MET stands for Metabolic Equivalent of Task, which is a ratio of a persons working metabolic rate relative to their resting metabolic rate. It is a measure of the intensity of an exercise or activity, with one MET being the energy you spend sitting at rest. The concept of MET was primarily designed to be used in epidemiological surveys, where survey respondents answer the amount of time they spend on specific physical activities.
One MET is defined as 1 kcal/kg/hour and is roughly equivalent to the energy cost of sitting quietly. It is also defined as oxygen uptake in ml/kg/min with one MET equal to the oxygen cost of sitting quietly, equivalent to 3.5 ml/kg/min. An activity with a MET value of 2, such as walking at a slow pace, would require twice the energy that an average person consumes at rest.
MET scores are used to provide general medical thresholds and guidelines to a population. They are also used to show an individuals level of cardiorespiratory fitness (CRF), or the ability of the heart and lungs to supply oxygen to muscles during physical exertion. Some doctors use MET scores to prescribe exercise for their patients, recommending a certain number of MET minutes per week.
When performing exercise, MET values are assigned to various forms of physical activity to determine how many calories are expended during that activity. The MET concept provides a convenient method to describe the functional capacity or exercise tolerance of an individual as determined from progressive exercise testing and to define a repertoire of physical activities in which a person may participate safely, without exceeding a prescribed intensity level.
