Which method measures the concentration of inspired oxygen and expired carbon dioxide to assess metabolic gas exchange?

• A. Indirect calorimetry
• B. Direct gas analysis
• C. Cycle ergometer
• D. Plyometrics

Answer: (B)

Indirect calorimetry analyzes metabolic gas exchange by measuring the concentrations of inspired oxygen and expired carbon dioxide to determine how much oxygen is consumed and how much carbon dioxide is produced. From these measurements you can calculate the respiratory quotient and energy expenditure, giving a clear picture of metabolic rate. This is typically done with a metabolic cart using a mask or hood to sample air as you breathe. The other options are exercise modes or a less directly relevant gas-measurement approach; they don’t provide the streamlined readout of O2 uptake and CO2 production used to assess metabolic gas exchange.