Electromyographic analysis of reach in individuals with cerebral palsy

Electromyographic analysis in both the time domain (root mean square EMG) and the frequency domain (mean power frequency EMG) of the biceps, triceps, wrist extensors and wrist flexors were analysed in six young cerebral palsied adults and six normal individuals. The subjects sat in a Rifton positioning chair. Each subject's right arm was positioned with the shoulder adducted, the elbow at 90 degrees and the hand resting on the arm rest. The subject then reached the right arm forward to grasp a dowel which was placed at shoulder level in front of the subject. There was no significant difference between the time it took the two groups to do the required movement. The RMS analysis indicated the muscle activation was variable among subjects, with evidence of concontraction of the antagonist muscles for the disabled group. The frequency analysis indicated that the disabled group had significantly lower mean power for the biceps and the wrist extensor muscles compared to the normal group. Neurological differences or fibre type abnormalities may account for these differences.