標槍投擲時槍體受力型態及地面反作用力型態之探討

Purpose: To investigate the force applied to javelin and ground reaction force (GRF) during final thrust and the relationship between javelin applied force and GRF by comparing the two different classes of throwers. Methods: Two Redlake cameras (250 Hz) synchronized with a Kistler force plate (1,250 Hz) were used to collect the javelin kinematic data and GRF, respectively. The force applied to javelin was calculated by the 3D inverse dynamics with three non co-linear markers on the javelin. The Matlab version 6.5 software was used to computer variables. Results: The peak axial and lateral force of elite group was significant larger than those of general group (p＜.05). The peak maximum GRFy of elite group was greater than that of general group in the propulsive phase. In addition, the elite group has a shorter duration of landing and more obviously jumping motion. The javelin release occurred in late breaking phase, at that moment and no significant change was observed on GRFy and GRFz. Conclusion: The breaking leg provides s a steady support base for transmission of the moment between ground and trunk, so no significant change on GRFs. It is suggested that after release, the general group should make the propulsive motion more completely during the following propulsive phase and try to increase the proportion of GRF on anterior-posterior direction.