Acute static vibration-induced stretching enhanced muscle viscoelasticity but did not affect maximal voluntary contractions in footballers. J Strength Cond Res 28(11): 3105-3114, 2014-The aim of this study was to compare the effects of acute vibration-enhanced static stretching and/or static stretching alone on the strength and flexibility of the hamstrings and quadriceps muscles. Twenty-one male footballers participated in this study (21.9 ± 1.8 years; 75.54 ± 7.3 kg; 178.7 ± 6.5 cm). The experiment started with 5 minutes standardized warm-up followed by (a) baseline flexibility pretest (Split Test); (b) maximal voluntary flexion and extension (isokinetic strength) of the knee; (c) Treatment or Sham involving 45-second stretch with or without vibration for the hamstring and quadriceps muscle groups with 10-second rest between; and (d) posttest repeating the measures of the pretest. Each player randomly performed both trials on separate occasions. The vibration device operated at 35 Hz with 2 mm amplitude. Stretching with vibration statistically increased hamstring flexibility by 7.8% (p ≥ 0.05) when compared with stretching without vibration. No statistical differences for hamstring or quadriceps strength were noted between treatment conditions. There was no statistical correlation between flexibility and strength measurements. In conclusion, flexibility increased with vibration-enhanced static stretching; however, no change was evident in the maximal voluntary contractions of the knee flexors and extensors.

The purpose of the present study was to investigate the acute effects of local vibration on muscle performance at different durations and frequencies. Fifteen male handball players participated in the study voluntarily. University&rsquo / s Ethics Committee approved the study and the informed consent forms were filled by all participants. Different vibration durations, (10 sec, 1 min, 10 min), different frequencies (40 and 80 Hz), dominancy (dominant and non-dominant) and conditions (vibration and no-vibration) were independent variables of study. Dependent variables were maximum isometric strength measures under different situations. One way Repeated measures ANOVA, Bonferoni adjusted paired sample t-tests and Two way Repeated ANOVA was used for statistical analyses. Result of this study demonstrated that local vibration (LV) induced significantly higher muscle activity than no vibration (NV) condition. Strength improvements were obtained in quadriceps muscles of dominant and non-dominant legs for 40 Hz and 80 Hz. When 40 Hz vibration was applied to dominant leg with different durations (10 sec, 1 min, 10 min), significantly higher strength measures were found than no vibration. When 80 Hz vibration was applied to dominant leg with different durations (10 sec, 1 min, 10 min), only 10-sec vibration duration revealed significant increase in strength measures. When 40 Hz vibration was applied to non-dominant leg with different durations, (10 sec, 1 min, 10 min) significantly higher strength measures were found than no vibration. When 80 Hz vibration was applied to non-dominant leg with different durations (10 sec, 1 min, 10 min), 10-sec and 1 min vibration durations revealed significant increase in strength measures. However, no significant difference was obtained when the different vibration durations were compared between 40 Hz and 80 Hz.

La recherche de méthodes permettant de lutter contre le déconditionnement neuromusculaire à la suite par exemple d’une opération chirurgicale ou d’une immobilisation prolongée intéresse la communauté scientifique depuis de nombreuses années. Ce projet visait à proposer la technique de vibration locale (LV) comme une méthode alternative aux méthodes classiquement utilisées (e.g. vibration corps entier, stimulation électrique neuromusculaire) pour lutter contre ce déconditionnement neuromusculaire. Le premier objectif de ce travail de thèse était de déterminer les effets d’une application aigüe de LV sur la fonction neuromusculaire des muscles fléchisseurs dorsaux et extenseurs du genou de sujets sains. Nos résultats montrent une modulation de l’excitabilité du système nerveux central en réponse à l’application aigüe de LV, ce qui nous a permis d’envisager de potentielles adaptations si cette technique était utilisée de façon répétée sur plusieurs semaines. Ainsi, la seconde orientation de ce travail était d’évaluer les effets d’une application chronique (entraînement) de LV sur les propriétés fonctionnelles (force, hauteur de saut) et nerveuses (mesurées par stimulation magnétique transcrânienne) de sujets sains, jeunes et âgés. Nos résultats ont montré qu’un entraînement par LV était efficace pour améliorer les capacités fonctionnelles de ces deux populations, ces gains s’accompagnant d’adaptations nerveuses. Ces travaux nous ont alors conduits à la mise en place d’une dernière étude (en cours) à visée clinique, qui évaluait l’efficacité de LV en rééducation post-ligamentoplastie du ligament croisé antérieur du genou. / There is a need to find new methods to limit neuromuscular deconditioning that occurs after a surgery or prolonged immobilization. This thesis aimed to assess local vibration (LV) training as an alternative to methods classically used (e.g. whole body vibration, neuromuscular electrical stimulation) to fight against neuromuscular deconditioning. The first aim of this project was to determine the effects of a 30-min acute exposure to LV on the neuromuscular function of dorsiflexor and knee extensor muscles in a healthy population. Our results showed that acute LV intervention changed central nervous system excitability, allowing us to consider long-term adaptations to prolonged LV. Thus, the second aim of this thesis was to assess the effects of a chronic application (training) of LV on functional (maximal strength, squat jump performance) and neural (assessed with transcranial magnetic stimulation) properties of healthy young and old subjects. Our results showed that 4 to 8 weeks of LV increase functional capacities that were due to neural adaptations. Based on these results, an on-going study assessing the effectiveness of LV during a rehabilitation program for subjects who suffered from anterior cruciate ligament lesion has been proposed.