are on eccentric orbits with [Formula: see text] 0.3, whereas the multiples are on nearly circular [Formula: see text] and coplanar [Formula: see text] degree) orbits similar to those of the solar system planets. Our results are consistent with previous studies of smaller samples and individual systems. We also show that Kepler multiples and solar system objects follow a common relation [[Formula: see text](1-2)[Formula: see text

  14. Initial partonic eccentricity fluctuations in a multiphase transport model

    Science.gov (United States)

    Ma, L.; Ma, G. L.; Ma, Y. G.

    2016-10-01

    Initial partonic eccentricities in Au+Au collisions at center-of-mass energy √{sN N}=200 GeV are investigated by using a multiphase transport model with a string-melting scenario. The initial eccentricities in different order of harmonics are studied by using participant and cumulant definitions. Eccentricity in terms of second-, fourth- and sixth-order cumulants as a function of number of participant nucleons are compared systematically with the traditional participant definition. The ratio of the cumulant eccentricities ɛ {4 }/ɛ {2 } and ɛ {6 }/ɛ {4 } are studied in comparison with the ratio of the corresponding flow harmonics. The conversion coefficients (vn/ɛn ) are explored up to fourth-order harmonics based on the cumulant method. Furthermore, studies on transverse momentum (pT) and pseudorapidity (η ) dependencies of eccentricities and their fluctuations are presented. As in ideal hydrodynamics, initial eccentricities are expected to be closely related to the final flow harmonics in relativistic heavy-ion collisions, studies of the fluctuating initial condition in the AMPT model will shed light on the tomography properties of the initial source geometry.

  15. Resistance training improves isokinetic strength and metabolic syndrome-related phenotypes in postmenopausal women

    Directory of Open Access Journals (Sweden)

    Oliveira PFA

    2015-08-01

    Full Text Available Pedro Ferreira Alves Oliveira,1 André Bonadias Gadelha,2 Rafael Gauche,2 Flávio Macedo Lahud Paiva,2 Martim Bottaro,2 Lauro C Vianna,2 Ricardo Moreno Lima2 1Department of Physical Education, Instituto Federal de Brasília, 2College of Physical Education, University of Brasília, Brasília, DF, Brazil Purpose: To examine the effects of resistance training (RT on metabolic syndrome-related phenotypes in postmenopausal women. Patients and methods: Twenty-two postmenopausal women (65.0±4.2 years underwent 12 weeks of whole body progressive training with intensity prescribed based on rating of perceived exertion. Dominant knee extension strength was assessed using an isokinetic dynamometer before and after the intervention. Moreover, all volunteers had blood samples collected for lipid profile, glycemic control, and C-reactive protein analyses. Waist circumference and arterial blood pressure were also measured at baseline and after the training period. Student’s t-tests for paired samples and repeated measures ANOVA were used to compare dependent variables, and statistical significance was set at P<0.05. Results: Isokinetic muscle strength significantly increased (P<0.01 with training. It was observed that waist circumference as well as total and low-density lipoprotein cholesterol levels significantly decreased with training (P<0.01. Total cholesterol/high-density lipoprotein cholesterol ratio, an important marker of cardiovascular disease incidence, was also significantly reduced (from 3.91±0.91 to 3.60±0.74; P<0.01 after the program. Blood glucose, basal insulin, and homeostatic model assessment of insulin resistance were also significantly reduced (P<0.01. No significant alterations were observed for resting blood pressure, triglycerides, or C-reactive protein. Conclusion: Based on the observed results, it can be concluded that a 12-week progressive RT program, besides increasing isokinetic muscle strength, induces beneficial alterations

  16. Reliability of isokinetic evaluation in passive mode for knee flexors and extensors in healthy children

    Directory of Open Access Journals (Sweden)

    Adriana N. Santos

    2013-04-01

    Full Text Available BACKGROUND: The isokinetic dynamometer has been considered the gold-standard measurement of muscle performance. However, the reliability for the passive mode in children has not been reported to date. OBJECTIVES: The purpose was to evaluate the reliability of the isokinetic dynamometer in passive mode in children. METHOD: Twenty-one healthy children (ten girls, eleven boys, aged 5 to 12 years (age: 8.5±2.2 years, were evaluated using an isokinetic dynamometer. Each participant was tested twice with a one-week interval and performed five consecutive cycles of knee extension and flexion. The test was performed at 60º/s in the concentric passive mode and the children performed maximal contractions. The measured variables were peak torque, average peak torque, total work, and average power, time to peak torque and angle of peak torque for dominant and non-dominant lower limbs. Reliabilities were determined using intraclass correlation coefficient (ICC3,1, standard error of measurement (SEM and SEM%, and coefficient of variation (CV. RESULTS: We found good reliability in both lower limbs for peak torque, average peak torque, total work and average power of knee flexors and extensors, with ICC3,1 values greater than 0.80; SEM ranging from 6.7 to 79.2; SEM% ranging from 10.4% to 16.8%; CV lower than 15%. Bland-Altman analysis showed that the bias was low than 10% and limits of agreement (LOAs ranging from 33.9% to 59.2%, and -28.8% and -52.8%, showing that measures tended to disagree. However, time to peak torque (ICC3,1 0.34; SEM%>37.4%; CV>41.7%; bias >24.0%; LOA>101.0% and angle of peak torque (ICC3,19.3; SEM%>27.6%; CV>15.3%; bias>11.0%; LOA>61.0% were not reliable. CONCLUSIONS: The findings indicate that isokinetic evaluation in passive mode for knee extensors and flexors of dominant and non-dominant lower limbs of children without disabilities was reliable for peak torque, average peak torque, work, and power. However, average time to peak

  17. Eccentric exercise and delayed onset muscle soreness of the quadriceps induce adjustments in agonist-antagonist activity, which are dependent on the motor task.

    Science.gov (United States)

    Vila-Chã, C; Hassanlouei, H; Farina, D; Falla, D

    2012-02-01

    This study investigates the effects of eccentric exercise and delayed onset muscle soreness (DOMS) of the quadriceps on agonist-antagonist activity during a range of motor tasks. Ten healthy volunteers (age, mean ± SD, 24.9 ± 3.2 years) performed maximum voluntary contractions (MVC) and explosive isometric contractions of the knee extensors followed by isometric contractions at 2.5, 5, 10, 15, 20, and 30% MVC at baseline, immediately after and 24 h after eccentric exercise of the quadriceps. During each task, force of the knee extensors and surface EMG of the vasti and hamstrings muscles were recorded concurrently. Rate of force development (RFD) was computed from the explosive isometric contraction, and the coefficient of variation of the force (CoV) signal was estimated from the submaximal contractions. Twenty-four hours after exercise, the subjects rated their perceived pain intensity as 4.1 ± 1.2 (score out of 10). The maximum RFD and MVC of the knee extensors was reduced immediately post- and 24 h after eccentric exercise compared to baseline (average across both time points: 19.1 ± 17.1% and 11.9 ± 9.8% lower, respectively, P eccentric exercise (up to 66% higher than baseline, P exercise during the presence of DOMS (P exercise and was accompanied by increased antagonist EMG for the explosive contraction only. On the contrary, reduced force steadiness was accompanied by a general increase in EMG amplitude of the vasti muscles and was accompanied by increased antagonist activity, but only at higher force levels (>15% MVC). This study shows that eccentric exercise and subsequent DOMS of the quadriceps reduce the maximal force, rate of force development and force steadiness of the knee extensors, and is accompanied by different adjustments of agonist and antagonist muscle activities.

  18. Learning effect of isokinetic measurements in healthy subjects, and reliability and comparability of Biodex and Lido dynamometers

    DEFF Research Database (Denmark)

    Lund, Hans; Søndergaard, K; Zachariassen, T

    2005-01-01

    The aim of this study was to examine the learning effect during a set of isokinetic measurements, to evaluate the reliability of the Biodex System 3 PRO dynamometer, and to compare the Biodex System 3 PRO and the Lido Active dynamometers on both extension and flexion over the elbow and the knee...... extension (P = 0.18) and elbow extension (P = 0.63). However, elbow flexion showed a 14.8% (95% CI: 11.2-18.4%; P = 0.0001) higher peak torque on Biodex. In conclusion, no learning effect was observed and the Biodex proved to be a highly reliable isokinetic dynamometer. A difference was observed when...

  19. Effects of Kinesio Tape application to quadriceps muscles on isokinetic muscle strength, gait, and functional parameters in patients with stroke.

    Science.gov (United States)

    Ekiz, Timur; Aslan, Meryem Doğan; Özgirgin, Neşe

    2015-01-01

    The aim of this study was to evaluate the effects of Kinesio Tape (KT) application to quadriceps muscles on isokinetic muscle strength, gait, and functional parameters in patients with stroke. Twenty-four patients were allocated into KT and control groups. All patients participated in the same conventional rehabilitation program 5 times/wk for 4 wk. In addition, KT was applied to quadriceps muscles bilaterally to the patients in the KT group. Compared with baseline, peak torque levels increased significantly in both groups (all p 0.05). KT application to quadriceps muscles in addition to conventional exercises for 4 wk is effective on isokinetic but not functional parameters.

  20. Crowding and eccentricity determine reading rate.

    Science.gov (United States)

    Pelli, Denis G; Tillman, Katharine A; Freeman, Jeremy; Su, Michael; Berger, Tracey D; Majaj, Najib J

    2007-10-26

    Bouma's law of crowding predicts an uncrowded central window through which we can read and a crowded periphery through which we cannot. The old discovery that readers make several fixations per second, rather than a continuous sweep across the text, suggests that reading is limited by the number of letters that can be acquired in one fixation, without moving one's eyes. That "visual span" has been measured in various ways, but remains unexplained. Here we show (1) that the visual span is simply the number of characters that are not crowded and (2) that, at each vertical eccentricity, reading rate is proportional to the uncrowded span. We measure rapid serial visual presentation (RSVP) reading rate for text, in both original and scrambled word order, as a function of size and spacing at central and peripheral locations. As text size increases, reading rate rises abruptly from zero to maximum rate. This classic reading rate curve consists of a cliff and a plateau, characterized by two parameters, critical print size and maximum reading rate. Joining two ideas from the literature explains the whole curve. These ideas are Bouma's law of crowding and Legge's conjecture that reading rate is proportional to visual span. We show that Legge's visual span is the uncrowded span predicted by Bouma's law. This result joins Bouma and Legge to explain reading rate's dependence on letter size and spacing. Well-corrected fluent observers reading ordinary text with adequate light are limited by letter spacing (crowding), not size (acuity). More generally, it seems that this account holds true, independent of size, contrast, and luminance, provided only that text contrast is at least four times the threshold contrast for an isolated letter. For any given spacing, there is a central uncrowded span through which we read. This uncrowded span model explains the shape of the reading rate curve. We test the model in several ways. We use a "silent substitution" technique to measure the

  1. The effects of kinesio tape on isokinetic muscular function of horse racing jockeys.

    Science.gov (United States)

    Kim, Hyeyoung; Lee, Byounghee

    2013-10-01

    [Purpose] The purpose of this study was to conduct a scientific analysis of the effectiveness of Kinesio taping at preventing injury and improving horse racing jockey' performance, by studying the effects on isokinetic muscular function of Kinesio taping applied to the knee joint muscle. [Subjects] Eight horse racing jockeys were selected for this study. [Methods] Measurement of isokinetic muscular function of both flexor and extensor muscles was performed at the angular velocities of 60°/sec and 180°/sec using a Biodex system 3, before and after application of Kinesio taping to the rectus femoris, vastus medialis, vastus lateralis, and hamstring. [Result] At the angular velocities of 60°/sec and 180°/sec, significant differences were observed in both flexor and extensor peak torque, average power, and total work of the knee joint after application of Kinesio taping. [Conclusion] The application of Kinesio taping has a positive effect on the function of both knee flexors and extensors, and also kinetic ability. Therefore, its use would lead to a significant increase in the muscle function of horse racing jockeys.

  2. Clinical assessment of the low-cost VariCom isokinetic knee exerciser.

    Science.gov (United States)

    Greenblatt, D; Diesel, W; Noakes, T D

    1997-04-01

    A low-cost isokinetic knee exerciser, known as the VariCom and developed with the emphasis on fulfilling the rehabilitation needs of developing countries, was subjected to a clinical evaluation. The evaluation was motivated by successful laboratory assessment of the exerciser as well as encouraging qualitative data acquired recently from a developing world hospital. The principal aim of this study was to demonstrate that the exerciser, employing a simple shock-absorber and lever mechanism, was capable of fulfilling the major criteria required from isokinetic equipment. Amongst the most important of these were attainment of a 'spectrum of velocities', patient safety, reliability, ease-of-use, patient comfort and estimation of the torque generated by the patient's knee-joint. It was ultimately demonstrated that the combination of design simplicity, durability and functionality renders the VariCom knee-exerciser technologically appropriate for use in developing countries. More generally, the success of the exerciser, combined with its low manufacturing cost, renders it a viable alternative to traditional up-market equipment.

  3. Assessment of the Relationship between Physical Activity Levels and Isokinetic Muscle Performance

    Directory of Open Access Journals (Sweden)

    Ahmet Miçooğulları

    2016-04-01

    Full Text Available Objective: To evaluate the association between physical activity levels and isokinetic muscle strength of knee. Materials and Methods: Thirty amateur athletes and 30 healthy volunters (aged between 20-24 were included in the study. Participants were divided into two groups as amateur athletes (group 1 and healthy controls (group 2. Physical activity levels of the participants were assessed by International Physical Activity Questionnaire (IPAQ. Dominant knee flexion and extension muscle strength of the participants were measured with an isokinetic dynamometer at 60°/s and 180°/s angular velocities. Results: There were no statistically significant difference between the groups in age, sex, weight, height, body mass index and, smoking status (p>0.05. There was a statistically significant difference in IPA scores between the groups (p0.05. Group 1 was divided into subgroups according to IPA scores. In patients with high activity level, peak torque values at the angular velocities of 60°/s and 180°/s for knee muscles were significiantly higher (p<0.05. Conclusion: Further studies that evaluating of the many factors that determining and affecting muscle strength are with larger groups will be beneficia

  4. Isokinetic imbalance of hip muscles in soccer players with osteitis pubis.

    Science.gov (United States)

    Mohammad, Walaa Sayed; Abdelraouf, Osama Ragaa; Elhafez, Salam Mohamed; Abdel-Aziem, Amr Almaz; Nassif, Nagui Sobhi

    2014-01-01

    In this study, we compared the isokinetic torques of hip flexors/extensors and abductors/adductors in soccer players suffering from osteitis pubis (OP), with normal soccer players. Twenty soccer male athletes with OP and 20 normal soccer athletes were included in this study. Peak torque/body weight (PT/BW) was recorded from hip flexor/extensor and abductor/adductor muscles during isokinetic concentric contraction modes at angular velocity of 2.1 rad · s(-1), for both groups. The results showed a significant difference between the normal and OP groups for hip flexors (P muscles (P > 0.05). Regarding the hip adductor/abductor PT ratio, there was no significant difference between the normal and OP groups of athletes (P > 0.05). The OP group displayed increase in hip flexor strength that disturbed the hip flexor/extensor torque ratio of OP. Therefore, increasing the hip extensor strength should be part of rehabilitation programmes of patients with OP.

  5. The comparison of knee isokinetic performances and anthropometric measurement of professional soccers who play different position

    Directory of Open Access Journals (Sweden)

    Enis Çolak

    2007-11-01

    Full Text Available The aim of our study is determine knee flexibility and knee isokinetic performance of soccer players who play different position. In this study nineteen professional soccer players who play in Kocaelispor were choosen as a subjects. Range of movement (ROMof knee and the knee flexion/extension muscle strengths were measured. In this measurement were used 60, 180 and 300 deg/sec con-con angular velocity protochol using biodex system III dynamometer.Statistically significant difference was found of total work of knee extensor in 60°/s between forwards and midfielders and also between forwards and defenders(p<0.05. Ekstansor muscle strength of forwards less than which of defenders and which of midfielders. Statistical differences were shown in 60°/s Peak Torque/body weight of between midfielders and defenders. Defenders have higher extensor muscle strength but lower values ROM. As the muscle strength and volume increase muscle get shorter. This can make risk for injures.While an exercise program is prepared play position must taken into consideration after isokinetic tests. Especially joint flexibility is indicator for future injures.

  6. The comparison of knee isokinetic performances and anthropometric measurement of professional soccers who play different position

    Directory of Open Access Journals (Sweden)

    Bergün Meriç

    2007-11-01

    Full Text Available The aim of our study is determine knee flexibility and knee isokinetic performance of soccer players who play different position. In this study nineteen professional soccer players who play in Kocaelispor were choosen as a subjects. Range of movement (ROMof knee and  the knee flexion/extension muscle strengths were measured. In this measurement were used  60, 180 and 300 deg/sec con-con angular velocity protochol using biodex system III dynamometer.Statistically significant difference was found of total work of knee extensor in 60°/s between forwards and midfielders and also between forwards and defenders(p<0.05. Ekstansor muscle strength of forwards less than which of defenders and which of midfielders. Statistical differences were shown in 60°/s Peak Torque/body weight of between midfielders and defenders. Defenders have higher extensor muscle strength but lower values ROM. As the muscle strength and volume increase muscle get shorter. This can make risk for injures.While an exercise program is prepared play position must taken into consideration after isokinetic tests. Especially joint flexibility is indicator for future injures.

