Relation between physical exertion and postural stability in hemiparetic participants secondary to stroke.

INTRODUCTION Chronic hemiparetic stroke individuals are at a higher risk of falling. This may be due to balance impairments, cardiovascular deconditioning, and muscle weakness associated with stroke effects. Postural instability associated with fatigue would likely be attained more rapidly for stroke individuals than for healthy individuals. OBJECTIVE To determine the effects of physical exertion induced by walking on postural stability in hemiparetic stroke participants. METHODS Twelve hemiparetic participants and 12 control participants walked over-ground for a duration of 6 min and 18 min at their comfortable speed. Postural stability was assessed using centre of pressure related parameters during double-legged stance and tasks before the walk, immediately after the walk, 15 min post-walk, and 30 min post-walk. Measures of physical exertion during walking were also obtained from cardiorespiratory parameters, time-distance parameters, and subjective scales. Variables on postural stability and on physical exertion were analyzed using two-way repeated measures ANOVA and Generalized Estimating Equations. RESULTS Physical exertion measures significantly increased when the duration of walk was increased from 6 min to 18 min in both control and hemiparetic participants. For postural stability measures, increasing the duration of walking led to a significant increase of postural sway in double-legged stance and sit-to-stand for the hemiparetic participants only. This effect on balance of hemiparetic participants was observed immediately after the end of the walk. CONCLUSION This study demonstrated that physical exertion can increase postural sway in hemiparetic participants which could possibly lead to an increased risk of falling in these individuals.