Fundamental muscle synergies for walking in children with cerebral palsy

Authors

• Y Kim
• TC Bulea
• DL Damiano

Abstract

Children with cerebral palsy typically have walking difficulties and demonstrate unique movement patterns attributable to multiple factors related to spasticity, decreased recruitment of motor units, poor selective muscle activation, and musculoskeletal changes with growth. However, it is still uncertain how muscle synergies for walking are altered in children with CP compared to healthy individuals. The aim of this study was to demonstrate fundamental muscle synergies for walking in the children with CP compared to normal adults. Participants in this study included 21 children with CP and 10 healthy adults. Participants walked at self-selected speed for 5 trials. Electromyography (EMG) and motion capture cameras were used to record muscle activity and kinematic variables for both legs during the task. The EMG data were decomposed into linear combinations of individual muscles, termed motor modules or synergies, using non-negative matrix factorization. Then, we examined the number of synergies required to account for 90% of the total variance. The results showed that children with CP had a variable number of synergies: two (19%), three (57%), or four (24%) modules whereas all normal controls required four modules. The number of modules in CP was inversely correlated with walking speed (r = -0.48) which indicates that those with fewer modules walked more slowly. The existence of fewer modules means less complexity and therefore greater neurological involvement. Thus muscle synergy analysis may describe the motor coordination deficits present in CP and could be used to suggest new rehabilitation training strategies.

Scientific Focus Area: Biomedical Engineering and Biophysics

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