Neural factors underlying reduced postural adaptability in children with cerebral palsy.

This study aimed to test mechanisms underlying impairments in balance control in children with cerebral palsy. We hypothesized that balance loss during large/fast perturbations could be due to reduced contraction of agonist muscles, delay in muscle contraction or simultaneous contraction of antagonist muscles, reducing the efficiency of the agonist burst. Electromyograms were recorded as children recovered from balance threats of varying magnitudes/velocities. In typically developing children muscle response magnitudes increased with larger/faster perturbations, while in children with cerebral palsy they did not. There was no difference in muscle onset latency or antagonist co-contraction between groups. Thus the primary constraint on balance recovery in these children is insufficient levels of contraction of agonist postural muscles.