Effectiveness of Single Leg Isometric Bridge and Nordic Hamstring Exercise Testing for Prediction of Hamstring Injury Risk in Professional Baseball Players

Background: Several investigations have examined various methods of measuring hamstring strength to determine the effectiveness of these tests in predicting hamstring injury (HSI) risk in athletes. However, no previous studies have examined the effectiveness of hamstring strength and interlimb asymmetry utilizing a newly developed modified single leg isometric bridge test (SLIBT) versus a standard Nordic hamstring exercise (NHE) to predict HSI in professional baseball players. Purpose: To determine whether preseason hamstring strength and interlimb asymmetry measured using a modified SLBIT versus an NHE are associated with future HSI in professional baseball players, as well as if measures of hamstring strength and interlimb asymmetry using the SLIBT are correlated to values from the NHE. Study Design: Cohort study; Level of evidence, 3. Methods: Professional baseball players (n = 465) from 8 teams affiliated with a single Major League Baseball organization completed a preseason hamstring strength assessment as part of routine athlete monitoring before the 2019, 2021, and 2022 seasons. A total of 38 new HSI events were recorded among 36 players over 751 player-seasons included in the analysis. Results: Lower hamstring strength levels in subsequent HSI limbs were observed compared with the 2-limb mean hamstring strength of healthy players for the SLIBT (365.1 ± 58.4 vs 390.9 ± 59.6 N; P = .014) and NHE (403.5 ± 90.4 vs 440.5 ± 76.0 N; P = .017). Players with NHE hamstring strength <377 N exhibited a significantly higher risk of HSI (RR, 2.49; 95% CI, 1.18-5.27; P = .027). Logistic regression indicated an inverse relationship between hamstring strength and HSI risk, with each 10-N increase in the SLIBT and NHE corresponding to a 7.4% and 6.2% risk reduction, respectively (with no interaction effects between tests). Interlimb asymmetry measures from both the SBILT and NHE were not indicative of subsequent HSI. Moderate significant correlations ( r = 0.33-0.39) were observed for absolute and relative hamstring strength measured utilizing the SLIBT versus the NHE. No significant correlations were found between measures of interlimb asymmetry when assessed by the SBILT versus the NHE. Conclusion: The current investigation indicates that low levels of hamstring strength measured in both the SLIBT and NHE are associated with an increased risk of future HSI. Thus, these measures could be utilized to identify at-risk players and to develop mitigation strategies to limit the rate of HSI and maximize time at play.