Date of Award

Spring 5-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology

First Advisor

David J. Szymanski

Abstract

Purpose: To identify how countermovement jump (CMJ) kinetics influence kinematics and momentum of the baseball pitching motion with a focus on lower body and proximal movement. Methods: Nineteen Division I collegiate pitchers (age = 19.9 ± 1.5 years; height = 1.86 ± 0.06 m; weight = 90.7 ± 13.8 kg) performed a bilateral CMJ test and threw 5 strike fastballs from the stretch with a slide step on a custom-made pitching mound built for a laboratory setting. A 3D motion capture system tracked whole-body kinematics at 240 Hz from 29 reflective markers. Two force plates recorded ground reaction forces (GRFs) from each leg at 1040 Hz during both jump test and pitching captures. A one-way ANOVA separating high and low fastball velocity groups by an athlete’s median performance identified differences in pitching mechanics and jump kinetic variables. Meaningful differences between the variables were determined by cohen’s d effect size with 95% confidence intervals. The same statistical calculations were repeated to identify differences in pitching mechanics and jump kinetic variables between two groups, split based on the medians of pitchers’ total linear momentum in anterior-posterior direction.

Results: High throwing velocity group showed a significant increase in absolute peak power (p < 0.01) and higher GRF (p < 0.01) than low throwing velocity group for CMJ. The high momentum group showed a significant increase in concentric impulse (p < 0.05) than the low momentum group. All of the pitching mechanics variables except for the momentum profiles did not show significant differences in both ANOVA tests.

Conclusions: Key findings suggest the importance of lower body power, as CMJ data has the potential to separate throwing velocity ability in pitchers, coupled with greater total mediolateral and transverse momentum with higher peak power in the CMJ.

Keywords: baseball pitching, countermovement jump, fastball velocity, ground reaction forces

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