Alterations of relative muscle contribution induced by hemiplegia: Straight and turning gaits

Little information is available about the characteristics in the turning gait of hemiplegic elderly, which occurs frequently in daily life. It is also difficult to examine the altered characteristics due purely to hemiplegia because of no consideration of aging-related factors. The aim of this study was to identify the altered characteristics of relative muscle activation in both straight and turning gaits together due to hemiplegia, through comparing healthy and hemiplegic elderly. Six healthy elderly and six hemiplegic elderly were participated. The center of body mass (COM) and the lower extremity joint angles were measured during straight and turning gaits at self-selected speed, using a motion capture system. A surface wireless electromyogram (EMG) system was used together to identify muscle contributions. Mediolateral (ML) sways of upper-body in hemiplegic elderly were ~174% for straight gait and ~26% for turning gait. Lower extremity joint angles in hemiplegic elderly were generally reduced by ~60-70% for both gaits. Muscle co-activation and relative muscle contributions were generally altered at all phases in hemiplegic elderly, but the patterns were different between straight and turning gaits. This study confirmed that the ML sways of hemiplegic elderly moved towards the non-paretic side more and joint angles showed large decreases. Muscles acted with different contributions, depending on the gait.