Spatial and temporal asymmetries in gait predict split-belt adaptation behavior in stroke

Background. Step asymmetries during gait in persons after stroke can occur in temporal or spatial domains. Prior studies have shown that split-belt locomotor adaptation can temporarily mitigate these asymmetries. Objective. We investigated whether baseline gait asymmetries affected how patients adapt and store new walking patterns. Methods. Subjects with stroke and age-matched controls were studied walking at a 2:1 speed ratio on the split-belt during adaptation and assessed for retention of the learned pattern (the after-effect) with both belts at the same speed. Results. Those with stroke adapted more slowly (P <.0001), though just as much as healthy older adults. During split-belt walking, the participants with stroke adapted toward their baseline asymmetry (eg, F = 14.02, P <.01 for step symmetry), regardless of whether the subsequent after-effects improved or worsened their baseline step asymmetries. No correlation was found between baseline spatial and temporal measures of asymmetry (P =.38). Last, the initial spatial and temporal asymmetries predicted after-effects independently of one another. The after-effects in the spatial domain (ie, center of oscillation difference) are only predicted by center of oscillation difference baseline (F = 15.3, P =.001), while all other parameters were nonsignificant (all Ps >.17). Temporal coordination (ie, phasing) after-effects showed a significant effect only from phasing baseline (F = 26.92, P <.001, all others P >.33). Conclusion. This work demonstrates that stroke patients adapt toward their baseline temporal and spatial asymmetries of walking independently of one another. We define how a given split-belt training session would affect asymmetries in these domains, which must be considered when developing rehabilitation interventions for stroke patients.