Infraspinatus Muscle Atrophy in Professional Baseball Players

Background: Infraspinatus muscle atrophy has been observed in athletes who stress their upper extremities in an overhead fashion. The majority of such case reports have been in volleyball players, with far fewer cases reported in baseball players. Hypothesis: Infraspinatus muscle atrophy occurs to a notable degree in professional baseball players. Study Design: Retrospective cohort study. Methods: At the end of the 1999 baseball season, data were collected from all Major League Baseball teams in regards to players affected with infraspinatus muscle atrophy. Results: Twelve of the 1491 major league professional baseball players were identified as having appreciable infraspinatus muscle atrophy. There was an increased prevalence of the muscle atrophy in professional pitchers (10 of 494, 4%) compared to position players (2 of 997, 0.2%) ( P