Improving Shoulder Internal Rotation Motion of In-season Throwing Athletes: A Randomized Controlled Trial

Abstract

PURPOSE: Throwing athletes commonly experience loss of shoulder internal rotation (IR). This adaptation, when combined with compromised resting posture, has the potential to increase risk of rotator cuff and biceps tendinopathy, labral tears, and elbow injuries. This study investigated the effectiveness of two methods prescribed to restore IR: the Sleeper Stretch (SS), which aims to stretch the capsule, and the Balloon Blow (BB) which aims to optimize breathing, posture, and scapular stability. Because the BB is less stressful to the shoulder joint, it may be a superior alternative. We hypothesized that when using the BB, IR would be increased either as effectively, or more so, than the SS. METHODS: Healthy in-season baseball and softball players were randomly assigned an intervention (BB or SS) to the dominant arm 2x/day for 5 consecutive days. After a 2-week period of no intervention, both groups crossed over and performed the alternate intervention. IR was passively measured in supine at baseline, immediately after a throwing session on day 1, after intervention on day 1, and prior to practice on days 2-5. On the last day of the study, each subject was asked if he/she had a preference for either exercise. Statistical analysis for comparisons of differences in IR among intervention type (SS and BB) were performed using an analysis of covariance (ANCOVA) for the 6 instances as listed above. Statistical significance was set a priori at α≤0.05. RESULTS: 13 softball players (17.49 ± 0.63 yrs.; BMI 28.4±5.6) and 10baseball players (17.07 ±0.56 yrs.; BMI 24.6±4.7) participated in the study. Both interventions increased IR over the course of the 5 days, but there was no significant difference (p=0.66) between SS and BB. When performing SS, the mean IR was 45.7±11.38 degrees immediately after the throwing session and incrementally improved to 53.06±10.95 degrees on day 5. When performing BB, the similar incremental increase was from 47.39±12.15 degrees to 53.56±8.61 degrees. There was no statistically significant difference in preference between the SS (51.1%) and the BB (48.9%). CONCLUSIONS: The BB and the SS were both observed to be effective at increasing IR ROM in healthy in-season baseball and softball players over 5 days, yet neither proved to be superior with regard to degree of improvement nor speed of attaining increased IR.