Influence of body weight support on motor control in typically developing children and children with cerebral palsy

Body weight support (BWS) is often provided during rehabilitation interventions or activities of daily living with assistive devices. For children with cerebral palsy (CP), interventions that provide support like BWS treadmill training, orthoses, or walkers have been shown to improve walking speed, endurance, and/or kinematics – although responses are variable and challenging to predict. How individuals alter their muscle activity and coordination in response to BWS provides insight into neuromuscular control and may inform the design of future interventions. The purpose of this study was to evaluate motor control while children with CP (n = 12) and typically developing (TD) peers (n = 8) walked on a treadmill with 1%, 20%, 40%, and 60% BWS. As BWS increased, activity of support muscles decreased for both CP and TD groups. Specifically, activity of the gluteus medius and gluteus maximus decreased by more than 35% for both groups at 60% BWS. The TD group also decreased soleus activity by 27% at 60% BWS, while the CP group decreased vastus lateralis activity by 26% at 60% BWS. Muscle synergy analysis was used to evaluate coordination. As expected, the children with CP had significantly reduced synergy complexity compared to TD peers (total variance accounted for by one synergy, tVAF₁ = 76.3 for CP versus 67.4 for TD averaged across all conditions). However, synergy complexity did not change with BWS for either group. These findings suggest that although BWS may assist mobility by reducing demand on support muscles, it does not directly modulate motor control.