The purpose of this study was to investigate tee-batting skills in relation to ground reaction forces. Eithteen batters tried seven swings on the force platform recording three-dimensional kinetic data. A video camera (60 fps) was used to measure ball velocity and swing velocity. The following results were obtnined. 1) A statistically significant correlation was observed between the swing velocity and the swing time. 2 Statistically significant correlations were observed between the swing velocity and the anteroposterior forces during backward swing phase, the mean power calculated from the anteroposterior force during forward swing phase. 3) Statistically significant correlations were obtained betwben the swing velocity, the ball velocity and the mediolateral distance of the CG of the body from the starting position during backward swing phase. 4) The swing velocity and the ball velocity significantly correlated with the mediolateral distance of the CG of the body between the starting phase and the impact phase. 5) Coefficient of variations (cv) of the vertical forces during backward swing phase and the mean power calculated from the vertical force significantly correlated with cv of the swing velocity. CV of the vertical power of the CG of the body significantly correlated with cv of the ball velocity. These findings suggest that the batter should move the body toward the opposite side of the ball and the anterior direction just before the starting phase of the forward swing to obtain the high swing velocity. The result also suggests that the batter should control the vertical movement during backward and forward swing to obtain the high reproducibility of batting.
