BACKGROUND: Success at high competition levels often hinges on performing well during high pressure (leverage) situations. Advanced baseball analytics enable teams to quantify the pressure of in-game situations, and markerless motion capture makes it possible to capture in-game biomechanical data. Research suggests consistent pitch release parameters improve performance across a season. Therefore, this study aimed to compare fastball release parameters and pitch velocity in college baseball pitchers between in-game high and low Leverage Index (LI) situations. METHODS: In-game markerless motion capture data (300Hz) for fifty-six NCAA Division 1 baseball pitchers (1.89±0.1m; 92.7±8.9kg) were analyzed. Pitch velocity and hand position (relative to the middle of the pitching rubber) in the anterior/posterior, superior/inferior, and medial/lateral directions at ball release were analyzed. Play-by-play data were scraped for LI components (score, innings, outs, and baserunners) and matched to the appropriate pitch. LI is an estimate of in-game pressure that measures the potential change in win expectancy and is calculated as the sum of the weighted change in win probability divided by the average win probability added per swing. Each pitcher’s highest and lowest LI fastball pitches were used for within-pitcher comparison. A one-way repeated measures multivariate analysis of variance (RM·MANOVA) determined if release parameters and pitch velocity differed between high and low LI situations (α = .05). RESULTS: Descriptive statistics (high LI mean ± SD vs. low LI mean ± SD) for the parameters analyzed are as follows: LI (2.8±1.6 vs. 0.4±0.5), pitch velocity (40.45±3.2 vs. 40.54±1.4 m/s), anterior/posterior hand position (1.72±0.1 vs. 1.73±0.1 m), medial/lateral hand position (0.52±0.2 vs. 0.47±0.2 m), and superior/inferior hand position (1.79±0.2 vs. 1.82±0.2 m). The RM·MANOVA revealed no significant differences in release parameters between high and low LI pitches (F4,52 =.322, p=.862). CONCLUSION: While prior research identified a relationship between consistency in the release position and season long performance, these release parameters are not influenced by high or low pressure (leverage) situations. Additional comparisons of high and low leverage situations, as determined by LI, should include analysis of additional kinematics, ball flight metrics, and ball/strike outcomes.

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