Association between pitching velocity and elbow varus torque

Abstract

Background: While there has been an increase in the number of biomechanical studies and usage across baseball, there often remains a dichotomy between performance enhancement and injury reduction.

Objective: To identify which variables have the highest influence on elbow varus torque while controlling for pitch velocity. The secondary purpose was to evaluate a minimal data set prediction model derived from the identified biomechanical variables.

Method: A retrospective review was performed on baseball pitchers who underwent biomechanical evaluation. Analysis of covariance and prediction modeling for varus torque and fastball velocity were utilized.

Results: 298 pitchers were included. Small associations were identified between the log of hip shoulder separation (0.12 (95 % CI: 0.01, 0.23), R²=0.10), maximum trunk rotation velocity (0.42 (0.15, 0.70), R²=0.12), trunk flexion at ball release (-0.11 (-0.20, -0.02), R²=0.10), and shoulder abduction at late cocking (-0.29 (-0.52, -0.06), R²=0.10) in relation to the log of elbow varus torque. The clinical prediction model for elbow varus torque resulted in poor prediction performance, calibration, and large error using minimal predictor variables (RMSE=1.15, R²=0.10, Calibration=0.78 (0.41, 1.15)).

Conclusion: Optimizing pitching efficiency by improving small aspects throughout the pitching delivery has potential to accomplish an improvement in velocity while maintaining lower levels of varus torque.

Keywords: Biomechanics; Elbow; Injury; Pitching; Pitching efficiency.