Different Error Size During Locomotor Adaptation Affects Transfer to Overground Walking Poststroke

Background. Studies in neurologically intact subjects suggest that the gradual presentation of small perturbations (errors) during learning results in better transfer of a newly learned walking pattern to overground walking. Whether the same result would be true after stroke is not known. Objective. To determine whether introducing gradual perturbations, during locomotor learning using a split-belt treadmill influences learning the novel walking pattern or transfer to overground walking poststroke. Methods. Twenty-six chronic stroke survivors participated and completed the following walking testing paradigm: baseline overground walking; baseline treadmill walking; split-belt treadmill/adaptation period (belts moving at different speeds); catch trial (belts at same speed); post overground walking. Subjects were randomly assigned to the Gradual group (gradual changes in treadmill belts speed during adaptation) or the Abrupt group (a single, large, abrupt change during adaptation). Step length asymmetry adaptation response on the treadmill and transfer of learning to overground walking was assessed. Results. Step length asymmetry during the catch trial was the same between groups (P = .195) confirming that both groups learned a similar amount. The magnitude of transfer to overground walking was greater in the Gradual than in the Abrupt group (P = .041). Conclusions. The introduction of gradual perturbations (small errors), compared with abrupt (larger errors), during a locomotor adaptation task seems to improve transfer of the newly learned walking pattern to overground walking poststroke. However, given the limited magnitude of transfer, future studies should examine other factors that could impact locomotor learning and transfer poststroke.