Effects of throwing the ball of small moment of inertia on normal pitching immediately afterwards.

(From the viewpoint of spin generation parameters)

Abstract

The aim of this study was to investigate the mechanism of the acute effect of using a ball with a reduced moment of inertia to 75% of that of a normal hardball (MOI-75). Release and spin generation parameters were analyzed and evaluated from the data of the sensor-embedded baseball (MA-Q), which was thrown before and after the MOI-75 ball. The results showed that for pitchers whose spin rate increased after throwing MOI-75, showed not only increased moment arm length at the ball release, but also increased velocity while unchanged spin rate at the onset of ball rolling in hand. These results suggest that not only the posture at the ball release but also the motion before the ball release, especially before the onset of ball rolling, needs to be improved.