KINEMATIC CHANGES AT BALL RELEASE IN BASEBALL PITCHING OVER A SIMULATED GAME OF BASEBALL
AbstractINTRODUCTION The defensive nature of baseball causes it to be dominated by the skill of the pitcher, who through speed of pitch or a combination of speed and guile in controlling the ball often determines the result of the game (Polk, 1982). Correct pitching mechanics enables a pitcher to throw the ball repeatedly at high velocities without undue risk of injury. Nowhere is this more important than in the late innings of a game. PURPOSES AND METHODS The purpose of this study was to kinematically describe and compare the changes in stride length, foot contact, ball release time, release height, ball velocity and knee, hip, and trunk angle at ball release over a simulated single game of baseball pitching in collegiate pitchers. Seven male collegiate pitchers were filmed pitching a simulated , 7inning baseball game. Each inning consisted of 14 pitches following the protocol as suggested by Potteiger, Blessing, and Wilson (1992). Every other pitch was to be thrown with 100% effort while the other pitches were to be thrown at 80% effort. The first, seventh, and thirteenth pitches of innings 1,4, and 7 were required to be fast balls and were filmed using the Peak5 2D video system. Film data were collected at 120 Hz. A Jugs radar gun was used to collect the velocity of the baseballs being pitched. A 3 x 3 analysis of variance with an alpha level set at p <. 05 was used to determine if differences occurred within and between innings. RESULTS - The results of this study showed that there were no significant changes in stride length, foot contactlball release time, release height, ball velocity and knee, and trunk angles at ball release. Hip angle at ball release did change between innings. CONCLUSIONS Because there were no significant differences in ball velocity over the course of the game, it was concluded that the pitchers did not reach a fatigue state. This may explain why there were no changes in all but one of the kinematic variables under investigation. There were differences in hip angle over the course of the game which may be linked to the pitcher's pregame routine or warmup. It appears that proper low back and leg stretching1 warmup routine may alleviate the hip angle changes. There may be psychological as well as physical factors that occur during a live game situation that could contribute to the fatigue of a pitcher that could not be duplicated under the simulated game conditions. REFERENCES Polk, R. (1982). Baseball Playbook. Mississippi State: Mississippi State University. Potteiger, J., Blessing, D., & Wilson, G. (1992). The physiological responses to a single game of baseball pitching. Journal of Applied Sport Science Research, 61 118.
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