HRM calorie difference

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BobbyDaniel
BobbyDaniel Posts: 1,460 Member
in Fitness and Exercise
I know HRM's have been...but i have a serious question: I used mine running for the first time tonight and it showed that i burned about 130 calories more than what MFP tells me i burn for same amount of exercise. Should there be that much of a difference?

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  • NewImprovedCnbethea1
    NewImprovedCnbethea1 Posts: 1,108
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    Funny yours is opposite of mines I just got my HRM and it is always less than what the cardio machines and the fitlinxx system says at the YMCA I just go by what the HRM read it is suppose to be the most accurate after all right?
  • BobbyDaniel
    BobbyDaniel Posts: 1,460 Member
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    That should read "have been discussed"...trying to type on a netbook isn't always easy.
  • Aeriel
    Aeriel Posts: 864 Member
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    If everything is set in your HRM for you....height, weight, age etc, then trust the HRM. MFP has exercises entered by users, so they have entered how their bodies burned calories. The system tries to calculate a number for you based on the numbers it has, but MFP does not take into account heart rate. Most of the exercises will be different than the HRM, some by more than others. Just remember with an HRM that you need to subtract the base calories that your body burns in a day with no activity,because MFP has already accounted for that. Go to tools, calculate your BMR there, and then take that number and divide it by 24, and then again by 60 to get a base calorie burn per minute.

    For example, if you have a BMR of 1600, your base calorie burn per minute is 1600/24/60=1.11calories per minute. So if you exercise 30 minutes using your HRM, subtract 30*1.11=33.33 calories from the total it gives you. I believe that the exercises in MFP already do that, so it will make the numbers a little closer.
  • BobbyDaniel
    BobbyDaniel Posts: 1,460 Member
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    based on that math equation which would drive my 8th grade/py pre-algebra daughter nuts...my HRM was still higher by about a 100 calories; that also explains why i've seen a lot more weight come off as i get more active over recent weeks. I probably need to tweak my calorie intake a bit i guess.
    Thanks for the info!
  • DKWaggoner
    DKWaggoner Posts: 185
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    follow the HRM. they are more accurate than MFP or any exercise equipment
  • Azdak
    Azdak Posts: 8,281 Member
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    based on that math equation which would drive my 8th grade/py pre-algebra daughter nuts...my HRM was still higher by about a 100 calories; that also explains why i've seen a lot more weight come off as i get more active over recent weeks. I probably need to tweak my calorie intake a bit i guess.
    Thanks for the info!

    HRMs measure heart rate and heart rate only. They use heart rate to estimate calories expended. They can do this because, under certain conditions, changes in heart rate reflect changes in oxygen uptake. It is the increase in oxygen uptake that actually leads to the increase in calories expended.

    Sites/tables like those on MFP use standard calculations to determine the energy cost of some activities. There are equations that have long been used to estimate the oxygen uptake of simple cardio activities such as walking and running.

    So your HRM and the MFP tables are actually measuring the effort two different ways. The HRM is estimating based on your heart rate response and the MFP table is estimating based on the energy cost of the activity itself. When it comes to simple activities such as walking or running, the MFP numbers should be more accurate, but not always. Hills, wind, or running on a treadmill instead of outdoors can affect the energy cost and are not taken into effect by the MFP database.

    OTOH, if you do not have accurate data programmed into your HRM, or you cannot program individual data into your HRM, or if the HRM is a cheaper model (i.e. not a Polar F6 or F11 or higher, not a Suunto), or you are in a warm climate, among other conditions, your HRM numbers may be off.

    The #1 reason why an HRM overestimates calories is because the individual has a higher-than-average maximum HR, but they have not, or cannot, program the HRM with that higher number. For example if your true HRmax is 200, but the HRM is programmed with a calculated HRmax of 180 and your exercise HR is 160, then the HRM thinks you are working at 88% of your maximum instead of 80%. Working harder burns more calories, so it overestimates because it thinks you are working harder.

    That's just some background FYI. In reality, a 100 calorie difference in not significant. Unless you have a metabolic cart, no tool we use to estimate exercise calories is anywhere close to accurate enough to be more accurate than to within 100-200 calories.

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