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.

Relationship Between Humeral Energy Flow During the Baseball Pitch and Glenohumeral Stability

“…This lack of significance indicates that the CKCUEST may be better suited assessing GH stability rather than energy transmission from more proximal segments across the GH joint. Efficient energy transmission between the trunk and humerus during the baseball pitch is primarily due to properly timed proximal segment (trunk) rotation [11,12,45]. Due to the absence of large amounts of trunk rotation during the CKCUEST, the CKCUEST's inability to directly relate to energy transmission from the trunk to the humerus in the baseball pitching motion should not be surprising.…”

“…To assess energy flow between the thorax, humerus and forearm, a segment power analysis similar to previously established methods was used [11,33]. Joint force power (JFP) represents the rate of work done on each segment by the joint forces and was defined as the scalar product of the resultant joint force and joint center linear velocity.…”

“…In essence, more efficient proximal segments (lower extremity and trunk) will contribute additional energy to the more distal portions of the kinetic chain (upper extremity); thus, alleviating joint loads of the distal segments [10]. According to Aguinaldo and colleagues, who compared high school and professional pitchers, variations in trunk rotation timing can alter the flow of segmental energy throughout the kinetic chain and result in increased joint loads such as elbow valgus torque [11]. Abiding by this theory, an efficient Researchers suggest that motion deriving energy from the more proximal segments of the body is important to reduce injury susceptibility.…”

“…This result provides preliminary support for the use of the closed kinetic chain upper extremity stability test as a clinical assessment of a pitcher's ability to efficiently transfer energy within the upper extremity during the pitch. pitching motion utilizing proximal stability for distal mobility would require less muscular torque from the shoulder because of efficient energy transfer from more proximal segments, potentially reducing the risk of injury [11][12][13]. However, the intersection of efficient energy flow and joint stability within the GH joint has not been examined.…”

“…Researchers have long attempted to describe what is meant by efficient movement. Segmental power analysis is a tool that can help quantify how energy is transferred among body segments [11]. Applying segmental power analysis to the baseball pitching motion, in addition to previously established biomechanical variables, allows researchers to understand the efficiency of the pitching motion in greater detail.…”