Reliability and comparison of electromyographic and kinetic measurements during a standing reach task in children with and without cerebral palsy

The purposes of this study of children with cerebral palsy (CP) and with typical development (TD) were to determine: (1) within session test–retest reliability of electromyography (EMG) of postural muscles [using motor coordination patterns (cMCP)] and center of pressure (COP) measures, (2) relationships between cMCP and COP measures, and (3) differences between children with CP and with TD. Data were collected twice during a standing reach task in 20 pairs of age and gender matched children, 8–14-years-old. Test–retest reliability was poor for cMCPs (κ = 0.16–0.21), but good for kinetic measures (ICC = 0.69–0.87). Both groups demonstrated strong reliance on anterior–posterior neuromuscular control with greater variability in the children with CP. The group with TD showed greater control in anterior–posterior COP movements than did the group with CP. Anterior–posterior COP measures were associated with more effective cMCPs in both groups. These data support the concept of the center of gravity as a potential control parameter working with a flexible neuromuscular system for postural control.