抄録
The purpose of this study was to investigate the effectiveness of the torso and upper extremity rotation for producing the bat-swing velocity in baseball batting. Seventeen male collegiate baseball players were asked to perform the batting trials using a batting-tee. Three-dimensional kinematic data were recorded by an optical motion capture system operating at 500Hz. The rigid link model consisting of five segments (pelvis, thorax, shoulder girdle, upper extremity and bat) developed to calculate the contribution of the torso and upper extremity rotation to producing the bat-swing velocity. In the early swing phase, the contribution of the pelvic rotation around the vertical axis was larger than the rotation of other segments. In the late swing phase, the contribution of the rotation of the upper extremity relative to the shoulder girdle and the bat relative to the upper extremity around the vertical axis were large.
