Worried my HRM is overestimating my cals

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Wezlfuss
Wezlfuss Posts: 122 Member
in Fitness and Exercise
Lately I've been doubting my HRM's estimations, because they always end up significantly higher than the amount of calories that MFP gives when you input the number of minutes you did a certain activity.

So I went for a walk today, about 61 minutes, keeping my heart rate between 140 and 170 (closer to 170 for the most part).
My HRM claims I burned 692 calories, which is almost 100 more than the MFP estimation for a 61 minute, 4.0 MPH walk. I checked a few other calories burned calculators, and they came out close to the MFP estimations as well.

I'm 23, 236lbs, and 5' 10" (70 inches). I know my resting heat rate is terrible (around 80), so I'm kinda worried that because of that, my heart rate is somehow tricking the HRM into thinking that I'm working out harder than I really am. I know that probably sounds silly, but I don't want to overestimate my calories and sabotage all my effort.

Should I trust that my HRM knows what it's doing? Or stick with the MFP calculations, just to be safe?

(ETA: It's a Bowflex Precision XT watch with a chest strap, if that helps at all :p)

Replies

  • meerkat70
    meerkat70 Posts: 4,616 Member
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    Have a search for posts by heybales and azdak on this subject - they both have useful, but quite technical things to say on the subject. There are ways to make your HRM more accurate.

    I doubt that your heart rate really is in the 140-170 range from walking, unless you're *extremely* new to any exercise at all. My heart rate tends to sit in the upper 140s and lower 150s when I'm running for a few hours - and has done since I was about your weight. I think you're probably right to be sceptical.

    are you really really walking 4mph? Are you using something to help you track speed and distance? That might give you a better iea of what's what.
  • karrathachick
    karrathachick Posts: 34 Member
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    That's a huge amount of cals to burn from walking in an hour but it all depends on the person and the intensity. Double check you have your settings right on your HRM- its worth a check. I had somehow put my height setting up by an extra couple of cm's and it started telling me I was burning HEAPS more calories than usual so I knew something was off. Hope that helps. See if you come up with a similar number again when you do the same workout.
  • andrewlazenby
    andrewlazenby Posts: 151
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    Lately I've been doubting my HRM's estimations, because they always end up significantly higher than the amount of calories that MFP gives when you input the number of minutes you did a certain activity.

    So I went for a walk today, about 61 minutes, keeping my heart rate between 140 and 170 (closer to 170 for the most part).
    My HRM claims I burned 692 calories, which is almost 100 more than the MFP estimation for a 61 minute, 4.0 MPH walk. I checked a few other calories burned calculators, and they came out close to the MFP estimations as well.

    I'm 23, 236lbs, and 5' 10" (70 inches). I know my resting heat rate is terrible (around 80), so I'm kinda worried that because of that, my heart rate is somehow tricking the HRM into thinking that I'm working out harder than I really am. I know that probably sounds silly, but I don't want to overestimate my calories and sabotage all my effort.

    Should I trust that my HRM knows what it's doing? Or stick with the MFP calculations, just to be safe?

    (ETA: It's a Bowflex Precision XT watch with a chest strap, if that helps at all :p)

    change the battery in the chest strap. back when i used to use one it would get kinda screwy when it was getting low.

    #2- yes, it is probably overestimating. thats all it can do is estimate. my typical answer to that is to always cut in half the number that my HR monitor would give me. It is not measuring VO2,or any other parameters that would allow it to increase its accuracy. Heck, get on a rollercoaster and your heart rate will increase and it will think you are excercising.

    3- don't get hung up on the numbers. Exerciser because it is making you feel better....not because you get a bigger number
  • Wezlfuss
    Wezlfuss Posts: 122 Member
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    Thanks guys! I'll check out that thread and try changing the battery.

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