Speed of Voluntary Stepping in Chronic Stroke Survivors Under Single- and Dual-Task Conditions: A Case-Control Study

Melzer I, Tzedek I, Or M, Shvarth G, Nizri O, Ben-Shitrit K, Oddsson LE. Speed of voluntary stepping in chronic stroke survivors under single- and dual-task conditions: a case-control study. Objective: To investigate voluntary step behavior of chronic stroke survivors during single- and dual-task conditions and compare the results to healthy age- and sex-matched controls. Design: Case-control. Setting: Laboratory-based study. Participants: Chronic stroke survivors (n=16) and healthy controls (n=16). Interventions: Not applicable. Main Outcome Measures: Forward and backward rapid voluntary stepping were performed as a reaction time task under 2 conditions: (1) awaiting a cutaneous cue (single task), and (2) awaiting a cutaneous cue while performing an attention-demanding task. Step initiation, preparatory and swing phases, foot-off time, and foot-contact time were extracted from center of pressure and ground reaction forceplate data. Results: Chronic stroke survivors were significantly slower than healthy controls in all step parameters under single- and dual-task conditions. For dual compared with single task, the foot-contact time increased from 1295ms to 1445ms (12%) in chronic stroke survivors and from 876ms to 1006ms (15%) in controls. Conclusions: The significant increase in step phase's duration during single- and dual-task conditions may be a factor contributing to the large number of falls seen in stroke patients. The interference effects of attention-demanding task were similar between groups, suggesting that both groups used similar strategies. Future research should determine whether step training can improve step decrements in chronic stroke survivors.