Segmental Momentum Sequencing: Implication for Injury and Performance Between Collegiate Pitchers With Different Arm Slots.

Background: Baseball pitching requires precise coordination of the upper extremities to generate and transfer angular momentum efficiently while minimizing joint loading. Although the importance of temporal sequencing is recognized, few studies have examined how segmental momentum sequences vary across arm slot styles. Therefore, the purpose of this study was to evaluate the temporal sequence of peak angular momentum across segments and determine its capacity to predict ball velocity and upper extremity joint loading among overhead (OH), three-quarter (QT), and sidearm (SA) collegiate pitchers. Purpose: To (1) quantify the timing of peak angular momentum in the torso, upper arm, forearm, and hand across different arm slot styles during baseball pitching; and (2) determine whether the relative timing of these segmental peaks predicts ball velocity and kinetic loads at the shoulder and elbow among various arm slot styles. Study Design: Descriptive laboratory study. Methods: A total of 363 National Collegiate Athletic Association Division I pitchers (90.99 ± 10.22 kg; 1.88 ± 0.49 m; 90.35 ± 40.39 ± 3.19 m/s) were analyzed using markerless motion capture and radar-based ball tracking during competition. A mixed-model multivariate analysis of variance tested interactions between arm slot and segmental timing, and multiple linear regressions within each arm slot predicted ball velocity and upper extremity kinetics. The overall significance level (α) was set at .05. Results: Across all arm slot styles, pitchers demonstrated a consistent proximodistal sequence (torso → upper arm → hand → forearm). Earlier torso peak momentum and later hand peak momentum predicted greater ball velocity in OH and QT pitchers, whereas SA showed weaker relationships between sequencing and velocity. In OH and QT, early forearm peak momentum and delayed hand peak momentum were linked to higher shoulder distraction force, suggesting that timing disruptions may elevate joint loading. In contrast, kinetic loading in SA appeared less timing dependent and more influenced by the magnitude of angular momentum. In OH and SA, delayed forearm peak momentum and early hand peak momentum were linked to higher elbow varus torque. In QT, early hand peak momentum were linked to higher elbow varus torque. Conclusion: These findings suggest that segmental sequencing influences both performance and joint loading across arm slot styles and that deviations from efficient timing may elevate injury risk. Training that improves trunk rotation and distal timing may enhance performance and reduce joint stress. Clinical Relevance: The association between segmental timing and upper-extremity loading suggests that timing characteristics may be an important factor when evaluating throwing-related injuries. Assessing arm slot-specific timing patterns may help clinicians and performance staff interpret mechanical variability and guide monitoring strategies in overhead athletes.