Analysis of 224 NCAA Division I Pitchers Finds Two Lead-Leg Knee Patterns and a 0.68 mph Ball Velocity Difference
A study published November 14 in Scientific Reports used a data-driven full-trajectory approach to identify lead-leg knee flexion-extension patterns in 224 NCAA Division I baseball pitchers, and examined their associations with ball velocity and peak elbow varus torque. In-game markerless motion-capture data from each pitcher's 10 fastest recorded fastballs were used, time-normalized from stride foot contact to ball release, with maximum shoulder external rotation aligned at 80 percent of the cycle.
Functional principal component analysis followed by competitive clustering identified two stable K-means profiles: Cluster 1 with 131 pitchers and Cluster 2 with 93.
Cluster 2 showed a modestly higher observed ball velocity than Cluster 1, a mean difference of 0.68 mph (0.30 m/s), with a p value of 0.032. After adjustment for fastball subtype, the difference was attenuated to 0.27 mph (0.12 m/s), with a p value of 0.454. Peak elbow varus torque did not differ between clusters, with a p value of 0.755.
Within Cluster 2, greater knee extension was associated with higher peak elbow varus torque from 27.6 to 71.3 percent of the pitching cycle, with a p value of 0.012. The association persisted after adjustment for ball velocity and body height, but was no longer significant after adjustment for body mass or normalization of torque to body size, and the direct cluster-by-torque interaction was not significant.
The authors are affiliated with Auburn University, the Louisiana State University Health Sciences Center and the Boston Red Sox, among other institutions. They say the findings identify two lead-leg knee patterns and an exploratory association between knee mechanics and absolute elbow torque that cannot be considered independent of body size. No funding was received for the manuscript.
Source: Scientific
Published by GSM · USA (original Chinese edition)
Photo: 图：加利福尼亚大学圣迭戈分校棒球队投手在比赛中投球。来源：Dirk Hansen，Wikimedia Commons，CC BY 2.0。 / Photo: A UC San Diego baseball pitcher throwing in a game. Source: Dirk Hansen, Wikimedia Commons, CC BY 2.0.