  7. Co-activation of sprinter and distance runner muscles in isokinetic exercise.

    Science.gov (United States)

    Osternig, L R; Hamill, J; Lander, J E; Robertson, R

    1986-08-01

    The purpose of this study was to investigate the extent of co-activation of quadriceps and hamstring musculature in sprinters and distance runners. Nine female intercollegiate track athletes performed maximal knee extensions and flexions on a modified orthotron isokinetic dynamometer at two speeds (100 degrees and 400 degrees X s-1). Simultaneous recordings of torque, joint position, and agonist/antagonist electromyographic activity from the quadriceps and hamstrings were computer-processed. The results revealed the hamstrings to be considerably more active during knee extension than the quadriceps during flexion. The integrated electromyographic activity of co-contracting hamstrings and quadriceps, throughout the joint range, averaged 33 and 6%, respectively, of the same muscle group during its agonist phase. Hamstring co-activation increased sharply during the last 25% of knee extension, generating 58% of the integrated electromyographic agonist activity. Co-activation of the sprinters' hamstrings was four times that of distance runners (57/14%), however, the faster speed of movement (400 degrees X s-1) increased hamstring coactivation of distance runners more acutely than sprinters in the final phase of extension. The data suggest that the hamstrings are used to a much greater extent than quadriceps for limb deceleration and that the distraction of antagonist muscle tension should be considered when analyzing agonist isokinetic torques. Furthermore, the relatively high co-activation of the hamstrings, particularly during the last 25% of extension, may induce hamstring soreness or strain in vulnerable subjects.

  8. Joint-specific power loss after eccentric exercise.

    Science.gov (United States)

    Elmer, Steven J; Martin, James C

    2010-09-01

    Previous investigators have reported changes in maximal power after eccentric exercise. The influence of eccentric joint-specific power absorption on subsequent concentric joint-specific power production during multijoint actions has not been reported. Our purposes were to determine the extent to which ankle, knee, and hip joint actions absorbed power during eccentric cycling (ECCcyc) and to evaluate changes in power produced by those joint actions during subsequent maximal concentric cycling (CONcyc). We hypothesized that joint actions that absorbed the most power during ECCcyc would exhibit the greatest reductions in power during subsequent maximal CONcyc. Nineteen cyclists performed baseline trials of maximal single-leg CONcyc immediately before and 24 h after acute single-leg ECCcyc (5 min, 40% maximum single-leg CONcyc power). Pedal forces and limb kinematics were determined with a force-sensing pedal and instrumented spatial linkage system, respectively. Joint-specific powers were calculated using inverse dynamics and averaged over complete crank revolutions and over extension and flexion phases. The largest power-absorbing actions during ECCcyc were eccentric knee extensor activity (-185 +/- 12 W) followed by eccentric hip extensor activity (-92 +/- 12 W). Power absorbed through ankle joint actions was small (-10 +/- 2 W). At 24 h, pedal power produced during maximal CONcyc was reduced by 11% +/- 3% relative to baseline. Compared with baseline, knee extension power was reduced by 19% +/- 0 7%, whereas hip extension power did not differ. Power absorbed through eccentric knee extension actions significantly reduced knee extension power produced during subsequent maximal CONcyc. Even with reduced knee extensor function, participants were able to deliver 89% of their baseline power to the environment. These results have implications for individuals who must continue to perform multijoint activities after eccentric exercise.

  9. Eccentric endurance exercise economically improves metabolic and inflammatory risk factors.

    Science.gov (United States)

    Zeppetzauer, Markus; Drexel, Heinz; Vonbank, Alexander; Rein, Philipp; Aczel, Stefan; Saely, Christoph H

    2013-08-01

    Exercise is a cornerstone of cardiovascular prevention. Because many individuals are not willing or not able to perform regular exercise, new methods of exercise (like eccentric exercise) are necessary. Eccentric endurance exercise is supposed to be less strenuous than concentric exercise but its effects on glucose and lipid metabolism in relation to energy expenditure are unclear. We randomly allocated 45 healthy sedentary individuals to one of two groups, each hiking upwards or downwards for 2 months, with a crossover for a further 2 months; for the opposite way, a cable car was used. The difference in altitude was 540 metres; the distance was covered between three and five times a week. Energy expenditure was assessed for each hiking period. Both eccentric and concentric endurance exercise improved glucose tolerance vs. baseline (by 4.1%, p = 0.136; 6.2%, p = 0.023, respectively). Of note, adjustment for energy expenditure per exercise unit (127 ± 22 kcal/unit with eccentric and 442 ± 78 kcal/unit with concentric exercise) revealed a significantly greater improvement of glucose tolerance per kilocalorie spent by eccentric than by concentric exercise (4-times more economical; 0.1123 mg h/dl/kcal vs. 0.0245 mg h/dl/kcal; p = 0.038). Also the decrease of low-density lipoprotein (LDL) cholesterol per kilocalorie spent was significantly stronger with eccentric exercise (0.0982 mg/dl/kcal vs. 0.0346 mg/dl/kcal, p = 0.014). Serum levels of C-reactive protein and creatine kinase activity were reduced in both groups. Eccentric endurance exercise economically improves glucose tolerance and LDL cholesterol. It therefore is a promising new exercise modality for individuals who are not able to participate in more strenuous exercise regimens.

  10. Exoplanet orbital eccentricity: Multiplicity relation and the Solar System

    Science.gov (United States)

    Limbach, Mary Anne; Turner, Edwin L.

    2015-01-01

    The known population of exoplanets exhibits a much wider range of orbital eccentricities than Solar System planets and has a much higher average eccentricity. These facts have been widely interpreted to indicate that the Solar System is an atypical member of the overall population of planetary systems. We report here on a strong anticorrelation of orbital eccentricity with multiplicity (number of planets in the system) among cataloged radial velocity (RV) systems. The mean, median, and rough distribution of eccentricities of Solar System planets fits an extrapolation of this anticorrelation to the eight-planet case rather precisely despite the fact that no more than two Solar System planets would be detectable with RV data comparable to that in the exoplanet sample. Moreover, even if regarded as a single or double planetary system, the Solar System lies in a reasonably heavily populated region of eccentricity−multiplicity space. Thus, the Solar System is not anomalous among known exoplanetary systems with respect to eccentricities when its multiplicity is taken into account. Specifically, as the multiplicity of a system increases, the eccentricity decreases roughly as a power law of index –1.20. A simple and plausible but ad hoc and model-dependent interpretation of this relationship implies that ∼80% of the one-planet and 25% of the two-planet systems in our sample have additional, as yet undiscovered, members but that systems of higher observed multiplicity are largely complete (i.e., relatively rarely contain additional undiscovered planets). If low eccentricities indeed favor high multiplicities, habitability may be more common in systems with a larger number of planets. PMID:25512527

  11. Exoplanet orbital eccentricities derived from LAMOST-Kepler analysis

    Science.gov (United States)

    Xie, Ji-Wei; Dong, Subo; Zhu, Zhaohuan; Huber, Daniel; Zheng, Zheng; De Cat, Peter; Fu, Jianning; Liu, Hui-Gen; Luo, Ali; Wu, Yue; Zhang, Haotong; Zhang, Hui; Zhou, Ji-Lin; Cao, Zihuang; Hou, Yonghui; Wang, Yuefei; Zhang, Yong

    2016-10-01

    The nearly circular (mean eccentricity e¯≈0.06) and coplanar (mean mutual inclination i¯≈3°) orbits of the solar system planets motivated Kant and Laplace to hypothesize that planets are formed in disks, which has developed into the widely accepted theory of planet formation. The first several hundred extrasolar planets (mostly Jovian) discovered using the radial velocity (RV) technique are commonly on eccentric orbits (e¯≈0.3). This raises a fundamental question: Are the solar system and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown. By using the precise spectroscopic host star parameters from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) observations, we measure the eccentricity distributions for a large (698) and homogeneous Kepler planet sample with transit duration statistics. Nearly half of the planets are in systems with single transiting planets (singles), whereas the other half are multiple transiting planets (multiples). We find an eccentricity dichotomy: on average, Kepler singles are on eccentric orbits with e¯≈0.3, whereas the multiples are on nearly circular (e¯=0.04-0.04+0.03) and coplanar (i¯=1.4-1.1+0.8 degree) orbits similar to those of the solar system planets. Our results are consistent with previous studies of smaller samples and individual systems. We also show that Kepler multiples and solar system objects follow a common relation [×i¯] between mean eccentricities and mutual inclinations. The prevalence of circular orbits and the common relation may imply that the solar system is not so atypical in the galaxy after all.

  12. Voluntary attention increases perceived spatial frequency.

    Science.gov (United States)

    Abrams, Jared; Barbot, Antoine; Carrasco, Marisa

    2010-08-01

    Voluntary covert attention selects relevant sensory information for prioritized processing. The behavioral and neural consequences of such selection have been extensively documented, but its phenomenology has received little empirical investigation. Involuntary attention increases perceived spatial frequency (Gobell & Carrasco, 2005), but involuntary attention can differ from voluntary attention in its effects on performance in tasks mediated by spatial resolution (Yeshurun, Montagna, & Carrasco, 2008). Therefore, we ask whether voluntary attention affects the subjective appearance of spatial frequency--a fundamental dimension of visual perception underlying spatial resolution. We used a demanding rapid serial visual presentation task to direct voluntary attention and measured perceived spatial frequency at the attended and unattended locations. Attention increased the perceived spatial frequency of suprathreshold stimuli and also improved performance on a concurrent orientation discrimination task. In the control experiment, we ruled out response bias as an alternative account by using a lengthened interstimulus interval, which allows observers to disengage attention from the cued location. In contrast to the main experiment, the observers showed neither increased perceived spatial frequency nor improved orientation discrimination at the attended location. Thus, this study establishes that voluntary attention increases perceived spatial frequency. This phenomenological consequence links behavioral and neurophysiological studies on the effects of attention.

  13. Serial assessment of local peripheral vascular function after eccentric exercise.

    Science.gov (United States)

    Stacy, Mitchel R; Bladon, Kallie J; Lawrence, Jennifer L; McGlinchy, Sarah A; Scheuermann, Barry W

    2013-12-01

    Muscle damage is a common response to unaccustomed eccentric exercise; however, the effects of skeletal muscle damage on local vascular function and blood flow are poorly understood. This study examined serial local vascular responses to flow-mediated (endothelial-dependent) and nitroglycerin-mediated (endothelial-independent) dilation in the brachial artery after strenuous eccentric exercise and serially assessed resting blood flow. Ten healthy males performed 50 maximal eccentric unilateral arm contractions to induce muscle damage to the biceps brachii. Changes in maximal isometric strength and vascular responses were assessed 1, 24, 48, and 96 h after exercise. Mean blood velocities and arterial diameters, measured with Doppler ultrasound, were used to calculate blood flow and shear stress (expressed as area under the curve). Eccentric exercise resulted in impaired maximal isometric strength for up to 96 h (p exercise, 9.4% ± 2.6%; 1 h after exercise, 5.1% ± 2.2%) and nitroglycerin responses (before exercise, 26.3% ± 6.5%; 1 h after exercise, 20.7% ± 4.7%) were observed in the 1 h after exercise and remained lower for 96 h (p exercise and remained impaired for 48 h (p eccentric exercise leads to impaired local endothelial and vascular smooth muscle function. Lower shear stress after exercise might contribute to the observed reduction in flow-mediated dilation responses, but the mechanism responsible for the attenuated endothelial-independent vasodilation remains unclear.

  14. Eccentric error and compensation in rotationally symmetric laser triangulation

    Institute of Scientific and Technical Information of China (English)

    Wang Lei; Gao Jun; Wang Xiaojia; Johannes Eckstein; Peter Ott

    2007-01-01

    Rotationally symmetric triangulation (RST) sensor has more flexibility and less uncertainty limits becauseof the abaxial rotationally symmetric optical system.But if the incident laser is eccentric,the symmetry of the imagewill descend,and it will result in the eccentric error especially when some part of the imaged ring is blocked.Themodel of rotationally symmetric triangulation that meets the Schimpflug condition is presented in this paper.The errorfrom eccentric incident 1aser is analysed.It iS pointed out that the eccentric error is composed of two parts.one is acosine in circumference and proportional to the eccentric departure factor,and the other is a much smaller quadricfactor of the departure.When the ring is complete,the first error factor is zero because it is integrated in whole ring,but if some part of the ring iS blocked,the first factor will be the main error.Simulation verifies the result of the a-nalysis.At last,a compensation method to the error when some part of the ring is lost is presented based on neuralnetwork.The results of experiment show that the compensation will make the absolute maximum error descend tohalf,and the standard deviation of error descends to 1/3.

  15. Temporary Capture of Asteroids by an Eccentric Planet

    Science.gov (United States)

    Higuchi, A.; Ida, S.

    2017-04-01

    We have investigated the probability of temporary capture of asteroids in eccentric orbits by a planet in a circular or eccentric orbit through analytical and numerical calculations. We found that, in the limit of the circular orbit, the capture probability is ∼0.1% of encounters to the planet’s Hill sphere, independent of planetary mass and semimajor axis. In general, temporary capture becomes more difficult as the planet’s eccentricity ({e}{{p}}) increases. We found that the capture probability is almost independent of {e}{{p}} until a critical value ({e}{{p}}{{c}}) that is given by ≃5 times the Hill radius scaled by the planet’s semimajor axis. For {e}{{p}}> {e}{{p}}{{c}}, the probability decreases approximately in proportion to {e}{{p}}-1. The current orbital eccentricity of Mars is several times larger than {e}{{p}}{{c}}. However, since the range of secular change in Martian eccentricity overlaps {e}{{p}}{{c}}, the capture of minor bodies by Mars in the past is not ruled out.

  16. Effects of age and eccentricity on visual target detection

    Directory of Open Access Journals (Sweden)

    Nicole eGruber

    2014-01-01

    Full Text Available The aim of this study was to examine the effects of aging and target eccentricity on a visual search task comprising 30 images of everyday life projected into a hemisphere, realizing a ± 90° visual field. The task performed binocularly allowed participants to freely move their eyes to scan images for an appearing target or distractor stimulus (presented at 10°; 30°, and 50° eccentricity. The distractor stimulus required no response, while the target stimulus required acknowledgment by pressing the response button. 117 healthy subjects (mean age=49.63 years, SD=17.40 years, age range 20-78 years were studied. The results show that target detection performance decreases with age as well as with increasing eccentricity, especially for older subjects. Reaction time also increases with age and eccentricity, but in contrast to target detection, there is no interaction between age and eccentricity. Eye movement analysis showed that younger subjects exhibited a passive search strategy while older subjects exhibited an active search strategy probably as a compensation for their reduced peripheral detection performance.

  17. From Voluntary Collective Action to Organized Collaboration?

    DEFF Research Database (Denmark)

    Hattke, Fabian; Blaschke, Steffen; Frost, Jetta

    2016-01-01

    internationalization. Based on our results, we suggest that, depending on the field of action, voluntary collective action and organized collaboration are substitutes with regard to performance. Our study contributes to the literature on collective action and to research on public organizations in pluralistic......Our study examines the relationship between voluntary collective action, organized collaboration, and the provision of public goods in pluralistic organizations. Using German higher education as a context, we investigate whether specialized central support structures contribute to performance...... in three fields of action: the training of young scientists, internationalization, and gender diversity. The findings indicate that organized collaboration may lead to improved performance in the training of young scientists and gender diversity. Conversely, voluntary collective action enhances...

  18. Voluntary reporting of greenhouse gases, 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The Voluntary Reporting Program for greenhouse gases is part of an attempt by the U.S. Government to develop innovative, low-cost, and nonregulatory approaches to limit emissions of greenhouse gases. It is one element in an array of such programs introduced in recent years as part of the effort being made by the United States to comply with its national commitment to stabilize emissions of greenhouse gases under the Framework Convention on Climate Change. The Voluntary Reporting Program, developed pursuant to Section 1605(b) of the Energy Policy Act of 1992, permits corporations, government agencies, households, and voluntary organizations to report to the Energy Information Administration (EIA) on actions taken that have reduced or avoided emissions of greenhouse gases.

