Functional implications of impaired control of submaximal hip flexion following stroke.

INTRODUCTION We quantified submaximal torque regulation during low to moderate intensity isometric hip flexion contractions in individuals with stroke and the associations with leg function. METHODS Ten participants with chronic stroke and 10 controls performed isometric hip flexion contractions at 5%, 10%, 15%, 20%, and 40% of maximal voluntary contraction (MVC) in paretic, nonparetic, and control legs. RESULTS Participants with stroke had larger torque fluctuations (coefficient of variation, CV), for both the paretic and nonparetic legs, than controls (P < 0.05) with the largest CV at 5% MVC in the paretic leg (P < 0.05). The paretic CV correlated with walking speed (r2 = 0.54) and Berg Balance Score (r2 = 0.40). At 5% MVC, there were larger torque fluctuations in the contralateral leg during paretic contractions compared with the control leg. CONCLUSIONS Impaired low-force regulation of paretic leg hip flexion can be functionally relevant and related to control versus strength deficits poststroke.