title: Mechanisms to increase propulsive force for individuals poststroke.
abstract: BACKGROUND
  Propulsive force generation is critical to walking speed. Trialing limb angle and ankle moment are major contributors to increases in propulsive force during gait. For able-bodied individuals, trailing limb angle contributes twice as much as ankle moment to increases in propulsive force during speed modulation. The aim of this study was to quantify the relative contribution of ankle moment and trailing limb angle to increases in propulsive force for individuals poststroke.
  
  
  METHODS
  A biomechanical-based model previously developed for able-bodied individuals was evaluated and enhanced for individuals poststroke. Gait analysis was performed as subjects (N = 24) with chronic poststroke hemiparesis walked at their self-selected and fast walking speeds on a treadmill.
  
  
  RESULTS
  Both trailing limb angle and ankle moment increased during speed modulation. In the paretic limb, the contribution from trailing limb angle versus ankle moment to increases in propulsive force is 74% and 17%. In the non-paretic limb, the contribution from trailing limb angle versus ankle moment to increases in propulsive force is 67% and 22%.
  
  
  CONCLUSIONS
  Individuals poststroke increase propulsive force mainly by changing trailing limb angle in both the paretic and non-paretic limbs. This strategy may contribute to the inefficiency in poststroke walking patterns. Future work is needed to examine whether these characteristics can be modified via intervention.
authors.affiliation: Biomechanics and Movement Science Program, University of Delaware, 540 S. College Avenue, Suite 201F, Newark, DE, 19716, USA. haoyuan@udel.edu.
authors.forename: HaoYuan
authors.initials: H
authors.lastname: Hsiao
authors.affiliation: Delaware Rehabilitation Institute, Newark, DE, 19716, USA. bknarr@udel.edu.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Knarr
authors.affiliation: Department of Mechanical Engineering, University of Delaware, Newark, DE, 19716, USA. higginso@udel.edu.
authors.forename: Jill S
authors.initials: JS
authors.lastname: Higginson
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE, 19716, USA. sbinder@udel.edu.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Binder-Macleod
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D000071939:Stroke Rehabilitation; D016138:Walking / Q000502:physiology*