Different neuromuscular parameters are associated with knee abduction and hip adduction angles during functional tasks

Abstract

Knee abduction and hip adduction during functional tasks may indicate increased joint injury risk and discriminate between pathological and healthy people. Muscles’ neuromuscular variables such as amplitude (EMGAMP) and onset (EMGONSET) have been used to explain kinematics. The study aimed to evaluate the correlation between two EMG variables of seven trunk and lower limb muscles and 3D kinematics during two tasks. Eighteen physically-active women participated in the study. The following variables were obtained during single-leg squat and anterior step-down: (i) EMGAMP and EMGONSET of fibularis longus (FL), tibialis anterior (TA), vastus medialis (VM), biceps femoris (BF), gluteus medius (GMED), ipsilateral (OB_IL) and contralateral (OB_CL) external obliques and (ii) knee abduction and hip adduction angular displacement (initial angle – angle at 60° of knee flexion). Spearman’s correlation coefficient was calculated between kinematic and EMG variables. Greater knee abduction was correlated with delayed TAONSET, GMEDONSET and OB_ILONSET during step-down. Greater hip adduction was correlated with lower VMAMP, BFAMP and delayed VMONSET during step-down. Although task-specific, these results suggest that EMGONSET may influence knee abduction, while both EMGONSET and EMGAMP may affect hip adduction. The identification of muscle activation patterns in relation to kinematics may help the development of injury prevention and rehabilitation programs.