THE CONTRIBUTION OF UPPER BODY KINEMATICS IN VERTICAL JUMPING

Abstract

The current trend in the analyses of vertical jumping has focused on coordination of the timing and sequencing of muscle action. However, many of these analyses have neglected dynamical rotational aspects. In addition, jumps are performed without arm swing in order to simplify modelling and to focus on coordination of lower extremities. The reality is that arm swing is necessary to achieve maximum vertical jump heights in several sports. Therefore, more insight into how arm swing dynamics contributes to overall body motion is needed. To evaluate the contribution of arm swing to the overall motion of vertical jumping, this paper investigates the following differences between jumping with or without arm swing: 1) lower extremity joint angles; 2) translational and rotational effective energy of segments and the total body; 3) resultant joint moments (RIM); and 4) proximal anddistal segmental velocity differences in relation to sequencing. Five women volleyball players chosen for their skill in executing two legged jumps. performed countermovement jumps (CUT) with and without arm swing. The subjects were properly warmed up and performed 10 jumps - 5 each of with and without arm swing. Landmarks were placed on the skin to correspond with the neck, shoulder, elbow. greater trochanter, knee, lateral malleolus, and the metatarsophalangeal joint. Anthropometric measurements were taken as described in Hanavan (1964). The jumps were filmed with a video camera, the maximum height jump with and without arm swing were digitized, and the landmark positions were stored. Profiles for each joint's angular accelerations were then calculated using the DLT alogrithm. These profiles were then inputed into a computer model based on Kane's dynamical equations and corresponding FUM's, velocities of segmental mass centers, and body mass center velocity were calculated. The contribution of arm swing to the overall motion of vertical jumping has been evaluated by comparing jumps with and without arm swing. Arm swing effects on segmental positioning, segmental effective energy. resultant joint movements, and sequencing were investigated. Detailed results and conclusions will be described in the presentation. REFERENCES Hanavan. E.P. (1%4) A mathematical model of the human body. (AMRL-TR-64-102), Wright-Patterson Air Force Base, OH; Aerospace Medical Research Laboratories.