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TOPIC: HRM vs MFP estimate question

 
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June 25, 2012 4:27 PM
So I read a lot of the time that you should go by what your HRM says about calories burned, because MFP often 'over' estimates.

Well, I went on a 3 mile power walk one day, and MFP estimated the calorie burn at about 215-ish calories. The next time I did the same walk but I wore my HRM, and my HRM estimated the calorie burn at 570-ish.

This is a HUGE difference and actually in contradiction to what I've read from other people on the forums. I'm guessing part of the problem was that I was walking at a faster speed than I thought I was, plus MFP can't factor in hills and such, but it is still a pretty large difference.

So when I got such a huge difference, I went somewhere in the middle and put it at a 450 calorie burn.

I was just wondering what other people recommend I should do when I get such a large difference? I want to go with the most accurate calorie burn possible, since I often do eat back -some- of my exercise calories (rarely all).

Thanks in advance!
June 25, 2012 4:30 PM
Since exercise calorie burns are all estimates (including from the HRM) I always go with the lower number just to be on the safe side.
  16722707
June 25, 2012 4:31 PM
I always go with my HRM because it has the best idea of how hard I worked. A website has no way of knowing how hard you actually worked.
  20022190
June 25, 2012 4:32 PM
Here's the thing about HRM... they're more accurate. And if you get a good one, it will subtract your BMR calories from your burn i.e. what you would have burned during that time if you had done nothing.

I can run the exact same run in different conditions and get a different burn. If I'm dehydrated or the weather is hot, my HR will be higher and I'll burn more. If I run the exact same distance faster or slower my burn will be different. Ironically, if I have an awesome workout and feel like a machine my burn isn't usually as good as when I'm suffering the whole time.

Illness also can have the same effect. So an HRM takes into account your HR at your weight, your height, your distance traveled (if enabled) and your workout time.

Some of the things I've tried tracking in MFP are too high (e.g. gardening) and some are too low (e.g. running). I use my HRM each time and trust its calculations. It works for me to do that.
June 25, 2012 4:33 PM
I think over time you will have more experience with that same walk and can compare it. Also you can choose different types of walking on MFP so maybe choose a more strenuous one and compare. I think you did the right thing by averaging a bit. Also, make sure your HRM is cleaned regularly and you wet the strap before putting it on. Plus is your weight and age put in there correctly? I forget to put my new weight in there sometimes when I lose weight.
I have found that MFP is high for me too. I always go with my HRM. So far so good.
  18191174
June 25, 2012 4:35 PM
The general rule of thumb is that you burn about 100 calories per mile. More if you weigh more and exert more, but there's not really a ton of difference.

For running & walking, I've found MFP to be fairly close to that. I'd rather underestimate my work outs than over estimate them and think I'm burning more calories than I actually am.
June 25, 2012 4:36 PM
Your HRM is measuring your heart rate. So, I would always default to that over a website that is just using a formula with no actual heart rate data.
June 25, 2012 4:38 PM
Thanks for the responses! I figured something in the middle was my best bet until I do the walk more times and get a better idea of what a normal burn is for me.

I have the Polar FT4, which I've read on here from quite a few people is a pretty good one for the price. I couldn't afford a more expensive one, but I think it works pretty well.

I do have my height and weight put in, but I didn't know about wetting the strap - thanks for the tip!

I'm not sure if my HRM subtracts the BMR, so I always take some calories off the amount whether it's from MFP or a HRM.

I really appreciate all the responses and advice. I am probably going to do something in the middle, closer to the HRM amount, and not eat everything back until I get a few more walks in and can see what is an average amount for me.
June 25, 2012 4:43 PM
QUOTE:

The general rule of thumb is that you burn about 100 calories per mile. More if you weigh more and exert more, but there's not really a ton of difference.

For running & walking, I've found MFP to be fairly close to that. I'd rather underestimate my work outs than over estimate them and think I'm burning more calories than I actually am.


I disagree that there's not a ton of difference. My burns are vastly different for running vs walking. For a thin fit person maybe 100 calories per mile works but for a less fit, obese person, it's not even close. I ran 3.5 miles tonight and probably walked another half a mile. My burn was between 600 and 650! Not 400.

Definitely go with the HRM. It accounts for how hard you work and your fitness level - assuming of course you're using an HRM with a chest strap like a Polar.
  7246266

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