Predictors of Peak Elbow Valgus Torque in Collegiate Baseball Pitchers

Context: The incidence of UCL tears in baseball is at an all-time high. ATs are in the position to identify those at risk and potentially prevent injury to the UCL. In baseball, research has associated elbow valgus torque as a potential predictor of injury risk. However, markerless analysis has not assessed possible predictors of injury to the UCL in baseball players. Objective: Identify the kinematic factors that influence peak elbow valgus torque through the sequence of a fastball pitch. Design: Cross-sectional study. Setting: Field study performed in university’s pitching development center. Participants: Division 1 collegiate baseball pitchers (N=21; 17RHP, 4LHP; 20 ± 1y, 190 ± 4cm, 98 ± 7kg). Main Outcome Measure(s): Using KinaTrax® markerless motion capture, Division 1 college baseball pitchers’ kinematics and kinetics of a single fastball pitch were analyzed. Peak elbow valgus torque, maximum glenohumeral external rotation, maximum glenohumeral internal rotation, glenohumeral angular velocity at ball release, elbow flexion at stride foot contact, and maximum hip shoulder separation. Results: Average velocity of pitches analyzed was 89.4 ± 3.6mph. Peak elbow valgus torque was 137.2 ± 26.2Nm. Maximum glenohumeral external rotation explain 42.4% variance in peak elbow valgus torque (r= -.651; P=.001). No other variables were significantly correlated with peak elbow valgus torque (P\u3e.949). Conclusions: Maximum glenohumeral external rotation during the pitching motion influences peak elbow valgus torque. The negative correlation, as described, is a result of the unique coordinate conventions used by KinaTrax®. Previous literature has identified that increases in maximum glenohumeral external rotation concomitantly increases fastball velocity. Because this variable can influence both velocity and elbow stress, further research is necessary to identify norms that allow for safe and effective play