  19. Investigating Dynamics of Eccentricity in Turbomachines

    Science.gov (United States)

    Baun, Daniel

    2010-01-01

    A methodology (and hardware and software to implement the methodology) has been developed as a means of investigating coupling between certain rotordynamic and hydrodynamic phenomena in turbomachines. Originally, the methodology was intended for application in an investigation of coupled rotordynamic and hydrodynamic effects postulated to have caused high synchronous vibration in the space shuttle s high-pressure oxygen turbopump (HPOTP). The methodology can also be applied in investigating (for the purpose of developing means of suppressing) undesired hydrodynamic rotor/stator interactions in turbomachines in general. The methodology and the types of phenomena that can be investigated by use of the methodology are best summarized by citing the original application as an example. In that application, in consideration of the high synchronous vibration in the space-shuttle main engine (SSME) HPOTP, it was determined to be necessary to perform tests to investigate the influence of inducer eccentricity and/or synchronous whirl motion on inducer hydrodynamic forces under prescribed flow and cavitation conditions. It was believed that manufacturing tolerances of the turbopump resulted in some induced runout of the pump rotor. Such runout, if oriented with an inducer blade, would cause that blade to run with tip clearance smaller than the tip clearances of the other inducer blades. It was hypothesized that the resulting hydraulic asymmetry, coupled with alternating blade cavitation, could give rise to the observed high synchronous vibration. In tests performed to investigate this hypothesis, prescribed rotor whirl motions have been imposed on a 1/3-scale water-rig version of the SSME LPOTP inducer (which is also a 4-biased inducer having similar cavitation dynamics as the HPOTP) in a magnetic-bearing test facility. The particular magnetic-bearing test facility, through active vibration control, affords a capability to impose, on the rotor, whirl orbits having shapes and

  20. BMD in elite female triathletes is related to isokinetic peak torque without any association to sex hormone concentrations

    DEFF Research Database (Denmark)

    Wulff Helge, E; Melin, Anna Katarina; Waaddegaard, M

    2012-01-01

    Female endurance athletes suffering from low energy availability and reproductive hormonal disorders are at risk of low BMD. Muscle forces acting on bone may have a reverse site-specific effect. Therefore we wanted to test how BMD in female elite triathletes was associated to isokinetic peak torque...

  1. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    Science.gov (United States)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  2. Isokinetic muscle performance and salivary immune-endocrine responses in handball players by Fourier transform infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    P.C. Caetano Júnior

    2017-09-01

    Conclusions: The handball players had good muscle performance of the lower limbs in the isokinetic evaluation. The Fourier transform infrared spectroscopy analysis identified the main absorption bands of cortisol and salivary cortisol and immunoglobulin A, as well as playing positions that demand higher stress levels, through changes of bands related to salivary cortisol.

  3. Effects of Two Warm-up Programs on Balance and Isokinetic Strength in Male High School Soccer Players.

    Science.gov (United States)

    Ghareeb, Dana M; McLaine, Alice J; Wojcik, Janet R; Boyd, Joni M

    2017-02-01

    Ghareeb, DM, McLaine, AJ, Wojcik, JR, and Boyd, JM. Effects of two warm-up programs on balance and isokinetic strength in male high school soccer players. J Strength Cond Res 31(2): 372-379, 2017-One of the most common warm-up programs used to prevent injury in soccer, FIFA11+, integrates aerobic, strength, and balance. The purpose of this study was to compare FIFA11+ to a new warm-up program (NWP) on balance and isokinetic strength of the quadriceps and hamstrings at 60, 180, and 300°·s in male high school soccer players. Participants at one school (n = 17) performed the NWP before practice for 6 weeks during one soccer season, whereas participants at another school (n = 17) performed FIFA11+. There were no differences at baseline. At posttest, players in NWP significantly improved (p 1.3. No changes were seen in FIFA11+. Isokinetic strength peak torque increased at 60°·s in the quadriceps and hamstrings in dominant and nondominant legs in NWP (p soccer conditioning by improving balance and isokinetic strength.

  4. BMD in elite female triathletes is related to isokinetic peak torque without any association to sex hormone concentrations

    DEFF Research Database (Denmark)

    Helge, Eva Wulff; Melin, Anna; Waaddegaard, Mette

    2012-01-01

    Female endurance athletes suffering from low energy availability and reproductive hormonal disorders are at risk of low BMD. Muscle forces acting on bone may have a reverse site-specific effect. Therefore we wanted to test how BMD in female elite triathletes was associated to isokinetic peak torq...

  5. Hemochromatosis Patients as Voluntary Blood Donors

    Directory of Open Access Journals (Sweden)

    Tara E Power

    2004-01-01

    Full Text Available The present study was designed to investigate hemochromatosis patients' suitability as blood donors as well as their perceptions and experience with the current public donation system. Participants were gathered from a list of current hemochromatosis patients (n=120 and members of the Canadian Hemochromatosis Society (n=1000. Of the 1120 surveys mailed out to these groups, 801 surveys were returned completed. The sample respondents had a mean age of 57.44 years (SD=12.73; range 19 to 87 years, and 57% were men. It was found that 20% (160 of the respondents have donated blood since their diagnosis; however, only 12% of the respondents indicated that they use voluntary blood donation as a means of maintaining their iron levels. Forty per cent of the respondents indicated that they had been refused from voluntary donation. Despite the fact that in May 2001 the Canadian Blood Services, in collaboration with the Canadian Hemochromatosis Society, began a promotion campaign to encourage hemochromatosis patients to become voluntary blood donors, the present study found that 15% of the respondents reported having been refused from the voluntary blood donation service due to the diagnosis of hemochromatosis. With respect to quality of life, it was found that individuals who donate blood were generally healthier with respect to physical functioning and bodily pain, however, these findings may indicate that hemochromatosis patients who are healthier are better able to donate at public blood banks, rather than that voluntary blood donation has an effect on the donors' physical functioning over phlebotomy clinic users. These study findings suggest that although there may be other medical factors limiting individuals from donating, hemochromatosis patients are interested in being voluntary blood donors and this potential resource is currently under-used.

  6. The institutional dynamics of voluntary organisations

    DEFF Research Database (Denmark)

    Aagaard, Peter

    this theoretical frame to analyse case studies of three voluntary organisations.  As a part of the analysis I describe four sets of institutional settings that can influence voluntary organisations ability to create institutional dynamic: institutionalization, moderation, self-organisation and loose-coupling....... organisations. I establish a theoretical frame of institutional dynamic, build primarily on J.G. March's theory on exploration and exploitation. I focus on two organisational arrangements drawn from the theory: The degree of strategic decision-making and the degree of diversity among the volunteers. I use...

  7. Effects of submaximal eccentric exercise on muscle activity at different elbow joint angles.

    Science.gov (United States)

    Kisiel-Sajewicz, Katarzyna; Jaskólska, Anna; Janecki, Damian; Andrzejewska, Renata; Marusiak, Jarosław; Jaskólski, Artur

    2014-01-01

    Our study aimed to determine whether electrical and mechanical factors contributing to acute or long-term maximal torque reduction and muscle soreness due to submaximal eccentric exercise (ECC) are elbow-joint-angle specific and to what extent the joint angle affects the contribution of antagonist coactivation to this torque reduction. Maximal isometric torque (MIT), muscle soreness assessment, agonist electromechanical activities, and antagonist coactivation during the maximal voluntary contraction (MVC) were measured at elbow joint angles of 60°, 90°, and 150° before ECC, immediately after exercise, and 24, 48, 72, and 120 hr after exercise. ECC causes an immediate decrease in MIT as well as increased antagonist coactivation at three angles. Antagonist coactivation returned to its baseline level at 24 hr regardless of joint angle. The most rapid torque recovery and the highest force level at which pain occurred were found after ECC at a joint angle of 60°. During the recovery period, no mechanomyographical changes were observed when measuring surface mechanomyography changes at three angles, while the electrical activity differed between angles.

  8. Xanthine oxidase in human skeletal muscle following eccentric exercise

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Frandsen, Ulrik; Orthenblad, N.

    1997-01-01

    1. The present study tested the hypothesis that the level of xanthine oxidase is elevated in injured human skeletal muscle in association with inflammatory events. Seven male subjects performed five bouts of strenuous one-legged eccentric exercise. Muscle biopsies from both the exercised and the ......1. The present study tested the hypothesis that the level of xanthine oxidase is elevated in injured human skeletal muscle in association with inflammatory events. Seven male subjects performed five bouts of strenuous one-legged eccentric exercise. Muscle biopsies from both the exercised...... the increase in xanthine oxidase in the muscle there were no detectable changes in the levels of muscle malondialdehyde or in plasma antioxidant capacity up to 4 days post-exercise. 5. It is concluded that eccentric exercise leads to an increased level of xanthine oxidase in human muscle and that the increase...

  9. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    Science.gov (United States)

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high intensity isokinetic fatigue test. In addition to provide sport scientists and coaches with measures of peak torque and ratios between agonists and antagonists muscles in a perspective of injury prevention, isokinetic dynamometry can also be used in the physiological assessment of athletes. However, some precautions should be taken in the interpretation of data. PMID:26957935

  10. Research on the Development of the Isokinetic Training Devices%等动训练器的开发研究

    Institute of Scientific and Technical Information of China (English)

    程桢; 王国凡

    2015-01-01

    研究运用机械传动原理,通过对变速自行车变速系统(档位)的改进和加入等动控制装置,使其实现“等动运动”;继而设计和制造出等动训练器。其工作原理:(1)将由传统训练器械的杠铃片产生的重量阻力替换为档位阻力,从而使训练者训练更加安全,也缩小了较多杠铃片所占的体积;(2)设计出的等动训练器可以灵活移动、安装,便于携带;(3)设计出的等动训练器可以通过移动固定点、安装变向滑轮、安装不同的手拉杆、套绳等,实现人体多部位的综合训练目的。%By using the principle of mechanical drive, based on the bicycle transmission system improvement and addition of Isokinetic control device, makes it realize“Isokinetic movement”and then design and manufacture Isokinetic training device. (1) It works mainly through repl-acing the traditional weight resistance produced by the barbell training apart-us forger resistance, so that the trainer more security and also narrowed more volume; (2) The Isokinetic training devices can move flexibly, installation, easy to carry; (3) Design of the Isokinetic training devices can move through a fixed point, install the turning pulley, install the different hand pull rod, rope etc, realize the human body parts comprehensive training objective.

  11. Arthroscopically assisted combined anterior and posterior cruciate ligament reconstruction with autologous hamstring grafts-isokinetic assessment with control group.

    Directory of Open Access Journals (Sweden)

    Tomasz Piontek

    Full Text Available OBJECTIVE: The aim of the study was to: 1 evaluate the differences in pre-post operative knee functioning, mechanical stability, isokinetic knee muscle strength in simultaneous arthroscopic patients after having undergone an anterior cruciate ligament (ACL and the posterior cruciate ligament (PCL with hamstring tendons reconstruction, 2 compare the results of ACL/PCL patients with the control group. DESIGN: Controlled Laboratory Study. MATERIALS AND METHODS: Results of 11 ACL/PCL patients had been matched with 22 uninjured control participants (CP. Prior to surgery, and minimum 2 years after it, functional assessment (Lysholm and IKDC 2000, mechanical knee joint stability evaluation (Lachman and "drawer" test and isokinetic tests (bilateral knee muscle examination had been performed. Different rehabilitation exercises had been used: isometric, passive exercises, exercises increasing the range of motion and proprioception, strength exercises and specific functional exercises. RESULTS: After arthroscopy no significant differences had been found between the injured and uninjured leg in all isokinetic parameters in ACL/PCL patients. However, ACL/PCL patients had still shown significantly lower values of strength in relative isokinetic knee flexors (p = 0.0065 and extensors (p = 0.0171 compared to the CP. There were no differences between groups regarding absolute isokinetic strength and flexors/extensors ratio. There was statistically significant progress in IKDC 2000 (p = 0.0044 and Lysholm (p = 0.0044 scales prior to (44 and 60 points respectively and after the reconstruction (61 for IKDC 2000 and 94 points for Lysholm. CONCLUSIONS: Although harvesting tendons of semitendinosus and/or gracilis from the healthy extremity diminishes muscle strength of knee flexors in comparison to the CP, flexor strength had improved. Statistically significant improvement of the knee extensor function may indicate that the recreation of joint mechanical stability is

  12. Isokinetic and isometric muscle function of the knee extensors and flexors during simulated soccer activity: effect of exercise and dehydration.

    Science.gov (United States)

    Ali, Ajmol; Williams, Clyde

    2013-01-01

    This study investigated the influence of dehydration during soccer-type intermittent exercise on isokinetic and isometric muscle function. Eight soccer players performed two 90-min high-intensity intermittent shuttle-running trials without (NF) or with (FL) fluid ingestion (5 ml · kg(-1) before and 2 ml · kg(-1) every 15 min). Isokinetic and isometric strength and muscular power of knee flexors and knee extensors were measured pre-exercise, at half-time and post-exercise using isokinetic dynamometry. Sprint performance was monitored throughout the simulated-soccer exercise. Isokinetic knee strength was reduced at faster (3.13 rad · s(-1); P = 0.009) but not slower (1.05 rad · s(-1); P = 0.063) contraction speeds with exercise; however, there was no difference between FL and NF. Peak isometric strength of the knee extensors (P = 0.002) but not the knee flexors (P = 0.065) was significantly reduced with exercise with no difference between FL and NF. Average muscular power was reduced over time at both 1.05 rad · s(-1) (P = 0.01) and 3.14 rad · s(-1) (P = 0.033) but was not different between FL and NF. Mean 15-m sprint time increased with duration of exercise (P = 0.005) but was not different between FL and NF. In summary, fluid ingestion during 90 min of soccer-type exercise was unable to offset the reduction in isokinetic and isometric strength and muscular power of the knee extensors and flexors.

  13. Protective effect by maximal isometric contractions against maximal eccentric exercise-induced muscle damage of the knee extensors.

    Science.gov (United States)

    Tseng, Kuo-Wei; Tseng, Wei-Chin; Lin, Ming-Ju; Chen, Hsin-Lian; Nosaka, Kazunori; Chen, Trevor C

    2016-01-01

    This study investigated whether maximal voluntary isometric contractions (MVIC) performed before maximal eccentric contractions (MaxEC) would attenuate muscle damage of the knee extensors. Untrained men were placed to an experimental group that performed 6 sets of 10 MVIC at 90° knee flexion 2 weeks before 6 sets of 10 MaxEC or a control group that performed MaxEC only (n = 13/group). Changes in muscle damage markers were assessed before to 5 days after each exercise. Small but significant changes in maximal voluntary concentric contraction torque, range of motion (ROM) and plasma creatine kinase (CK) activity were evident at immediately to 2 days post-MVIC (p < 0.05), but other variables (e.g. thigh girth, myoglobin concentration, B-mode echo intensity) did not change significantly. Changes in all variables after MaxEC were smaller (p < 0.05) by 45% (soreness)-67% (CK) for the experimental than the control group. These results suggest that MVIC conferred potent protective effect against MaxEC-induced muscle damage.

  14. Eccentric exercise as an adjuvant to influenza vaccination in humans.

    Science.gov (United States)

    Edwards, Kate M; Burns, Victoria E; Allen, Louise M; McPhee, Jamie S; Bosch, Jos A; Carroll, Douglas; Drayson, Mark; Ring, Christopher

    2007-02-01

    The immune response to vaccination in animals can be enhanced by exposure to acute stress at the time of vaccination. The efficacy of this adjuvant strategy for vaccination in humans requires investigation. The current study employed a randomised controlled trial design to examine the effects of eccentric exercise prior to influenza vaccination on the antibody and cell-mediated responses. Sixty young healthy adults (29 men, 31 women) performed eccentric contractions of the deltoid and biceps brachii muscles of the non-dominant arm (exercise group) or rested quietly (control group), and were vaccinated 6h later in the non-dominant arm. Change in arm circumference and pain were measured to assess the physiological response to exercise. Antibody titres were measured pre-vaccination and at 6- and 20-week follow-ups. Interferon-gamma in response to in vitro stimulation by the whole vaccine, an index of the cell-mediated response, was measured 8 weeks post-vaccination. Interferon-gamma responses were enhanced by exercise in men, whereas antibody titres were enhanced by eccentric exercise in women but not in men. Men showed greater increase in arm circumference after eccentric exercise than women but there was no difference in reported pain. The interferon-gamma response was positively associated with the percentage increase in arm circumference among the exercise group. Eccentric exercise exerted differential effects on the response to vaccination in men and women, with enhancement of the antibody response in women, but enhancement of the cell-mediated response in men. Eccentric exercise of the muscle at the site of vaccine administration should be explored further as a possible behavioural adjuvant to vaccination.

