Dynamic regulation of Lower-Limb joint loading during Foot-Abducted landing in wide Lunge: An analysis of muscle synergy and neuromuscular activation patterns.

Abstract

This study compares the relative contribution of knee joint medial and lateral compartmental loading, muscle synergy, and activation characteristics between two types of wide-lunge landing strategies to reveal the neuromuscular mechanisms by which foot-abducted landings reduce injury risk. Twenty male badminton players performed the lunge with two foot orientations: heel-to-second metatarsal (foot-forward) and 20° foot abduction (foot-abducted). The foot-abducted landing significantly reduced medial compartment peak shear force and pressure contributions from the semitendinosus, vastus medialis, and vastus lateralis (P < 0.05). It also decreased lateral compartment moments and muscle contributions from the biceps femoris, rectus femoris, and medial gastrocnemius (P < 0.05). Among the four identified muscle synergies, Syn1 was primarily active before landing. In foot-abducted landings, Syn2 exhibited higher activation of the vastus medialis and vastus lateralis (P < 0.05), while Syn3 showed greater gastrocnemius involvement (P < 0.05). Additionally, the co-activation index indicated higher gastrocnemius activity in foot-abducted landings (P < 0.05). These findings suggest that landing with foot abduction and initial lateral heel contact realigns force vectors, reducing knee joint loading. This strategy promotes a shift from single-joint control to a multi-joint kinetic-chain synergy, demonstrating a neuromuscular pattern associated with lower injury risk.