THE EFFECT OF PASSIVE AND ACTIVE IMPULSE ON THE PERFORMANCES OF DROP JUMPS

Abstract

This experiment is to investigate the ground reaction forces of lhree diHerent heights of drop-jumps (DJ) in order to understand the eHect of passive and active impulses on the performance of DJ. Eleven subjects were asked to perform DJs. AMIT force-platform and penny electrical gonia-meter were used to record the ground reaction forces and knee angular displacement. After treating the data and discussion, the conclusions were obtained. The active force as well as the active impulse are that of DJ20=DJ40=DJ60 whose result is consistent with the flight-height of these three diHerent DJ. On the other hand, the higher the jump-altitude is, the larger the passive impulse and passive force are. This result is very diHerent from that of flight-height, so the passive impulsive seems to have no help to prompt the performances of DJs. After further examination of the ground reaction force, we found that the key determinant process is the PARFD that slopes down as the jump-heights increase. The DJ60 induces the largest passive impulse but also accompanies negative PARFD. On other hand, the DJ20 induces the smallest passive impulse but accompanies positive PARFD. Finally, the performances of DJ20, DJ40 and DJ60 have no diHerence.