Effets de différents paramètres de récupération lors d'exercices de renforcement musculaire

L optimisation de la performance oblige l athlète à répéter des séances d entraînement à haute intensité de travail avec peu de récupération, ce qui génère une fatigue neuromusculaire qui peut être préjudiciable. Ainsi, dans le but de limiter ce phénomène et d améliorer l efficacité des séances d entraînement, le choix d une récupération adéquate s impose.La récupération active est la méthode la plus connue et la plus efficace relatée dans la littérature. En effet, de nombreuses études démontrent son effet bénéfique sur la fatigue provoquée lors d exercices globaux (types course ou pédalage). Cette modalité de récupération correspond à un exercice musculaire léger permettant une augmentation du flux sanguin périphérique et une élimination plus rapide des métabolites. A l heure actuelle, peu d études se sont intéressées à la récupération active appliquée de manière locale pour des exercices de renforcement de groupes musculaires spécifiques.L objectif de ce travail était donc d étudier la méthode la plus efficace, en termes de modalité et de moment d application, pour récupérer la force maximale de l athlète lors d un exercice de renforcement musculaire. De plus, afin d assurer une application de cette récupération active, spécifiquement sur les groupes musculaires souhaités, nous avons utilisé l électromyostimulation (EMS).Nos différents résultats suggèrent qu il n est pas nécessaire d appliquer une modalité particulière pour la récupération des exercices de renforcement musculaire réalisés à intensité maximale. En effet, la récupération active par EMS appliquée au cours d une séance (entre les séries) ou après une séance ne montre pas de différence avec une récupération passive. De plus, l application proximale ou distale de l EMS n a pas d influence sur la cinétique de récupération. L approche neuromusculaire de la fatigue, montre cependant, qu il s avère nécessaire d analyser l origine des perturbations engendrées par l exercice, afin de choisir la modalité de récupération la mieux adaptéeThe high frequency of resistance training sessions induces heavy strain and fatigue phenomenon, which could be prejudicial for subsequent performance. In this context, it appears necessary to apply proper recovery strategies in order to improve the athlete s ability to regain an adequate working state for subsequent training.Active recovery is widely described in the literature as the most efficient method for this purpose. It consists in low-intensity exercises, which could improve metabolites washout by increasing peripheral blood flow. To our knowledge, active recovery is usually applied globally, with exercises involving the whole body (light pedalling or running) but little is known regarding a local application after analytical exercises such as strengthening exercise. The aim of our research was therefore to determine the most effective method to recover from resistance training session in terms of maximal strength performance. Among the active recovery modes, electromyostimulation (EMS) is of particular interest since it can be applied on specific muscles groups. Our results showed that active recovery using EMS applied during a session (between the sets) or after a session, did not demonstrate any difference as compared with passive recovery. Also, we demonstrated that EMS was not more efficient when applied distally. However, we highlighted that the investigation of neuromuscular parameters is necessary to better understand the origin of the fatigue induced by a specific exercise in order to apply the most appropriated recovery modeDIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein

BACKGROUND: The effects of protein supplementation on muscle thickness and strength seem largely dependent on its composition. The current study aimed at comparing the impact of an oral supplementation with vegetable Pea protein (NUTRALYS®) vs. Whey protein and Placebo on biceps brachii muscle thickness and strength after a 12-week resistance training program. METHODS: One hundred and sixty one males, aged 18 to 35 years were enrolled in the study and underwent 12 weeks of resistance training on upper limb muscles. According to randomization, they were included in the Pea protein (n = 53), Whey protein (n = 54) or Placebo (n = 54) group. All had to take 25 g of the proteins or placebo twice a day during the 12-week training period. Tests were performed on biceps muscles at inclusion (D0), mid (D42) and post training (D84). Muscle thickness was evaluated using ultrasonography, and strength was measured on an isokinetic dynamometer. RESULTS: Results showed a significant time effect for biceps brachii muscle thickness (P < 0.0001). Thickness increased from 24.9 ± 3.8 mm to 26.9 ± 4.1 mm and 27.3 ± 4.4 mm at D0, D42 and D84, respectively, with only a trend toward significant differences between groups (P = 0.09). Performing a sensitivity study on the weakest participants (with regards to strength at inclusion), thickness increases were significantly different between groups (+20.2 ± 12.3%, +15.6 ± 13.5% and +8.6 ± 7.3% for Pea, Whey and Placebo, respectively; P < 0.05). Increases in thickness were significantly greater in the Pea group as compared to Placebo whereas there was no difference between Whey and the two other conditions. Muscle strength also increased with time with no statistical difference between groups. CONCLUSIONS: In addition to an appropriate training, the supplementation with pea protein promoted a greater increase of muscle thickness as compared to Placebo and especially for people starting or returning to a muscular strengthening. Since no difference was obtained between the two protein groups, vegetable pea proteins could be used as an alternative to Whey-based dietary products. TRIAL REGISTRATION: The present trial has been registered at ClinicalTrials.gov (NCT02128516)

Could Low-Frequency Electromyostimulation Training be an Effective Alternative to Endurance Training? An Overview in One Adult

