Muscle Activation and Energy-Requirements for Varying Postures in Children and Adolescents with Cerebral Palsy

Abstract

To determine energy expenditure and muscle activity among children and adolescents with cerebral palsy (CP), across several conditions that approximate sedentary behavior, and standing. Subjects with spastic CP (n = 19; 4-20 years of age; Gross Motor Function Classification System Expanded and Revised [GMFCS-E&R] levels I-V) participated in this cohort study. Energy-expenditure and muscle activity were measured during lying supine, sitting with support, sitting without support, and standing. Energy-expenditure was measured using indirect calorimetry and expressed in metabolic equivalents (METs). Muscle activation was recorded using surface electromyography. The recorded values were calculated for every child and then averaged per posture. Mean energy expenditure was >1.5 METs during standing for all GMFCS-E&R levels. There was a nonsignificant trend for greater muscle activation for all postures with less support. Only for children classified at GMFCS-E&R level III did standing result in significantly greater muscle activation (P < .05) compared with rest. Across all GMFCS-E&R levels, children and adolescents with CP had elevated energy expenditure during standing that exceeded the sedentary threshold of 1.5 METs. Our findings suggest that changing a child's position to standing may contribute to the accumulation of light activity and reduction of long intervals of sedentary behavior.