Long-Term Characteristics of Injured Shoulders in Overhead Sports: A Gender Comparison

Abstract

Overhead sports require high levels of mobility and force produced by the shoulder joint. Additionally, gender differences in glenohumeral joint mobility and upper extremity strength are apparent in various athletic populations. Previous studies have found relationships in shoulder range of motion (ROM) and strength in several shoulder injuries. However, data are lacking regarding the long-term effects of shoulder injuries and considerations with respect to gender. PURPOSE: To determine the long-term effects of shoulder injuries on shoulder ROM and strength and examine gender differences in collegiate overhead athletes. METHODS: 35 male (age:20.3±1.2yr, mass:84.1±9.7kg) and 25 female (age:19.6±0.8yr, mass:70.8±10.9kg) overhead athletes fully participating in NCAA division I baseball, softball, volleyball, or tennis were recruited and divided into injury history group and healthy group depending on the existence of a history of shoulder injury. Active ROM of shoulder internal rotation (IR), external rotation (ER) and horizontal adduction (HAD) were measured using a digital inclinometer. Isometric shoulder IR and ER strength were assessed using a hand-held dynamometer and normalized by body mass. A two (group) by two (gender) factorial ANOVA was used to evaluate the dominant shoulder ROM and strength. Cohen’s d effect sizes were calculated to assess the magnitude of differences. RESULTS: Females showed significantly lower IR ROM (p=.03, d=0.88), IR strength (p=.04, d=0.83), and ER strength (p=.04, d=0.86) in the injury history group versus the healthy group, whereas there were no group differences in males (p>.05). Additionally, male overhead athletes had lower IR (p=.01, d=0.67) and HAD ROM (p=.01, d=0.85) and greater IR strength (p=.02, d=0.64) compared to female overhead athletes. CONCLUSION: The results of this study indicate that shoulder injuries may have longer-lasting effects in female overhead athletes compared to male athletes. Furthermore, male overhead athletes demonstrated larger differences in posterior shoulder tightness and rotator cuff strength imbalances compared to female overhead athletes. This study may have significant implications for protocols aimed at preventing shoulder reinjury for specific genders in overhead sports.