ELECTROMYOGRAPHIC ANALYSIS OF POSTURAL RESPONSES DURING STANDING LEG FLEXION IN ADULTS WITH HEMIPARESIS

The purpose of this study was to examine muscle activation patterns du ring standing single leg flexion in adults with hemiparesis. Specifica lly, the electromyographic activation patterns of the flexing limb bic eps femoris and gluteus medius, and the stance limb gluteus medius mus cles were analyzed as a function of whether the muscles were paretic o r not. Delayed activation of the affected flexing side gluteus medius, as compared with unaffected flexing side gluteus medius, resulted in it being activated simultaneous with the flexing biceps femoris rather than preceding it as was previously found in healthy subjects. This s uggests a temporal change in the sequential mode of coordination of th e postural and intended components of the task. In addition, the magni tude of the electromyographic integrals of both the affected and unaff ected flexing side gluteus medius in the early propulsive phase of the task was significantly reduced in comparison with healthy subjects. T hese alterations can be attributed to spatial alterations in the seque ntial form of organization or to a shift to a different mode of neural control in order to perform a relatively novel task. These results su ggest a potential adaptive capacity in these individuals. (C) 1997 Els evier Science Ireland Ltd.