Effects of body orientation in space on tonic muscle activity of patients with cerebral palsy.

This study was designed to determine whether tonic activity of selected muscles of patients with cerebral palsy changed in response to changes in orientation of the body in space. Surface electrodes measured electromyographic activity of the low-back extensor, hip adductor and ankle plantar-flexor muscles when the body was at 0 degree (upright) and 30 degrees (recline) relative to the vertical. Muscle activity did change in response to body orientation, and was less in the upright position.