International audienceThis preliminary study aimed to investigate the effects of a six-week low-frequency electromyostimulation training (10Hz) on the cardiovascular, respiratory and muscular systems. To that purpose, aerobic capacity, knee extensor muscles strength and architecture, muscle sympathetic nervous activity, blood pressure and heart rate have been evaluated in one healthy male subject (33 year-old, 1.73 m, 73 kg). Results showed improvement of aerobic capacity (+4.5% and +11.5% for maximal oxygen uptake and ventilatory threshold) and muscle strength (+11% and +16% for voluntary and evoked force). Moreover, for the first time, this study demonstrated low-frequency training effects on muscle architecture (+3%, +12% and -11% for muscle thickness, pennation angle and fascicle length) and cardiovascular parameters (-22%, -18% and -21% for resting muscle sympathetic nervous activity, heart rate and mean blood pressure). Interestingly, these results suggest that this method may have beneficial effects on all systems of the body. The investigation of training effects on muscle architecture and cardiovascular parameters should therefore be pursued since highly deconditioned subjects are likely to fully benefit from these adaptations

Do Women and Men over 70 Years Old Similarly Benefit from a One-Year Training Program?

Background and Aims : Exercise capacity declines with age and is improved with exercise training. The aim of this study was to characterize the effects of a one-year combined exercise training in subjects over 70 years old, and to examine the eventual differences obtained between men and women. Methods : After baseline evaluation, 24 subjects (12 men and 12 women) over 70 years old underwent moderate intensity training with aerobic and resistance exercises, 3 hours a week over one year. Workload, oxygen uptake (VO2) and heart rate were measured during a symptom-limited exercise test. The distance walked in 6 minutes (6-MWT) was also registered, and the maximal strength was measured on knee extensor muscles. Results : After training, VO2 at ventilatory threshold was increased both in men (+17%, p<0.01) and women (+20%, p<0.01), as well as peak workload (+8% and +12%, respectively, p<0.05) and peak VO2 (+13%, p<0.05, and +19%, p<0.01, respectively). The 6-MWT distance was also improved both in men (+8%, p<0.01) and in women (+12%, p<0.01), whereas the maximal strength of knee extensor muscles was increased only in women (+28%, p<0.05). The amount of increase after training for these last two parameters was higher in women (p<0.05). Conclusion : This study have shown that one-year of combined exercise training in healthy subjects over 70 years old is well-tolerated and improves aerobic capacity, performance to field test and muscle strength. Moreover, women seem to better benefit of this program

Effects of between-set interventions on neuromuscular function during isokinetic maximal concentric contractions of the knee extensors

International audienceThe 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

Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles.

This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT

Effects of Electrical Stimulation Pattern On Quadriceps Force Production and Fatigue

International audienceIntroduction: Mixed stimulation programs (MIX) that switch from constant frequency trains (CFT) to variable frequency trains have been proposed to offset the rapid fatigue induced by CFT during electrical stimulation. However, this has never been confirmed with long stimulation patterns, such as those used to evoke functional contractions. The purpose of this study was to test the hypothesis that MIX programs were less fatiguing than CFTs in strength training-like conditions (6-s contractions, 30-min). Methods: Thirteen healthy subjects underwent 2 sessions corresponding to MIX and CFT programs. Measurements included maximal voluntary isometric torque and torque evoked by each contraction. Results: There were greater decreases of voluntary and evoked torque (P<0.05) after CFT than MIX, and mean torque was 13 +/- 1% higher during the MIX session (P<0.05). Conclusions: These findings confirm that combining train types might be a useful strategy to offset rapid fatigue during electrical stimulation sessions with long-duration contractions. Muscle Nerve49: 760-763, 201

Functional Electrical Stimulation: Cardiorespiratory Adaptations and Applications for Training in Paraplegia

International audienceRegular exercise can be broadly beneficial to health and quality of life in humans with spinal cord injury (SCI). However, exercises must meet certain criteria, such as the intensity and muscle mass involved, to induce significant benefits. SCI patients can have difficulty achieving these exercise requirements since the paralysed muscles cannot contribute to overall oxygen consumption. One solution is functional electrical stimulation (FES) and, more importantly, hybrid training that combines volitional arm and electrically controlled contractions of the lower limb muscles. However, it might be rather complicated for therapists to use FES because of the wide variety of protocols that can be employed, such as stimulation parameters or movements induced. Moreover, although the short-term physiological and psychological responses during different types of FES exercises have been extensively reported, there are fewer data regarding the long-term effects of FES. Therefore, the purpose of this brief review is to provide a critical appraisal and synthesis of the literature on the use of FES for exercise in paraplegic individuals. After a short introduction underlying the importance of exercise for SCI patients, the main applications and effects of FES are reviewed and discussed. Major findings reveal an increased physiological demand during FES hybrid exercises as compared with arms only exercises. In addition, when repeated within a training period, FES exercises showed beneficial effects on muscle characteristics, force output, exercise capacity, bone mineral density and cardiovascular parameters. In conclusion, there appears to be promising evidence of beneficial effects of FES training, and particularly FES hybrid training, for paraplegic individuals