title: Modeling Percentile Rank of Cardiorespiratory Fitness Across the Lifespan.
abstract: OBJECTIVE
  The purpose of this investigation was to create an equation for continuous percentile rank of maximal oxygen consumption (VO2max) from ages 20 to 99.
  
  
  METHODS
  We used a two-staged modeling approach with existing normative data from the American College of Sports Medicine for VO2max. First, we estimated intercept and slope parameters for each decade of life as a logistic function. We then modeled change in intercept and slope as functions of age (stage two) using weighted least squares regression. The resulting equations were used to predict fitness percentile rank based on age, sex, and VO2max, and included estimates for individuals beyond 79 years old.
  
  
  RESULTS
  We created a continuous, sex specific model of VO2max percentile rank across the lifespan.
  
  
  CONCLUSIONS
  Percentile ranking of VO2max can be made continuous and account for adults aged 20 to 99 with reasonable accuracy, improving the utility of this normalization procedure in practical and research settings, particularly in aging populations.
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center.
authors.forename: Rasinio S
authors.initials: RS
authors.lastname: Graves
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center; Department of Biostatistics, University of Kansas Medical Center.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Mahnken
authors.affiliation: Martinos Center for Biomedical Imaging, Massachusetts General Hospital.
authors.forename: Rodrigo D
authors.initials: RD
authors.lastname: Perea
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Billinger
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Vidoni
keywords: aging; cardiopulmonary exercise test; physical endurance; treadmill test