The accuracy of the ACSM cycle ergometry equation.
The purpose of this study was to determine the accuracy of the American College of Sports Medicine's equation for estimating the oxygen cost of exercise performed on a cycle ergometer. Sixty healthy males, ages 19-39 yr old, performed a five stage (30, 60, 90, 120, and 150 W) submaximal cycle ergometer test while their oxygen uptake was measured. Results indicated the standard error of estimate for the predicted oxygen values ranged from 0.11 to 0.22 l.min-1, with correlations between the actual and predicted values ranging from r = 0.22 to r = 0.50. Total errors ranged from 0.23 to 0.31 l.min-1. The actual oxygen cost was underestimated from 0.16 to 0.29 l.min-1 (P less than 0.05) by the equation at each workload. A revised equation was developed based upon the actual VO2-power relationship. The resulting slope was lower and the intercept higher when compared with the current ACSM equation. The slope and intercept of the revised equation are more consistent with values published in the literature. This equation appears as: VO2 (ml.min-1) = kgm.min-1 x 1.9 ml.min-1) + ((3.5 ml.kg-1.min-1 x kg body weight) + 260 ml.min-1). Predicted values from the revised equation were more accurate as reflected by slightly higher correlations, lower total errors, and lower mean differences from actual VO2 measurements than those from the current equation.