Intended for healthcare professionals


Meaningless METS: studying the link between physical activity and health

BMJ 2016; 354 doi: (Published 09 August 2016) Cite this as: BMJ 2016;354:i4200
  1. Philippe Autier, professor1 2,
  2. Cécile Pizot, research statistician2
  1. 1University of Strathclyde Institute of Global Public Health at iPRI, International Prevention Research Institute, Espace Européen, Building G, Allée Claude Debussy, 69130 Ecully Lyon, France
  2. 2International Prevention Research Institute (iPRI), 95 Cours Lafayette, 69006, Lyon, France
  1. Correspondence to: P Autier philippe.autier{at}

Future studies must streamline their measurement and reporting for real gains in knowledge

Physical activity is good for health. Few would oppose this contention. But, curiously, we do not definitively know how much the type (occupational, recreational, daily living) and quantity of physical activity reduces the risk of common conditions. This imprecision stems essentially from the myriad different ways physical activity has been appraised in epidemiological studies. Some studies investigated physical activity as a whole, while others concentrated on specific types of activity. Different metrics have been used for quantification from just dummy categories (such as high versus low) to quintiles of hours a week. The metabolic equivalent of tasks (MET) is a standardised metric that expresses the energy spent during a specific activity. The MET is defined as the ratio of the metabolic rate during that activity to the metabolic rate when resting.1 A classification system was developed in 19932 and updated …

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