  15. Hot Jupiters from Coplanar High-eccentricity Migration

    Science.gov (United States)

    Petrovich, Cristobal

    2015-05-01

    We study the possibility that hot Jupiters (HJs) are formed through the secular gravitational interactions between two planets in eccentric orbits with relatively low mutual inclinations (≲ 20{}^\\circ ) and friction due to tides raised on the planet by the host star. We term this migration mechanism Coplanar High-eccentricity Migration (CHEM) because, like disk migration, it allows for migration to occur on the same plane in which the planets formed. CHEM can operate from the following typical initial configurations: (i) the inner planet in a circular orbit and the outer planet with an eccentricity ≳ 0.67 for {{m}in}/{{m}out}{{({{a}in}/{{a}out})}1/2}≲ 0.3; (ii) two eccentric (≳ 0.5) orbits for {{m}in}/{{m}out}{{({{a}in}/{{a}out})}1/2}≲ 0.16. A population synthesis study of hierarchical systems of two giant planets using the observed eccentricity distribution of giant planets shows that CHEM produces HJs with low stellar obliquities (≲ 30{}^\\circ ), with a semi-major axis distribution that matches the observations, and at a rate that can account for their observed occurrence. A different mechanism is needed to create large obliquity HJs, either a different migration channel or a mechanism that tilts the star or the protoplanetary disk. CHEM predicts that HJs should have distant (a≳ 5 AU) and massive (most likely ˜1-3 times more massive than the HJ) companions with relatively low mutual inclinations (≲ 20{}^\\circ ) and moderately high eccentricities (e˜ 0.2-0.5).

  16. On the Eccentricity Excitation in Post-main-sequence Binaries

    Science.gov (United States)

    Rafikov, Roman R.

    2016-10-01

    Several classes of stellar binaries with post-main-sequence (post-MS) components—millisecond pulsars with the white dwarf companions (MSP+WD) and periods of {P}b∼ 30 days, binaries hosting post-asymptotic giant branch stars, or barium stars with {P}b ∼ several years—feature high eccentricities (up to 0.4) despite the expectation of their efficient tidal circularization during their post-MS evolution. It was suggested that the eccentricities of these binaries can be naturally excited by their tidal coupling to the circumbinary disk, formed by the material ejected from the binary. Here we critically reassess this idea using simple arguments rooted in the global angular momentum conservation of the disk+binary system. Compared to previous studies, we (1) fully account for the viscous spreading of the circumbinary disk, (2) consider the possibility of reaccretion from the disk onto the binary (in agreement with simulations and empirical evidence), and (3) allow for the reduced viscosity after the disk expands, cools, and forms dust. These ingredients conspire to significantly lower the efficiency of eccentricity excitation by the disk tides. We find that explaining eccentricities of the post-MS binaries is difficult and requires massive (≳ {10}-2 {M}ȯ ), long-lived (≳ {10}5 years) circumbinary disks that do not reaccrete. While disk tides may account for the eccentricities of the MSP+WD binaries, we show reaccretion to also be detrimental for these systems. Reduced efficiency of the disk-driven excitation motivates the study of alternative mechanisms for producing the peculiar eccentricities of the post-MS binaries.

  17. Eccentric contractions lead to myofibrillar dysfunction in muscular dystrophy.

    Science.gov (United States)

    Blaauw, Bert; Agatea, Lisa; Toniolo, Luana; Canato, Marta; Quarta, Marco; Dyar, Kenneth A; Danieli-Betto, Daniela; Betto, Romeo; Schiaffino, Stefano; Reggiani, Carlo

    2010-01-01

    It is commonly accepted that skeletal muscles from dystrophin-deficient mdx mice are more susceptible than those from wild-type mice to damage from eccentric contractions. However, the downstream mechanisms involved in this enhanced force drop remain controversial. We studied the reduction of contractile force induced by eccentric contractions elicited in vivo in the gastrocnemius muscle of wild-type mice and three distinct models of muscle dystrophy: mdx, alpha-sarcoglycan (Sgca)-null, and collagen 6A1 (Col6a1)-null mice. In mdx and Sgca-null mice, force decreased 35% compared with 14% in wild-type mice. Drop of force in Col6a1-null mice was comparable to that in wild-type mice. To identify the determinants of the force drop, we measured force generation in permeabilized fibers dissected from gastrocnemius muscle that had been exposed in vivo to eccentric contractions and from the contralateral unstimulated muscle. A force loss in skinned fibers after in vivo eccentric contractions was detectable in fibers from mdx and Sgca-null, but not wild-type and Col6a1-null, mice. The enhanced force reduction in mdx and Sgca-null mice was observed only when eccentric contractions were elicited in vivo, since eccentric contractions elicited in vitro had identical effects in wild-type and dystrophic skinned fibers. These results suggest that 1) the enhanced force loss is due to a myofibrillar impairment that is present in all fibers, and not to individual fiber degeneration, and 2) the mechanism causing the enhanced force reduction is active in vivo and is lost after fiber permeabilization.

  18. Effects from Periastron Advance of Eccentric Binary Stars

    Institute of Scientific and Technical Information of China (English)

    李瑾; 仲元红; 潘宇

    2012-01-01

    In this paper,we discuss the coefficients of Gravitational waveform due to eccentric binaries periastron advance with evolved eccentricity.For the basic harmonic modes(n ≤ 5),the frequency split and corresponding relative strengths in the spectrum are figured out.Taking the well known binary systems PSRB 1913+16 and PSRB 1534+12 as examples,we study the dominant harmonic and its frequency split caused by periastron advance in the spectra,and give an estimation of detectability for PSRB 1913+16 and PSRB 1534+12,which are the promising targets for space observatories of gravitational wave.

  19. Transmission line resonance technique for eccentric core optical fibers

    Science.gov (United States)

    Georgantzos, E.; Boucouvalas, A. C.

    2016-12-01

    In several cases optical fibers in telecommunications have cores of non circular geometry. Fibre optic deformations appear in optical fibres for many reasons. Optical fibre core ellipticity for example where the fibre optic core is not perfectly circular due to fibre optic manufacturing tolerances, is measured and often is a problem. Optical fibre core eccentricity, where the fibre core is not on the axis of the fibre, but it is offset by a small length. This is another issue and very important for ensuring performance low loss splices and connector losses. Both of ellipticity and eccentricity are specified in accordance to international standards for fibre optic manufacturing telecommunications grade fibres. The present paper studies ellipticity and core eccentricity specifically and presents a new method for analysing their effect. We present an extension of the transmission line technique as a means of studying such fibers and deriving necessary parameters. Conformal mapping on the other hand is a simple mathematical tool by which we can generate sets of orthogonal two-dimensional coordinate systems. Shortly a conformal map of Cartesian two-dimensional space is defined by any analytical function W(z) where z, w, are: z = x + jy, W = θ + j φ The function deriving by the conformal mapping transformation h(θ ,φ )=| ∂w/∂z | = 1/|∂z/∂w|, can be used in order to define ∇A → and ∇×A → where A → is the magnetic or electric field in the derived orthogonal coordinate system. Useful conformal maps for fiber optics applications should have the property that the equation θ(x, y) = constant, is forming closed curves in a Cartesian two-dimensional space (x,y). If θ(x, y) = constant represents a set of co-eccentric circles, we obtain the normal case of conventional fibers with circular cores. If θ(x, y) = constant represents a set of eclipses, we are have the formation of elliptic core optical fibers. If θ(x, y) = constant represents a set of

  20. A complete waveform model for compact binaries on eccentric orbits

    Science.gov (United States)

    Huerta, Eliu; Agarwal, Bhanu; George, Daniel; Kumar, Prayush

    2016-03-01

    The detection of compact binaries with significant eccentricity in the sensitivity band of gravitational wave detectors will provide critical insights on the dynamics and formation channels of these events. In order to search for these systems and place constraints on their rates, we present an inspiral-merger-ringdown time domain waveform model that describes the GW emission from compact binaries on orbits with low to moderate values of eccentricity. We use this model to explore the detectability of these events in the context of advanced LIGO.

  1. 77 FR 72941 - Voluntary Education Programs

    Science.gov (United States)

    2012-12-07

    ... decision will be made by the selected DoD contractor for the complete `third party review' process. Comment... seeks to enhance the educational opportunities to Service members who may have difficulty in completing... transitions to second careers in teaching. Voluntary education programs. Continuing, adult, or...

  2. Decentralized trade with bargaining and voluntary matching

    DEFF Research Database (Denmark)

    Tranæs, Torben; Sloth, Birgitte; Hendon, Ebbe

    1994-01-01

    Rubinstein and Wolinsky (1990) study a market with one seller, two buyers, and voluntary matching. Both the competitive outcomepc and the bilateral bargaining outcomepb are possible in subgame perfect equilibrium. We consider two variations. First, if there is a cost larger thanpc−pc to the seller...

  3. Social orienting: reflexive versus voluntary control.

    Science.gov (United States)

    Hill, Julia L; Patel, Saumil; Gu, Xue; Seyedali, Nassim S; Bachevalier, Jocelyne; Sereno, Anne B

    2010-09-24

    Many studies have shown that the direction of gaze of a face covertly facilitates the response to a target presented in the matching direction. In this study we seek to determine whether there exist separate reflexive and voluntary forms of such covert social orienting and how they interact with each other. We measured the effect of the predictive value of a gaze cue on manual choice reaction times. When the predictive value of the gaze cue was zero, a facilitatory cueing effect was still observed which peaked at a cue onset to target onset delay (CTD) of 150ms and largely diminished beyond a CTD of 500ms. When the gaze cue was 100% predictive of the future location of the target, at CTDs greater than 200, the predictive cue resulted in a significantly greater facilitation of response than occurred with a non-predictive cue. These results suggest that given enough time (about 200ms), the social cue is interpreted and a willful or voluntary spatially-specific social cueing effect occurs. In addition, we found that a predictive cue resulted in a significant slowing of the observer's responses up to a CTD of 200ms. These findings show that, similar to non-social spatial orienting, there appear to be two forms of social orienting including a reflexive component and voluntary component. We suggest a model of social orienting in which the voluntary social orienting system modulates tonic inhibition of the reflexive social orienting system. Published by Elsevier Ltd.

  4. Equality, self‐respect and voluntary separation

    NARCIS (Netherlands)

    M.S. Merry

    2012-01-01

    This paper argues that self‐respect constitutes an important value, and further, an important basis for equality. It also argues that under conditions of inequality‐producing segregation, voluntary separation in schooling may be more likely to provide the resources necessary for self‐respect. A prim

  5. School Ethical Climate and Teachers' Voluntary Absence

    Science.gov (United States)

    Shapira-Lishchinsky, Orly; Rosenblatt, Zehava

    2010-01-01

    Purpose: This paper aims to offer a theoretical framework for linking school ethical climate with teachers' voluntary absence. The paper attempts to explain this relationship using the concept of affective organizational commitment. Design/methodology/approach: Participants were 1,016 school teachers from 35 high schools in Israel. Data were…

  6. Voluntary Oral Administration of Losartan in Rats.

    Science.gov (United States)

    Diogo, Lucília N; Faustino, Inês V; Afonso, Ricardo A; Pereira, Sofia A; Monteiro, Emília C; Santos, Ana I

    2015-09-01

    Gavage is a widely performed technique for daily dosing in laboratory rodents. Although effective, gavage comprises a sequence of potentially stressful procedures for laboratory animals that may introduce bias into experimental results, especially when the drugs to be tested interfere with stress-dependent parameters. We aimed to test vehicles suitable for drug delivery by voluntary ingestion in rats. Specifically, Male Wistar rats (age, 2 to 3 mo) were used to test nut paste (NUT), peanut butter (PB), and sugar paste (SUG) as vehicles for long-term voluntary oral administration of losartan, an angiotensin II receptor blocker. Vehicles were administered for 28 d without drug to assess effects on the glucose level and serum lipid profile. Losartan was mixed with vehicles and either offered to the rats or administered by gavage (14 d) for subsequent quantification of losartan plasma levels by HPLC. After a 2-d acclimation period, all rats voluntarily ate the vehicles, either alone or mixed with losartan. NUT administration reduced blood glucose levels. The SUG group had higher concentrations of losartan than did the gavage group, without changes in lipid and glucose profiles. Our results showed that NUT, PB, and SUG all are viable for daily single-dose voluntary ingestion of losartan and that SUG was the best alternative overall. Drug bioavailability was not reduced after voluntary ingestion, suggesting that this method is highly effective for chronic oral administration of losartan to laboratory rodents.

  7. Staff's perceptions of voluntary assertiveness skills training.

    Science.gov (United States)

    McVanel, Sarah; Morris, Beth

    2010-01-01

    Clinicians' ability to be assertive when unsure or concerned about procedures, treatment modalities, or patients' symptoms is key in reducing risk and preventing sentinel events. In this article, the authors provide a framework for generic, voluntary assertiveness communication skills workshops that any educator can implement.

  8. Voluntary Organizations: Commitment, Leadership, and Organizational Effectiveness

    Science.gov (United States)

    Ekeland, Terry P.

    2004-01-01

    Voluntary organizations offer a unique opportunity to interpret participant relationships, leadership influences, and organizational effectiveness unencumbered by employment relationships. Regardless of organizational structure or purpose, all organizations are affected to some degree by their leadership and their membership. Based on the…

  9. Environmental Voluntary Agreements in the Dutch Context

    NARCIS (Netherlands)

    Bressers, Johannes T.A.; de Bruijn, Theo; Croci, Edoardo

    2005-01-01

    This paper describes and analyses the use of environmental voluntary agreements, or covenants, in Dutch environmental policy. Covenants have become a widely used policy instrument in the Netherlands. This trend reinforces the strong neo-corporatist traits of Dutch society with its tendency towards

  10. Voluntary Community Organisations in Metropolitan Development

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    While short-term enrolling of citizens in urban regeneration projects often has proven quite successful, permanent embedding of projects in voluntary community-based settings seems to be much more difficult to obtain. This has implications for long term sustainability of urban regeneration projec...

  11. Effect of kinesio taping on the isokinetic muscle function in football athletes with a knee injury.

    Science.gov (United States)

    Hong, SoonKwon; Shim, JeMyung; Kim, SungJoong; Namkoong, Seung; Roh, HyoLyun

    2016-01-01

    [Purpose] The purpose of this study was to determine the difference in isokinetic muscle function in football athletes with a knee injury with and without kinesio taping. [Subjects] The subjects for this study were 10 football athletes (males) with a knee injury. [Methods] Measurements were performed by using Cybex dynamometer under uniform motion before and after the application of kinesio tape to the quadriceps and hamstring muscle. Maximal concentric knee extension and flexion at three angular velocities (60°/s, 120°/s, and 180°/s) were measured. [Results] A significant difference was found in peak torque and total work of the flexion at 120°/s and 180°/s, as well as in the average power of extension at 180°/s. [Conclusion] Though it is not the main therapy for muscle function in football athletes with injury, kinesio taping was an effective adjunct therapy.

  12. Effect of stochastic modulation of inter-pulse interval during stimulated isokinetic leg extension

    Directory of Open Access Journals (Sweden)

    Efe Anil Aksöz

    2016-07-01

    Full Text Available Recumbent cycling exercise achieved by functional electrical stimulation (FES of the paralyzed leg muscles is effective for cardiopulmonary and musculoskeletal conditioning after spinal cord injury, but its full potential has not yet been realized. Mechanical power output and efficiency is very low and endurance is limited due to early onset of muscle fatigue. The aim of this work was to compare stochastic modulation of the inter-pulse interval (IPI to constant-frequency stimulation during an isokinetic leg extension task similar to FES-cycling. Seven able-bodied subjects participated: both quadriceps muscles were stimulated (n = 14 with two activation patterns (P1-constant frequency, P2-stochastic IPI. There was significantly higher power output with P2 during the first 30 s (p = 0.0092, the last 30 s (p = 0.018 and overall (p = 0.0057, but there was no overall effect on fatiguability when stimulation frequency was randomly modulated.

  13. Effect of Stochastic Modulation of Inter-Pulse Interval During Stimulated Isokinetic Leg Extension

    Science.gov (United States)

    Aksöz, Efe Anil; Laubacher, Marco; Binder-Macleod, Stuart; Hunt, Kenneth J.

    2016-01-01

    Recumbent cycling exercise achieved by functional electrical stimulation (FES) of the paralyzed leg muscles is effective for cardiopulmonary and musculoskeletal conditioning after spinal cord injury, but its full potential has not yet been realized. Mechanical power output and efficiency is very low and endurance is limited due to early onset of muscle fatigue. The aim of this work was to compare stochastic modulation of the inter-pulse interval (IPI) to constant-frequency stimulation during an isokinetic leg extension task similar to FES-cycling. Seven able-bodied subjects participated: both quadriceps muscles were stimulated (n = 14) with two activation patterns (P1-constant frequency, P2-stochastic IPI). There was significantly higher power output with P2 during the first 30 s (p = 0.0092), the last 30 s (p = 0.018) and overall (p = 0.0057), but there was no overall effect on fatiguability when stimulation frequency was randomly modulated. PMID:27990242

  14. Effect of kinesio taping on the isokinetic muscle function in football athletes with a knee injury

    Science.gov (United States)

    Hong, SoonKwon; Shim, JeMyung; Kim, SungJoong; Namkoong, Seung; Roh, HyoLyun

    2016-01-01

    [Purpose] The purpose of this study was to determine the difference in isokinetic muscle function in football athletes with a knee injury with and without kinesio taping. [Subjects] The subjects for this study were 10 football athletes (males) with a knee injury. [Methods] Measurements were performed by using Cybex dynamometer under uniform motion before and after the application of kinesio tape to the quadriceps and hamstring muscle. Maximal concentric knee extension and flexion at three angular velocities (60°/s, 120°/s, and 180°/s) were measured. [Results] A significant difference was found in peak torque and total work of the flexion at 120°/s and 180°/s, as well as in the average power of extension at 180°/s. [Conclusion] Though it is not the main therapy for muscle function in football athletes with injury, kinesio taping was an effective adjunct therapy. PMID:26957761

  15. Eligibility and Exclusion of Hemochromatosis Patients as Voluntary Blood Donors

    Directory of Open Access Journals (Sweden)

    M Levstik

    1998-01-01

    Full Text Available BACKGROUND: Hereditary hemochromatosis patients are excluded in many countries as voluntary blood donors. In 1991, changes in the Canadian Red Cross policy allowed healthy hemochromatosis patients to become voluntary donors.

