Validity and reproducibility of a whole‐room indirect calorimeter for the estimation of VO(2) , VCO(2) , and resting metabolic rate

Whole‐room indirect calorimeters (WRICs) provide accurate instruments for the measurement of respiratory exchange, energy expenditure, and macronutrient oxidation. Here, we aimed to determine the validity and reproducibility of a 7500 L WRIC for the measurement of ventilation rates and resting metabolic rate (RMR). Technical validation was performed with propane combustion tests (n = 10) whereas biological reproducibility was tested in healthy subjects (13 women, 6 men, mean ± SD age 39.6 ± 15.3) in two 60 min measurements separated by 24 h. Subjects followed a run‐in protocol prior to measurements. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated for ventilation rates of O2 (VO2), CO2 (VCO2), the respiratory quotient (RQ; VCO2/VO2), and RMR. Technical validation showed good validity with CVs ranging from 0.67% for VO(2) to 1.00% for energy expenditure. For biological reproducibility, CVs were 2.89% for VO(2); 2.67% for VCO(2); 1.95% for RQ; and 2.68% for RMR. With the exception of RQ (74%), ICCs were excellent for VO(2) (94%), VCO(2) (96%) and RMR (95%). Excluding participants that deviated from the run‐in protocol did not alter results. In conclusion, the 7500 L WRIC is technically valid and reproducible for ventilation rates and RMR.