Direction of gait asymmetry following stroke determines acute response to locomotor task

Background Given the prevalence of gait dysfunction following stroke, walking recovery is a primary goal of rehabilitation. However, current gait rehabilitation approaches fail to demonstrate consistent benefits. Furthermore, asymmetry is a prominent feature of gait dysfunction following stroke. Differential patterns of gait asymmetry may respond differently to gait training parameters. Objective The purpose of this study was to determine whether differential responses to locomotor task condition occur on the basis of direction of step length asymmetry (Symmetrical, NP short , P short ) observed during overground walking. Methods Participants first walked overground at their self-selected walking speed. Overground data were compared against three task conditions all tested during treadmill walking: self-selected speed with 0% body weight support (TM); self-selected speed with 30% body weight support (BWS); and fastest comfortable speed with 30% body weight support and nonparetic leg guidance (Guidance NP ). Our primary outcomes were: step length, single limb support duration, and stride length. Results We identified differences in the response to locomotor task conditions for each step length asymmetry subgroup. Guidance NP induced an acute spatial symmetry only in the NP short group and temporal symmetry in the Symmetrical group. Conclusions Task conditions consistent with locomotor training do not produce uniform effects across subpatterns of gait asymmetry. We identified differential responses to locomotor task conditions between groups with distinct asymmetry patterns, suggesting these subgroups may require unique intervention strategies. Despite group differences in asymmetry characteristics, improvements in symmetry noted in the Symmetrical and NP short groups were driven by changes in both the paretic and nonparetic limbs.