Metabolic equivalent: One size does not fit all
ABSTRACT 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 x kg(-1) x min(-1) or 1 kcal x kg(-1) x h(-1)) was first derived from the resting O2 consumption (VO2) 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 VO2 and energy cost corresponding with rest (2.6 +/- 0.4 ml O2 x kg(-1) x min(-1) and 0.84 +/- 0.16 kcal x kg(-1) x h(-1), respectively) were significantly lower than the commonly accepted 1-MET values of 3.5 ml O2 x kg(-1) x min(-1) and 1 kcal x kg(-1) x h(-1), respectively. Body composition (fat mass and fat-free mass) accounted for 62% of the variance in resting VO2 compared with age, which accounted for only 14%. For a large heterogeneous sample, the 1-MET value of 3.5 ml O2 x kg(-1) x min(-1) overestimates the actual resting VO2 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 x kg(-1) x min(-1) or kcal x kg(-1) x 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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- "Les équivalences en MET sont des approximations, et il est évident que la congruence en (1) n'a pas la prétention de remplacer une mesure du métabolisme de base, ni son estimation à partir d'équations dédiées  . En effet, appliquée strictement , elle conduit à une surestimation  surtout marquée chez les femmes et les personnes âgées qui présentent en moyenne une masse maigre réduite par rapport aux hommes et aux jeunes adultes. La principale raison est qu'elle ne se réfère qu'à la masse et que les facteurs âge, taille et sexe ne sont pas utilisés pour moduler l'évaluation (sauf dans certaines études où on utilise 0,95 kcal/kg/h chez la femme au lieu de (1)). "
ABSTRACT: For physical activity promotion to be effective from a public health view, adequate communication between the different actors is required. In this perspective, we propose to explicit the bioenergetic notions used to quantify and qualify intensity of physical activities, physical activity and sedentary behaviors, and lifestyles. Public health recommendations for physical activity in healthy adults from different authorities vary between 675 and 1350 METs/min per week, which, for example, is the equivalent of the energy spent with the participation 5 times per week in activities leading to a 4.5-times increase of the basal metabolic rate during 30 or 60 minutes for the low and high limit, respectively. For every population category, researchers in different scientific fields and all various responsible actors must work harder or better to reach successful physical activity promotion that would be evidenced by rarefaction of sedentary lifestyles. Very different lifestyles are compatible with energy expenditure large enough at a population scale to contribute to the prevention and control of many non-communicable diseases.Nutrition Clinique et Métabolisme 05/2015; 29(2). DOI:10.1016/j.nupar.2015.04.001 · 0.62 Impact Factor
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- "The direct method often converts the measures into metabolic equivalent of tasks (METs) that are widely accepted notion in energy expenditure of physical activity. It is commonly viewed as a measure that could provide a common descriptor of workload levels across populations (Byrne et al, 2005). Due to its optimal accuracy, the use of METs is commonly preferred to determine the level of physical activity (Ainsworth, 2009; Ainsworth et al, 2011). "
ABSTRACT: The purposes of this study were: 1) to show the item difficulty hierarchy of walking/moving construct of the International Classification of Functioning, Disability and Health-Activity Measure (ICF-AM), 2) to evaluate the item-level psychometrics for model fit, 3) to describe the relevant physical activity defined by level of activity intensity expressed as Metabolic Equivalent of Tasks (MET), and 4) to explore what extent the empirical activity hierarchy of the ICF-AM is linked to the conceptual model based on the level of energy expenditure described as MET. One hundred and eight participants with lower extremity impairments were examined for the present study. A newly created activity measure, the ICF-AM using an item response theory (IRT) model and computer adaptive testing (CAT) method, has a construct on walking/moving construct. Based on the ICF category of walking and moving, the instrument comprised items corresponding to: walking short distances, walking long distances, walking on different surfaces, walking around objects, climbing, and running. The item difficulty hierarchy was created using Winstep software for 20 items. The Rasch analyses (1-parameter IRT model) were performed on participants with lower extremity injuries who completed the paper and pencil version of walking/moving construct of the ICF-AM. The classification of physical activity can also be performed by the use of METs that is often preferred to determine the level of physical activity. The empirical item hierarchy of walking, climbing, running activities of the ICF-AM instrument was similar to the conceptual activity hierarchy based on the METs. The empirically derived item difficulty hierarchy of the ICF-AM may be useful in developing MET-based activity measure questionnaires. In addition to convenience of applying items to questionnaires, implications of the finding could lead to the use of CAT method without sacrificing the objectivity of physiologic measures.09/2013; 20(3). DOI:10.12674/ptk.2013.20.3.089
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- "It is noteworthy that absolute energy costs of any particular activity depend on an individual basal energy expenditure, age, sex, size, skill and level of fitness (WCRF/AICR, 2007). The MET scores in the Compendium were calculated considering of healthy 40 year old males with the average body mass of 70 kg, and may not correspond to absolute energy expenditure for females (Byrne et al., 2005). However, MET-scores are valid and useful when the relative energy expenditure is compared within populations (Ainsworth et al., 1993; Friedenreich et al., 1998). "
ABSTRACT: Scientific evidence for the primary prevention of cancer caused by physical activity of regular moderate-intensity or greater is rapidly accumulating in this field. About 300 epidemiologic studies on the association between physical activity and cancer risk have been conducted worldwide. The objectives of this paper were three-fold: (i) to describe briefly the components of physical activity and its quantification; (ii) to summarize the most important conclusions available from comprehensive reports, and reviews of the epidemiologic individual and intervention studies on a role physical activity in cancer prevention; (iii) to present proposed biological mechanisms accounting for effects of activity on cancer risk. The evidence of causal linked physical activity and cancer risk is found to be strong for colon cancer - convincing; weaker for postmenopausal breast and endometrium cancers - probable; and limited suggestive for premenopausal breast, lung, prostate, ovary, gastric and pancreatic cancers. The average risk reductions were reported to be 20-30%. The protective effects of physical activity on cancer risk are hypothesized to be through multiple interrelated pathways: decrease in adiposity, decrease in sexual and metabolic hormones, changes in biomarkers and insulin resistance, improvement of immune function, and reduction of inflammation. As there are several gaps in the literature for associations between activity and cancer risk, additional studies are needed. Future research should include studies dealing with limitations in precise estimates of physical activity and of a lack of consensus on what defines sedentary behavior of individuals and those linked with the proposed biomarkers to cancer risk and controlled exercise intervention trials.Asian Pacific journal of cancer prevention: APJCP 07/2013; 14(7):3993-4003. DOI:10.7314/APJCP.2013.14.7.3993 · 2.51 Impact Factor