Using METS to calculate calories burned
Todays fitness blog discusses the use of METS to estimate calorie expenditure.
METS, or metabolic equivalents, are a highly effective way for personal trainers to measure their clients’ progress. Treadmills and other gym equipment will often display METS and they are a useful method of working out how many calories are burned during a workout.
Your body will burn 3.5ml of oxygen per kg of bodyweight per minute when sitting still and this is equivalent to one MET.
To translate this into calories burned, the formula is:
1 METs = 3.5 x weight in kg ÷ 200
Taking an average man weighing 75kg, sitting still for one minute:
1 MET = 3.5 x 75kg ÷ 200 x 1 min = 1.31 calories burned per minute
The number of calories he can therefore consume in a day following this routine would be:
1.31 calories x 60 minutes x 24 hours = 1,886 calories
Once our man starts to move around, his heart rate will increase, his muscle fibres will be working to support his body weight and more oxygen will be used. So if he is working at two METS instead of one, this will burn 2.62 calories a minute.
Any kind of activity, from cleaning the house to playing with the children to walking the dog, will increase the amount of oxygen being burned and therefore the number of calories.
Now let’s take this into the gym. For a personal trainer whose client is running at 12km / 7.5mph an hour, they will be working at 12.5 METS (ACSM, 1995). Using the example of the average man weighing 75kg, it’s straightforward to calculate the calories burned in a 30-minute workout.
12.5 METS x 3.5 x 75kg ÷ 200 x 30 mins = 492 calories
With this information, a trainer can start to advise their clients on weight-loss or maintenance programmes.
Remember that someone weighing 100kg who introduces the same 30-minute activity into their daily routine will burn more calories and generally lose more weight per week than a person weighing 75kg. Exercising at a given speed with will burn more calories if it is done with additional load being applied.
Therefore the individual carrying an extra 25kg of fat mass through their workout will work harder at a given speed meaning their intensity of exercise will be higher.
The alternative is that the individual who weighs 100kg can work at a lower speed to burn the same amount of calories as they have a heavier frame to move.
This theory follows the assumption that the two clients have the same lean mass.
Professional personal trainers have found that clients who are schooled in this approach of using METS to calculate weight loss tend to stick to it.
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