  16. Results of the global survey on Voluntary Sustainability Standards

    OpenAIRE

    Lernoud, Julia

    2015-01-01

    Results of the global survey on Voluntary Sustainability Standards: - Voluntary Sustainability Standards (VSS) area worldwide and selected commodities - Cocoa: Area growth by VSS 2008-2014 - Growth of VSS compliant area worldwide 2008-2013 (selected crops)

  17. China Initiates Voluntary Certification of Public Security Products

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Reporters learned from the Certification and Accreditation Administration of China(CNCA)that burglar-proof door became the first batch of voluntary certification product in public security products.China has formally initiated voluntary certification of public security products.

  18. Voluntary sterilization in Serbia: Unmet need?

    Directory of Open Access Journals (Sweden)

    Rašević Mirjana M.

    2002-01-01

    Full Text Available Is voluntary sterilization as a birth control method accepted in Serbia? This is certainly a question that is being imposed for research, regardless of the fact that voluntary sterilization is neither accessible nor promoted. Most importantly because there is no understanding in the social nor political sphere for legalization of voluntary sterilization as a form of birth control, apart from the clear necessity for this, first, step. They are: the recognition that voluntary sterilization is an efficient and safe birth control method, respectability of basic human as well as sexual and reproductive rights, spreading of sterilization as a form of birth control among population of both developed and developing countries and an epidemic diffusion of repeated induced abortions in Serbia. Thus individual recognition of the advantages of relying on voluntary sterilization, in a non-encouraging atmosphere, certainly represents one more argument to enable couples to prevent conception by sterilization. Since it was impossible to carry out a representative research among the population of men and women who are at risk for conception, an attempt was made to obtain a reply to the set question among women who decided to induce abortion. It was done out of at least two reasons. The first being that women with induced abortion in their reproductive history were the target group for voluntary sterilization. The second reason was based on the assumption that bringing a decision on induced abortion is preceded by the reconsideration of an earlier adopted strategy regarding children, giving birth and contraception and thus its rational component is revealed more and therefore more easily measurable. The research was carried out in the University Clinic of Obstetrics and Gynecology 'Narodni front' in Belgrade from January 21st o March 1st 2002, and included 296 women. By comparing the social and demographic characteristics of the female respondents, as well as

  19. Analysis of isokinetic muscle function and postural control in individuals with intermittent claudication

    Directory of Open Access Journals (Sweden)

    Morgan Lanzarin

    2016-02-01

    Full Text Available BACKGROUND: Intermittent claudication (IC is a debilitating condition that mostly affects elderly people. IC is manifested by a decrease in ambulatory function. Individuals with IC present with motor and sensory nerve dysfunction in the lower extremities, which may lead to deficits in balance. OBJECTIVE: This study aimed to measure postural control and isokinetic muscle function in individuals with intermittent claudication. METHOD: The study included 32 participants of both genders, 16 IC participants (mean age: 64 years, SD=6 and 16 healthy controls (mean age: 67 years, SD=5, which were allocated into two groups: intermittent claudication group (ICG and control group (CG. Postural control was assessed using the displacement and velocity of the center of pressure (COP during the sensory organization test (SOT and the motor control test (MCT. Muscle function of the flexor and extensor muscles of the knee and ankle was measured by an isokinetic dynamometer. Independent t tests were used to calculate the between-group differences. RESULTS: The ICG presented greater displacement (p =0.027 and speed (p =0.033 of the COP in the anteroposterior direction (COPap during the MCT, as well as longer latency (p =0.004. There were no between-group differences during the SOT. The ICG showed decreased muscle strength and power in the plantar flexors compared to the CG. CONCLUSION: Subjects with IC have lower values of strength and muscle power of plantiflexores, as well as changes in postural control in dynamic conditions. These individuals may be more vulnerable to falls than healthy subjects.

  20. Effect of creatine supplementation during rapid body mass reduction on metabolism and isokinetic muscle performance capacity.

    Science.gov (United States)

    Oöpik, V; Pääsuke, M; Timpmann, S; Medijainen, L; Ereline, J; Smirnova, T

    1998-06-01

    Well-trained subjects (n = 6) were studied before and after losing a mean 3.0%-4.3% of body mass to determine whether muscle performance could be maintained or even enhanced by dietary creatine supplementation. During a 5-day period of loss of mass the subjects were randomly assigned to a creatine or placebo supplemented diet. All the subjects were measured before and after loss of mass on both supplements for isokinetic peak torque (PT) and work at peak torque (W(PT)) of knee extensors, also for intermittent high intensity working capacity of the same muscle group. The latter test consisted of submaximal isokinetic knee extensions at an angular velocity of 1.57 rad x s(-1) for 45 s at the rate of 30 contractions each min (submaximal work, Ws max) followed by 15-s maximal effort (maximal work, Wmax). Total duration of the test was 3 min. Haematocrit was measured and haemoglobin, ammonia, lactate, glucose and urea concentrations were analysed in blood samples obtained at rest and after cessation of muscle performance tests. The results indicated that creatine supplementation in comparison with placebo treatment during rapid body mass reduction may help to maintain muscle PT and W(PT)1 at high angular velocities, not influencing Wmax and the rate of fatigue development during Wmax, but affecting adversely Ws max. Within the limitations of the present study the reasons for the partially detrimental effect of creatine administration remain obscure, but it is suggested that impaired creatine uptake in muscle during body mass loss as well as creatine induced changes in muscle glucose and glycogen metabolism may be involved.

  1. Effects of photobiomodulation on the fatigue level in elderly women: an isokinetic dynamometry evaluation.

    Science.gov (United States)

    Vassão, P G; Toma, R L; Antunes, H K M; Tucci, H T; Renno, A C M

    2016-02-01

    Aging is responsible by a series of morphological and functional modifications that lead to a decline of muscle function, particularly in females. Muscle tissue in elderly people is more susceptible to fatigue and, consequently, to an increased inability to maintain strength and motor control. In this context, therapeutic approaches able of attenuating muscle fatigue have been investigated. Among these, the photobiomodulation demonstrate positive results to interacts with biological tissues, promoting the increase in cell energy production. Thus, the aim of this study was to investigate the effects of photobiomodulation (808 nm, 250 J/cm(2), 100 mW, 7 J each point) in the fatigue level and muscle performance in elderly women. Thirty subjects entered a crossover randomized double-blinded placebo-controlled trial. Photobiomodulation was delivered on the rectus femoris muscle of the dominant limb immediately before the fatigue protocol. In both sessions, peripheral muscle fatigue was analyzed by surface electromyography (EMG) and blood lactate analysis. Muscle performance was evaluated using an isokinetic dynamometer. The results showed that photobiomodulation was able of reducing muscle fatigue by a significant increase of electromyographic fatigue index (EFI) (p = 0.047) and decreasing significantly lactate concentration 6 min after the performance of the fatigue protocol (p = 0. 0006) compared the placebo laser session. However, the photobiomodulation was not able of increasing muscle performance measured by the isokinetic dynamometer. Thus, it can be conclude that the photobiomodulation was effective in reducing fatigue levels. However, no effects of photobiomodulation on muscle performance was observed.

  2. Measurement variability and sincerity of effort: clinical utility of isokinetic strength coefficient of variation scores.

    Science.gov (United States)

    Birmingham, T B; Kramer, J F; Speechley, M; Chesworth, B M; MacDermid, J

    1998-06-01

    Although the use of measures of strength variability as a means of judging sincerity of effort is becoming common practice, the accuracy of doing so has been questioned. Coefficient of variation (CV) cut-off points, indicating the upper limit of variability for repeated maximal efforts, are routinely used to identify workers providing submaximal efforts during various strength tests. However, the stability of the CV itself has not been considered when comparing an individual's observed CV score to these cut-off points. The purpose of the present study was to examine the day-to-day variability of the CV calculated from maximal isokinetic knee extension efforts, and to describe how this measurement error affects the accuracy of the CV as a distinguishing criterion between maximal and submaximal efforts. Thirty-one healthy males (mean age 25 +/- 4.5 years) completed three maximal and three submaximal isokinetic knee extension efforts on two separate occasions. Although submaximal CVs were significantly greater than maximal CVs (15.6 versus 3.7%; p < 0.01), there was considerable overlap between submaximal and maximal CV frequency distributions. More importantly, an individual observed CV could vary +/- 3.1% as a result of day-to-day variation or measurement error. This range in possible CV scores should be considered when comparing an individual's score to proposed cut-off points. Since individual CVs vary considerably from day-to-day, and since precise cut-off values distinguishing between maximal and submaximal conditions cannot be identified, CV scores must be interpreted cautiously, and the potential errors in relying extensively on this approach to identifying insincere efforts should be recognised.

  3. Progressive Resistance Exercise with Eccentric Loading for the Management of Knee Osteoarthritis

    National Research Council Canada - National Science Library

    Hernandez, Haniel J; McIntosh, Valerie; Leland, Azadeh; Harris-Love, Michael O

    2015-01-01

    .... The use of an eccentric training paradigm may prove to be beneficial for older adults with knee OA since eccentric muscle actions are involved in the energy absorption at the knee joint during gait...

  4. THE ROLE AND IMPLEMENTATION OF ECCENTRIC TRAINING IN ATHLETIC REHABILITATION: TENDINOPATHY, HAMSTRING STRAINS, AND ACL RECONSTRUCTION

    Science.gov (United States)

    Reiman, Michael

    2011-01-01

    The benefits and proposed physiological mechanisms of eccentric exercise have previously been elucidated and eccentric exercise has been used for well over seventy years. Traditionally, eccentric exercise has been used as a regular component of strength training. However, in recent years, eccentric exercise has been used in rehabilitation to manage a host of conditions. Of note, there is evidence in the literature supporting eccentric exercise for the rehabilitation of tendinopathies, muscle strains, and in anterior cruciate ligament (ACL) rehabilitation. The purpose of this Clinical Commentary is to discuss the physiologic mechanism of eccentric exercise as well as to review the literature regarding the utilization of eccentric training during rehabilitation. A secondary purpose of this commentary is to provide the reader with a framework for the implementation of eccentric training during rehabilitation of tendinopathies, muscle strains, and after ACL reconstruction. PMID:21655455

  5. Effects of transcranial magnetic stimulation during voluntary and non-voluntary stepping movements in humans.

    Science.gov (United States)

    Solopova, I A; Selionov, V A; Kazennikov, O V; Ivanenko, Y P

    2014-09-05

    Here, we compared motor evoked potentials (MEP) in response to transcranial magnetic stimulation of the motor cortex and the H-reflex during voluntary and vibration-induced air-stepping movements in humans. Both the MEPs (in mm biceps femoris, rectus femoris and tibialis anterior) and H-reflex (in m soleus) were significantly smaller during vibration-induced cyclic leg movements at matched amplitudes of angular motion and muscle activity. These findings highlight differences between voluntary and non-voluntary activation of the spinal pattern generator circuitry in humans, presumably due to an extra facilitatory effect of voluntary control/triggering of stepping on spinal motoneurons and interneurons. The results support the idea of active engagement of supraspinal motor areas in developing central pattern generator-modulating therapies. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Orbital Eccentricity and the Stability of Planets in the Alpha Centauri System

    Science.gov (United States)

    Lissauer, Jack

    2016-01-01

    Planets on initially circular orbits are typically more dynamically stable than planets initially having nonzero eccentricities. However, the presence of a major perturber that forces periodic oscillations of planetary eccentricity can alter this situation. We investigate the dependance of system lifetime on initial eccentricity for planets orbiting one star within the alpha Centauri system. Our results show that initial conditions chosen to minimize free eccentricity can substantially increase stability compared to planets on circular orbits.

  7. Moving from voluntary euthanasia to non-voluntary euthanasia: equality and compassion.

    Science.gov (United States)

    Amaraskekara, Kumar; Bagaric, Mirko

    2004-09-01

    The recent Dutch law legalising active voluntary euthanasia will reignite the euthanasia debate. An illuminating method for evaluating the moral status of a practice is to follow the implications of the practice to its logical conclusion. The argument for compassion is one of the central arguments in favour of voluntary active euthanasia. This argument applies perhaps even more forcefully in relation to incompetent patients. If active voluntary euthanasia is legalised, arguments based on compassion and equality will be directed towards legalising active non-voluntary euthanasia in order to make accelerated termination of death available also to the incompetent. The removal of discrimination against the incompetent has the potential to become as potent a catch-cry as the right to die. However, the legalisation of non-voluntary euthanasia is undesirable. A review of the relevant authorities reveals that there is no coherent and workable "best interests" test which can be invoked to decide whether an incompetent patient is better off dead. This provides a strong reason for not stepping onto the slippery path of permitting active voluntary euthanasia.

  8. 5 CFR 919.1020 - Voluntary exclusion or voluntarily excluded.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Voluntary exclusion or voluntarily excluded. 919.1020 Section 919.1020 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED...) Definitions § 919.1020 Voluntary exclusion or voluntarily excluded. (a) Voluntary exclusion means a person's...

  9. 37 CFR 351.2 - Voluntary negotiation period; settlement.

    Science.gov (United States)

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Voluntary negotiation period... CONGRESS COPYRIGHT ROYALTY JUDGES RULES AND PROCEDURES PROCEEDINGS § 351.2 Voluntary negotiation period..., the Copyright Royalty Judges will announce the beginning of a voluntary negotiation period and...

  10. 15 CFR 12.3 - Development of voluntary product standards.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Development of voluntary product... AND LABELING § 12.3 Development of voluntary product standards. (a) Invitation to participate in the development of a voluntary product standard. Whenever the Secretary publishes a final determination of...

  11. The effect of eccentricity and spatiotemporal energy on motion silencing.

    Science.gov (United States)

    Choi, Lark Kwon; Bovik, Alan C; Cormack, Lawrence K

    2016-01-01

    The now well-known motion-silencing illusion has shown that salient changes among a group of objects' luminances, colors, shapes, or sizes may appear to cease when objects move rapidly (Suchow & Alvarez, 2011). It has been proposed that silencing derives from dot spacing that causes crowding, coherent changes in object color or size, and flicker frequencies combined with dot spacing (Choi, Bovik, & Cormack, 2014; Peirce, 2013; Turi & Burr, 2013). Motion silencing is a peripheral effect that does not occur near the point of fixation. To better understand the effect of eccentricity on motion silencing, we measured the amount of motion silencing as a function of eccentricity in human observers using traditional psychophysics. Fifteen observers reported whether dots in any of four concentric rings changed in luminance over a series of rotational velocities. The results in the human experiments showed that the threshold velocity for motion silencing almost linearly decreases as a function of log eccentricity. Further, we modeled the response of a population of simulated V1 neurons to our stimuli. We found strong matches between the threshold velocities on motion silencing observed in the human experiment and those seen in the energy model of Adelson and Bergen (1985). We suggest the plausible explanation that as eccentricity increases, the combined motion-flicker signal falls outside the narrow spatiotemporal frequency response regions of the modeled receptive fields, thereby reducing flicker visibility.

  12. Eccentric or Concentric Exercises for the Treatment of Tendinopathies?

    DEFF Research Database (Denmark)

    Couppé, Christian; Svensson, René B; Silbernagel, Karin Grävare

    2015-01-01

    with respect to parameters like load magnitude, speed of movement, and recovery period between exercise sessions. Future studies should control for these loading parameters, evaluate various exercise dosages, and also think beyond isolated eccentric exercises to arrive at firm recommendations regarding...

  13. Gluon field fluctuations in nuclear collisions: Multiplicity and eccentricity distributions

    CERN Document Server

    Schenke, Björn; Venugopalan, Raju

    2013-01-01

    We discuss different sources of fluctuations in nuclear collisions and their realization in the IP-Glasma model. We present results for multiplicity distributions in p+p and p+A collisions and compare eccentricity distributions in A+A collisions to the flow harmonic distributions in 10 centrality classes measured by the ATLAS collaboration.

