METs, which is short for metabolic equivalents, is a number you might’ve seen on your wearable device. As fitness trackers get more and more advanced, the amount of information they give you multiplies. Once upon a time, it was a miracle if your watch could track your step count and heart rate. Now, that’s as basic as it gets.
If you have a wearable device that tracks METs, you might simply scroll past it without paying much attention. Given the amount of information available on fitness trackers, that’s understandable. However, if you know more about what the numbers mean, you can use them for valuable feedback.
RESTING METABOLIC RATE AND METS
According to Angel Baez, a New York City-based personal trainer, METs are measured using resting metabolic rate (RMR). Resting metabolic rate represents the amount of oxygen used by the body at rest. If a workout uses 8 METs, it simply means your body uses 8 times the amount of oxygen it does when you’re at rest, explains Baez.
This probably seems like a lot of work to figure out your workout intensity, and that’s a fair point. Another way to estimate METs is by using calories — roughly 1 calorie for every 2.2 pounds of body weight per hour. For example, a 150-pound person burns roughly 68 calories at rest per hour. Every time they increase their calorie burn by 68 they add one MET. If they work out for an hour and burn 272 calories, that means their average intensity was 4 METs.
Even though that might seem like a lot of work to figure out your workout intensity, it’s a lot easier than measuring how much oxygen you use. The beauty of this formula is you can use something that calculates calories burned to calculate METs.
Fitness trackers, and even some fitness equipment, track your calories burned. That means some of them can easily tack on this METs number.
WHY TRACK METS?
METs can be used to classify exercise intensity. Anything below 3 METs is considered resting or below the cutoff for physical activity. That means things like standing, folding laundry and washing dishes doesn’t make the cut.
Between 3–6 METs is considered moderate physical activity. Things like jogging, swimming, climbing stairs or snorkeling are considered moderate. Anything above 6 is considered vigorous. Strenuous hiking, kayaking, faster running and cycling are considered vigorous.
Such simplistic measurements of exercise intensity are helpful for comparing large amounts of people. The number system is much smaller and easier to manage than heart rate, which is a bigger number that differs greatly between people. On the other hand, heart rate is more accurate for measuring the difficulty of an individual’s workout.
Ben Walker, a personal trainer from Anywhere Fitness in Dublin, Ireland, uses METs and heart rate together. He likes METs because the easy-to-use number system allows him to quickly track intensity from workout to workout. If your METs are lower than the previous workout, that means your intensity dropped. The opposite is also true.
Since METs are a measurement made for the masses, it’s not always accurate. METs can be overestimated in overweight and out of shape people. While people who are very fit can be underestimated by METs.
To obtain a truly accurate MET score, you’d have to be connected to a machine that can measure your oxygen usage. A separate study from the Journal of Internet Medical Research found popular fitness trackers tend to miscalculate METs by 1–1.7 points. The study, which was performed on wrist-wearers, also found that activities in which the arms don’t move, such as cycling or weight training, are less accurate. That’s because they can’t use the step count feature.
THE BOTTOM LINE
You can use METs as a rule of thumb, especially if you don’t like to use measurements like heart rate or calories burned. METs are a simple measurement you can use to track the intensity of your workouts. Just keep in mind it can be inaccurate.
Check out “Workout Routines” in the MyFitnessPal app to discover and log workouts or build your own with exercises that fit your goals.