Softball Pitchers' Body Segment Girths Are Associated with Varied Biomechanics at Ball Release of the Pitch

Purpose: The purpose of this study was to examine the relationships between pitcher trunk and throwing arm girth with kinematics at ball release of the softball pitch. Softball pitchers can be of various shapes and sizes; however, it is unknown if segment girth might influence pitch biomechanics. Because of the importance of body positioning at ball release of the windmill pitch, this study examined the relationship between segment girth and pitch biomechanics at ball release.

Methods: Forty-two pitchers volunteered to participate (1.706 ± 0.061 m, 74.98 ± 15.94 kg, 15.5 ± 1.7 yr). Participants' throwing upper arm, chest, waist, and hip girth were measured. Participants then pitched fastballs to a catcher (43 ft) while an electromagnetic motion capture system synced with a force plate and motion analysis software collected kinematic data (sampled at 240 Hz).

Results: Linear regressions revealed that upper arm, chest, and waist girth were associated with throwing arm shoulder horizontal abduction. Greater segment girth was associated with less horizontal abduction at ball release of the pitch.

Conclusions: Segment girth is related to pitch biomechanics and may influence body positions at crucial softball pitch events such as ball release.

Clinical relevance: Understanding biomechanical differences according to body segment girth is important for safe and optimal player development and performance.