A re-examination of the metabolic equivalent concept in individuals with coronary heart disease.
OBJECTIVE
The metabolic equivalent (MET) is a commonly used method of quantifying the energy cost and intensity of physical activity. Recent studies have questioned the accuracy of the well-accepted value of a MET of 3.5 mL O2.kg(-1).min(-1). The goal of the present study was to compare the traditionally accepted value for 1 MET to direct measures of resting metabolic rate in a group of stable individuals with coronary heart disease (CHD).


METHODS
The primary cohort consisted of 109 (60 men and 49 women) subjects with documented coronary heart disease and a body mass index >or=25 kg/m2. Measurements included indirect calorimetry, body composition, and exercise capacity (peak oxygen uptake [VO2]). In a substudy of 17 (10 men, 7 women) normal weight subjects (body mass index <25 kg/m2), metabolic rate in the seated position was also measured.


RESULTS
Mean resting value for 1 MET was a VO2 value of 2.58 +/- 0.4 mL O2.kg(-1).min(-1) for overweight subjects measured in the supine position and 2.84 +/- 0.59 mL O2.kg(-1).min(-1) for normal weight individuals measured in the seated position. Caloric expenditure value was 0.74 +/- 0.12 kcal.kg(-1).h(-1) rather than the expected value of 1 kcal.kg(-1).h(-1). Values were similar between men and women. Women on beta-blockers had a lower resting metabolic rate (2.47 +/- 0.27 vs. 2.71 +/- 0.38 mL O2.kg(-1).min(-1)) (P < .05) than women not on beta-blocker therapy, whereas there was no effect of beta-blockers in men.


CONCLUSIONS
Findings confirm recent studies of otherwise healthy individuals and indicate that the average resting metabolic rate in subjects with coronary heart disease is 23% to 36% lower than the widely accepted value of 3.5 mL O2.kg(-1).min(-1). Results demonstrate the limitation of the convention of expressing energy expenditure in multiples of an assumed constant.
Savage
Patrick D
PD
Division of Cardiology, Department of Medicine, University of Vermont College of Medicine and Fletcher Allen Health Care, Burlington, VT 05401, USA.
Toth
Michael J
MJ
Ades
Philip A
PA
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001481:Basal Metabolism; D050218:Body Fat Distribution; D015992:Body Mass Index; D002151:Calorimetry; D015331:Cohort Studies; D003327:Coronary Disease / Q000378:metabolism*; D004734:Energy Metabolism; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010809:Physical Fitness; D011187:Posture; D012044:Regression Analysis; D012737:Sex Factors
D000319:Adrenergic beta-Antagonists