L’objectif de cette thèse a été d’analyser l’effet de l’exercice physique réalisé sur plateforme vibrante (whole-body vibration, WBV) sur l’activité musculaire des membres inférieurs, de développer des outils d’analyse méthodologiques et de proposer des recommandations pratiques d’utilisation. Deux études méthodologiques ont été menées pour identifier la méthode optimale permettant de traiter les signaux d'électromyographie de surface (sEMG) recueillis pendant la vibration et d'analyser l'influence de la méthode de normalisation de l'activité sEMG. Une troisième étude visait à mieux comprendre si les pics sEMG observés dans le spectre de puissance du signal contiennent des artéfacts de mouvement et/ou de l'activité musculaire réflexe. Les trois études suivantes avaient pour but de quantifier l’effet de la WBV sur l’activité musculaire en fonction de différents paramètres tels que, la fréquence de vibration, l'amplitude de la plateforme, une charge supplémentaire, le type de plateforme, l'angle articulaire du genou, et la condition physique du sujet. En outre, l'objectif a été de déterminer l'accélération verticale minimale permettant de stimuler au mieux l'activité musculaire des membres inférieurs. En résumé, les recherches menées au cours de cette thèse fournissent des solutions pour de futures études sur : i) comment supprimer les pics dans le spectre du signal sEMG et, ii) comment normaliser l'activité musculaire pendant un exercice WBV. Enfin, les résultats de cette thèse apportent à la littérature scientifique de nouvelles recommandations pratiques liées à l’utilisation des plateformes vibrantes à des fins d’exercice physique. / The aim of this thesis was to analyze the effect of whole-body vibration (WBV) exercise on lower limb muscle activity and to give methodological implications and practical applications. Two methodological studies were conducted that served to evaluate the optimal method to process the surface electromyography (sEMG) signals during WBV exercise and to analyze the influence of the normalization method on the sEMG activity. A third study aimed to gain insight whether the isolated spikes in the sEMG spectrum contain motion artifacts and/or reflex activity. The subsequent three investigations aimed to explore how the muscle activity is affected by WBV exercise, with a particular focus on the vibration frequency, platform amplitude, additional loading, platform type, knee flexion angle, and the fitness status of the WBV user. The final goal was to evaluate the minimal required vertical acceleration to stimulate the muscle activity of the lower limbs. In summary, the research conducted for this thesis provides implication for future investigations on how to delete the excessive spikes in the sEMG spectrum and how to normalize the sEMG during WBV. The outcomes of this thesis add to the current literature in providing practical applications for exercising on a WBV platform.

The first aim of this master thesis was to summarize the information on injuries of ligamentous apparatus of an ankle, lateral instability of a talar joint, conservative and operative therapy of these injuries with the emphasis on physiotherapeutical procedures in the therapy of ankle sprains. The second aim of the master thesis was to introduce surface electromyography as a possibility to examine objectively the differences in the activation of foot and shank muscles with healthy people and people with chronic instability of an ankle in different postural situations. The third aim was to use the theoretical knowledge in practice with patients who have sprained their ankle and to make a subjective and objective assessment of the therapy effect which is in progress. Powered by TCPDF (www.tcpdf.org)

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Title: The reflection kinesiology analyse of cross country skiing Purposes: To compare coordination of chosen muscles on leg during reflection of cross country skiing classic technique, skating and herringbone. Methods: Comparative analysis: the dates were measured by surface electromyography and 2-D video-analysis. Results: We founded statistical significance by comparisons muscle activation on right leg during kick during cross country skiing: classic technique, diagonal stride and herringbone and V-1 skating and herringbone. In case the left leg the statistical significance was disprove by: m. peroneus longus sin during comparison of diagonal stride and herringbone and m. gastrocnemius medialis sin V-1 skating and herringbone. We founded high level of laterality of diagonal stride and herringbone. In case V-1 skating, the significant similarity was not founded for m. vastus lateralis and m. gluteus medialis. Key words: Cross country skiing, classical technique, skating, herring bone, kinesiology, surface electromyography (EMG), muscles activation

