This experiment is to investigate the ground reaction forces from three different heights of drop-jumps (DJ20, DJ40, DJ60) induced by Taiwan athletics in order to understand the training status with plyometrics movement. Eleven subjects were asked to perform DJs. AMIT force-platform and penny electrical gonio-meter were used to record the ground reaction forces and knee angular displacement. After treating the data and discussion, the conclusions were obtained. The flight-heights of these three different DJ induced were not different. On the other hand, the higher the jump-heights is, the larger the passive impulses is, which is very different from that of flight-height, implying that the passive impulses seem to have no help to promote the performances of DJs. The active impulses are the same which is in consistent with the result of flight-heights, demonstrating that the ability of push-off remains the same while facing the different intensity of the DJs, even the heavy intensity of DJ60. After further examination of the ground reaction force, we found that the rate of force developed between passive and active forces (coupling RFD) decreases as the jump-heights increase. The coupling RFD of DJ40 began to negatively develop, and the DJ60 induces much more negative coupling RFD, implying that the training status of medium and heavy intensity of DJs are not well prepared, and still have a lot of space to improve.
This experiment is to investigate the ground reaction forces from three different heights of drop-jumps (DJ20, DJ40, DJ60) induced by Taiwan athletics in order to understand the training status with plyometrics movement. Eleven subjects were asked to perform DJs. AMIT force-platform and penny electrical gonio-meter were used to record the ground reaction forces and knee angular displacement. After treating the data and discussion, the conclusions were obtained. The flight-heights of these three different DJ induced were not different. On the other hand, the higher the jump-heights is, the larger the passive impulses is, which is very different from that of flight-height, implying that the passive impulses seem to have no help to promote the performances of DJs. The active impulses are the same which is in consistent with the result of flight-heights, demonstrating that the ability of push-off remains the same while facing the different intensity of the DJs, even the heavy intensity of DJ60. After further examination of the ground reaction force, we found that the rate of force developed between passive and active forces (coupling RFD) decreases as the jump-heights increase. The coupling RFD of DJ40 began to negatively develop, and the DJ60 induces much more negative coupling RFD, implying that the training status of medium and heavy intensity of DJs are not well prepared, and still have a lot of space to improve.