Extrapolated maximal oxygen consumption was similar to measured values but remained effectively independent of exercise duration when analyzed at 90%, 75%, and 66% of exercise.
Observational (n=26)
Does extrapolated maximal oxygen consumption provide an accurate and duration-independent measure of cardiorespiratory functional reserve compared to direct measurement in healthy volunteers and heart failure patients?
A novel mathematical model for extrapolated maximal oxygen consumption provides an objective measure of cardiorespiratory reserve that is independent of exercise duration.
Respiratory gas exchange was measured during maximal treadmill exercise testing in six healthy volunteers and 20 patients with chronic heart failure. A curve of equation y = ax-bx2 was used to model the relation between the rate of oxygen consumption (y axis) and the rate of carbon dioxide production (x axis). The constants "a" and "b" were used to calculate the maximal value of the expression ax-bx2. This value was termed the "extrapolated maximal oxygen consumption". For all subjects a close fit between experimental data and mathematical model was obtained and the values of the measured maximal rate of oxygen consumption and "extrapolated maximal oxygen consumption" were similar. Respiratory gas exchange was reanalysed using only those values obtained during the first 90%, 75%, and 66% of exercise. In contrast with the value for the measured rate of oxygen consumption, the value of "extrapolated maximal oxygen consumption" was effectively independent of exercise duration. Extrapolated maximal oxygen consumption provides an objective measure of cardiorespiratory functional reserve that, within limits, is independent of exercise duration. Extrapolated maximal oxygen consumption is complementary to the direct measurement of the maximal rate of oxygen consumption and increases the amount of information derived from a single exercise test.
Buller et al. (1988) conducted an observational in Chronic heart failure (n=26). Extrapolated maximal oxygen consumption method vs. Direct measurement of maximal rate of oxygen consumption was evaluated on Extrapolated maximal oxygen consumption compared to measured maximal rate of oxygen consumption. Extrapolated maximal oxygen consumption was similar to measured values but remained effectively independent of exercise duration when analyzed at 90%, 75%, and 66% of exercise.