The Effects of Body Composition on Female Softball Pitching Biomechanics

Abstract

Additional mass is often considered beneficial for softball pitching performance; however, there may be adverse effects of increased body mass and body fat on softball pitching biomechanics. The purpose of this project was to identify the effects of segmental and whole body fat percentage (BF%) on softball pitchers’ kinematics, kinetics, and pitch velocity. High school and collegiate softball pitchers were recruited to participate. Pitchers completed all consent and health history forms, then underwent a full-body dual-energy x-ray absorptiometry scan. Pitchers then completed ten full effort fastball pitches; the first three fastest strikes were averaged and used for analysis. Kinematic and kinetic data were captured using an electromagnetic system and an in-ground force plate synced with motion analysis software, The MotionMonitor (Innovative Sports Training, Chicago, IL). Pitchers were grouped into healthy-fat% (<32 BF%) and high-fat% (>=32 BF%) categories. Results indicated healthy-fat% pitchers displayed increased peak medial GRF (p < .05) during pitch propulsion. Additionally, whole-body fat mass, whole-body lean mass, and throwing arm lean mass were associated with increased peak throwing shoulder distraction force (p < .05), and BF% was negatively associated with pitch velocity (F4,42 = 4.23, p = .006). Also, increased segmental girth was correlated with decreased shoulder plane of elevation at ball release (p < .05). Lastly, increased elbow and wrist flexion velocity were associated with increased pitch velocity (p < .05), while statistical parametric mapping revealed differences in time series segmental angular velocities between pitcher groups (p < .05). Biomechanical differences exist in the softball pitch according to pitcher body fat percentage. While attaining a healthy body composition is suggested for young softball pitchers, more research is necessary to develop how biomechanical alterations according to pitcher body composition may benefit or inhibit performance variables and injury risk factors.