Hamstring Injuries in Major League Soccer: A 10-Year Analysis of Injury Rate, Return to Play, and Performance Metrics by Player Position

Background: Hamstring injuries are common in athletes performing high-intensity sports, such as soccer, impacting performance and return to play (RTP) times. This study aimed to evaluate the effect of hamstring injuries on RTP and performance among Major League Soccer (MLS) players over 10 years. Purpose: To evaluate the effect of hamstring injuries on RTP times and performance metrics among MLS players over 10 years, with a focus on injury characteristics, rehabilitation practices, and positional differences. Study Design: Cohort study; Level of evidence, 3. Methods: From 2010 to 2021, 2715 MLS players with hamstring injuries were identified by the MLS Injury Surveillance Database and analyzed. RTP times, injury rates, and reinjury rates were compared between the 2010-2015 and 2016-2021 cohorts. Performance metrics (games, minutes, goals, and assists) were extracted. Uninjured controls were matched 2 to1 by position, age, and experience. T tests were used to assess postinjury performance differences. Results: Game-related injuries required longer RTP than practice injuries (27.8 vs 21.9 days; P = .023), and acute noncontact injuries took more time to recover than chronic injuries (24.9 vs 13.2 days; P < .0001). RTP times increased in the 2016-2021 cohort compared with the 2010-2015 cohort for minimal/first-degree injuries (15.09 ± 31.29 vs 10.13 ± 28.53 days; P = .018) and overall (20.26 vs 13.60 days; P = .002), despite stable injury rates ( P = .405). Reinjury rates decreased nonsignificantly ( P = .603); however, RTP after reinjury was longer in the 2016-2021 cohort (25.05 vs 10.03 days; P = .025). Defenders saw reduced minutes played 2 years after injury compared with controls (–221.60 ± 833.66 vs −34.80 ± 792.11; P = .007). RTP times were unaffected by playing surface grass versus turf ( P = .620) or player position (forward, midfielder, defender, and goalkeeper) ( P = .900). Conclusion: Injury rates were unchanged in the 2010-2015 and 2016-2021cohorts; however, RTP times increased in the latter cohort, especially for recurrent injuries. Game-related and acute noncontact injuries required longer RTP, and defenders showed the greatest performance decline. Future studies are needed to further highlight mechanisms of injury and treatment for preventative protocols.