Segmental Power Analysis of Sequential Body Motion and Elbow Valgus Loading During Baseball Pitching: Comparison Between Professional and High School Baseball Players

Abstract

Background: Pitching-related elbow injuries remain prevalent across all levels of baseball. Elbow valgus torque has been identified as a modifiable risk factor of injuries to the ulnar collateral ligament in skeletally mature pitchers.

Purpose: To examine how segmental energy flow (power) influences elbow valgus torque and ball speed in professional versus high school baseball pitchers.

Study design: Descriptive laboratory study.

Methods: A total of 16 professional pitchers (mean age, 21.9 ± 3.6 years) and 15 high school pitchers (mean age, 15.5 ± 1.1 years) participated in marker-based motion analysis of baseball pitching. Ball speed, maximum elbow valgus torque (MEV), temporal parameters, and mechanical power of the trunk, upper arm, and forearm were collected and compared using parametric statistical methods.

Results: Professional pitchers threw with a higher ball speed (36.3 ± 2.9 m/s) compared with high school pitchers (30.4 ± 3.5 m/s) (P = .001), and MEV was greater in professional pitchers (71.3 ± 20.0 N·m) than in high school pitchers (50.7 ± 14.6 N·m) (P = .003). No significant difference in normalized MEV was found between groups (P = .497). Trunk rotation time, trunk power, and upper arm power combined to predict MEV (r = 0.823, P < .001), while trunk rotation time and trunk power were the only predictors of ball speed (r = 0.731, P < .001). There were significant differences between the professional and high school groups in the timing of maximum pelvis rotation velocity (42.9 ± 9.7% of the pitching cycle [%PC] vs 27.9 ± 23.4 %PC, respectively; P < .025), maximum trunk rotation (33 ± 16 %PC vs 2 ± 23 %PC, respectively; P = .001), and maximum shoulder internal rotation velocity (102.4 ± 8.9 %PC vs 93.0 ± 11.7 %PC, respectively; P = .017).

Conclusion: The power of trunk motion plays a critical role in the development of elbow valgus torque and ball speed. Professional and high school pitchers do not differ in elbow torque relative to their respective size but appear to adopt different patterns of segmental motion.

Clinical relevance: Because trunk rotation supplies the power associated with MEV and ball speed, training methods aimed at core stabilization and flexibility may benefit professional and high school pitchers in reducing the injury risk and improving pitching performance.

Keywords: biomechanics; kinetics; mechanical energy; segmental motion.

Figure 1.

Elbow valgus torque (top) and mechanical power (bottom) of the trunk, upper arm, and forearm during the pitching cycle, defined from front foot contact (FC) to ball release (BR), for a representative professional pitcher in the study. MER, maximum shoulder external rotation; MEV, maximum elbow valgus torque.

Figure 2.

Elbow valgus torque (top) and mechanical power (bottom) of the trunk, upper arm, and forearm during the pitching cycle, defined from front foot contact (FC) to ball release (BR), for a representative high school pitcher in the study. MER, maximum shoulder external rotation; MEV, maximum elbow valgus torque.

Figure 3.

The timing of maximum values of pelvis rotation velocity, trunk rotation, trunk rotation velocity, elbow valgus torque (MEV), shoulder external rotation (MER), and shoulder internal rotation velocity (MIRV) was statistically different across events (P < .001) and between professional and high school pitchers (P = .008). The timing of a specific event is expressed as a percentage of the pitching cycle, where 0% and 100% correspond to front foot contact (FC) and ball release (BR), respectively.