title: Physical performance in peripheral arterial disease: a slower rate of decline in patients who walk more.
abstract: BACKGROUND
  Exercise rehabilitation programs increase treadmill walking performance in patients with peripheral arterial disease (PAD) and intermittent claudication. However, it is unknown whether patients with PAD who walk for exercise regularly have less functional decline than those with less walking activity.
  
  
  OBJECTIVE
  To determine whether patients with PAD who report that they walk for exercise 3 or more times per week have less annual functional decline than those who walk for exercise less frequently.
  
  
  METHODS
  Prospective cohort study with a median follow-up of 36 months (interquartile range, 24 to 36 months).
  
  
  METHODS
  Academic medical center.
  
  
  METHODS
  417 men and women with PAD.
  
  
  METHODS
  Participants were classified at baseline and annually according to the number of times they reportedly walked for exercise each week. Functional assessments (6-minute walk distance, 4-meter walking speed, summary performance score) were measured at baseline and annually. Results were adjusted for age, sex, ethnicity, comorbid conditions, body mass index, ankle-brachial index, education, leg symptoms, cigarette use, geriatric depression score, previous year's level of functioning, and patterns of missing data.
  
  
  RESULTS
  Compared with those who exercised less frequently, patients who walked for exercise 3 or more times per week had a significantly smaller average annual decline in 6-minute walking distance (-48.0 feet per year compared with -56.6 feet per year for those who walked 1 to 2 times per week and -79.4 feet per year for nonexercisers; P for trend = 0.037). Patients who walked for exercise at least 3 times per week experienced a smaller average annual decline in the usual-paced 4-meter walking velocity (-0.014 m/s per year compared with -0.022 m/s per year for those who walked 1 to 2 times per week and -0.045 m/s per year for nonexercisers; P = 0.005). Similar findings were observed for the fast-paced 4-meter walk. The subset of asymptomatic patients who walked for exercise 3 or more times per week had annual declines in 6-minute walking performance (P = 0.107), normal-paced walking velocity (P = 0.065), and the summary performance score (P = 0.115); however, these declines were smaller than those observed in asymptomatic participants who walked fewer than 3 times per week.
  
  
  CONCLUSIONS
  Because this was an observational study, associations reported here cannot be construed as causal relationships. Sample sizes for subgroup analyses were small, which limited statistical power.
  
  
  CONCLUSIONS
  Among patients with PAD, self-directed walking exercise performed at least 3 times weekly is associated with significantly less functional decline during the subsequent year. Similar trends were observed in the subset of asymptomatic patients with PAD. These findings may be particularly important for the numerous patients with PAD who do not have access to supervised walking exercise programs.
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA. mdm608@northwestern.edu
authors.forename: Mary McGrae
authors.initials: MM
authors.lastname: McDermott
authors.forename: Kiang
authors.initials: K
authors.lastname: Liu
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Michael H
authors.initials: MH
authors.lastname: Criqui
authors.forename: Philip
authors.initials: P
authors.lastname: Greenland
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.forename: Lu
authors.initials: L
authors.lastname: Tian
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Schneider
authors.forename: William H
authors.initials: WH
authors.lastname: Pearce
authors.forename: Jin
authors.initials: J
authors.lastname: Tan
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Martin
mesh_terms: D004185:Disability Evaluation; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007383:Intermittent Claudication / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000150:complications / Q000628:therapy*; D011446:Prospective Studies; D016138:Walking