earticle

영어

The throwing motion is considered as simple projectile motion, the horizontal distance is determined by the initial state of pitcher's motion which include the projectile velocity, projectile angle, angular momentum at the moment of ball realease. The purpose of this study was to investigate the throwing motion of baseball for the elementary school children. It was considered that a common movement pattern as well as distinctive movement patterns between athletes might be identified. Four male baseball athletes who achieved at least 8th in the Korea Regional Baseball Game Meetings during 2006 and 2007 were selected as subjects. The Direct Linear Transformation technique was adopted from the beginning of filming to the final stage of data extraction. This study was conducted to investigate the kinematic relationship between the throwing motion and horizontal distance performed by elite baseball athletes. This investigation examined the kinematic parameters of the upper and lower extremities and the contribution of body segments to the ball velocity. It was found that: The mean projectile velocity of the subjects at the instant of ball release was 22.83±2.12m/s, and the mean height of the center of gravity at the instant of release was equivalent to 51.02±6.09% normalized height of the subjects. The mean ball projectile angle at the instant of release was 24.03±3.19°. By throwing the motion, multiple regression equation of horizontal distance prediction was Y = 4.77PV(velocity at the instant ball release) + 4.21HH((C.O.G height at the instant ball release) - 0.99WAV(waist angular velocity at the instant ball release+ 1.45BA(body lean angle at the instant ball release)2 - 0.12BA + 4.50 (R2 = 0.76, p<0.000). Within the limitations of this study it is concluded: In order to increase base-ball horizontal distance, several conditions must be fullfilled at the instant of ball release. First, the projectile velocity should be fast at the instant of ball release from the hand. Second, the body normalized height(%height) should be raised at the instant of ball release from the hand. Third, the total forward angular velocity with respect to a transverse axis through the center of gravity should be increased during ball release from the hand. Fourth, the contribution of the upper arm and fore-arm to the hand tip velocity with respect to a transverse axis through the center of gravity should be raised at the instant of ball release from the hand.