The effects of the pitcher-ground interaction on fastball pitching velocity
Baseball is one of the most popular sports worldwide and participation continues to rise, including the number of pitchers per team. Previous studies have investigated the relationship between ground reaction forces (GRF) and pitch velocity; however, no study has fully defined the pitcher-ground interaction as it relates to fastball pitch velocity. Therefore, the purpose of this study was to investigate the relationship between the pitcher-ground interaction variables and normalized linear wrist velocity (NLWV), an indirect indicator of pitch velocity, in experienced baseball pitchers. Fifteen male baseball pitchers (4 left-handed; age = 20.9 ± 5.2 years; height = 177.2 ± 7.6 cm; mass = 80.0 ± 10.8 kg; experience = 5.6 ± 5.2 years) were recruited for participation. All participants were able to throw at least 10 full-effort fastballs and had consistent pitching mechanics. This study utilized a 10-camera motion capture system and a custom pitching mound with three imbedded force plates. Pitchers were asked to throw 10 successful fastballs at top velocity to a target. Variables measured were maximum NLWV, GRF for the drive, stride, and combined feet in the up/down (U/D), towards/away (T/A), and left/right (L/R) directions, and pitcher-ground interaction moments [ground reaction force moment (GRFM) and total external moment] for the drive, stride, and combined feet about the U/D, T/A, and L/R axes. It was determined that maximum GRF of the drive foot in the towards direction, and the stride foot and combined feet in the up and away directions were significantly (p < .05) and strongly correlated with NLWV. Additionally, maximum GRFM and total external moment of the drive foot about the L/R axis, and total external moment of the combined feet about the T/A axis during the first peak were significantly and strongly correlated with NLWV. Based on these findings, the drive foot is responsible for creating large external moments, while the primary role of the stride foot is to generate large external forces prior to ball release, which are associated with increased NLWV. Therefore, pitchers may choose to adapt a pitching style that maximizes the pitcher-ground interaction prior to ball release.