An Inferential Investigation Into Countermovement Jump Determinants of Ulnar Collateral Ligament Injuries in Collegiate Baseball Pitchers.

Background: Countermovement jump (CMJ) analyses can predict ulnar collateral ligament (UCL) injuries in professional baseball pitchers, yet a biomechanical determinant linking CMJ analytics to UCL sprains is unknown.

Purpose/hypothesis: The purpose of this study was to evaluate CMJ parameters in collegiate pitchers with high and low elbow varus torque (EVT) and investigate multilinear regression relationships between CMJ and EVT kinetics. It was hypothesized that pitchers with greater EVT would have greater CMJ measures, and CMJ kinetics would explain the variance in EVT kinetics.

Study design: Descriptive laboratory study.

Methods: Analyses of 19 Division I collegiate baseball pitchers (age, 19.9 ± 1.5 years; body height, 1.87 ± 0.08 m; body mass, 90.0 ± 13.4 kg) were performed with integrated ball release speed, 3-dimensional motion capture, and ground reaction force (GRF) technology. A 1-way between-participant analysis of variance was used to compare CMJ and ball velocity metrics, while Pearson correlations (r) were used to evaluate the association between EVT and CMJ kinetic variables. An alpha level of .05 indicated statistical significance for all tests that included effect size calculations (η²) for mean differences.

Results: The EVT rate of torque development (EVTRTD) was significantly greater in pitchers with a higher EVT (high EVT: 605 ± 74 vs low EVT: 353 ± 103 N·m·s^-1; P < .001; η² = 0.41). CMJ data were similar between groups, yet correlation models indicated that changes in peak CMJ GRF (r = 0.60, P < .001) and power (r = 0.53, P < .05) can explain variance in EVTRTD.

Conclusion: Compared with absolute EVT, CMJ kinetics were more associated with the rate of EVT in collegiate pitchers.

Clinical relevance: Therefore, as it relates to injury surveillance, identifying pitchers who display increases in peak GRF, concentric impulse, and peak CMJ power may provide early detection in protecting athletes from elbow valgus overload.