Potentially stupid (and over-worked) question

rachmass1 · June 2012

If you wear a HRM (Polar FT7), does the calories it shows you burned in an hours worth of exercise include your BMR? For example, if your BMR is 1200 or 50 calories an hour on average, and the HRM shows you burned 50 in an hour, is that on top of the BMR or basically just measuring your BMR? Those are not my numbers BTW, just throwing it out for simple math sake.

Thanks in advance! Rachel

omma_to_3 · June 2012

To my knowledge, the FT7 does include your BMR. But I don't know for sure! I have an FT7 as well. I only subtract my BMR if my workout was an hour or more (which is rare). Less than an hour, and I don't worry about it anyway.

rachmass1 · June 2012

I was wondering about this as I walk for hours each day and it shows typically that I burn about 80 calories an hour but my BMR is supposed to be about 60 per Scooby. So that means walking an hour only burns an additional 20 calories, which doesn't make a lot of sense to me because I travel about 1.5 miles in that time. From what I understand most people burn about 80-100 calories per mile, which means I should be burning between 120-150 calories over that same time that the HRM says 80. I am sooooooo confused!!!

SanyamKaushik · June 2012

Good Question. I was asking this myself few months ago... Answer is simple: Use your HRM while sitting idle/ watching TV. If it shows no calories, or very less calories then the HRM is not considering BMR in your workout calories. Hope this helps !

GauchoMark · June 2012

http://forum.polar.fi/showthread.php?p=44453

rachmass1 · June 2012

thanks for the link.

This makes no sense to me. I burn almost as much sitting on my duff as I do walking? Or only a small fraction more walking? Nah, I don't buy that and think something is off on the readings. I do see that my burn from walking isn't very much but 20 calories an hour for walking 1.5 miles isn't logical.

omma_to_3 · June 2012

thanks for the link.

This makes no sense to me. I burn almost as much sitting on my duff as I do walking? Or only a small fraction more walking? Nah, I don't buy that and think something is off on the readings. I do see that my burn from walking isn't very much but 20 calories an hour for walking 1.5 miles isn't logical.

What's your average heart rate for you walk and how long does it take you?

When I'm walking at least 3.5 mph, I would burn around 350 calories for 50 minutes to an hour, according to my HRM. That has lowered a lot as I've become more fit.

yarwell · June 2012

yes it includes your basic sedentary metabolism. I sat at the computer for 15 minutes and clocked the equivalent of 2000+ calories per day, so it's including BMR etc etc.

rachmass1 · June 2012

I think it is because my heart rate is so low. I have a resting heart rate around 52-55 and when walking it goes as high as 70-75 unless I push it (can't, bad hip forces slow walks). I walk at my desk 3-4 hours most days of the week and I know it is helping me lose weight and I am burning calories, just not high. The 20 difference just seems too low given the 80 calorie per mile minimum I have found elsewhere on the internet.

I am wearing my HRM most of the day today and will see what the average is that it gives me after 10 hours or so and see if it shows any change from the low amount it was reading earlier.

Thanks all of you for your help!

mcarter99 · June 2012

I was wondering about this as I walk for hours each day and it shows typically that I burn about 80 calories an hour but my BMR is supposed to be about 60 per Scooby. So that means walking an hour only burns an additional 20 calories, which doesn't make a lot of sense to me because I travel about 1.5 miles in that time. From what I understand most people burn about 80-100 calories per mile, which means I should be burning between 120-150 calories over that same time that the HRM says 80. I am sooooooo confused!!!

You're walking 1.5mph for hours? Is that at a treadmill desk? It's a lot slower than you'd walk outdoors. Most of us walk at least 3mph.

I'm guessing your HR is barely elevated so the HRM thinks you're not doing much, which is sort of true. I don't think they're designed to be accurate at non-elevated HRs?

Maybe consider a Fitbit instead?

Someone posted an article from a running magazine that said most women at a walk only burn about 75 calories a mile, if that helps. I don't recall if that was over and above BMR, though. I think it was. A mile at that 1.5mph crawl might be less. The point of the article was that at a run it's higher, not the 100 average for both we often say.

yarwell · June 2012

I think the accuracy of the calorie estimate is debatable unless you've elevated the heart rate into an exercise zone, it'll be yet another y=mx+c correlation.. The watches have functions to pause during exercise presumably so it doesn't clock up extra calories from rest periods. There's a posting somewhere by heybales about how to set the things up to reflect anything you know about your own VO2max and HR rather than leaving it with standard assumptions - by fibbing about your age and height you can tune it to your stats.

mcarter99 · June 2012

If you want your HRM to assign you a lower BMR based on your low RHR, I think you can just tell it you're older and/or smaller than you are.

rachmass1 · June 2012

yes, I have a treadmill desk. I walk at work 3-4 hours a day. I have lost most of my weight through walking and cutting back on calories to slightly under TDEE per the Fitbit but really would like to have an accurate guage on how much I am using during the day. I can only walk 1.5 MPH on the treadmill due to a bad hip and inability to type accurately past 1.7 at best. When I walk outside it is around 2MPH but that accounts for dogs stopping to pee constantly.

rachmass1 · June 2012

Well I wore it for six hours and about 2 of those were walking. It said I burned 557 calories in just over six hours so it was 92.83 per hour on average and I guess it is calculating more than I thought it was. Don't know what I set up differently that time but I was up and down, on the treadmill, sitting at my desk, just doing my normal stuff. I am glad to see it is recognizing the movement more than last time I measured with it. Yeah!

Thanks again guys.

heybales · July 2012

Well I wore it for six hours and about 2 of those were walking. It said I burned 557 calories in just over six hours so it was 92.83 per hour on average and I guess it is calculating more than I thought it was. Don't know what I set up differently that time but I was up and down, on the treadmill, sitting at my desk, just doing my normal stuff. I am glad to see it is recognizing the movement more than last time I measured with it. Yeah!

Thanks again guys.

So the HRM calc's are only valid in aerobic zone, about 90-160 bpm, so you are far enough under it's accuracy is out the window, even if you had correct stats entered in it.
That's why wearing a HRM all day is useless stats, except for the time with steady-state aerobic activity, not correct.
Here's a site with link to a study by Polar bearing out this info.
http://www.braydenwm.com/calburn.htm

Below is a more accurate measurement, since the energy to move so much mass so fast up so much an incline is pretty known.
Plus this calculator lets you view gross and net, and for MFP purpose, you'd want net.

But then again, you'd probably be better served just upping your activity level in MFP to take into account you are active through out the day actually, not sitting at the desk.
I wouldn't even log the dog-walking, as that is just more excellent fat-burning type of activity you don't need to replenish.

http://www.exrx.net/Calculators/WalkRunMETs.html

Potentially stupid (and over-worked) question

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