  14. A massive millisecond pulsar in an eccentric binary

    Science.gov (United States)

    Barr, E. D.; Freire, P. C. C.; Kramer, M.; Champion, D. J.; Berezina, M.; Bassa, C. G.; Lyne, A. G.; Stappers, B. W.

    2017-02-01

    The recent discovery of a population of eccentric (e ˜ 0.1) millisecond pulsar (MSP) binaries with low-mass white dwarf companions in the Galactic field represents a challenge to evolutionary models that explain MSP formation as recycling: All such models predict that the orbits become highly circularized during a long period of accretion. The members of this new population exhibit remarkably similar properties (orbital periods, eccentricities, companion masses, spin periods), and several models have been put forward that suggest a common formation channel. In this work, we present the results of an extensive timing campaign focusing on one member of this new population, PSR J1946+3417. Through the measurement of both the advance of periastron and the Shapiro delay for this system, we determine the mass of the pulsar, mass of the companion and the inclination of the orbit to be 1.828(22) M⊙, 0.2656(19) M⊙ and 76.4 ± 0.6 degrees, respectively, under the assumption that general relativity is the true description of gravity. Notably, this is the third highest mass measured for any pulsar. Using these masses and the astrometric properties of PSR J1946+3417, we examine three proposed formation channels for eccentric MSP binaries. While our results are consistent with circumbinary disc-driven eccentricity growth or neutron star to strange star phase transition, we rule out rotationally delayed accretion-induced collapse as the mechanism responsible for the configuration of the PSR J1946+3417 system.

  15. Effect of eccentric versus concentric exercise training on mitochondrial function.

    Science.gov (United States)

    Isner-Horobeti, Marie-Eve; Rasseneur, Laurence; Lonsdorfer-Wolf, Evelyne; Dufour, Stéphane Pascal; Doutreleau, Stéphane; Bouitbir, Jamal; Zoll, Joffrey; Kapchinsky, Sophia; Geny, Bernard; Daussin, Frédéric Nicolas; Burelle, Yan; Richard, Ruddy

    2014-11-01

    The effect of eccentric (ECC) versus concentric (CON) training on metabolic properties in skeletal muscle is understood poorly. We determined the responses in oxidative capacity and mitochondrial H2 O2 production after eccentric (ECC) versus concentric (CON) training performed at similar mechanical power. Forty-eight rats performed 5- or 20-day eccentric (ECC) or concentric (CON) training programs. Mitochondrial respiration, H2 O2 production, citrate synthase activity (CS), and skeletal muscle damage were assessed in gastrocnemius (GAS), soleus (SOL) and vastus intermedius (VI) muscles. Maximal mitochondrial respiration improved only after 20 days of concentric (CON) training in GAS and SOL. H2 O2 production increased specifically after 20 days of eccentric ECC training in VI. Skeletal muscle damage occurred transiently in VI after 5 days of ECC training. Twenty days of ECC versus CON training performed at similar mechanical power output do not increase skeletal muscle oxidative capacities, but it elevates mitochondrial H2 O2 production in VI, presumably linked to transient muscle damage. © 2014 Wiley Periodicals, Inc.

  16. Eccentric binaries of compact objects in strong-field gravity

    Energy Technology Data Exchange (ETDEWEB)

    Gold, Roman

    2011-09-27

    In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on

  17. Electrical stimulation and isokinetic training: effects on strength and neuromuscular properties of healthy young adults Estimulação elétrica e treinamento isocinético: efeitos na força e propriedades neuromusculares de adultos jovens sadios

    Directory of Open Access Journals (Sweden)

    MA Avila

    2008-12-01

    Full Text Available OBJECTIVE: To assess the effects of neuromuscular electrical stimulation (NMES associated with an isokinetic training program in healthy young men and women. METHODS: Twenty participants (ten men, ten women; 21±1.5 years underwent an isokinetic training program for knee extensors of both sides (three sets of ten concentric repetitions at 30°/s twice a week for four weeks. One limb underwent only the isokinetic strength training (Ex while the other underwent the same training but with NMES associated with each contraction (Ex+NMES. The current used for NMES was the Russian current (frequency of 2,500Hz, 50 bursts/s and pulse duration of 200µs. Isometric and isokinetic concentric extensor torque at 30°/s were evaluated. RESULTS: The groups increased their peak torque in both test procedures, with no difference between Ex and Ex+NMES. The angle of peak torque increased for the Ex limb, thus showing a change in the tension-length relationship of the muscle group tested, which did not occur for the Ex+NMES limb. There was also a decrease in acceleration time in both limbs, without any effects from NMES on this variable. CONCLUSIONS: These results showed that the association between NMES and isokinetic concentric voluntary strength training did not improve the strength gains and neuromuscular properties of voluntary strength training itself for healthy young participants of both genders.OBJETIVO: Verificar os efeitos da estimulação elétrica neuromuscular (EENM associada a um programa de treinamento isocinético em homens e mulheres jovens e sadios. MÉTODOS: Vinte indivíduos (dez homens, dez mulheres, 21±1,5 anos submeteram-se a um programa de treinamento isocinético de ambos os seus extensores de joelho (três séries de dez repetições concêntricas a 30°/s duas vezes por semana por quatro semanas. Um membro foi submetido apenas ao treinamento de força isocinético (Ex enquanto o outro foi submetido ao mesmo treinamento, mas com EENM

  18. Eccentric exercise in adults with cardiorespiratory disease: a systematic review.

    Science.gov (United States)

    Ellis, Rachel; Shields, Nora; Lim, Kwang; Dodd, Karen J

    2015-12-01

    To determine if eccentric exercise is effective, tolerable and safe for adults with chronic cardiorespiratory disease. We searched electronic databases from inception until January 2015 (Medline, CINAHL, Embase, SportDiscus, PEDro, Cochrane Central and AMED) supplemented by citation tracking and reference list scanning. Included articles had to report effects of eccentric exercise, alone or as a primary component of intervention, of any intensity and duration, on adults with chronic cardiorespiratory disease. Trials needed to be reported as full text in a peer-reviewed journal and include control data (randomised, quasi-randomised and single group cross-over design trials). Any outcomes or comparison interventions were accepted. Methodological rigor was assessed using the PEDro scale. Of 22 potentially relevant articles, 10 met inclusion criteria. They reported results from seven trials with a total of 112 participants across the diseases. PEDro scores were low (median 3). Eccentric exercise increased strength and mobility to comparable levels as concentric exercise, however, it did so with lower oxygen consumption (effect size as large as d = -3.07 (-4.12, -1.80)), and four-fold power output (effect size d = -3.60 (-5.03, -1.66)). There were no adverse events reported for eccentric exercise. Pain was avoided with familiarisation sessions and individual exercise prescription. Eccentric exercise is beneficial and at least comparable with traditional exercise in improving walking and strength for people with chronic cardiorespiratory disease. It was well tolerated and we identified no safety concerns for the use of this intervention for this population. © The Author(s) 2015.

  19. Burrowing as a novel voluntary strength training method for mice : A comparison of various voluntary strength or resistance exercise methods

    NARCIS (Netherlands)

    Roemers, P; Mazzola, P N; De Deyn, P P; Bossers, W J; van Heuvelen, M J G; van der Zee, E A

    2017-01-01

    BACKGROUND: Voluntary strength training methods for rodents are necessary to investigate the effects of strength training on cognition and the brain. However, few voluntary methods are available. NEW METHOD: The current study tested functional and muscular effects of two novel voluntary strength

  20. Validation of a Compact Isokinetic Total Water Content Probe for Wind Tunnel Characterization at NASA Glenn Icing Research Tunnel and at NRC Ice Crystal Tunnel

    Science.gov (United States)

    Davison, Craig R.; Landreville, Charles; Ratvasky, Thomas P.

    2017-01-01

    A new compact isokinetic probe to measure total water content in a wind tunnel environment has been developed. The probe has been previously tested under altitude conditions. This paper presents a comprehensive validation of the probe under a range of liquid water conditions at sea level in the NASA Glenn Icing Research Tunnel and with ice crystals at sea level at the NRC wind tunnel. The compact isokinetic probe is compared to tunnel calibrations and other probes.

  1. Shedding Light on the Eccentricity Valley: Gap Heating and Eccentricity Excitation of Giant Planets in Protoplanetary Disks

    CERN Document Server

    Tsang, David; Cumming, Andrew

    2013-01-01

    We show that the first order (non co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the "Eccentricity Valley" noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between $\\sim 0.1$ and $\\sim 1$ AU compared to metal-rich systems (Dawson & Murray-Clay 2013). We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius $\\sim 0.1$ AU, which is known to exist for several T Tauri systems. In the shadowed region between $\\sim 0.1$ and $\\sim 1$ AU lack of gap insolation allows disk interac...

  2. Voluntary reporting of greenhouse gases 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-05-01

    The Voluntary Reporting of Greenhouse Gases Program, required by Section 1605(b) of the Energy Policy Act of 1992, records the results of voluntary measures to reduce, avoid, or sequester greenhouse gas emissions. In 1998, 156 US companies and other organizations reported to the Energy information Administration that, during 1997, they had achieved greenhouse gas emission reductions and carbon sequestration equivalent to 166 million tons of carbon dioxide, or about 2.5% of total US emissions for the year. For the 1,229 emission reduction projects reported, reductions usually were measured by comparing an estimate of actual emissions with an estimate of what emissions would have been had the project not been implemented.

  3. Voluntary simulation workshops in nursing education

    DEFF Research Database (Denmark)

    Selberg, Hanne; Nielsen, Mette Elisabeth

    2012-01-01

    Voluntary simulation workshops in nursing education Hanne Selberg1, Mette Elisabeth Nielsen1, Mette Wenzel Horsted2, Karen Bertelsen2, Marianne Linnet Rasmussen2,Rikke Lohmann Panton3, Copenhagen, Mette Kjeldal Jensen4 Background Changes in nursing education in Denmark towards an academic approach...... with more theory and less practical training have resulted in discussions regarding the lack of practical skills amongst novice nurses. A Danish study of students’ drop-out from the nursing education indicates that difficulties in combining theory and practice are one of the motivating factors behind...... the students’ decision to drop out (Jensen et al. 2008). Within the past year our faculty has conducted several projects with the aim of integrating simulation into the curriculum. Furthermore, voluntary simulation workshop has been carried out as an additional offer in the nursing education. The purpose has...

  4. The Political Importance of Voluntary Work.

    Science.gov (United States)

    Kunneman, Harry

    This paper aims to develop a complex articulation of the civic meaningfulness of voluntary work that clarifies its political importance as a countervailing narrative pointing beyond dominant neoliberal and consumptive articulations of a good life. To start with, it sketches a hermeneutic perspective on civic meaningfulness based on the work of Paul Ricoeur. Subsequently, it introduces the ideas of 'ethical complexity', 'epistemological complexity' and 'diapoiesis', building on insights from critical complexity thinking and relational biology. It argues that these notions can provide a bridge between hermeneutic perspectives on meaning and values, on the one hand, and questions of meaning and values on the level of scientific and technological developments and within professional organizations, on the other. Thus a broader, more complex picture emerges of the civic meaningfulness of voluntary work in our times.

  5. Voluntary Management Earnings Forecasts and Discretionary Accruals

    DEFF Research Database (Denmark)

    Gramlich, Jeffrey; Sørensen, Ole Vagn

    2004-01-01

    This paper seeks to determine whether Danish managers exercise discretionary accruals to reach earnings forecast targets they voluntarily specify in conjunction with initial public offerings (IPOs). Because the Danish accounting and legal environment is more permissive than the US, we use Denmark...... as a natural laboratory for learning how business would occur without strict rules, enforcement and sanctions. Danish managers often volunteer pro forma financial statements for results that are expected to occur subsequent to the IPO. We examine a sample of 58 Danish firms that issue voluntary management...... earnings forecasts in connection with IPOs that occur between 1984 and 1996. The evidence we uncover strongly suggests that pre-managed earnings are adjusted toward these targets. In contrast with Kasznik's (1999 Kasznik, R. (1999). On the association between voluntary disclosure and earnings management...

  6. Towards a general method for estimating the unbalanced magnetic pull in mixed eccentricities motion including sufficiently large eccentricities in a hydropower generator and their validation against EM simulations

    Science.gov (United States)

    Calleecharan, Yogeshwarsing; Jauregui, Ricardo; Aidanpää, Jan-Olov

    2013-08-01

    Electromagnetic (EM) analysis of hydropower generators is common practice but rotor whirling is little studied. This paper suggests a novel semi-analytical method for estimating the steady state unbalanced magnetic pull (UMP) when the rotor centre is undergoing mixed eccentricities motion. The ability to estimate the UMP for mixed eccentricities motion in finite element method (FEM)-based modelling software packages is rare. The proposed methodology in its formulation takes advantage of the fact that a purely dynamic eccentricity motion including non-synchronous whirling and a purely static eccentricity motion can be more amenable to implement in existing FEM-based EM modelling software products for UMP estimation. After these initial separate UMP results are obtained, the proposed method can be applied for virtually any mixed eccentricities motion cases up to sufficiently large eccentricities for quick analysis instead of running the mixed eccentricities simulations directly in a FEM-based software package. Good agreement between the UMP from the actual EM mixed eccentricities motion simulations in a commercial FEM-based software package and the UMP estimations by the novel method is made for a wide range of eccentricities that may commonly occur in practice. A modified feature selective validation (FSV) method, the FSV-UPC, is applied to assess the similarities and the differences in the UMP computations.

  7. Factors that affect voluntary vaccination of children in Japan.

    Science.gov (United States)

    Shono, Aiko; Kondo, Masahide

    2015-03-10

    Some important vaccinations are not included in the routine childhood immunization schedule in Japan. Voluntary vaccinations are usually paid as an out-of-pocket expense. Low voluntary vaccination coverage rates and high target disease incidence are assumed to be a consequence of voluntary vaccination. Therefore, this study aimed to explore factors associated with voluntary vaccination patterns in children. We conducted an online survey of 1243 mothers from a registered survey panel who had at least one child 2 months to vaccination mainly correlated positively with annual household income and mothers' positive opinions about voluntary vaccinations, but negatively with number of children. Financial support, especially for low income households and households with more than one child, may motivate parents to vaccinate their children. Communication is also an important issue. More opportunities for education and information about voluntary vaccinations should be provided to mothers without distinguishing between voluntary and routine vaccination.

  8. Mitigating greenhouse gas emissions: Voluntary reporting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    The Voluntary Reporting Program, developed pursuant to Section 1605(b) of the Energy Policy Act of 1992, permits corporations, government agencies, households, and voluntary organizations to report on their emissions of greenhouse gases, and on actions taken that have reduced or avoided emissions or sequestered carbon, to the Energy Information Administration (EIA). This, the second annual report of the Voluntary Reporting Program, describes information provided by the participating organizations on their aggregate emissions and emissions reductions, as well as their emissions reduction or avoidance projects, through 1995. This information has been compiled into a database that includes reports from 142 organizations and descriptions of 967 projects that either reduced greenhouse gas emissions or sequestered carbon. Fifty-one reporters also provided estimates of emissions, and emissions reductions achieved, for their entire organizations. The projects described actions taken to reduce emissions of carbon dioxide from energy production and use; to reduce methane and nitrous oxide emissions from energy use, waste management, and agricultural processes; to reduce emissions of halocarbons, such as CFCs and their replacements; and to increase carbon sequestration.

  9. Voluntary Green Power Market Forecast through 2015

    Energy Technology Data Exchange (ETDEWEB)

    Bird, L.; Holt, E.; Sumner, J.; Kreycik, C.

    2010-05-01

    Various factors influence the development of the voluntary 'green' power market--the market in which consumers purchase or produce power from non-polluting, renewable energy sources. These factors include climate policies, renewable portfolio standards (RPS), renewable energy prices, consumers' interest in purchasing green power, and utilities' interest in promoting existing programs and in offering new green options. This report presents estimates of voluntary market demand for green power through 2015 that were made using historical data and three scenarios: low-growth, high-growth, and negative-policy impacts. The resulting forecast projects the total voluntary demand for renewable energy in 2015 to range from 63 million MWh annually in the low case scenario to 157 million MWh annually in the high case scenario, representing an approximately 2.5-fold difference. The negative-policy impacts scenario reflects a market size of 24 million MWh. Several key uncertainties affect the results of this forecast, including uncertainties related to growth assumptions, the impacts that policy may have on the market, the price and competitiveness of renewable generation, and the level of interest that utilities have in offering and promoting green power products.

  10. Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    Science.gov (United States)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  11. Origin and Implications of high eccentricities in massive black hole binaries at sub-pc scales

    CERN Document Server

    Roedig, Constanze

    2011-01-01

    We outline the eccentricity evolution of sub-parsec massive black hole binaries (MBHBs) forming in galaxy mergers. In both stellar and gaseous environments, MBHBs are expected to grow large orbital eccentricities before they enter the gravitational wave (GW) observational domain. We re--visit the predicted eccentricities detectable by space based laser interferometers (as the proposed ELISA/NGO) for both environments. Close to coalescence, many MBHBs will still maintain detectable eccentricities, spanning a broad range from <10^{-5} up to <~ 0.5. Stellar and gas driven dynamics lead to distinct distributions, with the latter favoring larger eccentricities. At larger binary separations, when emitted GWs will be observed by pulsar timing arrays (PTAs), the expected eccentricities are usually quite large, in the range 0.01-0.7, which poses an important issue for signal modelling and detection algorithms. In this window, large eccentricities also have implications on proposed electromagnetic counterparts to...

  12. ELECTROMAGNETIC VIBRATION DISTURBING FORCES AT THE ECCENTRICITY OF ROTOR OF TURBOGENERATOR

    Directory of Open Access Journals (Sweden)

    Yu.M. Vaskovskyi

    2016-09-01

    Full Text Available Electromagnetic vibration disturbing forces in different variants of the rotor displacement from an axis of the stator bore is carried out. Investigation for ТG type ТGV-200-2 by finite element method in COMSOL Multiphysics is carried out. The field mathematical model of static and dynamic eccentricity is described. The amplitude vibration disturbing forces are greatest, when a static eccentricity direction coincides with an axis of the stator winding phase is shown. The diagnostic features static and dynamic eccentricities are formulated. The most value of forces in the point with minimal air gap is shown. The diagnostic features static and dynamic eccentricities and the method of diagnostic eccentricity are formulated. Diagnostic feature of static eccentricity is to change the amplitude Maxwell stress tensor is established. The dynamic eccentricity diagnostic features are appearance in the spectrum of vibration disturbing forces rotating and multiple harmonics.

  13. Short-term effects of kinesio tape on joint position sense, isokinetic measurements, and clinical parameters in patellofemoral pain syndrome.

    Science.gov (United States)

    Kurt, Emine Eda; Büyükturan, Öznur; Erdem, Hatice Rana; Tuncay, Figen; Sezgin, Hicabi

    2016-07-01

    [Purpose] To evaluate the short-term effects of kinesio tape on joint position sense, isokinetic measurements, kinesiophobia, symptoms, and functional limitations in patients with patellofemoral pain syndrome. [Subjects and Methods] A total of 90 patients (112 knees) with patellofemoral pain syndrome were randomized into a kinesio tape group (n=45) or placebo kinesio tape group (n=45). Baseline isokinetic quadriceps muscle tests and measurements of joint position sense were performed in both groups. Pain was measured with a Visual Analog Scale, kinesiophobia with the Tampa kinesiophobia scale, and symptoms and functional limitations with the Kujala pain scale. Measurements were repeated 2 days after kinesio tape application. [Results] No differences were found between baseline isokinetic muscle measurements and those taken 2 days after application. However, significant improvements were observed in the kinesio tape group, with regard to joint position sense, pain, kinesiophobia, symptoms, and functional limitations after treatment. Examination of the differences between pre- and post-treatment values in both groups revealed that the kinesio tape group demonstrated greater improvements compared to the placebo kinesio tape group. [Conclusion] Although short-term kinesio tape application did not increase hamstring muscle strength, it may have improved joint position sense, pain, kinesiophobia, symptoms, and daily limitations.

  14. [Chronic chondromalacia of the patella: comparison of morphological (magnetic resonance) and functional findings (isokinetic parameters) after rehabilitation].

    Science.gov (United States)

    Felicetti, G; Avanza, F; Fiori, M; Brignoli, E; Rovescala, R

    1996-01-01

    The knee is a common site for injuries of the cartilage, capsule and ligament, which calls for the use of noninvasive techniques to assess injury severity properly and to plan adequate rehabilitation. Our study was aimed at comparing MR with isokinetic findings. To this purpose, 40 patients were examined; they were all affected with chondromalacia patellae, grades I-III, previously diagnosed at arthroscopy. Namely, 8 patients had grade I and 32 grades II and III chondromalacia. After MR and isokinetic exams, all patients were submitted to a standardized rehabilitation program. Our results indicate a marked decrease in quadriceps strength, especially in the most severe cases; in less severe cases, recovery was complete at 6 months, while the deficit remained in grades II and III injuries. MR yield was not relevant in 4 of 8 cases, while isokinetic findings were negative in one case. Both methods were positive in the most severe cases. At 6 months, both functional and MR findings were normal in grade I injuries, while some alterations remained in the others.

  15. Short-term effects of kinesio tape on joint position sense, isokinetic measurements, and clinical parameters in patellofemoral pain syndrome

    Science.gov (United States)

    Kurt, Emine Eda; Büyükturan, Öznur; Erdem, Hatice Rana; Tuncay, Figen; Sezgin, Hicabi

    2016-01-01

    [Purpose] To evaluate the short-term effects of kinesio tape on joint position sense, isokinetic measurements, kinesiophobia, symptoms, and functional limitations in patients with patellofemoral pain syndrome. [Subjects and Methods] A total of 90 patients (112 knees) with patellofemoral pain syndrome were randomized into a kinesio tape group (n=45) or placebo kinesio tape group (n=45). Baseline isokinetic quadriceps muscle tests and measurements of joint position sense were performed in both groups. Pain was measured with a Visual Analog Scale, kinesiophobia with the Tampa kinesiophobia scale, and symptoms and functional limitations with the Kujala pain scale. Measurements were repeated 2 days after kinesio tape application. [Results] No differences were found between baseline isokinetic muscle measurements and those taken 2 days after application. However, significant improvements were observed in the kinesio tape group, with regard to joint position sense, pain, kinesiophobia, symptoms, and functional limitations after treatment. Examination of the differences between pre- and post-treatment values in both groups revealed that the kinesio tape group demonstrated greater improvements compared to the placebo kinesio tape group. [Conclusion] Although short-term kinesio tape application did not increase hamstring muscle strength, it may have improved joint position sense, pain, kinesiophobia, symptoms, and daily limitations. PMID:27512259

  16. The determination of isokinetic performance values of knee joint and Hamstring (flexor/Quadriceps (extensor ratios differences in Volleyball players’

    Directory of Open Access Journals (Sweden)

    Özlem Yenigün

    2008-06-01

    Full Text Available The aim of this study was to determined the values of isokinetic performance in knee joint and the ratios of hamstring/quadriceps (H/Q between volleyball players and controls. 30 male volleyball players (age: 19,46±2,1 and 30 male controls (age: 19,66±2,0 were participated in this study. This study investigated hamstring and quadriceps muscles strength ratio obtained during concentric muscle contraction. The ratio of H/Q muscle strength which was an indicator of normal balance between the knee flexors and extensor and it is important to estimate of the capacity for stabilization of knee joint and the preventation of disability. Knee flexion and extension measurements were tested on biodex system–3 dynamometer in %60, %180 and %300 deg/sec test protocols. The range of motion of knee Joint was evaluated by biodex system–3 dynamometer. There was no statistical difference in the ROM of the knee joint between volleyball players and controls (p>0,05. The isokinetic values of volleyball players were significantly higher than controls (p<0,05. H/Q values must be determined to prevent disability. For the aim of get ready for the season and supply the continuity of performance level increases, preseason isokinetic testing of athletes may be helpful to test for strength imbalance and to determine the correct exercises which is suitable for remove the H/Q disproportion.

  17. Relative appendicular skeletal muscle mass is associated with isokinetic muscle strength and balance in healthy collegiate men.

    Science.gov (United States)

    Kim, Sung-Eun; Hong, Ju; Cha, Jun-Youl; Park, Jung-Min; Eun, Denny; Yoo, Jaehyun; Jee, Yong-Seok

    2016-11-01

    There are few studies on the relationship between skeletal muscle mass and balance in the young ages. We investigated the relationship between appendicular skeletal muscle mass, isokinetic muscle strength of lower extremity, and balance among healthy young men using relative skeletal muscle index. Thirty men were grouped according to relative appendicular skeletal muscle mass index: higher skeletal muscle group (n = 15) and lower skeletal muscle group (n = 15). Static and dynamic balance abilities were measured using the following: a test where participants stood on one leg with eyes closed, a modified Clinical Test of Sensory Interaction on Balance (mCTSIB) with eyes open and eyes closed, a stability test, and limits of stability test. The muscle strength of lower extremities was measured with an isokinetic analyser in hip, knee, and ankle joints. Participants with higher appendicular skeletal muscle mass were significantly more stable in maintaining dynamic balance than those with lower appendicular skeletal muscle mass. Moreover, appendicular skeletal muscle mass index was positively correlated with dynamic balance ability. Participants with higher appendicular skeletal muscle mass had stronger strength in the lower extremity, and there were significant differences in the isokinetic torque ratios between groups. From these results, it can be inferred that higher appendicular skeletal muscle mass relates to muscle strength and the alteration in the peak torque ratio of the lower extremity, contributing to the maintenance of balance.

  18. Seasonal variation in isokinetic strength of knee flexors and extensors in soccer players

    Directory of Open Access Journals (Sweden)

    Michal Lehnert

    2015-06-01

    Full Text Available BACKGROUND: Muscle strength is an important factor in soccer from the performance and health perspective. There is a lack of knowledge about changes in muscle strength of the knee flexors and extensors and their ratios during annual training cycle. OBJECTIVES: The aim of this study was to evaluate the seasonal variability of the observed parameters of isokinetic strength of the knee flexors and extensors in soccer players, U19, from the performance and health perspective. METHODS: The strength of the knee flexors and extensors was measured in players U19 category (n = 9; the average age 18.5 ±0.4 years on the isokinetic dynamometer IsoMed 2000 in angular velocity 60° × s-1. Measurement was performed in concentric/concentric and excentric/excentric mode of muscle action at the beginning of the winter preparatory period, at the end of the preparatory period and at the end of the spring competitive period. Monitored parameters were absolute peak torque (PT, conventional H/Q ratio (H/QCON, functional H/Q ratio (H/QFUN and functional H/Q ratio in range 10-30° of knee flexion (H/QFUN_10-30. RESULTS: Significant change in PT (p < .05 was noted only in cases of the knee extensors of the nondominant leg in the concentric mode. The evaluation of imbalance of the knee flexors and extensors by H/QCON and H/QFUN ratios did not show any significant changes, but there was found a significant decrease of the H/QFUN_10-30 ratio in the dominant leg between measurements at the beginning and at the end of the winter preparatory period. CONCLUSIONS: The results of the current study indicate that throughout the monitored periods of the annual training cycle desirable changes in knee flexors and extensors strength did not occur. The values suggest the disruption of the dynamic stabilization of the knee joint and increase in injury risk. Different dynamics of the three observed ratios confirmed that they provide different information about the physical fitness of

  19. Articulate torque and electromyographic activity of biceps femoris and semitendinosus muscles during isokinetic knee flexion movements in soccer athletes

    Directory of Open Access Journals (Sweden)

    Eduardo Bodnariuc Fontes

    2007-09-01

    Full Text Available The objective of the present study was to analyze the articulate torque (TO and the electromyographic activity (EMG of soccer athlete’s long head Biceps Femoris (BF and Semitendinosus (ST muscles during isokinetic knee fl exion movements (concentric-CON and eccentric-ECC actions at differing velocities, carried out in the ventral decubitus position. Fourteen soccer players aged 19 and 20 years old (71.2 ± 6.5 kg, 176.6 ± 6.4 cm were enrolled from the Associação Atlética Ponte Preta under- 20 team. They followed a protocol specifying 5 repetitions of fl exion (CON and ECC action of the knee at three velocities (60, 180 and 300º/s at random. The recovery interval between series adopted was 3 minutes. EMG Activity was recorded using surface electrodes and data were expressed in terms of root mean squares (RMS. Statistical analysis employed analysis of variance (Friedman test for repeated measures followed by the Wilcoxon test when necessary, with the level of signifi cance set at P ABSTRACT O objetivo do presente estudo foi analisar o torque articular (TO e a atividade eletromiográfi ca (EMG dos músculos Bíceps Femoral (BF cabeça longa e semitendíneo (ST durante movimentos isocinéticos de fl exão do joelho (ação concêntrica-CON e excêntrica-EXC, em diferentes velocidades de execução, na posição de decúbito ventral em atletas de futebol. Fizeram parte do estudo 14 atletas de futebol da equipe sub-20, da Associação Atlética Ponte Preta, com idade entre 19 e 20 anos (71,24 ± 6,53 kg, 176,59 ± 6,44 cm. Os atletas realizaram uma série de cinco repetições de fl exão (ação CON e EXC do joelho, em 3 velocidades (60, 180 e 300°/s, defi nidas anteriormente aleatoriamente. O intervalo de recuperação adotado entre as séries foi de 3 minutos. A atividade EMG foi coletada, utilizando-se eletrodos de superfície e os dados foram expressos em root mean square (RMS. Para análise estatística, foi empregada a análise de vari

  20. An Eccentric Binary Millisecond Pulsar in the Galactic Plane

    Science.gov (United States)

    Champion, David J.; Ransom, Scott M.; Lazarus, Patrick; Camilo, Fernando; Bassa, Cess; Kaspi, Victoria M.; Nice, David J.; Freire, Paulo C. C.; Stairs, Ingrid H.; vanLeeuwen, Joeri; Stappers, Ben W.; Cordes, James M.; Hessels, Jason W. T.; Lorimer, Duncan R.; Arzoumanian, Zaven; Backer, Don C.; Bhat, N. D. Ramesh; Chatterjee, Shami; Cognard, Ismael; Deneva, Julia S.; Faucher-Giguere, Claude-Andre; Gaensler, Bryan M.; Han, JinLin; Jenet, Fredrick A.; Kasian, Laura

    2008-01-01

    Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass (M.) companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk, or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 +/- 0.04 Solar Mass, an unusually high value.

  1. The Eccentric Binary Millisecond Pulsar in NGC 1851

    CERN Document Server

    Freire, Paulo C C; Gupta, Yashwant

    2007-01-01

    PSR J0514-4002A is a 5-ms pulsar is located in the globular cluster NGC 1851; it belongs to a highly eccentric (e = 0.888) binary system. It is one of the earliest known examples of a numerous and fast-growing class of eccentric binary MSPs recently discovered in globular clusters. Using the GBT, we have obtained a phase-coherent timing solution for the pulsar, which includes a measurement of the rate of advance of periastron: 0.01289(4) degrees per year, which if due completely to general relativity, implies a total system mass of 2.453(14) solar masses. We also derive m_p 0.96 solar masses. The companion is likely to be a massive white dwarf star.

  2. Tidal disruption flares from stars on eccentric orbits

    Directory of Open Access Journals (Sweden)

    Loeb A.

    2012-12-01

    Full Text Available We study tidal disruption and subsequent mass fallback for stars approaching supermassive black holes on bound orbits, by performing three dimensional Smoothed Particle Hydrodynamics simulations with a pseudo-Newtonian potential. We find that the mass fallback rate decays with the expected -5/3 power of time for parabolic orbits, albeit with a slight deviation due to the self-gravity of the stellar debris. For eccentric orbits, however, there is a critical value of the orbital eccentricity, significantly below which all of the stellar debris is bound to the supermassive black hole. All the mass therefore falls back to the supermassive black hole in a much shorter time than in the standard, parabolic case. The resultant mass fallback rate considerably exceeds the Eddington accretion rate and substantially differs from the -5/3 power of time.

  3. Chaos in the Test Particle Eccentric Kozai-Lidov Mechanism

    CERN Document Server

    Li, Gongjie; Holman, Matt; Loeb, Abraham

    2014-01-01

    The Kozai-Lidov mechanism can be applied to a vast variety of astrophysical systems involving hierarchical three-body systems. Here, we study the Kozai-Lidov mechanism systematically in the test particle limit at the octupole level of approximation. We investigate the chaotic and quasiperiodic orbital evolution by studying surfaces of section and the Lyapunov exponents. We find that the resonances introduced by the octupole level of approximation cause orbits to flip from prograde to retrograde and back as well as cause significant eccentricity excitation, and the chaotic behaviors occur when the mutual inclination between the inner and the outer binary is high. We characterize the parameter space that allows large amplitude oscillations in eccentricity and inclination.

  4. Chaos in the test particle eccentric Kozai-Lidov mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gongjie; Naoz, Smadar; Holman, Matt; Loeb, Abraham, E-mail: gli@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States)

    2014-08-20

    The Kozai-Lidov mechanism can be applied to a vast variety of astrophysical systems involving hierarchical three-body systems. Here, we study the Kozai-Lidov mechanism systematically in the test particle limit at the octupole level of approximation. We investigate the chaotic and quasi-periodic orbital evolution by studying the surfaces of section and the Lyapunov exponents. We find that the resonances introduced by the octupole level of approximation cause orbits to flip from prograde to retrograde and back as well as cause significant eccentricity excitation, and chaotic behavior occurs when the mutual inclination between the inner and the outer binary is high. We characterize the parameter space that allows large amplitude oscillations in eccentricity and inclination.

