An accurate and feasible field test for estimating health promotion effects on fitness: Predicting cardiorespiratory fitness in men using a simple three minute assessment

Increasing levels of physical activity and fitness has become an increasingly important and common target of health promotion programs. Although the direct measurement of maximal oxygen consumption (VO₂max) is the most valid and widely accepted measure of cardiorespiratory fitness, it is not feasible to use this rigorous methodology with numerous study subjects. The Queen's College Step Test (QCT) is a brief submaximal assessment that estimates VO₂max using recovery heart rate that we successfully used across 8 research sites with over 1000 participants. However, that research demonstrated the need for improvement of the regression equation for predicting VO₂max in men. Thirty-six college-aged males, purposefully selected to represent various fitness levels, completed the QCT and a maximal exercise test in random order and separated by seven days to compare predicted and directly measured VO₂max and create a new regression equation. The original, published prediction equation overestimated VO₂max by 10% (50.55 vs 46.01 ml·kg^-1·min^-1). Stepwise regression that included recovery heart rate and measured weight resulted in a more accurate prediction of VO₂max [88.38 + (-.157*HR in BPM) + (-.25*weight in Kg)]. When study subjects were stratified into low-, moderate-, and high-fit tertiles based on measured VO₂max, the new prediction equation outperformed the published equation for the low and average fitness tertiles. This study demonstrated that it is possible to improve upon the published regression equation for estimating cardiorespiratory fitness via the QCT by adding an easily measured variable, weight. This will provide a more accurate, yet feasible, analysis of our health promotion efforts.