From the Guidelines
METs are defined as the energy cost of a given activity divided by resting energy expenditure, where 1 MET equals 3.5 mL O2 kg-1 min-1 oxygen consumption (VO2), as estimated in the 2016 European guidelines on cardiovascular disease prevention in clinical practice 1. To put this into practice:
- 1 MET represents a resting state
- Light activities like walking and light household work are around 1.1-2.9 METs
- Moderate activities like brisk walking, slow cycling, and gardening are about 3-5.9 METs
- Vigorous activities like race-walking, jogging, or running are typically above 6 METs METs are useful for prescribing exercise intensity and comparing different activities, allowing for a standardized way to measure and compare the metabolic cost of various activities across individuals of different body sizes, as outlined in the guidelines 1. The concept of METs is based on the body's increased energy demands during physical activity, where oxygen consumption and energy expenditure increase with exercise intensity, reflected in higher MET values, making it a valuable tool for exercise physiology and clinical practice 1. Key points to consider when using METs in clinical practice include:
- Estimating the energy cost of activities to prescribe appropriate exercise intensity
- Comparing the metabolic cost of different activities to tailor exercise programs to individual needs
- Using METs to monitor progress and adjust exercise intensity over time, as supported by the guidelines 1.
From the Research
Definition of Metabolic Equivalent of Task (METs)
- One metabolic equivalent (MET) is defined as the amount of oxygen consumed while sitting at rest, equal to 3.5 ml O2 per kg body weight x min 2
- The MET concept represents a simple, practical, and easily understood procedure for expressing the energy cost of physical activities as a multiple of the resting metabolic rate 2
- The energy cost of an activity can be determined by dividing the relative oxygen cost of the activity (ml O2/kg/min) by 3.5 2
Limitations of the MET Concept
- 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% 3
- The MET concept does not apply well to all individuals, as it does not take into account individual differences in body composition, age, and other factors 3, 4
- The use of a standard MET value can lead to inaccurate estimates of physical activity energy expenditure, particularly in individuals with high levels of adiposity 5
Importance of Individualized MET Values
- Using measured or predicted resting metabolic rate (RMR) as a correction factor can appropriately adjust for individual differences when estimating the energy cost of physical activities 3
- Individualized MET values can provide a more accurate estimate of physical activity energy expenditure, particularly when using accelerometers to measure physical activity 6
- Practitioners should estimate RMR with equations taking into account individual characteristics, such as sex, age, and Body Mass Index, rather than relying on the standard 1-MET value 4