Reproducibility of 24-h energy expenditure, substrate utilization and spontaneous physical activity in obesity measured in a respiration chamber.
OBJECTIVE
Determination of within-subject day-to-day coefficients of variations (CV) of 24-h measurements of spontaneous physical activity (SPA), macronutrient oxidation, energy expenditure (EE) and heart rate (HR).


METHODS
Two 24-h measurements in respiration chamber, separated by 14 days of strict weight stability.


METHODS
22 healthy obese subjects, 15 females and seven males (age 27-64 y, BMI: 30-39 kg/m2).


METHODS
SPA assessed by microwave radar, substrate oxidation and EE measured by indirect calorimetry and heart rate measured by telemetry.


RESULTS
For 24-h measurements CV was 0.8% for RQ, 6.7% for fat oxidation, 5.6% for carbohydrate oxidation, 14.5% for protein oxidation, and 4.3% for heart rate. SPA assessed by microwave radar was also reproducible (CV = 9.7%). Within-subject day-to-day coefficients of variations (CV) were 1.5 and 1.8% for 24-h EE and sleeping EE, and 4.1% for RMR. Both on day 1 and 14, 93.4% of the variation in 24-h EE could be explained by differences in fat-free mass (92.3 and 92.4%, respectively) and SPA (1.1 and 1.0%), respectively). Also the algorithm and correlation between 24-h RQ and 24-h energy balance were highly reproducible (r = 0.56, P < 0.01 and r = 0.48, P < 0.05).


CONCLUSIONS
Both macronutrient oxidation, SPA and EE in obese patients can be determined with high reproducibility in a respiration chamber.
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D001713:Biphenyl Compounds / Q000494:pharmacology; D001835:Body Weight / Q000502:physiology; D002153:Calorimetry, Indirect; D002940:Circadian Rhythm / Q000502:physiology*; D004044:Dietary Proteins / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005951:Glucose Tolerance Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology*; D010084:Oxidation-Reduction; D011804:Quinolines / Q000494:pharmacology; D015203:Reproducibility of Results; D012119:Respiration / Q000502:physiology*
D000318:Adrenergic beta-Agonists; D001713:Biphenyl Compounds; D004044:Dietary Proteins; D011804:Quinolines; C081112:ICI D8731