Muscle Excitation of the Lower Extremity During a Single Leg Rotational Squat in Individuals With and Without a Previous Hamstrings Strain Injury

The hamstrings muscles work with quadriceps and gluteal muscles to stabilize the hip and knee during multidirectional movements. The purpose of this study was to determine muscle excitation patterns of the lower extremity during a single leg rotational squat (SLRS) in individuals with and without a previous hamstrings injury. Twenty physically active individuals between 19-23 years old participated in the study, ten with previous injury and ten without. The Hamstring Outcome Score was used to assess participants’ perceived physical abilities (Hamstring=89.37+7.2%, Control=96.75+2.83%; p=0.011). Participants completed five trials of a SLRS moving through four phases to a 72bpm metronome and reaching to maximum excursion. Wireless electromyography (EMG) was collected on the hamstrings, quadriceps, and gluteal muscles. Mean EMG of each muscle was normalized and reported as %EMG. Between group differences were assessed using one-way ANOVAs for each muscle by phase. Limb differences for the hamstring group were assessed using paired samples t-tests. Significance was set at p\u3c0.05. No statistically significant differences were observed between groups (P\u3e0.05). A statistical difference was observed within group for the biceps femoris during the down phase (P=0.023). The results suggest that individuals with a previous injury perceive a physical deficit, but muscle excitation patterns are similar to their healthy counterpart when performing a SLRS that requires strength and stability. Individuals with previous injury exhibit greater muscle excitation in the biceps femoris of the previously injured limb when moving into a squat position compared to the non-injured leg