Stride-Phase Kinematic Parameters That Predict Peak Elbow Varus Torque

Abstract

Background: During baseball pitching, a high amount of elbow varus torque in the arm cocking-to-acceleration phase is thought to be a biomechanical risk factor for medial elbow pain and injury. The biomechanics of the stride phase may provide preparation for the arm cocking-to-acceleration phase that follows it. Purpose: To determine the kinematic parameters that predict peak elbow varus torque during the stride phase of pitching. Study Design: Descriptive laboratory study. Methods: Participants were 107 high school baseball pitchers (age range, 15-18 years) without shoulder or elbow problems. Whole-body kinematics and kinetics during fastball pitching were analyzed using 3-dimensional measurements from 36 retroreflective markers. A total of 26 kinematic parameters of the upper and lower limbs during the stride phase leading up to the stride foot contact were extracted for multiple regression analysis to assess their combined effect on the magnitude of peak elbow varus torque. Results: Increased wrist extension, elbow pronation, knee flexion on the leading leg, knee extension on the trailing leg at stride foot contact, and upward displacement of the body’s center of mass in the stride phase were significantly correlated with decreased peak elbow varus torque (all P < .05). Moreover, 38% of the variance in peak elbow varus torque was explained by a combination of these 5 significant kinematic variables ( P < .001). Conclusion: We found that 5 kinematic parameters during the stride phase and the combination of these parameters were associated with peak elbow varus torque. The stride phase provides biomechanical preparation for pitching and plays a key role in peak elbow varus torque in subsequent pitching phases. Clinical Relevance: The present data can be used to screen pitching mechanics with motion capture assessment to reduce peak elbow varus torque. Decreased peak elbow varus torque is expected to reduce the risk of elbow medial pain and injury.

Association Between Increased Elbow Carrying Angle and Lateral Epicondylitis

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Potential injury mechanisms in ulnar collateral ligament injuries; magnitude and variability of elbow load in repetitive baseball pitching

“…For injury prevention, the next step is to understand why one pitcher shows an increase and another a decrease or no changes in within-individual load magnitude and variability when performing relatively long sessions of repetitive pitching. Biomechanical variables proximal to the elbow, like, leading leg knee extension and trailing leg knee exion, and an earlier trunk rotation are associated with an increased external valgus torque (Aguinaldo & Chambers 2009;Tanaka et al 2020). Alterations within an individual in these variables and other proximal intersegmental interactions could increase the external valgus torque magnitude and variability during repetitive pitching.…”

Effect of elbow carrying angle on lateral epicondylitis development

“…Increasing this distance will result in higher stress and accordingly the decrease in elbow carrying angle and shift to varus will cause additional stress on the ECRB. [ 14 ] As a result, the decrease in elbow caryying angle causes an abrasive effect on the ECRB tendon.…”