Foot-placement accuracy during planned and reactive target stepping during walking in stroke survivors and healthy adults

Background: The high prevalence of falls due to trips and slips following stroke may signify difficulty adjusting foot-placement in response to the environment. However, little is known about under what circumstances foot-placement adjustment becomes difficult for stroke survivors (SS), making the design of targeted rehabilitation interventions to improve independent community mobility difficult. Research question: To investigate the effect of planned and reactive target-stepping on foot-placement accuracy in stroke survivors and young and older healthy adults? Methods: Young (N=11, 30±6 years) and older (N=10, 64±8 years) healthy adults and SS (N=11, 67±9 years) walked, at preferred pace, on a force instrumented treadmill. Each participant walked to illuminated targets, visible two steps in advance (planned) or appearing at contralateral midstance (reactive). Foot-placement error (magnitude and bias) and number of missed targets were compared. Results: All participants missed more reactive than planned targets (p=0.05), and SS missed more targets than young (p<0.001) and older (p=0.001) adults. But no interaction showing SS missed more reactive targets than other groups was found. For all groups: reactive adaptations to steps in the anterio-posterior plane resulted in lower error than planned adaptations (p=0.027). Lengthening steps where undershot more than shortening (p