Posterior thigh muscles activity during the active H-test: An electromyographic and kinematic analysis

The Askling's H-test is considered a useful return to play criterion after a hamstring muscle injury (HMI). However, it assesses only the active and passive flexibility of posterior thigh muscles. This may lead the practitioner to underestimate a compensation or abnormal movement pattern. The aim of this study was to analyze these kinematic aspects and their reliability, and evaluate the hamstring (HM) and gluteus maximus (GM) muscles' activities. Twelve healthy male volunteers were tested during two session of three trials for passive and active tests. Dynamic flexibility (97.2 ± 6.0°) was significantly greater than the passive one (70.5 ± 14.7°) (p < 0.001), and good intra-individual reproductibility for most kinematic characteristics was observed. Biceps Femoris long head, semitendinosus and GM mean activities (20.1 ± 11.2%; 14.3 ± 7.3% and 25.2 ± 22.1%, respectively) were found to be low to moderate, indicating that only a moderate level of activity occurred during the active H-test, in comparison to other movements such as sprinting itself. In addition, the activity of the posterior thigh muscles during the active H-test appeared to be variable among the volunteers. These findings suggest that the H-test should be interpreted on an individual basis rather than relying on general characteristics, and be considered as an intermediate tool before more strenuous activities such as returning to sprint. With this comprehensive approach, clinicians can gain a more accurate understanding of their patients' progress and make more informed decisions about their readiness to return to play.