HRM.... Can I trust this?

lf4179
lf4179 Posts: 37 Member
in Health and Weight Loss
Hi... Quick on me, I am 34 (almost 35) and 158 ish pounds. Right now I have a HRM that is a watch only. I am looking into getting one w/ a chest strap but don't have one yet. I take my reading quite often as it says to in order to get the most accurate reading. I average about 160.... sometimes a few lower and sometimes a little higher.

So today I was on my stationary bike for 35 minutes. It said I burned 574 calories which seems like a lot to me. When I log into MFP under "stationary bike vigorous effort" (which to me I am) for 35 min it says 440 calories. From what I read it seems like people say MFP puts cals too high so should I be logging even less than the 440 calories even though my HRM says I burned more?? Thanks for any insight.

Replies

  • wilsoje74
    wilsoje74 Posts: 1,720 Member
    Yes seems really high
  • FJDodd
    FJDodd Posts: 140 Member
    I have heard that chest strap HRM are much more accurate than the wrist ones. I have a HRM and every time i log the exercise MFP overestimates by 20-50%.
  • michael300891
    michael300891 Posts: 275
    depends quite a bit on your weight

    Im an idiot just realised you had written it, seems reasonable or slightly towards high at that weight.
  • lf4179
    lf4179 Posts: 37 Member
    So I use the 440 calories that MFP has and hope that it isn't giving me too much credit or should I put less in for it? What would you do? ....Man, I really need to get the chest strap one. I will be interested to see what difference it gives me.
  • fercar3000
    fercar3000 Posts: 286 Member
    I have a polar F7 with a chest strap and I love it ... now I can see exactly the calories I'm burning ... at least for me it was a good investment :D
    Regardless the brand get one with chest strap
  • MarliQQ
    MarliQQ Posts: 112 Member
    That is really high. You would be on track to burn 1000cals in an hour, which is much more elusive than people on MFP seem to think...how fast were you going??
  • Francl27
    Francl27 Posts: 26,371 Member
    It seems like a lot. What did the bike machine say? I'd take the average between that, MFP, your HRM, and reduce it by 30%.
  • michellekicks
    michellekicks Posts: 3,624 Member
    I am only slightly older and slightly heavier and can only burn about 700 calories if I run for an hour at 8:45-9:00/mi. That's high for a stationary bike.
  • lauriebeakley1
    lauriebeakley1 Posts: 91
    I have a Polar FT4 with a chest strap & it is very accurate. I, too recommend the chest strap.
  • DownsizingAaron
    DownsizingAaron Posts: 127 Member
    When I go for walks I've tracked the same walk with 3 fitness apps and they report 10% difference in distance and 20% difference in calories burned. I've taken to using the lowest numbers to be safe. On the MFP side, I try to only eat back 60%-70% of my calorie burn from exercise to ensure I haven't overestimated. So on days I have really big workouts, I end up with a larger deficit in MFP than days I don't.

    And yes, a chest strap HRM is much more accurate.
  • amberflo143
    amberflo143 Posts: 94 Member
    I did a little study of my own and even MFP is very generous on calories burned compared to a heart rate monitor chest strap. I would just be careful eating all of your exercise calories back as it isn't very accurate.
  • bwogilvie
    bwogilvie Posts: 2,130 Member
    That seems really high. For comparison, I burn 11-12 calories a minute when cycling at 17-19 miles per hour outside or on rollers with resistance that closely mimics outdoor flat cycling. I'm 45 and weigh 165 lb., and when I'm going that fast, my average heart rate is 155-160 or so. At that amount of effort, I need to use a sweatband to keep sweat out of my eyes, and if I'm doing a stationary ride, I need a fan so that my shorts and jersey aren't soaked with sweat. At that intensity, I feel like I'm at around 8 on the Borg Rating of Perceived Exertion scale (the 1-10 version).

    I think you'd be safe logging around 300-325 calories for that workout, presuming it was a hard effort. Best thing to do, though, is to compare your log with results after a couple of weeks.

    HRMs are useful, but even higher-end models with chest straps aren't always accurate. One study of the Polar F6 showed that, even calibrated with subjects' actual VO2max and HRmax, it overestimated energy expenditure by 27% (http://www.ncbi.nlm.nih.gov/pubmed/21178923). An earlier study showed that the Polar S410 overestimated energy expenditure in women by 12% (http://www.ncbi.nlm.nih.gov/pubmed/15292754). Another study found that the Polar S810i overestimated expenditure when exercising lightly but not moderately (http://www.jssm.org/vol9/n3/21/v9n3-21abst.php). The research seems to suggest that HRMs are less accurate for women than they are for men.

    Firstbeat, a Finnish company, has a proprietary algorithm that they claim is accurate to within 7-10%, not much worse than indirect calorimetry. Google them if you want to find out more; some HRMs from Suunto and Garmin use their algorithm. My Garmin Edge 800 and Forerunner 620 use Firstbeat technology, and their estimates are substantially lower than my Sigma and Timex HRMs.

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