yet another hrm question

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peacefulsong
peacefulsong Posts: 223 Member
in Fitness and Exercise
So, earlier this year I bought a stationary bike. This bike came with a built in hrm. You put in your height, weight, age etc, put on the chest strap that came with it, and it reads the signal coming from the chest strap. I always assumed this would be reasonably accurate.

This week I bought a Polar Ft40 hrm watch for when I do other things. I decided to try it out on my bike just to see if it gave me a very different reading. So I used the strap/transmitter that I got this week instead of the one that came with the bike. The bike apparently read the signal from this one too, so the watch and the bike were both working from the transmitter I was wearing.

When I finished, my bike told me I'd burned 238 calories. The watch told me I'd burned 469 calories. Those aren't even close!! So....which one should I believe?? How could they be so different? Is the bike not really taking into account all the height/weight info I put into it?

I'm completely confused now and don't have any idea which one I should be considering accurate. Any thoughts?

Replies

  • skinnyitaliannn
    skinnyitaliannn Posts: 187
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    I'd go with the HRM. Polar is an amazing brand and it's way more personal than the bike, considering you actually wear the strap and everything. Just my opinion. I could be wrong? x:
  • peacefulsong
    peacefulsong Posts: 223 Member
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    Yeah, the weird thing is that the bike came with a polar strap that you wear, too. I think until I look into it a little more I'll go with a number somewhere in the middle. :)
  • anemoneprose
    anemoneprose Posts: 1,805 Member
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    How intense did the workout feel? Were you sweating loads, did you feel your heart pumping hard?

    I wonder if the signals crossed somehow. Maybe you could try riding a bike outside (if you can somehow make it a comparable workout) and see what your Polar reads. Or next time, check it a few times against the old school method of counting the pulse at your neck for 10 seconds.
  • Pebble321
    Pebble321 Posts: 6,554 Member
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    Have you checked that you have accuratly entered any info required in both devices - like weight, age, gender etc. If you have missed one of those fields it might be giving you incorrect info.
    Or, perhaps they are using a different formula to estimate your burn.....
  • rmac18
    rmac18 Posts: 185 Member
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    I wish I had an answer to this myself. I wear an HRM and have the thing on my watch that has all my data (age, sex, height, weight). Many of the cardio machines at the gym pick up the signal from my chest strap and they also allow me to enter the same data. They are often widely different than my watch and it's inconsistent from machine to machine. The watch is always behind the machine for the first 30 minutes yet sometimes over the next 10-30 minutes the watch will overtake the machine. If I use the charts on MFP then it is typically a fair bit higher than anything else. I really can't figure it out so I always log the lowest reading, better safe than sorry.
  • peacefulsong
    peacefulsong Posts: 223 Member
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    If by program it you mean did I set it up with all the info, yes of course I did. It's all accurately entered, as is the info on the bike.

    The watch does have a "Polar Fitness Test" that, according to the manual, is "an easy and quick way to measure your cardiovascular fitness and aerobic capacity. The test result is a value called OwnIndex. OwnIndex is comparable to maximum oxygen uptake (VO2max), a common aerobic capacity measure. The OwnIndex value can enhance the accuracy of calories calculation during training."

    I did that, too, so maybe that is where the difference is. Still, that's a big difference. I just read that the result of that test is pretty dependent on the activity level it asks for before you take it. I set mine at moderate since moderate is supposed to be 1-3 hours per week of 'recreational sports, eg running 3-6 miles per week or 1-3 hours of comparable physical activity" which I'd assume the bike 3-4 times a week would qualify. I try to do other things too, but that one is one I know I do regularly.

    Blah, I thought getting this thing would make it easier, not more complicated. :P
  • quilteryoyo
    quilteryoyo Posts: 6,025 Member
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    It's sort of like the old saying: If you have one clock you always know what time it is. If you have 2, you're never quiet sure!

    If I were you, I'd just pick the one you want to use and go with it. You'll know from your results if it is accurate or not.

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