It is fairly common for individuals to engage in a variety of exercise activities and at different rates of intensity. This can make it challenging to evaluate just how much activity they are actually doing across the week. Taking these activities and transforming them into a common value would be great way to get a snap shot of the week’s activities which would be helpful for tracking exercise habits and progress.
That common value is MET minutes. Let’s review what a MET is. The metabolic equivalent of task (MET), or simply metabolic equivalent, is a physiological measure expressing the energy cost (or calories) of physical activities. One MET is the energy equivalent expended by an individual while seated at rest. While exercising, the MET equivalent is the energy expended compared to rest so MET values indicate the intensity. An activity with a MET value of 5 means you are expending 5 times the energy (number of calories) than you would at rest.
Okay so now that we are refreshed on what a MET is, what is a MET minute? MET minutes are simply the time engaged in an activity with consideration to the number of METs. So if you walked at a pace equivalent to 5 METs for 30 minutes it would be calculated as follows:
5 METs x 30 minutes = 150 MET minutes
MET minutes per week can also be calculated. If you participated in this activity 5 days per week:
150 MET minutes per day X 5 days per week = 750 MET minutes per week.
If you participated in this activity 3 days per week but another activity 2 days per week that was equivalent to 6 METs for 20 minutes you could tally the two together like this:
5 METs x 30 minutes = 150 MET minutes
6 METs x 20 minutes = 120 MET minutes
150 MET minutes x 3 days = 450 MET minutes
120 MET minutes x 2 days = 240 MET minutes
450 MET minutes + 240 MET minutes = 690 MET minutes per week
The most current Physical Activity Guidelines for Americans suggest that there are substantial health benefits for adults engaging in 500-1,000 MET minutes per week. These two examples, therefore, meet the current recommendations.
The Guidelines designate the following aerobic intensity categories based on MET levels.
Many cardiovascular machines display the MET value of your selected activity and intensity. You can also access the Compendium of Physical Activities to find the MET value of a number of different activities. The Compendium is quite comprehensive. You can select an activity like walking and it provides the MET value for numerous different scenarios (over 50) like hiking with a back pack, race walking, or walking while doing house work.
Beyond MET value though, many are interested in the number of calories they are burning. An estimation of this can be calculated as well. The equation used is listed below. Not that the bolded numbers 3.5 and 200 are both constants and do not change. You simply have to provide the MET value of your activity and your weight in kilograms. To convert your body weight in pounds to kilograms divide by 2.2.
_____MET Value x 3.5 x _____kg body weight ÷ 200 = calories burned per minute.
For a 150 pound person (68.2 kg) doing brisk walking (approximately 4 mph) for 150 minutes per week at 5 METs the total calories burned would be 900.
5 METs x 3.5 x 68.2 kg ÷ 200 = 6 calories per minute
150 minutes each week X 6 calories per minute = 900 calories burned per week.
For health benefits for most adults, the national guidelines suggest burning 1,000 calories per week. For weight loss and even greater health benefits an expenditure of 2,000 calories per week is suggested.
In summary, tracking volume of exercise can be challenging, especially when including a variety of activities of different intensities and duration. For the purpose of tracking progress and summaries of activities, both MET minutes per week and MET calories per week can be useful in activity logging, in goal setting and quite motivating.
Bushman, B. A. (2012). How can I use METS to quantify the amount of aerobic exercise. ACSM's Health & Fitness Journal, 16(No. 2), 5-7.