Generation of angular impulse during the contact phase of goal directed tasks requires that the performer control the center of mass (CM) relative to the reaction force so that linear and angular related task objectives at take-off are satisfied. During goal directed tasks initiated from rest, the CM position relative to the feet is controlled by coordinating the trunk, arms, and leg motion, and the reaction force is generated by rapid extension of the joints (Miller and Munro, 1984). In contrast, during tasks performed with an initial CM velocity, the position of the feet relative to the CM is controlled at touchdown so that the CM trajectory and the net linear and angular impulse generated during foot contact satisfies the linear and angular related task objectives (Hay, 1986). These observed between task differences in CM control relative to the feet led us to hypothesize that the initial total body momentum contributes to between task differences in 1) mechanisms of reactio n force generation and 2) mechanisms of coordinating trunk-leg motion to satisfy CM trajectory requirements of the task. Between task differences in initial momentum induced between task differences in mechanisms used to generate angular impulse. However, the role of legs and trunk contributing to the CM orientation and reaction force generation were consistent between tasks.
© Copyright 2004 Annual Meeting of the American Society of Biomechanics. (Presented on poster September 9-10, 2004 at the ASB meeting in Portland). Alle Rechte vorbehalten.