GLOSSARY

Respiratory Quotient (RQ) Table

RER measured at the mouth approximates cellular RQ only under suitable steady-state conditions; protein contribution and acid buffering complicate interpretation.

Respiratory Quotient (RQ) is metabolic carbon dioxide production relative to oxygen consumption.

Respiratory quotient relates metabolic carbon dioxide production to oxygen use; respiratory exchange ratio measures the corresponding external gas exchange. They can approximate each other at steady state, but ventilation and buffering during hard exercise separate them. A high value is not automatically an exact carbohydrate percentage. Nonprotein calculations correct protein contribution under defined assumptions. Identify measurement level and conditions rather than treating every breathing ratio as a precise intracellular fuel measurement in all situations.

Direct calorimetry measures heat; indirect approaches estimate energy through gas exchange. Metabolic carts need calibration, sound collection and appropriate stable conditions. Substrate calculations have assumptions and do not interpret every intensity or rapid transition equally well. Record feeding, activity and test purpose. A device value is not error-free reality or an independent diet prescription, and comparing measurements requires method consistency rather than merely matching the equipment's displayed units.