title: Stepping in persons poststroke: comparison of voluntary and perturbation-induced responses.
abstract: OBJECTIVE
  To examine the stepping performance during voluntary and waist-pull perturbation-induced step initiation in people with chronic stroke.
  
  
  METHODS
  Repeated-measures single-case design.
  
  
  METHODS
  University-based research laboratory.
  
  
  METHODS
  Community-dwelling stroke survivors (N=10).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Ground reaction forces and kinematic data were recorded to assess anticipatory postural adjustments (APAs) and step characteristics for both voluntary and induced stepping conditions.
  
  
  RESULTS
  Induced stepping was performed with both the paretic (35% trials) and nonparetic legs (65% trials). Induced first steps occurred earlier and were executed faster than rapid voluntary steps. Compared with voluntary stepping, induced first step APAs were shorter in duration. Step height was higher with the nonparetic leg for both stepping conditions. Use of the paretic leg increased (52%) during the diagonal perturbations that passively unloaded the stepping limb compared with the use of the paretic leg (33%) for forward perturbations.
  
  
  CONCLUSIONS
  The results indicated differences in executing voluntary and induced stepping, and between the paretic and nonparetic limbs in individuals with chronic stroke. The findings suggested guidelines for using stepping as a component of neurorehabilitation programs for enhancing balance and mobility. Additional larger-scale studies remain to be undertaken to further investigate these issues.
authors.affiliation: Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL. Electronic address: k-martinez@northwestern.edu.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Martinez
authors.affiliation: Aix-Marseille Université, CNRS, ISM UMR 7287, Marseille; Université Sud Toulon-Var, La Garde, France; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Mille
authors.affiliation: Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rogers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010291:Paresis / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology; D020521:Stroke / Q000503:physiopathology*; D014836:Volition / Q000502:physiology
keywords: ANOVA; APA; BOS; COM; COP; Postural balance; Rehabilitation; Stroke; analysis of variance; anticipatory postural adjustment; base of support; center of mass; center of pressure