  5. Biomechanical characteristics of the eccentric Achilles tendon exercise

    DEFF Research Database (Denmark)

    Henriksen, Marius; Aaboe, Jens; Bliddal, Henning

    2009-01-01

    muscles were recorded. Joint kinematics, GRF frequency contents, average EMG amplitudes, and Achilles tendon loads were calculated. FINDINGS: The eccentric movement phase was characterized by a higher GRF frequency content in the 8-12 Hz range, and reduced EMG activity in the lower leg muscles...... into the biomechanics of the exercise may improve our understanding. METHODS: Sixteen healthy subjects performed one-legged full weight bearing ankle plantar and dorsiflexion exercises during which three-dimensional ground reaction forces (GRF), ankle joint kinematics and surface electromyography (EMG) of the lower leg....... No differences in Achilles tendon loads were found. INTERPRETATION: This descriptive study demonstrates differences in the movement biomechanics between the eccentric and concentric phases of one-legged full weight bearing ankle dorsal and plantar flexion exercises. In particular, the findings imply...

  6. Effects of antioxidant therapy in women exposed to eccentric exercise.

    Science.gov (United States)

    Bloomer, Richard J; Goldfarb, Alan H; McKenzie, Michael J; You, Tonjian; Nguyen, Linh

    2004-08-01

    The purpose of this study was to determine the effects of antioxidant therapy on indirect markers of muscle damage following eccentric exercise (EE). Eighteen women were randomized to an antioxidant supplement or a placebo before a bout of EE. Plasma creatine kinase (CK) activity, muscle soreness (MS), maximal isometric force (MIF), and range of motion (ROM) were assessed before and through 14 d postexercise. Eccentric exercise resulted in an increase in CK activity and MS, and a drop in MIF and ROM during the days following EE, which returned to baseline values 14 d after EE in both groups. Antioxidants attenuated the CK activity and MS response to the EE, while little difference was noted between groups in MIF or ROM. These findings suggest that antioxidant supplementation was helpful in reducing the elevations in plasma CK activity and MS, with little impact on MIF and ROM loss.

  7. Spectrum of 100-kyr glacial cycle: orbital inclination, not eccentricity.

    Science.gov (United States)

    Muller, R A; MacDonald, G J

    1997-08-05

    Spectral analysis of climate data shows a strong narrow peak with period approximately 100 kyr, attributed by the Milankovitch theory to changes in the eccentricity of the earth's orbit. The narrowness of the peak does suggest an astronomical origin; however the shape of the peak is incompatible with both linear and nonlinear models that attribute the cycle to eccentricity or (equivalently) to the envelope of the precession. In contrast, the orbital inclination parameter gives a good match to both the spectrum and bispectrum of the climate data. Extraterrestrial accretion from meteoroids or interplanetary dust is proposed as a mechanism that could link inclination to climate, and experimental tests are described that could prove or disprove this hypothesis.

  8. An Eccentric Binary Millisecond Pulsar in the Galactic Plane

    CERN Document Server

    Champion, D J; Lazarus, P; Camilo, F; Bassa, C; Kaspi, V M; Nice, D J; Freire, P C C; Stairs, I H; Van Leeuwen, J; Stappers, B W; Cordes, J M; Hessels, J W T; Lorimer, D R; Arzoumanian, Z; Backer, D C; Bhat, N D R; Chatterjee, S; Cognard, I; Deneva, J S; Faucher-Giguere, C -A; Gaensler, B M; Han, J L; Jenet, F A; Kasian, L; Kondratiev, V I; Krämer, M; Lazio, J; McLaughlin, M A; Venkataraman, A; Vlemmings, W

    2008-01-01

    Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 ms in a highly eccentric (e = 0.44) 95-day orbit around a solar mass companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster then ejecting it into the Galactic disk or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74+/-0.04 Msun, an unusually high value.

  9. 补充运动饮料可加速等动肌力峰力矩产生%Increased Rate of Peak Torque Development in Human Skeletal Muscle following Isokinetic Training with Sports Beverages

    Institute of Scientific and Technical Information of China (English)

    朱荣; 王守都

    2015-01-01

    Objective :The present study examined the effect of isokinetic training with sports beverages on the rate of peak torque development in athlete skeletal muscle during maximal muscle contraction .Methods :Twenty-seven taekwondo athletes in universitiy were randomly divided into four groups ,TD group (n= 7) with routine professional training and isokinetic ex-ercise with sports beverages ,T group (n= 6) with routine professional training and isokinetic exercise with water ,D group (n=7) with routine professional training and with beverages ,C group (n= 7) with routine professional training and with water .Experimental session for 10 weeks ,included training for 6 weeks and detraining 4 weeks .Subjects were asked to complete quadriceps and hamstring muscle isokinetic training in two legs ,including 2 sets of 7 repetitions concentric contraction at 60 °/s and 18 repetitions concentric contraction at 180 °/s ,and 7 rep-etitions eccentric contraction at 20°/s ,then 18 repetitions concentric contraction at 180 °/s ,1-min rest in set ,3- min rest interval set ,3 days a week .Moment of skeletal muscle eccentric contraction was 150% of the maximum moment of resistance in the first 3 weeks ,and 220%in last 3 weeks .Sports beverages were carbohydrate solution (6% wt/vol) including creatine (0 .1g/kg weight) ,carbohydrate (1g/kg weight) and protein (0 .4g/kg weight) .Drank 1/3 before isokinetic exercise ,then 150 ml per 15 minutes until finishing exercise ,the remaining solution was drunk up after finishing exercise in TD group and Dgroup .The volume of water was (kg weight)/6% ml .The maximum torque ,iEMG and completion time were measured in predominant leg at 60°/s and 180°/s before training ,after 6 weeks training and 4 weeks de-training ,calculated RFD and RER .Results :(1 ) RFD and RER of hamstring muscle increased in TD group than D group at 60°/s ( P< 0 .05 ) after 6 weeks training .RFD and RER of quadriceps were higher in TD group than T ,D ,C groups at 180

  10. António Reis and Margarida Cordeiro, eccentric filmmakers

    Directory of Open Access Journals (Sweden)

    Lucas Tavares Neves

    2016-02-01

    Full Text Available The international symposium "António Reis and Margarida Cordeiro, eccentric filmmakers" took place in Paris between the 3rd and the 4th of June, 2015. Speakers exchanged on the political, social and poetical aspects of the duo's cinematography, as well as on the reverberations of titles such as Jaime (1974 and Trás-os-montes (1976 on the Portuguese filmic landscape of the decades that followed.

  11. Eccentric Pumping Unit: Cost-effective and Reliable

    Institute of Scientific and Technical Information of China (English)

    Zhang Shaobo; Gao Heping; Chen Yibao; Shi Linsong; Zhang Huiwen

    1996-01-01

    @@ The beam-type pumping unit is the most widely used ty pe of pumping unit because of its simple geometry and its reliability. However. when its stroke exceeds five meters, the structure of the unit becomes massive and its cost becomes quite high. In order to make full use of the advantages of the beam pumping unit and to enhance its stroke. a new type of pumping unit - the ECCENTRIC PUMPING UNIT - has been designed after two years of the research work.

  12. Gluon field fluctuations in nuclear collisions: Multiplicity and eccentricity distributions

    Energy Technology Data Exchange (ETDEWEB)

    Schenke, Björn [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Tribedy, Prithwish [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Venugopalan, Raju [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2014-06-15

    We discuss different sources of fluctuations in nuclear collisions and their realization in the IP-Glasma model. We present results for multiplicity distributions in p+p and p+A collisions and compare eccentricity (ε{sub 2}, ε{sub 3}, ε{sub 4}) distributions in A + A collisions to the v{sub n} distributions in 10 centrality classes measured by the ATLAS Collaboration.

  13. Ischemic Preconditioning Blunts Muscle Damage Responses Induced by Eccentric Exercise.

    Science.gov (United States)

    Franz, Alexander; Behringer, Michael; Harmsen, Jan-Frieder; Mayer, Constantin; Krauspe, Rüdiger; Zilkens, Christoph; Schumann, Moritz

    2017-08-22

    Ischemic preconditioning (IPC) is known to reduce muscle damage induced by ischemia and reperfusion-injury (I/R-Injury) during surgery. Due to similarities between the pathophysiological formation of I/R-injury and eccentric exercise-induced muscle damage (EIMD), as characterized by an intracellular accumulation of Ca, an increased production of reactive oxygen species and increased pro-inflammatory signaling, the purpose of the present study was to investigate whether IPC performed prior to eccentric exercise may also protect against EIMD. Nineteen healthy men were matched to an eccentric only (ECC) (n=9) or eccentric proceeded by IPC group (IPC+ECC) (n=10). The exercise protocol consisted of bilateral biceps curls (3x10 repetitions at 80% of the concentric 1RM). In IPC+ECC, IPC was applied bilaterally at the upper arms by a tourniquet (200 mmHg) immediately prior to the exercise (3x5 minutes of occlusion, separated by 5 minutes of reperfusion). Creatine Kinase (CK), arm circumference, subjective pain (VAS score) and radial displacement (Tensiomyography, Dm) were assessed before IPC, pre-exercise, post-exercise, 20 minutes-, 2 hours-, 24 hours-, 48 hours- and 72 hours post-exercise. CK differed from baseline only in ECC at 48h (pexercise. After 24h, 48h and 72h, CK was increased in ECC compared to IPC+ECC (between groups: 24h: p=0.004, 48h: pexercise, when compared to IPC+ECC (between groups: all pexercise days in ECC (all peccentric exercise of the elbow flexors blunts EIMD and exercise-induced pain, while maintaining the contractile properties of the muscle.

  14. Does high muscle temperature accentuate skeletal muscle injury from eccentric exercise?

    Science.gov (United States)

    Castellani, John W; Zambraski, Edward J; Sawka, Michael N; Urso, Maria L

    2016-05-01

    Hyperthermia is suspected of accentuating skeletal muscle injury from novel exercise, but this has not been well studied. This study examined if high muscle temperatures alters skeletal muscle injury induced by eccentric exercise (ECC). Eight volunteers (age, 22.5 ± 4.1 year; height, 169.5 ± 10.8 cm; body mass, 76.2 ± 12.6 kg), serving as their own control, and who were not heat acclimatized, completed two elbow flexor ECC trials; in one trial the biceps were heated >40°C (HEAT) and in the other trial there was no heating (NON). HEAT was applied with shortwave diathermy (100 W) for 15 min immediately before the first ECC bout and for 2 min in between each bout. Individuals were followed for 10 days after each ECC session, with a 6-week washout period between arms. The maximal voluntary isometric contraction decreased by 41 ± 17% and 46 ± 20% in the NON and HEAT trials, respectively. Bicep circumference increased by 0.07 ± 0.08 mm (4%, P = 0.04) and relaxed range of motion decreased by 11.5 ± 8.2° (30%, P 40°C muscle temperature does not alter skeletal muscle injury or functional impairments induced by novel ECC. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  15. Dano muscular: resposta inflamatória sistêmica após ações excêntricas máximas Daño muscular: respuesta inflamatoria sistémica después de acciones excéntricas máximas Muscle damage: systemic inflammatory response after maximal eccentric actions

    Directory of Open Access Journals (Sweden)

    Ricardo Paes de Barros Berton

    2012-09-01

    émica.The objective of this study was to analyze the magnitude of the inflammatory response induced by a high number of eccentric actions (AE of the elbow flexors. Participated on this study nine young men who performed 35 sets of six AE of the elbow flexors, with an one minute interval, using an isokinetic dynamometer at 210º.s-1. Maximum voluntary isometric contraction (MVIC, range of motion (ROM, delayed onset muscle soreness (DOMS, interleukin 6 (IL-6 and tumor necrosis factor alpha (TNF-α were measured. Significant changes were observed for markers of muscle damage (MVIC, ROM and DOMS, however, there were no changes on inflammatory markers IL-6 and TNF-α. In conclusion, the results show that even with large numbers of AE and changes in indirect markers of muscle damage, no change was observed in the systemic inflammatory response.

  16. Transition from inspiral to plunge for eccentric equatorial Kerr orbits

    CERN Document Server

    O'Shaughnessy, R

    2003-01-01

    Ori and Thorne have discussed the duration and observability (with LISA) of the transition from circular, equatorial inspiral to plunge for stellar-mass objects into supermassive ($10^{5}-10^{8}M_{\\odot}$) Kerr black holes. We extend their computation to eccentric Kerr equatorial orbits. Even with orbital parameters near-exactly determined, we find that there is no universal length for the transition; rather, the length of the transition depends sensitively -- essentially randomly -- on initial conditions. Still, Ori and Thorne's zero-eccentricity results are essentially an upper bound on the length of eccentric transitions involving similar bodies (e.g., $a$ fixed). Hence the implications for observations are no better: if the massive body is $M=10^{6}M_{\\odot}$, the captured body has mass $m$, and the process occurs at distance $d$ from LISA, then $S/N \\lesssim (m/10 M_{\\odot})(1\\text{Gpc}/d)\\times O(1)$, with the precise constant depending on the black hole spin. For low-mass bodies ($m \\lesssim 7 M_\\odot$...

  17. Evidence for Reflected Light from the Most Eccentric Exoplanet Known

    CERN Document Server

    Kane, Stephen R; Hinkel, Natalie R; Roy, Arpita; Mahadevan, Suvrath; Dragomir, Diana; Matthews, Jaymie M; Henry, Gregory W; Chakraborty, Abhijit; Boyajian, Tabetha S; Wright, Jason T; Ciardi, David R; Fischer, Debra A; Butler, R Paul; Tinney, C G; Carter, Brad D; Jones, Hugh R A; Bailey, Jeremy; O'Toole, Simon J

    2015-01-01

    Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve the our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.25 degrees, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the pla...

  18. [The recovery of visual performance in strabismus with eccentric fixation].

    Science.gov (United States)

    Rusu, V

    1997-01-01

    The purpose of this work is to realise a general view about the diagnosis, therapeutic methods and the results obtained in eccentric fixation strabismus. We realised a six years retrospective study on 144 eccentric strabismus, watching dynamic the evolution by testing: the orthophoric status, visual acuity, binocular vision and the type of fixation. Medium follow un time was of 19.6 months. In the end of the treatment we notice: visual acuity between 0.1-0.5 in 14% cases; central fixation in 52 children (36%); first degree of binocular vision in 15 children (10.4%) and second degree in 5 cases (3.47%). This study showed that the early installation of eccentric fixation strabismus was in 53% cases before reaching one year old and in 90% before two years old. The functional results was negative influenced by the delay in presentation (42% come after 2 years) and the difficulties in family cooperation (46.5% were followed up lesenban 6 months).

  19. Muscle preservation in long duration space missions: The eccentric factor

    Science.gov (United States)

    Buchanan, Paul; Dudley, Gary A.; Tesch, Per A.; Hather, Bruce M.

    1990-01-01

    In our quest to understand, and eventually prevent, the loss of muscle strength and mass that occurs during prolonged periods in microgravity, we have organized our research approach by systems and useful terrestrial analogs. Our hypothesis was that: The eccentric movement, or lengthening component, of dynamic, resistive exercise, is required for the production of the greatest gains in strength and muscle hypertrophy in the most metabolically efficient, and time effective manner. The exercises selected were leg presses, leg (knee) extensions, and hamstring curls. In this 30 week study, 38 male subjects, between the ages of 25 and 50, were divided into four groups. One group performed 5 sets of 8-12 repetitions per set of conventional concentric/eccentric (CON/ECC) exercises. Another group performed only the concentric (CON) movement on the same schedule. The third group performed twice the number of sets in the concentric only mode (CON/CON), and the last group served as controls. We interpret these data as convincing evidence that the eccentric component of heavy resistance training is required along with the concentric for the most effective increase in strength and muscle fiber size in the least time. We also conclude that such heavy exercise of any such muscle group need not consume inordinately long periods of time, and is quite satisfactorily effective when performed on 72 hour centers.

  20. Orbital Eccentricity Distribution of Solar-Neighbour Halo Stars

    CERN Document Server

    Hattori, Kohei

    2011-01-01

    We present theoretical calculations for the differential distribution of stellar orbital eccentricity for a sample of solar-neighbour halo stars. Two types of static, spherical gravitational potentials are adopted to define the eccentricity e for given energy E and angular momentum L, such as an isochrone potential and a Navarro-Frenk-White potential that can serve as two extreme ends covering in-between any realistic potential of the Milky Way halo. The solar-neighbour eccentricity distribution \\Delta N(e) is then formulated, based on a static distribution function of the form f(E,L) in which the velocity anisotropy parameter \\beta monotonically increases in the radial direction away from the galaxy center, such that beta is below unity (near isotropic velocity dispersion) in the central region and asymptotically approaches \\sim 1 (radially anisotropic velocity dispersion) in the far distant region of the halo. We find that \\Delta N(e) sensitively depends upon the radial profile of \\beta, and this sensitivit...