Abstract
Many children with cerebral palsy (CP) show impairments in trunk postural control, which significantly
impact their walking capacity and daily activities. For instance, children with severe CP, who have difficulties
sitting independently, show poor directional specificity, with antagonists activating before agonists, which is
distinct from typically developed children. Compared to typically developed peers, children with CP have a
large range of motion for pelvis tilt, thorax, head, and kyphosis and lordosis during gait, even for some high
functioning children with CP. While the significance of trunk motor control dysfunction in children with CP has
been recognized, effective interventions for this core deficit are still lacking. Children with CP often receive or
participate in a wide range of passive and active interventions aimed to improve postural control, but results
have shown that current intervention approaches are not often effective in improving postural control in
children with CP. For instance, hippotherapy, an intervention strategy that applies rhythmical force
perturbations to the pelvis during sitting astride using horseback movement, has been used for improving
balance and gait in children with CP for decades. However, while some studies showed improvements in
balance and motor function in children with CP after hippotherapy, other studies indicated a mixed result
regarding the effect of hippotherapy on Gross Motor Function Measure scores in children with CP. Thus, there
is a critical need to improve the efficacy of current interventions for improving trunk postural control and gait in
children with CP, which requires a thorough examination of the underlying neuromuscular mechanisms of the
interventions. Our long-term goal is to develop rational-based intervention strategies to improve trunk postural
control and gait in children with CP. The overall objective of this study is to examine the neuromuscular
mechanisms of the trunk muscles to a force perturbation applied to the pelvis during sitting astride, and
determine whether repeated exposure to pelvic perturbations during sitting astride using a robotic system will
be effective in improving trunk postural control and gait in children with CP. Our central hypothesis is that
repetitive activation of specific sensorimotor pathways through applying targeted force perturbations will
improve postural control in children with CP, which may be due to the reinforcement in circuits and synapses
used for trunk postural control through a use-dependent neuroplasticity mechanism. The rationale for the
proposed study is that an understanding of the neuromuscular mechanisms of trunk muscle control in children
with CP and determination of the therapeutic effect of targeted force perturbation are likely to provide a strong
scientific foundation whereby new force perturbation based intervention strategies can be developed to
improve postural control and gait in children with CP. The results from this study may be used to develop
innovative clinical therapies aimed at improving trunk postural control and walking function in children with CP.