title: The effect of pulmonary rehabilitation on critical walk speed in patients with COPD: a comparison with self-paced walks.
abstract: BACKGROUND
  Walking is frequently used in the exercise rehabilitation of patients with COPD. Walking ability can be characterized by the two-parameter hyperbolic relationship between endurance and speed. One parameter, critical walk speed (s_critical), represents the maximum speed that can be endured indefinitely. The purpose of this study was to: (1) determine the effect of pulmonary rehabilitation on the critical speed and (2) compare the critical speed with the speed chosen during self-paced walking.
  
  
  METHODS
  We estimated critical speed in patients with COPD before and after rehabilitation. Patients completed four high-intensity constant-speed walk tests to intolerance on a 30-m course. The parameters of the hyperbolic relationship were determined using nonlinear regression of endurance on speed. Participants also completed self-paced walks: (1) for as long as they could, (2) at their "usual" and "fast" speeds, and (3) as a 6-min walk test.
  
  
  RESULTS
  Twelve participants (FEV(1) [SD], 41 [16] % predicted; FEV(1)/FVC, 41 [12]) completed the study. At baseline, the critical speed (65 [12] m/min) was not significantly different from the self-paced, usual, or 6-min walk speeds (65 [12], 67 [14], and 63 [15] m/min, respectively). There was a significant increase in critical speed (6 [1-10] m/min) and 6-min speed (16 [10-21] m/min) after rehabilitation, without changes in the self-paced, usual, or fast speeds.
  
  
  CONCLUSIONS
  Patients with COPD increase their critical walk speed after pulmonary rehabilitation. The pace chosen during common walk tasks is closely related to critical speed; this relationship is altered after rehabilitation.
  
  
  BACKGROUND
  ClinicalTrials.gov; No.: NCT00781183; URL: www.clinicaltrials.gov.
authors.affiliation: Department of Respiratory Medicine, University of Toronto, Toronto, ON, Canada; Respiratory Diagnostic and Evaluation Services, West Park Healthcare Centre, Toronto, ON, Canada.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dolmage
authors.affiliation: Department of Respiratory Medicine, University of Toronto, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Evans
authors.affiliation: Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; School of Physiotherapy and Curtin Health Innovation Research Institute, Curtin University, Bentley, WA, Australia; Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, University of Western Australia, Crawley, WA, Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Hill
authors.affiliation: Department of Respiratory Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Blouin
authors.affiliation: Department of Respiratory Medicine, University of Toronto, Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, Toronto, ON, Canada.
authors.forename: Dina
authors.initials: D
authors.lastname: Brooks
authors.affiliation: Department of Respiratory Medicine, University of Toronto, Toronto, ON, Canada; Respiratory Diagnostic and Evaluation Services, West Park Healthcare Centre, Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada. Electronic address: rgoldstein@westpark.org.
authors.forename: Roger S
authors.initials: RS
authors.lastname: Goldstein
mesh_terms: D000054:Acceleration; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation*; D012044:Regression Analysis; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology*