• Force generating ability of quadriceps femoris and triceps surae (MVIC)
  
• Voluntary muscle activation during a Maximal Volitional Isometric Contraction (MVIC)
  
• Antagonist coactivation during an agonist MVIC
  
• Contractile properties as assessed via electrically-elicited tests
  
• Fatiguability of muscle as assessed via electrically-elicited tests
  
• Muscle cross-sectional area of quadriceps femoris and triceps surae (via MRI with fat suppression)
  
• Spatiotemporal parameters of gait
  
• Gross Motor Function Measure
  
• Timed Up and Go
  
• Parent and child report via questionnaires (PODCI, COPM)
  

The overall goal of this study is to determine if using high-intensity, short-duration, intermittent neuromuscular electrical stimulation (NMES) is better than volitional exercise in increasing quadriceps femoris and triceps surae force-generating potential and gross motor function in children with cerebral palsy. This study consists of a randomized controlled trial in which the effects of NMES applied to the quadriceps femoris and triceps surae are compared to the effects of volitional isometric exercise and a non-exercising control group. This project assesses the ability of NMES to increase muscle force generating ability, the mechanisms behind changes in force generating ability, and the effects of training on spatiotemporal parameters of gait and gross motor function in children with cerebral palsy.

Subjects is the NMES group will be implanted with percutaneous electrodes in the medial and lateral heads of the gastrocnemius and the quadriceps (3 electrodes in each lower extremity, implanted bilaterally). During the intervention phase, these subjects will undergo 15 electrically-elicited contractions in each of the implanted muscle groups three times/week (at home), while positioned on an exercise board to maintain good alignment and facilitate isometric contractions. Subjects in the volitional group will perform 15 isometric contractions in each muscle group (quadriceps, triceps surae), while positioned on an exercise board. The non-exercise control group will continue with typical activities, but no intervention will be administered. Subjects are assessed at baseline, 6 weeks into the intervention, 12 weeks into the intervention (at which point the intervention is withdrawn), and at a follow-up assessment 12 weeks after the withdrawal of the intervention.