Over the last two decades, plyometric training has been extensively adopted by athletes, coaches and sport scientists with a primary aim to improve vertical jump height. The focus of these plyometric programmes has been to train the lower-extremity musculature in order to enhance jump performance. However, the lower-extremities are not the only contributing factor to vertical jump performance, as the use of an arm-swing during vertical jumping has also been shown to contribute to achieving maximum vertical jump height, yet training programmes for improving the arm-swing during the vertical jump are limited. Therefore, the primary aim of this thesis was to examine the full arm-swing mechanics during vertical jumping, and to then develop and assess the suitability of an upper-extremity plyometric programme for increasing both arm-swing kinematics and jump height. Firstly, a descriptive study was conducted to assess if an arm-swing countermovement was utilised during the vertical jump, which was deemed the prerequisite for using plyometric training to improve the arm-swing. Then an experimental study was conducted comparing vertical jumps performed with and without an arm-swing countermovement. The results showed that jumps performed with an arm-swing countermovement significantly increased mean peak shoulder angular velocity (ω) (+67.5 deg·s-1) and mean jump height (+ 6.2 cm) when compared to jumps performed using no arm-swing countermovement. During the final chapter of this thesis, a group of elite basketball players volunteered to participate in upper-extremity plyometric training aimed at increasing vertical jump height by training only the upper-extremities. Vertical jump height and full body kinematics were analysed using a 3 dimensional (3D) motion capture system, and key kinematic jump variables and various arm-swing performance measurements were collated both before and after a 4 week upper-extremity plyometric intervention. The use of upper-extremity plyometric training significantly increased the mean jump height (+ 7.2 cm), mean peak shoulder ω (+ 167.1 deg·s-1), mean peak frontal shoulder ω (+ 121 deg·s-1) and mean active range of motion at the shoulder joint (+ 5.3°), when compared to a control group. Furthermore, the use of a large active range of motion armswing during the arm-swing countermovement was shown to be the preferred arm-swing condition for increasing arm-swing kinematics. The increase in arm-swing kinematics and jump height after the 4 week upper-extremity plyometric programme was attributed to the participants’ improved ability to use the stretch-shortening cycle, elastic energy transfer system and stretch reflex system. Therefore, the use of upper-extremity plyometric exercises as part of a training regime for improving vertical jump performance should be advocated.

Le triple saut est une discipline de l’athlétisme qui exige un mouvement combinant puissance, vitesse ainsi que résistance articulaire et musculaire. Au terme d’une course d’élan durant laquelle l’athlète développe une vitesse utilisable de manière efficiente pour la continuité du saut, le triple sauteur prend un « appel » sur la planche d’appel destinée à cette action. Cette prise d’appel est réalisée à partir du pied propulseur de l’athlète dont l’efficience est dépendante du bon équilibre de l’appui.Les objectifs de ce travail de thèse ont été de préciser, à partir des instruments de mesure d’un cabinet de podologie, l’influence de la pratique du triple saut sur la fonction d’équilibration et sur la qualité de l’appui. A cet effet, trois études ont été menées successivement. Le premier objectif a déterminé l'influence de la répétition de sauts sur la fonction d'équilibration. Le deuxième objectif a illustré, à travers une étude statique et dynamique, la comparaison des appuis plantaires avant et après un concours de triple saut. Enfin, le troisième objectif a évalué l’effet d’une chaussure d’entraînement sur la répartition de l’appui lors d’une prise d’appel.Les résultats de ces différentes recherches ont permis tout d’abord, de mettre en évidence les effets positifs de la répétition d’une tâche sur la fonction d’équilibration. Ensuite, la modification structurelle du pied engendrée par la succession des prises d’appel ne semble pas être un facteur dégradant la performance du saut. Enfin, la chaussure d’entraînement apparaît comme un élément important à la fois dans la prévention des blessures mais également dans la contribution à la performance. / The triple jump is an athletics discipline that requires a movement combining power, speed as well as joint and muscular resistance. At the end of an elk race during which the athlete develops an optimum speed, the triple jumper carry out a "take-off". This take-off is made from the booster foot of the athlete whose efficiency is dependent on the correct balance of the support foot.The aims of this thesis work have been to specify the influence of the practice of the triple jump on the balancing function and on the quality of the support. To this end, three studies have been carried out successively. The first objective determined the influence of the repetition of jumps on the equilibrium function. The second objective illustrated, through a static and dynamic study, the comparison of the plantar supports before and after a triple jump event. Finally, the third objective assessed the effect of a training shoe on the distribution of support during the take-off.The results of these various researches first made it possible to highlight the positive effects of repetition of a task on the equilibrium function. Secondly, the structural alteration of the foot generated by the succession of take-off does not appear to be a factor degrading the performance of the jump. Finally, the training shoe appears as an important element both in the prevention of injuries as well as in the contribution to the performance.