Continuous measurement of ventilatory exchange ratio during exercise

Abstract

The ventilatory gas exchange ratio (R) has been measured continuously during exercise from end-tidal CO2 and N2 concentrations recorded with gas analyzers. Studies in normal subjects and patients with different working capacities indicate that the change in R at different levels of work lasting several minutes on an ergometer gives an excellent measure of the balance between oxygen supply and demand in the working muscles. The level of work at which R increases appreciably above its resting level corresponds to the level at which arterial lactate increases and plasma bicarbonate falls. The continuous measurement of R can be readily incorporated into work tests for the assessment of exercise performance in both normal subjects and patients with cardiovascular diseases. blood bicarbonate; work test; anaerobic metabolism; physical fitness; blood lactate Submitted on December 30, 1963