ゆか運動の後転とびにおける腕の振りと踏み切りのタイミングについて

抄録

This study was intended to clarify the timing of the arm swing and the take-off of back handspring from the standing position. Results obtained in this study are as follows. As a result of the analyses of the reproducibility of the back handspring motions, motion technique of the trained group exhibited high correctness and stability, but that of the unskilled group was unstable from a viewpoint of special and temporal motions. The cause of the phenomenon of knee forward was thought to be the back bending movement of a learner who had learned a faulty form. The upper arm swing motion of the back handspring was analyzed. As a result, the maximum upper arm angular acceleration in the first movement phase was assumed that the motion of which the arms follow the descending speed of the body when the knees were crooked to use the bounce of legs. The maximum upper arm acceleration in the second movement phase is used for backward body declining. Increasing the angular acceleration of the upper arms at θ = 0 degree may effectively increase the horizontal floor reaction force at take-off. The maximum upper arm angular acceleration of the third movement phase is assumed the motion of which the upper arms follow the backward body declining speed. The timing of the arm swing and take-off were examined. For the arm swing motion, it was concluded that a condition where arms exhibit the greatest angular acceleration at θ =0 in the second movement phase is the best motion. For the take-off motion, it was concluded that the take-off is performed in the third movement phase when upper arm angular acceleration is highest.