The effects of scapular kinematics, glenohumeral range-of-motion, and shoulder muscle strength on kinematics and kinetics of maximum effort baseball throwing

摘要

A wide spectrum of shoulder injuries has been identified in baseball players. Scapular kinematics during pace-controlled scaption, glenohumeral joint range of motion, and shoulder muscle strength have been associated with shoulder injuries in baseball players. The purpose of this study was to investigate scapular kinematics during maximum effort baseball throwing and to identify the potential association among these measures and scapular kinematics during pace-controlled scaption, glenohumeral range of motion, shoulder muscle strength, and shoulder kinetics during maximum effort baseball throwing.ududThirty-five subjects (age 23.3±5.8yrs, height 180.1±7.8cm, weight 83.3±13.8kg) with previous experience in organized baseball (15.2±5.8yrs) were recruited. Passive video-based motion analysis was used for capturing maximum effort throwing and pace-controlled scaption. Glenohumeral range of motion and shoulder muscle strength were measured. Pearson’s product-moment correlation coefficient was used to evaluate the correlation among the measured variables.ududPositive correlations were observed between scapular kinematics during scaption and throwing at the same arm elevation angle at stride foot contact and the occurrence of maximum shoulder compression force, indicating that kinematic patterns that appeared during scaption also appeared during throwing. Maximum shoulder inferior force was negatively correlated to decreased posterior shoulder tightness and increased supraspinatus strength. Subjects with tighter posterior shoulder and stronger supraspinatus tended to have greater shoulder inferior force. Scapular retraction and posterior tilt were both positively correlated to maximum shoulder compression force. Subjects with a more retracted and posteriorly tilted scapula generated greater shoulder compression force.ududEvidential support for using a scaption test as a tool to evaluate baseball players’ shoulder function was established. Examination of posterior shoulder tightness and supraspinatus strength may be appropriate for screening for high shoulder forces during throwing. The current findings also presented a potential approach to reduce shoulder force by adjusting scapular kinematics, although future research is needed to confirm the existence of causality.ud