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 (kappa=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.