Title: Upper body muscles activity in V2 skating technique, double poling and on a skiing machine Concept 2 Objectives: Comparison of involvement upper body muscles during V2 skating technique, double poling and on a skiing machine Concept 2. Methods: Comparative analysis: the dates were measured by surface electromyography and 2-D video-analysis. Results: We found statistically significant coordination similarity by comparisons muscle preactivation and activation during V2 skating technique and double poling. Trunk flexors musculus obliquus abdominis externus and musculus rectus abdominis showed unlike the main propulsion muscles, musculus pectoralis major, musculus triceps brachii and musculus latissimus dorsi, significantly higher preactivation during V2 skating technique and double poling in comparison to skiing machine Concept 2. Activation of the main propulsion muscles on a skiing machine Concept 2 is significantly higher than during V2 skating technique and double poling. Skiing machine Concept 2 cannot be considered as a specific training method for cross-country skiing. Long-term application may cause disruption of double poling technique. Key words: Cross country skiing, V2 skating technique, double poling, skiing machine Concept 2 (SkiErg), kinesiology, surface electromyography

Title: The reflection kinesiology analyse of cross country skiing Purposes: To compare coordination of chosen muscles on leg during reflection of cross country skiing classic technique, skating and herringbone. Methods: Comparative analysis: the dates were measured by surface electromyography and 2-D video-analysis. Results: We founded statistical significance by comparisons muscle activation on right leg during kick during cross country skiing: classic technique, diagonal stride and herringbone and V-1 skating and herringbone. In case the left leg the statistical significance was disprove by: m. peroneus longus sin during comparison of diagonal stride and herringbone and m. gastrocnemius medialis sin V-1 skating and herringbone. We founded high level of laterality of diagonal stride and herringbone. In case V-1 skating, the significant similarity was not founded for m. vastus lateralis and m. gluteus medialis. Key words: Cross country skiing, classical technique, skating, herring bone, kinesiology, surface electromyography (EMG), muscles activation

Title: Upper body muscles activity in V2 skating technique, double poling and on a skiing machine Concept 2 Objectives: Comparison of involvement upper body muscles during V2 skating technique, double poling and on a skiing machine Concept 2. Methods: Comparative analysis: the dates were measured by surface electromyography and 2-D video-analysis. Results: We found statistically significant coordination similarity by comparisons muscle preactivation and activation during V2 skating technique and double poling. Trunk flexors musculus obliquus abdominis externus and musculus rectus abdominis showed unlike the main propulsion muscles, musculus pectoralis major, musculus triceps brachii and musculus latissimus dorsi, significantly higher preactivation during V2 skating technique and double poling in comparison to skiing machine Concept 2. Activation of the main propulsion muscles on a skiing machine Concept 2 is significantly higher than during V2 skating technique and double poling. Skiing machine Concept 2 cannot be considered as a specific training method for cross-country skiing. Long-term application may cause disruption of double poling technique. Key words: Cross country skiing, V2 skating technique, double poling, skiing machine Concept 2 (SkiErg), kinesiology, surface electromyography

L'objectif de ce travail de thèse est d'étudier d'une part les spécificités de la commande nerveuse lors de la contraction excentrique en explorant les mécanismes impliqués au niveau spinal et d'autre part d'examiner les mécanismes nerveux responsables de la plasticité du système neuromusculaire après un entraînement de force excentrique sous-maximal. A travers ce travail de thèse, nous mettons en évidence la contribution de l'inhibition récurrente à la réduction de l'activation musculaire classiquement observée lors de la contraction excentrique. Par ailleurs, nous montrons que l'inhibition récurrente est majorée lors des contractions sous-maximales indépendamment du mode de contraction. Ces résultats soulignent le rôle important de l'inhibition récurrente dans la spécificité de la commande nerveuse lors de la contraction excentrique. Nous confirmons que le pilotage nerveux de la contraction excentrique peut être modulé par l'entraînement de force excentrique même si les modulations de l'excitabilité spinale semblent dépendre des caractéristiques de l'entraînement. / The purpose of this PhD research is, on the one hand, to study the neural drive specificities during eccentric contractions by exploring the neural mechanisms involved at spinal level and, on the other hand, to examine the neural mechanisms responsible for the modulations of neuromuscular system following a strength submaximal eccentric training. Through this PhD research we highlight the contribution of recurrent inhibition by the Renshaw cell to the decrease of muscular activation typically observed during eccentric contraction. Furthermore, we show that recurrent inhibition is enhanced during submaximal contractions regardless of the contraction type. These results emphasize the important role of recurrent inhibition in the specificity of neural control during eccentric contractions. We confirm that the neural drive of the eccentric contraction may be modulated by eccentric strength training although modulations of spinal excitability seem to depend on the characteristics of training.