Background: 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.
Objective: The goal of the present study was to compare the traditionally accepted value for 1 MET to direct measures of resting metabolic rate (RMR), obtained while in the seated position, in a group of stable individuals with coronary heart disease (CHD).
Methods: The cohort consisted of 66 (49 men and 17 women) nonsmoking subjects with a mean age of 67 +/- 10 years and body mass index of (BMI) 29.5 +/- 5.8 kg/m2. RMR was measured in a seated position for 15 minutes in the postabsorptive state using indirect calorimetry. Participants refrained from vigorous activity for at least 48 hours and beta-blocker (BB) therapy was withheld the day of testing.
Results: Mean resting value for 1 MET was a Vo2 of 2.8 +/- 0.5 mL O2 kg-1 min-1. MET values were similar between men and women (2.9 +/- 0.5 vs 2.7 +/- 0.6 mL O2 kg-1 min-1, respectively) (P < .20) and individuals with a BMI of <= 25 or > 25 (2.9 +/- 0.5 vs 2.8 +/- 0.5 mL O2 kg-1 min-1, respectively) (P < .33). There was also no difference between individuals on chronic BB therapy (N = 60) (2.8 +/- 0.5 mL O2 kg-1 min-1) versus participants not treated with a BB (N = 6) (2.5 +/- 0.2 mL O2 kg-1 min-1) (P < .18).
Conclusions: Our findings confirm recent studies of otherwise healthy individuals and indicate that the average resting metabolic rate (MET) in subjects with CHD is 20% lower than the widely accepted value of 3.5 mL O2 kg-1 min-1. Our results demonstrate the limitation of the convention of expressing energy expenditure in multiples of an assumed constant.