Upper Extremity and Hip Range of Motion Changes Throughout a Season in Professional Baseball Players.

Background: Loss of upper and lower extremity range of motion (ROM) is a significant risk factor for injuries in professional baseball players.

Purpose/hypothesis: The purpose was to determine changes in ROM in professional baseball players over the course of a single season and their careers. We hypothesized that pitchers and position players would lose ROM, specifically total shoulder motion (total ROM [TROM]) and hip internal rotation (IR), over the course of a season and their careers.

Study Design: Case series; Level of evidence, 4.

Methods: Upper and lower extremity ROM measurements were recorded during pre-, mid-, and postseason on all professional baseball players for a single organization between 2011 and 2018. ROM measurements were compared for pitchers and position players over the course of the season and their careers. Also, ROM measurements over the pre-, mid-, and postseason were compared between pitchers and position players.

Results: A total of 166 professional baseball players (98 pitchers, 68 position players) were included. Pitcher hip external rotation (ER; .001), IR ( .010), and TROM ( .001) for lead and trail legs decreased over the course of the season. Pitcher shoulder ER ( = .005), TROM ( .042), and horizontal adduction ( .001) significantly increased over the course of the season. Position player shoulder flexion ( .046), hip ER ( .001, lead leg; .001, trail leg), and hip TROM ( .001; .002) decreased over the course of the season. Position player shoulder ER ( .031) and humeral adduction ( .001) significantly increased over the course of the season. Over the course of pitchers' careers, there was decreased shoulder IR ( .014), increased shoulder horizontal adduction ( .001), and hip IR ( .042) and hip TROM ( .027) for the lead leg. Position players experienced loss of hip TROM ( .010, lead leg; .018, trail leg) over the course of their careers. Pitchers started with and maintained more shoulder ER and gained more shoulder TROM over a season as compared with position players.

Conclusion: Pitchers and position players saw overall decreases in hip ROM but increases in shoulder ROM over the course of the season and career.