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).
- SourceAvailable from: Anne Vuillemin
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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 · 0.29 Impact Factor
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- "To our knowledge, this attempt to identify the relationship between measured MET values and activity counts for a sample of elderly participants had not previously been performed. In agreement with previous research [14, 16], resting metabolic rate in our group of elderly individuals was significantly less than the younger participants. However, the average resting metabolic rate for the older participants was similar to the standard MET value of 3.5 mL·kg−1·min−1 whereas the average resting metabolic rate for the younger adults was significantly higher than the standard MET value of 3.5 mL·kg−1·min−1. "
ABSTRACT: The purpose of this investigation was to compare accelerometer activity counts and oxygen consumption between young and elderly individuals. Sixteen young (21.3 ± 2.5 yrs) and sixteen elderly (66.6 ± 2.9 yrs) participants completed 30 minutes of resting oxygen consumption to determine resting metabolic rate and four 6 min walking intensities ranging from 27 to 94 m·min(-1). Resting oxygen uptake was significantly lower for the older participants. Exercise oxygen consumption was significantly higher for the elderly group. There were no significant differences in activity counts between groups at each of the exercise intensities. When using measured resting metabolic rate, activity counts of 824 and 2207 counts·min(-1) were associated with moderate (3 METs) physical activity intensity for the older and young participants, respectively. However, using standard resting metabolic rate (3.5 mL·kg(-1)·min(-1)), activity counts of 784 and 2009 counts·min(-1) were associated with moderate physical activity intensity for the elderly and young participants, respectively. These findings indicate that activity counts are similar across age groups even though the oxygen consumption of exercise is greater among elderly individuals.Journal of aging research 05/2014; 2014:184693. DOI:10.1155/2014/184693
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- "The cardiopulmonary exercise test (CPET) is generally considered as the “gold standard” in the assessment of exercise capacity [1,2]. However, patients undergoing elective major orthopedic surgery associated with severe postoperative morbidity (including cardiac ischemic events) may not able to undergo this or other subjective measures of cardiorespiratory reserve, such as metabolic equivalency tests (METs) [3,4], since mobility in these patients may be limited . Moreover, in patients at increased risk of postoperative morbidity, non-invasive stress testing (presumed to simulate the adrenergic stress of surgery and the perioperative period) is expensive and has been shown to have a low predictive positive value (i.e., it has a high false positive rate), which might cause more harm than good [6,7]. "
ABSTRACT: The aim of this study was to evaluate pre- and post-operative brain natriuretic peptide (BNP) levels and compare the power of this test in predicting in-hospital major adverse cardiac events (MACE: atrial fibrillation, flutter, acute heart failure or non-fatal/fatal myocardial infarction) in patients undergoing elective prosthesis orthopedic surgery to that of the Revised Cardiac Risk Index (RCRI) and American Society of Anesthesiology (ASA) class, the most useful scores identified to date. The study was an observational study of consecutive patients undergoing elective prosthesis orthopedic surgery. Surgical risk was established using RCRI score and ASA class criteria. Venous blood was sampled before surgery and on postoperative day 1 for the measurement of BNP. The intraoperative data collected included details of the surgery and anesthesia and any MACE experienced up until hospital discharge. MACE occurred in 14 of the 227 patients treated (6.2%). Age was statistical associated with MACE (p < 0.004). Preoperative BNP levels were higher (p < 0.0007) in patients who experienced MACE than in event-free patients (median values: 92 and 35 pg/mL, respectively). Postoperative BNP levels were also greater (p < 0.0001) in patients sustaining MACE than in event-free patients (median values: 165 and 45 pg/mL, respectively). ROC curve analysis demonstrated that for a cut-off point >= 39 pg/mL, the area under the curve for preoperative BNP was equal to 0.77, while a postoperative BNP cut-off point >= 69 pg/mL gave an AUC of 0.82. Both pre- and post-operative BNP concentrations are predictors of MACE in patients undergoing elective prosthesis orthopedic surgery.BMC Anesthesiology 03/2014; 14(1):20. DOI:10.1186/1471-2253-14-20 · 1.38 Impact Factor