抄録
This study investigated the characteristic of legs during takeoff in the spike jump.70 volleyball players were done questionnaire investigation of before an experiment. The questionnaire investigation showed that players of 75.71% were taught by a coach to take off a tiptoe for, and players of 61.54% were experienced the injury of lower extremity. Six university women volleyball players spiked and they were analyzed movement of spiking using the 3D direct liner transformation（DLT）method. We divided the players into two groups : Type SH（n=3），players who spike jumped introvert foot angle -40deg or more; and Type FL（n=3），players who spike jumped at -40deg or less. Horizontal velocity of the approaching phase was 1.83 ± 0.08 m / s for type SH and 1.45 ± 0.15 m / s for type FL. The vertical velocity at take-off was 3.26± 0.16 m / s for type SH and 2.81 ± 0.09 m / s for type FL. The jump height of type SH was 0.57 ± 0.04 m, and the type FL was 0.54 ± 0.02m. Efficiency of conversion from horizontal velocity to vertical velocity at the foot sole grounding（ ECHV） of type FL was 194.92±20.62％, and ECHV of type SH was 178.43 ±13.40％ . A ratio of the vertical velocity when the hip joint of the leg which player took off bent it most for the vertical velocity when stepping forward leg just before the jump（ RCR） of type FL was 52.11±2.93%, and ECHV of type SH was 36.63±3.66%. Those results thought that the analysis that we focused on an introvert foot angle difference could offer precious information to players and the coaches. In addition, it became clear that type FL was superior in skill to convert approach velocity into plumb velocity effectively.
