Relationship between Ball Graspability and Run-up during Ball Velocity Acquisition Process

Abstract

Kinematic parameters during throwing were analyzed to examine whether the absence of run-up before ball release or ball graspability was associated with ball velocity acquisition process in 33 participants. Three-dimensional coordinates were measured using a motion analysis system with eight infrared cameras with a sampling rate of 250 Hz. The captured motion data were computed to calculate the kinematic parameters. Path analysis, a structural equation modeling technique, was applied to the obtained kinematic parameters to clarify the “strength” and “direction” of the interrelationship among the observed parameters because it can detect the relationship of each parameter in the complicated theoretical model. When throwing small graspable softballs “without” run-up, the velocity of the center of the body mass influenced the ball velocity. However, in that case, a greater backward trunk tilt with a longer acceleration distance is necessary to acquire greater ball velocity. When throwing large non-graspable dodgeballs with and without run-up and/or throwing small graspable softballs “with” run-up, the horizontal velocity of the thrower’s center of the body mass positively affected the ball velocity via pull distance due to the acceleration distance of the ball and increased step length. The non-graspable dodgeball accelerated with a shorter pull distance in the lateral direction, and the presence or absence of run-up did not affect the ball velocity acquisition process in non-graspable ball throwing.