Changes in collegiate starting pitchers' range of motion after single game and season

The relationship of changes in glenohumeral range of motion (ROM) in a pitcher's throwing shoulder to a single pitching episode is not well described, and the causes of such changes over a season are controversial. We hypothesized that in pitchers for a collegiate baseball team, external rotation (ER) would increase, internal rotation (IR) would decrease, total ROM would be maintained, and the glenohumeral IR deficit would worsen in starting pitchers' shoulders after single pitching episodes and after the season. Participants were 6 starting pitchers for all 25 home games from a Division III National Collegiate Athletic Association team during 1 regular spring season. One examiner measured glenohumeral ER, IR, and total ROM with the arm abducted 90° pregame before stretching or throwing and immediately postgame before shoulder icing. Bilateral measurements were obtained on supine pitchers via a long-arm goniometer and custom bubble inclinometer. Innings, pitch count, and types of pitches were recorded for possible associations with any glenohumeral motion changes. Paired t tests were used to compare dominant and nondominant glenohumeral differences in ROM (significance, P < 0.05). Compared with pregame values, single-start postgame glenohumeral ER significantly increased (7.9° ± 2.2°), single-start IR did not significantly change, and single-start total ROM significantly increased (7.4° ± 3.4°). Compared with preseason values, postseason glenohumeral ER significantly increased (10.2° ± 6.2°), IR significantly decreased (-17.8° ± 6.7°), and total ROM significantly decreased (-7.7° ± 5.2°). In the collegiate throwing shoulder, changes in ER and total ROM occurred after 1 episode of starting pitching, and changes in ER, IR, and total ROM occurred over the full season. There was no association between the ROM changes and innings pitched, pitch count, or types of pitches thrown. In conclusion, for collegiate pitchers, changes in glenohumeral ROM occur after single starts and over the season, suggesting that monitoring motion changes throughout the season may be beneficial.