Asymmetry of gait initiation in hemiparetic stroke subjects.

OBJECTIVE To investigate symmetry of gait initiation in healthy and hemiparetic subjects. DESIGN Survey. SETTING Kinematic laboratory affiliated with a hospital-based department of rehabilitation. PATIENTS OR OTHER PARTICIPANTS Ten healthy and 14 hemiparetic stroke subjects starting five times with their right and left leg, respectively. MAIN OUTCOME MEASURES Duration of defined periods, step length, center of pressure, and center of mass were recorded and calculated using two triaxial force plates, contact switches, and a video camera system. RESULTS Healthy subjects displayed a high degree of independence of kinetic and kinematic parameters of the starting limb. Hemiparetic patients showed differences with respect to the starting limb: when starting with the nonaffected leg, the swing period and step length was shorter and the center of pressure displayed a more marked medio-lateral sway with no corresponding initial movement of the center of mass; when starting with the affected leg the movement pattern of the center of pressure and center of mass was comparable to that of normal subjects. CONCLUSIONS The trajectories of the center of pressure and center of mass and the symmetry parameters are in accordance with a higher degree of uncertainty when starting with the non-affected limb in hemiparetic subjects.