Effect of progressive horizontal resistive force on the comfortable walking speed of individuals post-stroke

Background: individuals post-stroke select slow comfortable walking speeds (cws) and the major factors used to select their cws is unknown. objective: to determine the extent to which slow cws post-stroke is achieved through matching a relative force output or targeting a particular walking speed. methods: ten neurologically nonimpaired individuals and fourteen chronic stroke survivors with hemiplegia were recruited. participants were instructed to walk at the speed that feels most comfortable on a treadmill against 12 progressively increasing horizontal resistive force levels applied at the pelvis using a robotic system that allowed participant to self-select their walking speed. we compared slope coefficients of the simple linear regressions between the observed normalized force vs. normalized speed relationship in each group to a slope of-1.0 (i.e. ideal slope for a constant relative force output) and 0.0 (i.e. ideal slope for a constant relative speed). we also compared slope coefficients between groups. results: the slope coefficients were significantly greater than-1.0 (p < 0.001 for both) and significantly less than 0 (p < 0.001 for both). however,compared with nonimpaired individuals,people post-stroke were less able to maintain their walking speed (p = 0.003). conclusions: the results of this study provide evidence for a complex interaction between the regulation of relative force output and intention to move at a particular speed in the selection of the cws for individuals post-stroke. this would suggest that therapeutic interventions should not only focus on task specific lower-limb strengthening exercises (e.g. walking against resistance),but should also focus on increasing the range of speeds at which people can safely walk. © 2015 hurt et al.; licensee biomed central.