Drive leg ground reaction forces and rate of force development over consecutive windmill softball pitches

Windmill softball pitching is a highly skilled movement, combining whole body coordination with explosive force. Successful pitching requires sequential movement to transfer energy produced by the lower extremity to the pitching arm. Therefore, drive leg ground reaction force (GRF) and the time over which a pitcher can develop force during push off, defined as rate of force development (RFD), is essential for optimal performance. The aim of this study was to examine GRF and RFD in the drive leg during the windmill softball pitch, as well as pitch velocity, throughout a simulated game.

Fourteen softball pitchers (17.9±2.3 years, 166.4±8.7cm, 72.2±12.6kg) pitched a simulated game. Pitch velocity and anterior-posterior and vertical GRF and RFD, each normalized to body weight, were collected for each inning. Average pitch speed remained consistent across all seven innings, 49.57±0.42mph. Changes in GRF and RFD were assessed, with level of significance set as P<0.05.

A one-way repeated measures analysis of variance showed no significant differences in apGRF%BW (P=0.297), vGRF%BW (P=0.574), apRFD (BW/s) (P=0.085) and vRFD (BW/s) (P=0.059).

Training programs can be improved with the knowledge of the magnitude and rate in which forces are developed by the drive leg during push-off of the windmill softball pitch.