Biomechanical features of a novel step-down-and-pivot task in football players with hip/groin pain.

Identifying biomechanical impairments in young, physically active populations with hip/groin pain is crucial for early intervention. This study characterized the biomechanical features of a novel task, the , in competitive football players, comprising 36 individuals with hip/groin pain (28 ± 6 years) and 11 controls (26 ± 4 years). Experimental motion data and ground forces were input into biomechanical models to calculate joint angles and moments, then transformed into principal components and input into a feature selection pipeline. Ten main biomechanical features were identified for each limb, i.e. the pivot limb and the swing limb, that could discriminate between symptomatic and control groups with < 0.05. In symptomatic individuals, the main features were as follows: : smaller hip flexion and knee extension angles, delayed initiation of hip flexion and increased ankle dorsiflexion moment; : reduced hip flexion moment, increased hip internal rotation moment, delayed hip adduction and knee extension moments, and reduced ankle dorsiflexion angle. The largest group differences occurred during the transitions from step-down to pivot, and pivot to step-forward, supporting a potential role for multi-phase and/or multi-planar tasks when assessing biomechanical impairments due to hip/groin pain. Although biomechanical alterations in our symptomatic participants were small, they could be identified and characterized using feature selection.