title: Test-retest reliability and validity of the 400-meter walk test in healthy, middle-aged women.
abstract: BACKGROUND
  The 400 m walk test has been used in older adults; however, the applicability in middle-aged populations is unknown.
  
  
  METHODS
  Data were obtained from the Evaluation of Physical Activity Measures in Middle-Aged Women (PAW) Study and included 66 women (52.6 ± 5.4 years). Participants were instructed to walk at a brisk, maintainable pace; time taken to complete the 400 m was recorded in seconds. Intraclass correlation coefficients (ICC) were used to assess test-retest reliability. Spearman rank order correlation coefficients were used to examine the concurrent validity of the walk test with cardiorespiratory fitness and associations with physical activity, body composition, flexibility, static balance, and muscular fitness, adjusted for age and body mass index.
  
  
  RESULTS
  Participants completed the walk at visits 4 and 5 in 248.0 and 245.0 seconds, respectively. The walk test had excellent reproducibility [ICC = 0.95 (95% CI: 0.92, 0.97)] and was significantly associated with estimated (ρ = -0.43; P < 0.0001) and measured (ρ = -0.56; P < 0.001) VO2max. The walk test was also significantly related to physical activity, body composition, flexibility, and balance.
  
  
  CONCLUSIONS
  These findings support the utility of the 400 m walk test to estimate cardiorespiratory fitness and reflect free-living physical activity in healthy, middle-aged women.
authors.affiliation: Division of Epidemiology and Disease Control, University of Texas School of Public Health, Austin Regional Campus, Austin, TX, USA.
authors.forename: Kelley K
authors.initials: KK
authors.lastname: Pettee Gabriel
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Rankin
authors.forename: Chong
authors.initials: C
authors.lastname: Lee
authors.forename: Mary E
authors.initials: ME
authors.lastname: Charlton
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Swan
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Ainsworth
mesh_terms: D003625:Data Collection / Q000379:methods*; D015444:Exercise; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010809:Physical Fitness; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014481:United States; D016138:Walking