Metabolic equivalent: One size does not fit all

Byrne, Nuala M., Hills, Andrew P., Hunter, Gary R., Weinsier, Roland L., & Schutz, Yves (2005) Metabolic equivalent: One size does not fit all. Journal of Applied Physiology, 99(3), pp. 1112-1119.

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The metabolic equivalent (MET) is a widely used physiological concept that represents a simple procedure for expressing energy cost of physical activities as multiples of resting metabolic rate (RMR). The value equating 1 MET (3.5 ml O2•kg–1•min–1 or 1 kcal•kg–1•h–1) was first derived from the resting O2 consumption (O2) of one person, a 70-kg, 40-yr-old man. Given the extensive use of MET levels to quantify physical activity level or work output, we investigated the adequacy of this scientific convention. Subjects consisted of 642 women and 127 men, 18–74 yr of age, 35–186 kg in weight, who were weight stable and healthy, albeit obese in some cases. RMR was measured by indirect calorimetry using a ventilated hood system, and the energy cost of walking on a treadmill at 5.6 km/h was measured in a subsample of 49 men and 49 women (26–45 kg/m2; 29–47 yr). Average O2 and energy cost corresponding with rest (2.6 ± 0.4 ml O2•kg–1•min–1 and 0.84 ± 0.16 kcal•kg–1•h–1, respectively) were significantly lower than the commonly accepted 1-MET values of 3.5 ml O2•kg–1•min–1 and 1 kcal•kg–1•h–1, respectively. Body composition (fat mass and fat-free mass) accounted for 62% of the variance in resting O2 compared with age, which accounted for only 14%. For a large heterogeneous sample, the 1-MET value of 3.5 ml O2•kg–1•min–1 overestimates the actual resting O2 value on average by 35%, and the 1-MET of 1 kcal/h overestimates resting energy expenditure by 20%. Using measured or predicted RMR (ml O2•kg–1•min–1 or kcal•kg–1•h–1) as a correction factor can appropriately adjust for individual differences when estimating the energy cost of moderate intensity walking (5.6 km/h).

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ID Code: 8497
Item Type: Journal Article
Refereed: Yes
Additional Information: Articles free to read on journal website after 12 months
Additional URLs:
Keywords: exercise prescription, body composition, exercise intensity, energy expenditure
DOI: 10.1152/japplphysiol.00023.2004
ISSN: 1522-1601
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > HUMAN MOVEMENT AND SPORTS SCIENCE (110600)
Divisions: Current > Research Centres > Centre for Health Research
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2005 The American Physiological Society
Deposited On: 10 Jul 2007 00:00
Last Modified: 03 Feb 2015 03:09

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