Estimating VO2peak from a non-exercise prediction model; The HUNT Study, Norway Short title: Prediction of VO2peak

PURPOSE: Cardiorespiratory fitness is suggested to be an important marker of cardiovascular risk, but is rarely evaluated in healthcare settings. In the present study directly measured peak oxygen uptake data (VO2peak) from a diverse population of 4637 healthy participants were used to develop and cross-validate a new non-exercise regression model of cardiorespiratory fitness for men and women. METHODS AND RESULTS: Multivariable regression analysis was used to develop a nonexercise model of cardiorespiratory fitness for men and women separately with VO2peak as the outcome. In the final models 2067 men (mean age 48.8) and 2193 women (mean age 47.9) were included, respectively. Cross-validation of the models was done by standard datasplitting procedures with evaluation of constant error and total error of a model developed on one sample and cross-validated on another sample. Age, waist circumference, leisure time physical activity and resting heart rate, successively, were the most potent predictors of VO2peak for both men and women. Together 61 and 56 % of variance in VO2peak, for men and women respectively, were explained by the full models. Standard error of the estimate was 5.70 and 5.14 for the models including men and women, respectively. CONCLUSIONS: The non-exercise regression model developed in the present study was fairly accurate in predicting VO2peak in this healthy population of men and women. The model might be generalized to other healthy populations and be a valid tool for a rough assessment of cardiorespiratory fitness in an outpatient setting.