Quantification of antagonist muscle coactivation in children with spastic diplegia

The purpose of this study was to investigate the use of the Pearson Product‐Moment correlation coefficient to quantify muscle coactivation using electromyography. The subjects were two children with spastic diplegia. Surface electrodes were used to record muscle activity from the soleus and tibialis anterior muscles during voluntary attempts at dorsiflexion and plantarflexion of the ankle against resistance. The linear envelope signals were smoothed with a Hamming filter at a cutoff frequency of 4 Hz and intervals of the resultant pairs of curves subjected to the PPM test. Both subjects demonstrated significant coactivation on their right side and independent activity on the left, indicated by high positive and negative coefficients, respectively. This method shows promise for description of side differences in diplegics and for assessing the effects of physical therapy and other interventions. Clin. Anat. 11:314–319, 1998. © 1998 Wiley‐Liss, Inc.