Efficacy of Prescribing Endurance Training Intensity Using the Ventilatory Equivalents for Oxygen and Carbon Dioxide in Untrained Men and Women

The purpose of this study was to compare the cardiorespiratory adaptations to 12 weeks of endurance cycle training performed using intensities based on the ventilatory equivalents for oxygen and carbon dioxide. Forty-four untrained subjects (9 men and 35 women) were randomly assigned into two groups: a low-intensity training (LIT) group (n = 21) that trained at an intensity equivalent to the first metabolic threshold (VT1), as determined by the ventilatory equivalent for oxygen (V_E/VO₂); and a moderate-intensity training (MIT) group (n = 23) that trained at the second metabolic threshold (VT2), as indicated by the ventilatory equivalent for carbon dioxide (V_E/VCO₂). Total work during each training session was equated by altering the duration of each workout and by keeping frequency of training the same. Both groups had a significant increase in the power output (PO) and VO₂ at VT1 and VT2 and peak VO₂ that was similar in magnitude, regardless of the different intensities of training. These findings show that prescribing training intensity using the metabolic thresholds determined by the ventilatory equivalents for oxygen and carbon dioxide is a viable method and can produce similar aerobic fitness improvements in untrained subjects provided total work is equated during training.