Abstract
Studies on the development of automatic postural responses in both typically developing children and children with cerebral palsy were performed. With the appearance of ''pull-to-stand'' behavior, typically developing children first began to show muscle responses to platform movements in mainly the ankle muscles. With increased development, additional agonist muscles were added to the response pattern and a consistent distal to proximal sequence began to emerge. Well-organized responses were seen with the onset of independent stance and walking, along with the reduction of antagonist muscle co-activation. The older children with cerebral palsy who were pre-walkers had immature muscle activation patterns like those seen in the typically developing children at the pull-to-stand stage of development. These included disorganized muscle responses and increased frequency of coactivation of both proximal-distal and agonist-antagonist muscles. In order to determine if musculoskeletal constraints contributed to these response pattens, normal children were asked to stand in a crouched posture similar to that of children with CP. This caused postural muscle response patterns to more closely approximate those of children with spastic diplegia.