Lower extremity muscle activity during cycling in adolescents with and without cerebral palsy.

BACKGROUND: In individuals with cerebral palsy, adaptation and plasticity in the neuromuscular system can lead to detrimental changes affecting gait. Cycling may be an effective method to improve mobility. The biomechanics of cycling in adolescents with cerebral palsy have been studied, but further analysis of the frequency and amplitude characteristics of the electromyographic signals can assist with interpretation of the cycling kinematics.
METHODS: Data were analyzed from 10 adolescents with typical development (mean=14.9, SD=1.4 years) and 10 adolescents with cerebral palsy (mean=15.6, SD=1.8 years) as they cycled at two different cadences. Analyses of the lower extremity electromyographic signals involved frequency and amplitude analysis across the cycling revolution.
FINDINGS: Examination of cycling cadence revealed that adolescents with cerebral palsy had altered electromyographic characteristics in comparison to adolescents with typical development across the entire crank revolution for all muscles. Analyses of individual muscles indicated both inappropriate muscle activation and weakness.
INTERPRETATION: A more comprehensive analysis of electromyographic activity has the potential to provide insight into how a task is accomplished. In this study, the control of the several muscles, especially the rectus femoris, was significantly different in adolescents with cerebral palsy. This, combined with muscle weakness, may have contributed to the observed deviations in joint kinematics. Interventions that increase muscle strength with feedback to the nervous system about appropriate activation timing may be beneficial to allow individuals with cerebral palsy to cycle more efficiently.