title: Reliability of the 400-m usual-pace walk test as an assessment of mobility limitation in older adults.
abstract: OBJECTIVE
  To assess the test-retest reliability of the 400-m usual-pace walk test (400-MWT), and to determine whether the 4-m walk test predicts inability to walk 400 m.
  
  
  METHODS
  Observational.
  
  
  METHODS
  Community, 20-m tract course.
  
  
  METHODS
  Sixty study participants (aged>or=65) were enrolled from the community and met the following eligibility criteria: self-reported difficulty in two or more of four functional domains (mobility and exercise tolerance, upper extremity function, basic self-care, higher functional tasks of independent living) and a score of 18 or higher on the Mini-Mental State Examination.
  
  
  METHODS
  The 400-MWT and 4-m walk test were each repeated within 7 days.
  
  
  RESULTS
  The mean age+/-standard deviation of the study population was 84.3+/-6.3; 88.3% were women. Nineteen participants (31.7%) failed both 400-MWTs, and 41 successfully completed both tests (kappa=1). Mean walking speed for the 4-m test was 0.87+/-0.18 m/s for those who completed the 400-MWT and 0.53+/-0.17 m/s for those who failed (P<.001). The Spearman correlation coefficient between 4-m and 400-m walking speeds was 0.93. The estimated area under the receiver operating characteristic curve between 4-m walking speed and the ability to perform the 400-MWT was 0.91. The 4-m gait speed averaged less than 0.6 m/s in 80% of subjects who failed the 400-MWT.
  
  
  CONCLUSIONS
  The test-retest reliability for inability to complete the 400-MWT is high. Four-m walking speed is highly predictive of ability to perform the 400-MWT. These findings may prove useful to future clinical trials and observational studies that involve assessment of mobility limitations in older adults.
authors.affiliation: Sticht Center on Aging, Section on Gerontology and Geriatric Medicine, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA. yves.rolland@9online.fr
authors.forename: Yves M
authors.initials: YM
authors.lastname: Rolland
authors.forename: Matteo
authors.initials: M
authors.lastname: Cesari
authors.forename: Michael E
authors.initials: ME
authors.lastname: Miller
authors.forename: Brenda W
authors.initials: BW
authors.lastname: Penninx
authors.forename: Hal H
authors.initials: HH
authors.lastname: Atkinson
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D017079:Exercise Tolerance; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D016138:Walking