Effect of balance training on muscle activity used in recovery of stability in children with cerebral palsy: a pilot study.

This study explored possible neural mechanisms that contribute to improvements in balance control produced by reactive balance training in children with cerebral palsy (CP). Six children with CP (four males, two females; mean age 9y 4mo), two with spastic hemiplegia (Gross Motor Function Classification System [GMFCS] level I) and four with spastic diplegia (GMFCS level II,) were given 5 days of intensive training in reactive balance control (100 perturbations per day on a moveable force platform). Surface electromyography was used to characterize changes in neuromuscular responses pretraining, immediately posttraining, and 1 month posttraining. Training in reactive balance control resulted in improvements in directional specificity of responses (a basic level of response organization) and other spatial/temporal characteristics including: (1) faster activation of muscle contraction after training, allowing children to recover stability faster; (2) emergence of a distal-proximal muscle sequence; and (3) improved ability to modulate the amplitude of muscle activity (increased amplitude of agonist and decreased amplitude of antagonist, reducing coactivation). Each child with spastic hemiplegia or diplegia showed a different combination of factors that contributed to improved performance; the level of change in neural factors depended on the severity of involvement of the child: hemiplegia vs diplegia, and level of involvement within each diagnostic category.