Following up on my post about the Peloton display numbers (and a little arithmetic regarding Output), a visitor to the site asked about METs, so I thought I’d post a follow-up….
Calculating METs is unfortunately considerably more difficult than calculating output in kilojoules. Well, it’s not that it’s so difficult, it’s that the level of precision is much less. METs are fundamentally different from metrics like power and output. Power is power, regardless of who you are. Lifting a ten pound dumbbell a foot in one second takes about 13 watts, and it doesn’t matter who you are. Find any person or machine that can output more than about 13 watts, and it can lift the dumbbell. (More about power and output in my post about the Peloton metrics.)
Metabolic Equivalents, or METs, on the other hand, is a measurement of the amount of energy exerted, a more complex topic than merely work done. Remember when you first got your Peloton bike and you PR’d almost every ride? Part of that could be explained by a quick elevation of your fitness level (you ex-couch potato, you), but a lot of it had to do with your improved efficiency. You learned the bike and, as you got more efficient you could do more work with the same amount of effort (or, you were able to do the same amount of work with less effort.)
How to Measure METs
To really measure METs the way they were intended to be measured, you’d need to know how much oxygen you are consuming during the exercise. If you don’t have access to a lab, that’s not something you can measure directly. In that case, there are other MET calculators that substitute other metrics that can be used as proxies for oxygen consumption, such as calories burned (don’t get me started on calorie calculations! If I ever have enough free time I’ll do a blog post on that.)
I personally am skeptical about the ability to use METs for something like a stationary bicycle. Since body weight is a factor in the calculation, it would seem to me that heavier athletes have an easier time of things on a stationary bike as opposed to an actual bike. I’d suggest you stick with watts and kilojoules, which are much easier to measure accurately (if your bike’s resistance is calibrated, of course, which it’s probably not… but that’s my next post’s topic).
Formula for METs
I don’t want you to go away empty-handed, though, so I will offer a MET calculator that uses something that Peloton does give you to work with: Watts. It may not be as accurate a calculation as one that actually measures oxygen consumption, but it’ll work well enough if your goal is to try to track your fitness gains over time.
The calculation for (approximate) METs, then, is:
METs = 1.163 * watts / kg
(Kg being body weight in kilograms)
For the arithmetic-challenged, I offer this handy online form:
I’m not entirely sure how useful all of this was, but hopefully if you are really into METs and a Peloton rider, it’ll give you want you were looking for. Cheers!
Update: After this blog post was created, Peloton introduced their “Strive Score“, a metric that attempts to measure individual effort (as opposed to output). Check it out.
— #LeftShark
I see that this post is quite old, but I came across it while looking for MET formulas. According to your calculator, if I ride my bike at 85 watts and weigh 240 lbs, then I am working at .9 METs. Since 1 MET is what I would be working at if stationary, this does not seem right.
Try this. Make sure your Peloton profile has your correct weight and age and you use a heartrate monitor synced up. Then at the end of your workout, note the total calories burned. I believe this number is calculated based on your kilojoules of work, heartrate, etc (adjusted for your age, gender and weight.) I find it easier the think in terms of METs per minute, so I divide the total calories burned by workout length. Today I did 663 calories in 45 minutes, or about 14.73 kcal per minute. Now use this formula: cal/min *200, then divide by 3.5 and divide again by your weight in Kg. I’m a fat old man at 118 Kg, so the calculation gives me 7.12 METs per minute (avg), so my MET-minutes was about 320. CDC says we need 500 to 1000 Met-minutes per week, so I’m on my way (its only Monday!) good luck!!
I appreciate this post. It seems like your formula may use the wrong power reading. The Peloton watts readout is peer delivered to the bike, right? The machine estimates torque times angular rate and yields a power. My guess—as an airline pilot I’m an expert in all things, see—is that we want energy expended by our bodies, not energy delivered to the bike. Our simian meat is not super efficient, so we deliver a fraction of the expended power to the pedals. So like the other poster pointed out, to get a meaningful MET estimate (in the absence of a lab), we need to use metabolic power. Metabolic power would be roughly (like you said) estimated by kcal per minute. This, I think, is why it shows me at 2 METs at 180 watts, which I assess to be way too low.