How Accurate Are Heart Rate Monitors?

AKosky585

How accurate are the calories burned on a heart rate monitor? I have a Polar FT4 and have all of my stats plugged in to it. Today I did a walk/job on the treadmill for 35 minutes ranging from 4mph and 5mph. My heart rate was anywhere from 135 bpm to 172 bpm.

In 35 minutes, it said I burned 334 calories. Does this sound right? I just got the HRM a week or so before Christmas and have been using it mainly for P90X. Maybe I was WAY underestimating before on the treadmill before using the HRM.

Mollydolly10

Well you can't just take the number from the HRM and put that in as exercise calories burned. Since MFP is set up to already calculate what you burn at rest, you only want to input the number you burned during EXERCISE ALONE.

That being said, you need to do some subtraction It seems a little confusing at first, but hopefully it makes sense.

If you go to your home page and then to goal, on the right side of the screen it lists calories burned from daily activity (this is the exact same number you'd get if you went to settings > diet/fitness goals, and set your loss to "maintain weight," but looking under goals is just much easier haha).

Personally, my calories burned from daily activity was 1,630. You do the math to find out how many calories you burn in ONE MINUTE at rest...

1,630/24 (hr/day) = 67.91/hour
67.91/60 = 1.13/min

So then, I subtract 1.13 cals for every minute I work out, because MFP already accounts for that amount of resting caloric burn. Example: 30 minutes of working out, I would subtract 33.9 calories from what my HRM says I burned in order to get the calories burned from exercise alone.

33.9 calories may not seem like a lot, but when you start adding it up over the long-term.. say I work out 5 times a week for 30 minutes and didn't subtract my resting calorie burn... I would be 169.5 calories off during the week. It adds up! And also consider workouts LONGER than 30 minutes. Jump to a 60 minute workout and I should be subtracting 67.91 - multiple for 5 days a week - that's 339.55 calories OFF I would be for the week if I didn't subtract.

This seems especially important for those eating their exercise calories back. You don't want to have a false impression of how much you burned when you are deciding what to eat after a workout, that's no good!!

Anyways, that is just the way that it is set up, and MFP gives you the tools to do some quick math and make sure you are entering data that is as accurate as possible!!

erickirb

Thanks Molly, I could not have answered that question any better myself

r_jen

bump

AKosky585

Thank you so much!

GiGi76

bump