Factors influencing bilateral deficit and inter-limb asymmetry of maximal and explosive strength: motor task, outcome measure and muscle group

Purpose The purpose of the present study was to investigate the influence of strength outcome (maximal voluntary contraction (MVC) torque vs. rate of torque development (RTD)), motor task (unilateral vs. bilateral) and muscle group (knee extensors vs. flexors) on the magnitude of bilateral deficits and inter-limb asymmetries in a large heterogeneous group of athletes. Methods 259 professional/semi-professional athletes from different sports (86 women aged 21 ± 6 years and 173 men aged 20 ± 5 years) performed unilateral and bilateral “fast and hard” isometric maximal voluntary contractions of the knee extensors and flexors on a double-sensor dynamometer. Inter-limb asymmetries and bilateral deficits were compared across strength outcomes (MVC torque and multiple RTD measures), motor tasks and muscle groups. Results Most RTD outcomes showed greater bilateral deficits than MVC torque for knee extensors, but not for knee flexors. Most RTD outcomes, not MVC torque, showed higher bilateral deficits for knee extensors compared to knee flexors. For both muscle groups, all RTD measures resulted in higher inter-limb asymmetries than MVC torque, and most RTD measures resulted in greater inter-limb asymmetries during unilateral compared to bilateral motor tasks. Conclusions The results of the present study highlight the importance of outcome measure, motor task and muscle group when assessing bilateral deficits and inter-limb asymmetries of maximal and explosive strength. Compared to MVC torque and bilateral tasks, RTD measures and unilateral tasks could be considered more sensitive for the assessment of bilateral deficits and inter-limb asymmetries in healthy professional/semi-professional athletes

Strength, jumping and change of direction speed asymmetries in soccer, basketball and tennis players

Despite growing research in the field of inter-limb asymmetries (ILAs), little is known about the variation of ILAs in different populations of athletes. The purpose of this study was to compare ILAs among young basketball, soccer and tennis players. ILAs were assessed in three different types of tests (strength, jumping and change of direction (CoD) speed), each including different tasks: (1) bilateral and unilateral counter movement jump, (2) isometric strength of knee extensors (KE) and knee flexors (KF), and (3) 90° and 180° CoD. Generally, the absolute metrics showed strong reliability and revealed significant differences (p < 0.05) among the three groups in KE maximal torque, KE and KF rate of force development and in both CoD tests. For jumping ILAs, power and force impulse metrics exhibited significant between-limb differences between groups, compared to jump height. For strength and CoD speed ILAs, only KF maximal torque and 180° CoD exhibited significant differences between groups. Greater KF strength ILAs in soccer players and counter-movement jump ILAs in tennis players are most probably the result of sport-specific movement patterns and training routines. Sport practitioners should be aware of the differences in ILAs among sports and address training programs accordingly

Effects of Neuromuscular Electrical Stimulation Training on Endurance Performance

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Neuromuscular Electrical Stimulation as a Potential Countermeasure for Skeletal Muscle Atrophy and Weakness During Human Spaceflight

This is the final version. Available on open access from Frontiers Media via the DOI in this recordHuman spaceflight is associated with a substantial loss of skeletal muscle mass and muscle strength. Neuromuscular electrical stimulation (NMES) evokes involuntary muscle contractions, which have the potential to preserve or restore skeletal muscle mass and neuromuscular function during and/or post spaceflight. This assumption is largely based on evidence from terrestrial disuse/immobilization studies without the use of large exercise equipment that may not be available in spaceflight beyond the International Space Station. In this mini-review we provide an overview of the rationale and evidence for NMES based on the terrestrial state-of-the-art knowledge, compare this to that used in orbit, and in ground-based analogs in order to provide practical recommendations for implementation of NMES in future space missions. Emphasis will be placed on knee extensor and plantar flexor muscles known to be particularly susceptible to deconditioning in space missions

Immigration polonaise et pratique sportive en milieu de grande industrie

Ancienne ville minière, Montceau-les-Mines compte une importante communauté polonaise. À leur arrivée en masse au début des années vingt, les migrants polonais créent leurs propres associations de loisirs dans un territoire dominé par la pratique du cyclisme et de la gymnastique. Loin de témoigner d’un engouement partagé avec les Montcelliens pour le sport, la vitalité du réseau associatif polonais indique la persistance d’une frontière culturelle. À contre-pied des supposées vertus intégratrices du sport, la pratique des loisirs à Montceau-les-Mines écrit l’histoire d’une non-rencontre

Neuromuscular electrical stimulation for preventing skeletal-muscle weakness and wasting in critically ill patients:a systematic review

BACKGROUND: Neuromuscular electrical stimulation (NMES) therapy may be useful in early musculoskeletal rehabilitation during acute critical illness. The objective of this systematic review was to evaluate the effectiveness of NMES for preventing skeletal-muscle weakness and wasting in critically ill patients, in comparison with usual care. METHODS: We searched PubMed, CENTRAL, CINAHL, Web of Science, and PEDro to identify randomized controlled trials exploring the effect of NMES in critically ill patients, which had a well-defined NMES protocol, provided outcomes related to skeletal-muscle strength and/or mass, and for which full text was available. Two independent reviewers extracted data on muscle-related outcomes (strength and mass), and participant and intervention characteristics, and assessed the methodological quality of the studies. Owing to the lack of means and standard deviations (SDs) in some studies, as well as the lack of baseline measurements in two studies, it was impossible to conduct a full meta-analysis. When means and SDs were provided, the effect sizes of individual outcomes were calculated, and otherwise, a qualitative analysis was performed. RESULTS: The search yielded 8 eligible studies involving 172 patients. The methodological quality of the studies was moderate to high. Five studies reported an increase in strength or better preservation of strength with NMES, with one study having a large effect size. Two studies found better preservation of muscle mass with NMES, with small to moderate effect sizes, while no significant benefits were found in two other studies. CONCLUSIONS: NMES added to usual care proved to be more effective than usual care alone for preventing skeletal-muscle weakness in critically ill patients. However, there is inconclusive evidence for its benefit in prevention of muscle wasting

Motor Skill Acquisition and Retention after Somatosensory Electrical Stimulation in Healthy Humans

Somatosensory electrical stimulation (SES) can increase motor performance, presumably through a modulation of neuronal excitability. Because the effects of SES can outlast the period of stimulation, we examined the possibility that SES can also enhance the retention of motor performance, motor memory consolidation, after 24 hours (Day 2) and 7 days (Day 7), that such effects would be scaled by SES duration, and that such effects were mediated by changes in aspects of corticospinal excitability, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF). Healthy young adults (n = 40) received either 20 (SES-20), 40 (SES-40), or 60 minutes (SES-60) of real SES, or sham SES (SES-0). The results showed SES-20 increased visuomotor performance on Day 2 (15%) and Day 7 (17%) and SES-60 increased visuomotor performance on Day 7 (11%; all p < 0.05) compared with SES-0. Specific responses to transcranial magnetic stimulation (TMS) increased immediately after SES (p < 0.05) but not on Days 2 and 7. In addition, changes in behavioral and neurophysiological parameters did not correlate, suggesting that paths and structures other than the ones TMS can assay must be (also) involved in the increases in visuomotor performance after SES. As examined in the present study, low-intensity peripheral electrical nerve stimulation did not have acute effects on healthy adults’ visuomotor performance but SES had delayed effects in the form of enhanced motor memory consolidation that were not scaled by the duration of SES