An exploration of muscle co-activation during different walking speeds and the association with lower limb joint stiffness

Abstract

The aim of this study was to determine the muscle co-activations and joint stiffnesses around the hip, knee, and ankle during different walking speeds and to define the relationships between muscle co-activation and joint stiffness. Twenty-seven healthy subjects (age: 19.6±2.2 years, height: 176.0±6.0 cm, mass: 69.7±8.9 kg) were recruited. Muscle co-activations (CoI) and lower limb joints stiffnesses were investigated during stance phase at different walking speeds using Repeated Measures ANOVA with Sidak post-hoc tests. Correlations between muscle co-activations, joints stiffnesses, and walking speeds were also investigated using Pearson Product Moment correlations. The results indicated that the hip and ankle joints stiffness increased with walking speed (p<0.001) during the weight acceptance phase; in addition, a positive correlation between walking speed and Rectus Femoris (RF) and Biceps Femoris (BF) CoI (p<0.001), and a negative correlation was between walking speed and tibialis anterior (TA) and lateral gastrocnemius (LG) 17 CoI (p<0.001) during the weight acceptance phase, and the RF/BF CoI during pre swing, were observed. These results provide new information on the variations in muscle co-activation around the hip, knee and ankle joints and their association with joint stiffness, and on the responses of stiffness and muscle co-activation to walking speed. The techniques presented could have further application and provides an aid to understanding of the effects of gait retraining and injury mechanisms.