Suprised with HRM result

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mariapuhl
mariapuhl Posts: 529 Member
in Fitness and Exercise
My birthday was yesterday and I got a Polar FT4 from my mom. I've wanted it for a while, so I couldn't wait to try it out.

I do my normal hour on the elliptical today using it for the first time. I expected the "calories burned" to be much lower than MFP, which is notoriously high, but I also expected it to be lower than what the elliptical tells me I burned. Yes, I enter my weight and age on the elliptical, but still.

The elliptical said I burned 632 calories.
The heart rate monitor said I burned 667 calories.

Not the results I was expecting, but I'm happy with them, if it's right.

Has anyone else had surprising results that they weren't expecting? Or is this a big red flag?

Replies

  • mariapuhl
    mariapuhl Posts: 529 Member
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    No one has any thoughts? :(
  • Azdak
    Azdak Posts: 8,281 Member
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    The problem with HRMs -- and especially more basic models like the FT4--is that they automatically estimate a max heart rate based on your age. Yet, in the general population, a number of people have an actual max HR that is significantly higher than the estimated number.

    In other words, if the HRM assumes your HRmax is 180, but you can easily reach 175 during your workout and sustain that for 30 min, the HRM will OVERestimate your calorie burn--because it assumes that you are working at 97% of maximum (when you are more likely at 65%-70%).

    One of the reasons I come to this conclusion based on your numbers is because ellipticals usually overestimate calories burned--often by 25%-30%. There are only 2 models of Life Fitness cross trainers that I know have accurate calorie counts and they are still not that widely available.

    So, in your case, it is more likely that your HRM calories are an overestimate and that's why the numbers are more in agreement with the elliptical --which is likely also an overestimate.

    Here is one way to check: try walking on a treadmill without handrail support. Choose a comfortable walking speed and then increase the elevation to 7%-8%. Get to a level that feels like your normal exercise effort. Again, do not hold on to the handrails. Enter weight into the treadmill console. Do this for 20 min and compare the calorie numbers with your HRM. They should be reasonably close (e.g. within 10%). If the HRM is substantially higher, you will need to tweak the max HR settings (if possible).
  • mariapuhl
    mariapuhl Posts: 529 Member
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    Ok thank you for that suggestion, Azdak.

    I know my average heart rate during the workout was 157 but the highest I got was 177 for a couple of mins.

    I will try out your treadmill suggestion. Thanks again.
  • schnarfo
    schnarfo Posts: 764 Member
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    how long were u on the machine for?
  • autumnlily31185
    autumnlily31185 Posts: 279 Member
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    that sounds about right. I have the same HRM as you and I love it. My numbers are actually higher than what MFP has in there database. ( I do an hour of stationary biking) I take my number and then subtract half of the difference of what is given in the database, this just gives me a little peace of mind that I am not overestimating too much.

    Hope that helps
  • CMGoodie
    CMGoodie Posts: 93 Member
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    You also need to set your HRM to your info. The booklet gives you the instructions to do so.
  • schnarfo
    schnarfo Posts: 764 Member
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    some machines will synch with polar monitors too which may be why your readings were the same as the machine?
  • mariapuhl
    mariapuhl Posts: 529 Member
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    An hour, as I stated.

    And yes, I set up the HRM to my info. Haha. I'm not that technologically disadvantaged.
  • JewelsinBigD
    JewelsinBigD Posts: 661 Member
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    My PT4 broke the bad news to me that even though I felt like I was killing myself- my heart rate was getting nowhere near my top end. In fact- it showed I burned about 30%+ less calories than I anticipated!
    SO for Zumba - doing high impact _ I was only burning 350 calories on a good day! Really upsetting news...so I have decided I need to supplement whatever I do to get to a minimum calorie burn of at least 400 - which usually means time on the treadmill running afterwards...
    While this news sux- it did shed some light into why I was not losing as fast as I anticipated- it was because I was not burning as much either!
  • mariapuhl
    mariapuhl Posts: 529 Member
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    some machines will synch with polar monitors too which may be why your readings were the same as the machine?

    Thought that too, but the machine usually says I burn around 615-640 anyway, so really what it showed was 'normal" for me, which is just throwing me for that much more of a curveball.
  • Azdak
    Azdak Posts: 8,281 Member
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    some machines will synch with polar monitors too which may be why your readings were the same as the machine?

    Some brands may be upgrading to some advanced consoles that I am not aware of, but for all existing brands that I know, the heart rate display on the machine console just picks up the chest strap signal. The calorie calculations displayed on the machine are independent of heart rate and do not interface with Polar in any way. That is actually appropriate since, if actual workload is being measured--as it is on a machine--heart rate is irrelevant to determine calories burned.

    When elliptical calories are off, it's because they use poorly-compatible algorithms to estimate calories, not because they lack heart rate input.

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