Walking Speed and Step Length Asymmetry Modify the Energy Cost of Walking After Stroke

Abstract

Background. A higher energy cost of walking poststroke has been linked to reduced walking performance and reduced participation in the community. Objective. To determine the contribution of postintervention improvements in walking speed and spatiotemporal gait asymmetry to the reduction in the energy cost of walking after stroke. Methods. In all, 42 individuals with chronic hemiparesis (>6 months poststroke) were recruited to participate in 12 weeks of walking rehabilitation. The energy cost of walking, walking speed, and step length, swing time, and stance time asymmetries were calculated pretraining and posttraining. Sequential regression analyses tested the cross-sectional (ie, pretraining) and longitudinal (ie, posttraining changes) relationships between the energy cost of walking versus speed and each measure of asymmetry. Results. Pretraining walking speed (β = −.506) and swing time asymmetry (β = .403) predicted pretraining energy costs: adj R2 = 0.713; F(3, 37) = 34.05; P < .001. In contrast, change in walking speed (β = .340) and change in step length asymmetry (β = .934) predicted change in energy costs with a significant interaction between these independent predictors: adj R2 = 0.699; F(4, 31) = 21.326; P < .001. Moderation by the direction or the magnitude of pretraining asymmetry was not found. Conclusions. For persons in the chronic phase of stroke recovery, faster and more symmetric walking after intervention appears to be more energetically advantageous than merely walking faster or more symmetrically. This finding has important functional implications, given the relationship between the energy cost of walking and community walking participation.