Lower-limb muscle synergies in children with cerebral palsy

Muscle synergies were considered to be building blocks underlying motor behaviors. The goal of this paper is to explore lower-limb muscle synergies of children with cerebral palsy (CP). In 5 healthy adults and 8 children with CP, surface electromyography (sEMG) signals were collected from 8 lower-limb muscles during forward walking at a comfortable speed. And muscle synergies were extracted through nonnegative matrix factorization algorithm. We found that muscle synergies of CP children were different from those of adults in aspects of number and structure. Four or five muscle synergies were required for adult subjects. And muscle activation of CP children could be reconstructed by two, three or four muscle synergies. Some synergies in CP subjects were in accord with synergies in healthy adults while the other synergies were unique to CP subjects. For some CP subjects, different number of muscle synergies were required for two legs to perform a walk. It suggested that muscle synergies also account for walking of CP children. And Differences of motor modules between CP children and adults may explain the motor impairment and reduced walking performance.