title: 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)R(2) = 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)R(2) = 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.
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, USA Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE, USA.
authors.forename: Louis N
authors.initials: LN
authors.lastname: Awad
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, USA Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE, USA.
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Palmer
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, USA Delaware Clinical and Translational Research Accel Program, University of Delware, Newark, DE, USA.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Pohlig
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, USA Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE, USA Delaware Clinical and Translational Research Accel Program, University of Delware, Newark, DE, USA.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Binder-Macleod
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, USA Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE, USA dreisman@udel.edu.
authors.forename: Darcy S
authors.initials: DS
authors.lastname: Reisman
mesh_terms: D003430:Cross-Sectional Studies; D004558:Electric Stimulation; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D010101:Oxygen Consumption / Q000502:physiology; D010291:Paresis / Q000209:etiology / Q000534:rehabilitation*; D011187:Posture; D012720:Severity of Illness Index; D020521:Stroke / Q000150:complications; D016138:Walking / Q000502:physiology*
keywords: gait; oxygen consumption; stroke; symmetry