Key result
Optimized 90:20 Isometric Posterior Chain Test shows greater sensitivity detecting post-match hamstring fatigue versus original.
Why the study?
Original instructions and vertical force parameters of the 90:20 IPCT may not ideally represent hamstring strength or sensitive detection of hamstring muscle fatigue.
Does the optimized version of the 90:20 IPCT improve the detection of hamstring muscle fatigue compared to the original version in soccer players?
Observational (n=12)
No
Does the optimized version of the 90:20 IPCT improve the detection of hamstring muscle fatigue compared to the original version in soccer players?
Standardized Mean Difference: 0.82
Absolute Event Rate: -9.3% vs -7.9%
p-value: p=0.005
The optimized vertical-horizontal instruction for the 90:20 Isometric Posterior Chain Test is more sensitive for detecting hamstring muscle fatigue in soccer players than the original vertical instruction.
May enhance post-match hamstring fatigue detection in soccer; hypothesis-generating and needs larger validation before adoption.
Hamstring strain injuries (HSI) are associated with low hamstring strength (HSS) and hamstring muscle fatigue (HMF). Therefore, the frequent testing of HSS can play an important role in the prevention of HSI. The 90:20 Isometric Posterior Chain Test (90:20 IPCT) efficiently assesses HSS via force plate; yet, the original instruction and its parameter (vertical force) of this very test may not represent HSS ideally. We, therefore, compared HSS assessed via the optimized instruction and parameter of this very test with the original version to evaluate which version of the 90:20 IPCT is more sensitive to detect HMF over the course of a competitive soccer match. Therefore, body mass normalized HSS of twelve outfield soccer players was assessed pre- and post-match and compared via one-tailed paired samples t-tests and Hedge’s g effect size as a measure of sensitivity to detect HMF. In addition, we carried out one-tailed one sample t-tests with the decrease of HSS [%] for each parameter. The optimized version of the 90:20 IPCT shows increased sensitivity to detect hamstring muscle fatigue compared to the original version of this very test for both the dominant and non-dominant leg in the paired samples t-tests (g = 0.82; p = 0.005 and g = 1.00; p = 0.002 vs. g = 0.50; p = 0.046 and g = 0.77; p = 0.008, respectively). Regarding the percentage-wise decrease in HSS, the optimized version of the 90:20 IPCT showed a strong significant decrease in HSS for both the dominant (g = 0.80; p = 0.006) and the non-dominant leg (g = 1.07; p = 0.001), while the original version did not detect a significant decrease in HSS in the dominant leg ( p = 0.079) but a strong decline in HSS for the non-dominant leg (g = 0.75; p = 0.009). Although all parameters measured a similar percentage-wise amount of HMF, the optimized version of the 90:20 IPCT shows higher Hedge’s g effect sizes than the original version in the pre- vs. post-match comparisons of HSS and also detected HMF, where the original version of the 90:20 IPCT did not. The optimized version should therefore be preferred when assessing HSS or HMF via the 90:20 IPCT, respectively.
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Rasp et al. (2025) conducted an observational in Hamstring muscle fatigue (n=12). Optimized 90:20 Isometric Posterior Chain Test (vertical-horizontal instruction) vs. Original 90:20 Isometric Posterior Chain Test (vertical instruction) was evaluated on Decrease in hamstring strength from pre- to post-match (Hedge's g effect size for dominant leg) (Hedge's g 0.82, 95% CI 0.22-∞, p=0.005). The optimized 90:20 Isometric Posterior Chain Test demonstrated greater sensitivity in detecting hamstring muscle fatigue post-match compared to the original version (Hedge's g 0.82 vs 0.50 for the dominant leg).
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