Ratio of the volume of CO2 produced to the volume of O2, consumed in the body as a whole.
The respiratory exchange ratio is assessed through assessment of expired gases as the volume of carbon dioxide produced divided by the volume of oxygen consumed. RER provides an indication of the respiratory quotient (RQ), which describes the ratio of metabolic gas exchange at the level of the cell. RQ gives an indication of the mixture of fuels utilized for energy at rest or during a specific task. In general, as RQ approaches 1.00, carbohydrate is providing a larger percentage of fuel for metabolism. Conversely, as RQ approaches 0.70, fat is providing a larger percentage of fuel being utilized. The RQ of protein is typically about 0.82 but is not assessed by exhaled gases.
A qualitative measure denoting the type of fuel (either carbohydrate or fat) undergoing metabolic processing to furnish the body with energy.
This phenomenon, akin to the respiratory quotient, pertains to the measurement of oxygen consumption and carbon dioxide production at the lungs, rather than the level of activity within the tissue beds.