Abstract

Baseball pitching places unique stress on the glenohumeral joint, with the upper extremity rotating at a rate of over 7,000o/s. Despite efforts to address the high rate of shoulder and elbow injuries in baseball pitchers, injury prevalence continues to rise. Multiple risk factors have been identified, including fatigue, height, and mass. Another previously identified independent risk factor for shoulder and elbow injuries in pitchers is a lack of dorsiflexion in the ankle of the pitcher’s back leg. There was no causation established between a lack of ankle dorsiflexion and increased prevalence of elbow and shoulder injuries in baseball pitchers in the previous study. Therefore, the purpose of this study was to assess the relationship between ankle dorsiflexion and plantarflexion, and normalized varus torque at the medial elbow of the throwing arm in collegiate baseball pitchers. Seventeen male (age 21.6 ± 1.90) collegiate baseball players participated in this study. Participants completed goniometric measurement of ankle dorsiflexion and plantarflexion, as well as the Y-balance lower extremity test. Participants also wore an inertial measurement unit on their medial elbow to measure arm speed and varus torque at the medial elbow while throwing. Pearson’s correlations were conducted to assess relationships between normalized varus torque at the medial elbow, anterior reach, posterolateral reach, posteromedial reach, active plantarflexion of the front and back leg, active dorsiflexion of the front and back leg, arm speed, height, and mass. An independent samples t-test was run to assess differences in normalized varus torque between participants with less than 10 degrees of active dorsiflexion in their back leg and participants with 10 or more degrees of dorsiflexion in their back leg. Significant positive correlations were found between normalized varus torque, height, and mass. However, no significant correlations were found between normalized varus torque and measures of dynamic and static ankle range of motion. Individuals with 10 or more degrees of active ankle dorsiflexion in their back foot experienced 13.8% more normalized varus torque at the medial elbow when throwing (t(15) = -2.45, p = .027). These results suggest an increase in varus torque at the medial elbow may not be the causative factor for increase shoulder and elbow injuries in pitchers with lower ankle dorsiflexion. Future research should look further into the effects of dynamic and static ankle range of motion on pitching mechanics and other factors that may predispose pitchers to shoulder and elbow injuries.