HRM accuracy? calories burned?

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mmreed
mmreed Posts: 436 Member
in Fitness and Exercise
I am curious how reliable the calories burned tracking is with a HRM - I have a Polar FT7 and wear the chest strap during my cardio.

Im 6ft, 290lbs, male, 42 years old.

My cardio is basically brisk walking - around 3.5-3.7 and an incline of 1.5 to 2.0 for 30 mins, then switch to an elliptical machine for 20 mins on a low intensity setting (easier than the treadmill) then back to the treadmill for a 10 min 3.6 2.0 incline finish. My HR bounces between 120 and 140 during these cardio session, hovering around 125-135 most of the time.

Cardio - HRM tracked 65min 712cal
Cardio - HRM tracked 65min 721cal
Cardio - HRM tracked 63min 648cal

is what the latest HRM logs were.

This seems very high to me - especially since MFP says a 60 min 3.5mph walk should burn 500cal and a 65 min 3.5 is 542 cal.

MFP says a 4.0mph walk for 60 min burns 658

granted bodies are different ect... but I have always heard MFP says things burn TOO MUCH rather than too little like in my case.

Do my HRM results seem possibly accurate? Any ways to check this or calibrate my burning?

Id hate to be thinking im burning that much if there is no possible way I am... so Im asking for the pros to chime in with some guidance.

Replies

  • MoveTheMountain
    MoveTheMountain Posts: 764
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    I am curious how reliable the calories burned tracking is with a HRM - I have a Polar FT7 and wear the chest strap during my cardio.

    Im 6ft, 290lbs, male, 42 years old.

    My cardio is basically brisk walking - around 3.5-3.7 and an incline of 1.5 to 2.0 for 30 mins, then switch to an elliptical machine for 20 mins on a low intensity setting (easier than the treadmill) then back to the treadmill for a 10 min 3.6 2.0 incline finish. My HR bounces between 120 and 140 during these cardio session, hovering around 125-135 most of the time.

    Cardio - HRM tracked 65min 712cal
    Cardio - HRM tracked 65min 721cal
    Cardio - HRM tracked 63min 648cal

    is what the latest HRM logs were.

    This seems very high to me - especially since MFP says a 60 min 3.5mph walk should burn 500cal and a 65 min 3.5 is 542 cal.

    MFP says a 4.0mph walk for 60 min burns 658

    granted bodies are different ect... but I have always heard MFP says things burn TOO MUCH rather than too little like in my case.

    Do my HRM results seem possibly accurate? Any ways to check this or calibrate my burning?

    Id hate to be thinking im burning that much if there is no possible way I am... so Im asking for the pros to chime in with some guidance.

    The readings are probably accurate, but if you want to know how many calories you burned *from the exercise itself* you need to convert the gross calories to net calories. Use a site like this one:

    http://www.shapesense.com/fitness-exercise/calculators/net-versus-gross-calorie-burn-conversion-calculator.aspx

    If you just add the gross calories and try to eat those back, you're double dipping, and you'll go over.
  • patchesgizmo
    patchesgizmo Posts: 244 Member
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    what is your highest heart rate at? This is based on heart rate. The faster your hr, the more calories you burn. What do you have your zones set for? That is all part of it also.

    My problem is that my hr is medically set low so for a 30 minute walk it says I only burn like 70 calories.
  • raerae514
    raerae514 Posts: 171 Member
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    I'm no pro but given your stats, I would say those calories sound about right.

    I just got a new HRM as well and I feel like my amounts are also too high... but it's not going to LIE to me about my heart rate, right? It's simple math and that should give much more accurate results than MFP.

    But I too am curious to see what the "pros" will say; I'm keeping an eye on this thread :)
  • MoveTheMountain
    MoveTheMountain Posts: 764
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    Following up: Gross calories are a measure of how many calories you burned by (being alive) + (exercise). When MFP gives you a calorie goal, it's already factoring in that you're alive, so you want to factor that out of your HRMs calorie burn number. You only want to count the calories burned from the exercise itself - depending on the duration of your workout, you might lose 100 calories or more when you convert the gross calories to net.
  • chivalryder
    chivalryder Posts: 4,391 Member
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    Those readings look alright to me. When I used to mtb, I could easily burn 2000 kcal in an hour and a half to two hours.
  • wcmyers74
    wcmyers74 Posts: 11
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    I have the same HRM and it works great. I think it is very accurate. Just make sure the personal information you input is still accurate. I went 3 months and I noticed my calorie burns were different than others and sure enough, I forgot to update my weight as I lost it. So just keep that in mind and also that these things are still just estimates. No one can know for sure how many calories they burn. I do notice that my trend is 10 per minute on high intesity workouts. I also burn a lot after the workout. I would suggest you don't eat back those calories as someone else already mentioned. That won't help you at all. A recovery shake or meal is one thing, but don't TRY to eat them back. Keep up the good work!
  • raerae514
    raerae514 Posts: 171 Member
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    Those readings look alright to me. When I used to mtb, I could easily burn 2000 kcal in an hour and a half to two hours.

    What's a kcal?
  • chivalryder
    chivalryder Posts: 4,391 Member
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    Those readings look alright to me. When I used to mtb, I could easily burn 2000 kcal in an hour and a half to two hours.

    What's a kcal?

    This isn't meant to confuse anyone, but a kcal is 1 calorie that we burn/eat. It is composed of 1000 "chemistry" calories. I'm just being nit-picky when it comes to the terminology that I use.

    'kcal' is just the correct way of saying calorie, when referring to the energy we eat/use.
  • omma_to_3
    omma_to_3 Posts: 3,265 Member
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    I have the same HRM and it works great. I think it is very accurate. Just make sure the personal information you input is still accurate. I went 3 months and I noticed my calorie burns were different than others and sure enough, I forgot to update my weight as I lost it. So just keep that in mind and also that these things are still just estimates. No one can know for sure how many calories they burn. I do notice that my trend is 10 per minute on high intesity workouts. I also burn a lot after the workout. I would suggest you don't eat back those calories as someone else already mentioned. That won't help you at all. A recovery shake or meal is one thing, but don't TRY to eat them back. Keep up the good work!

    Yes, the results are likely more accurate than MFP, but still an error rate. I too burn 10 to 12 calories per minute on high intensity. To combat the "I forgot to update my weight" issue, I set my weight to 10 lbs. less than I really am. Then I don't change it until I hit that new weight and then I lower it another 10. Works for me so I'm not changing the darn thing weekly and ever so slightly underestimates my burns.

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