Modeling Percentile Rank of Cardiorespiratory Fitness Across the Lifespan.

PURPOSE:The purpose of this investigation was to create an equation for continuous percentile rank of maximal oxygen consumption (VO2 max) 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 VO2 max. 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 VO2 max, and included estimates for individuals beyond 79 years old. RESULTS:We created a continuous, sex specific model of VO2 max percentile rank across the lifespan. CONCLUSIONS:Percentile ranking of VO2 max 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.