Abstract
PURPOSE: Overhead sports such as baseball are associated with a high incidence of shoulder injuries due to repetitive stress, throwing biomechanics, and cumulative workload on periarticular structures. Rotator cuff pathology and subacromial impingement are among the most prevalent conditions, often presenting asymptomatically. However, little is known about how rotator cuff tissues adapt throughout a competitive season and whether pitchers and position players exhibit different patterns of adaptation. This study aimed to evaluate seasonal changes in supraspinatus tendon (SST) thickness, subacromial space (SAS), and the subacromial occupation ratio (OR = SST/SAS) in collegiate baseball players using musculoskeletal ultrasonography.
METHODS: Twenty-nine collegiate baseball players (16 pitchers, 13 position players) were evaluated at the beginning and end of a season. Ultrasonographic measurements were obtained for SST thickness and SAS using a long-axis view. SST thickness was measured with the athlete in the modified Crass position. SAS was measured with the arm in a neutral position from the anterolateral acromial tip to the cortical surface of the humeral head. The occupation ratio (SST/SAS) was calculated for each session. A MANOVA was conducted to assess within-subject and between-group differences across the season.
RESULTS: Mean SST thickness was 0.727 cm in pitchers and 0.707 cm in position players. Mean SAS was 1.265 cm in pitchers and 1.257 cm in position players. The mean OR was 0.602 for pitchers and 0.569 for position players. No statistically significant differences were observed between positions or across time points for any variable (p > 0.05).
CONCLUSIONS: No significant seasonal changes were observed in SST thickness, SAS, or OR between pitchers and position players. This suggest that collegiate-level throwing loads may not induce measurable morphologic adaptations of the SST or SAS over a single competitive cycle. Future studies should examine the relationship between sonographic findings, clinical presentation, and tendon mechanical properties to better characterize adaptive and maladaptive responses to repetitive overhead loading.