Maximal oxygen intake and nomographic assessment of functional aerobic impairment in cardiovascular disease

Maximal oxygen intake (V?o₂max) was measured, using an open circuit technique, during the last 2 to 4 minutes of a multistage treadmill test of maximal exercise in 151 men and 144 women of 29 to 73 years of age. V?o₂max was higher in men than in women (P < 0.0001), lower in sedentary than in physically active persons (P < 0.001 in men, < 0.01 in women), and diminished with age in cross-sectional comparisons. It was highly correlated with duration of exercise by this standardized protocol. Accordingly, by regression equations average normal values for healthy persons could be predicted from sex, activity status, and age; values expected on testing could be estimated from the duration of exercise.Over 800 measurements of V?o₂max were also made during submaximal exercise to define the aerobic requirements under these conditions of testing. This revealed different coefficients for slope and intercept of regression equation for relationship of V?o₂submax to duration of submaximal exercise.Functional aerobic impairment (FAI) is the per cent difference between observed (or estimated) V?o₂max and that predicted from age, sex, and activity status by regression equations. Nomograms for rapid derivation of FAI from age in years and duration of maximal exercise were constructed for healthy men, women, and cardiac men to facilitate clinical usage of these methods.Functional aerobic impairment was 23 per cent in a group of symptomatic hypertensive men; it was 24 per cent in men with healed myocardial infarction, free from angina on maximal exertion, but 41 per cent in men with angina of effort, with or without evidence of prior infarction. In men with either angina or only healed myocardial infarction, impairment was reduced during treatment with nitroglycerin.