抄録
The purpose of this study was to analyze three-dimensionally two groups of baseball strikers, i.e. high and low swing speed groups, and to compare the kinematics of their upper limb motion. Sixteen skilled male strikers were videotaped with two synchronized high-speed video cameras operating at 200 Hz. One trial in which the maximum bat head speed was achieved was selected for each subject and digitized to obtain three-dimensional coordinates of the segment end-points and the bat using a DLT technique. Subjects were divided into High (n=8) and Low (n=8) groups according to the bat head speed. The angles compared between the two groups were abduction-adduction, horizontal abduction-adduction, flexion-extension and internal-external rotation for both shoulders, flexion-extension for both elbows, supination-pronation for both forearms, radius-ulnar flexion, and dorsi-palmar flexion for both hands. The sequential data were normalized with the time from the point when the speed of the grip was over 3 m/s to the ball impact, and then averaged.
