Motor variability predicts motor learning of improved trunk postural control through repeated trunk perturbations during walking in children with cerebral palsy

A greater range of motion in trunk movement in the frontal plane is commonly observed in children with cerebral palsy (CP), occurring at a rate of 72% in this population, which may compromise their walking ability. In this study, we examined the effect of providing lateral perturbation force at the trunk during walking on improving trunk control in children with CP. Fourteen children with CP participated in two conditions: PERTURB and CONTROL. For the PERTURB condition, participants walked on a treadmill without force for 1 min (baseline), with a bilateral controlled perturbation force applied to pull the trunk toward the ipsilateral stance leg for 7 min (adaptation), and without force for 2 min (postadaptation), and with perturbation force for another 5 min (re-adaptation). Overground walking was tested before, immediately after, and 10 min after treadmill walking. For the CONTROL condition, no force was applied during treadmill walking. Kinematics and electromyography (EMG) were recorded during walking. Participants showed decreased trunk obliquity toward the stronger side immediately after the removal of the perturbation during the postadaptation period for PERTURB condition (<i>P</i> < 0.05). Decreased trunk obliquity at the postadaptation period was correlated with greater motor variability at baseline (<i>P</i> < 0.05). In conclusion, repeated motor adaptation to trunk perturbation force during walking may promote motor learning of improved trunk control in children with CP. Motor variability of trunk movement can predict motor learning ability of trunk postural control in children with CP.<b>NEW & NOTEWORTHY</b> We examined the effect of providing lateral perturbation force at the trunk during walking on improving trunk control in children with cerebral palsy (CP). We found that repeated motor adaptation to trunk perturbation force during walking may promote motor learning of improved trunk control in children with CP. In particular, we found that motor variability of trunk movement can predict motor learning ability of trunk postural control in children with CP.