A Reference Equation for Normal Standards for VO2 Max: Analysis from the Fitness Registry and the Importance of Exercise National Database (FRIEND Registry)

Existing normal standards for maximal oxygen uptake (VO2 max) are problematic because they tend to be population specific, lack normal distribution and portability, and are poorly represented by women. The objective of the current study was to apply the Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND) Registry to improve upon previous regression formulas for normal standards for VO2 max using treadmill testing. Maximal treadmill tests were performed in 7783 healthy men and women (20-79 years; maximal RER >1.0) from the FRIEND registry and a separate validation cohort of 1287 subjects. A regression equation for VO2 max was derived from the FRIEND registry and compared to the validation cohort and two commonly used equations (Wasserman and European). Age, gender, and body weight were the only significant predictors of VO2 max (multiple R = 0.79, R-2 = 0.62, p < 0.001). The equation for predicting VO2 max was: VO2 max (ml.kg(-1).min(-1)) = 79.9-(0.39 x age) -(13.7 x gender [0 = male; 1 = female]) - (0.127 x weight [lbs]). Marked differences were observed in percentage predicted VO2 max achieved between commonly used reference equations, particularly among women, overweight and obese subjects. In the validation sample, the FRIEND equation closely paralleled measured VO2 max, with the validation group yielding a percent predicted VO2 max of 100.4% based on the FRIEND equation. An equation for age-predicted VO2 max derived from the FRIEND registry provided a lower average error between measured and predicted VO2 max than traditional equations, and thus may provide a more suitable normal standard relative to traditional equations. Published by Elsevier Inc.