The purpose of this study was to investigate the similarities of upper torso rotation and pelvic rotation around the vertical axis of the global coordinate system with trunk rotation during throwing and striking movements. We enrolled twenty-three right-handed male college students, who performed baseball pitching and batting movements and the golf driver shot. During the throwing and striking movements, 3D coordinates of body landmarks were obtained using the VICON 612 system with 10 cameras operating at 120 frames per second. The ball speed during pitching and the head speed during batting and the driver shot were measured using a high-speed camera at 250 frames per second and analyzed using WINanalyze (2D motion analyzer). The angles of rotation of the upper torso and pelvis were calculated as the angles between the respective segment and the global x-axis. The trunk rotation angle was calculated as the angle between the upper torso segment and the pelvic segment. The sequential data for rotational movement variables were normalized from the onset of the minimum upper torso angle until release or impact.
There were significant positive correlations between the ball speed during pitching, head speed during batting, and head speed during the driver shot (pitching vs. batting, r=0.627, p<0.01; pitching vs. driver shot, r=0.670, p<0.01; batting vs. driver shot, r=0.554, p<0.01). There were significant positive correlations between the two striking movements with regard to the maximum angular velocity of upper torso rotation (r=0.567, p<0.01) and pelvic rotation (r=0.523, p<0.05). The batting and driver shot showed similarity of trunk rotation and pelvic rotation in that the contribution of pelvic angular velocity to the maximum upper torso angular velocity was larger than the contribution of trunk rotational angular velocity to the maximum upper torso angular velocity. Upon trunk rotation, there were no significant positive correlations among the pitching, the batting, and the driver shot with regard to maximum angular velocity. These results indicate that the ball and head speeds are strongly related during pitching, batting, and the driver shot. The upper torso rotation and pelvic rotation around the vertical axis of the global coordinate system are related only during batting and the driver shot.