Objectives: To evaluate kinematic and kinetic parameters for high school (HS) and professional (PRO) pitchers differentiated by stride width.
Design: Descriptive laboratory study.
Methods: HS (n = 36) and PRO (n = 172) baseball pitchers pitched 8-12 fastballs using 3D-motion capture (480-Hz). Pitchers were 1:1 propensity-scored matched by age, height, weight, and ball velocity based on 'narrow' versus 'wide' stride widths and kinematics and kinetics were compared using independent t-tests. Independent associations between variables and stride width were determined utilizing linear regressions.
Results: At foot contact, HS wide (n = 18) had significantly less lead knee flexion (41 ± 9° vs. 49 ± 6°, p = 0.007, d = -1.0) and less pelvis rotation (66 ± 9° vs. 57 ± 14°, p = 0.003 d = 0.8) compared to HS narrow (n = 18). PRO wide (n = 86) at ball release had significantly less pelvis rotation (-10 ± 10° vs. -15 ± 14°, p = 0.008, d = 0.4) and increased shoulder horizontal adduction (4±8° vs. -1±9°, p=0.003, d=0.5) compared to PRO narrow (n = 86). For every 10 cm increase in stride width, pelvis rotation at ball release decreased by 2° (B:0.10, β:0.20, p < 0.001) in HS and 1.3° (B:0.08, β:0.13, p = 0.002) in PRO.
Conclusions: HS and PRO pitchers differentiated by stride width demonstrated no significant difference in throwing arm kinetics. For both groups, wider stride width was associated with decreased pelvis rotation, which may contribute to inefficient utilization of kinetic energy. Ultimately, coaches and players may better focus their efforts on refining other kinematics for enhanced performance outcomes and safe pitching mechanics.
Keywords: Baseball; Biomechanics; Foot placement; Motion-capture; Shoulder; Torque.
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