T2 Hamstring Muscle Activation during the Single-Leg Roman Chair: Impact of Prior Injury

Abstract

ABSTRACT Introduction/Purpose Previous studies have shown inhibition of previously injured hamstrings during eccentric exercises, but it is unknown whether this effect is also present during an isometric position-control exercise such as the single-leg Roman chair hold (SLRCH). Methods This cross-sectional study investigated muscle activation during the SLRCH in individuals with prior hamstring injuries. Twelve recreationally active male soccer players and athletes performed the SLRCH with a five-repetition maximum load. Muscle activation was assessed using the transverse relaxation (T2) time for the biceps femoris long and short heads (BFlh and BFsh), semitendinosus (ST), semimembranosus, and adductor magnus and compared within and between legs. Muscle cross-sectional area (CSA) was also quantified. Results T2 times significantly increased for all muscles except the adductor magnus in both legs. In both legs, the ST showed a significantly larger increase in T2 time compared with all other muscles. The BFlh showed a significantly smaller increase in T2 time in the injured leg compared with the uninjured leg (−7.1%), whereas there were no significant differences between legs for the other muscles. Muscle CSA for any of the muscles did not significantly differ between the injured and uninjured legs. Conclusion The ST was preferentially activated during the SLRCH in both the uninjured and injured legs, but the magnitude of preferential activation was smaller (~10%) than observed previously during eccentric exercises (~17%–30%). Furthermore, the BFlh in the previously injured leg was activated less compared with the BFlh in the uninjured leg, despite no differences in muscle CSA.