Is Workload Associated With Oblique Injuries in Professional Baseball Players?

Background: Oblique strains have become a common injury among professional baseball players. The influence of player workload on oblique strains remains unknown. Purpose/Hypothesis: To determine whether workload is a risk factor for oblique strains in professional baseball players. We hypothesized that fewer days of rest, more innings pitched/fielded per game, and more batters faced/plate appearances per game would significantly increase a player's risk of sustaining an oblique strain. Study Design: Case-control study; Level of evidence, 3. Methods: All professional baseball players who sustained an oblique strain between 2011 and 2017 were identified using the Major League Baseball Health and Injury Tracking System. A separate dataset of player usage-days of rest per game, innings pitched or fielded per game, and batters faced or plate appearances per game-was used to determine the workload. We compared these usage variables between player games <= 2, <= 6, <= 12, and >12 weeks before a documented oblique strain with player games from a control group of players with no oblique strains. In a paired analysis, we compared acute (player games <= 2, <= 6, and <= 12 weeks preinjury) versus chronic (player games >12 weeks preinjury) workloads. Results: There were 311 oblique strains in pitchers and 392 oblique strains in position players during the study period. In pitchers, more innings pitched and more batters faced were associated with a subsequent oblique strain (P < .001 for all). In position players, fewer days of rest, more innings fielded, and more plate appearances were associated with a subsequent oblique strain (P < .001 for all). Pitchers who pitched >= 7 innings per game had a 2.4-fold (95% CI, 1.4-4.9) increased risk of subsequent oblique strain compared with those who pitched 1 inning per game. The percentage of position players with a subsequent oblique strain increased by 2.1-fold (95% CI, 1.3-3.5) with >4 plate appearances compared with 1 plate appearance per game. Conclusion: Our analysis demonstrated that workload was associated with an increased risk of sustaining an oblique injury in professional baseball players. High workload over time was more predictive of oblique strains compared to acute increases over chronic baseline workload.