HRM accuracy

frenkinstein
frenkinstein Posts: 37 Member
in Fitness and Exercise
Hey guys, so I have a polar FT4 HRM and just started using it. I ran the first day of C25K for 30 mins today and it says I burned 420 calories! That seems high to me but I really don't know. Any opinions on it?

Replies

  • frenkinstein
    frenkinstein Posts: 37 Member
    Bump. Anyone?
  • GetSoda
    GetSoda Posts: 1,267 Member
    I was just talking about HRMs to a few friends...

    Consider the following:

    1> It doesn't know fat from muscle. Two people at the same weight will burn radically different calories based on body composition.

    2> what if you just have a naturally low or high heart rate? My wife's heart rate is around 150 walking. Mine is 90. Despite the fact I'm way bigger than her; her HRM reads more calories. Think about that for a second.

    3> calorie burn correlates with, not causes, high heart rate. Correlation is not causation.

    5> Finally, how does the HRM know if I'm running, or if I'm sitting on my *kitten* doing nothing while my heart pounding?

    I posit that a heart rate monitor is only accurate for reading heart rate, and not for counting calories due to the large number of variables and the singular source of data.
  • LydsVille77
    LydsVille77 Posts: 126 Member
    Depending on how much you weigh... this could be pretty accurate for 30 min of running. I also have the polar FT4, and i think its pretty much in line with MFP exercise database and if i use other apps like Runtastic, they are all pretty close. As long as your resting heart rate is close to normal when you start the session.

    Because I mostly use it for running/jogging I pretty much know what to expect, roughly 100 cals a mile.
  • beccajay03
    beccajay03 Posts: 2 Member
    You're right, the hrm doesn't know if you're sitting or jogging, but even at rest your body is burning calories to keep itself functioning.
    An interesting experiment is to wear the monitor all day, through all your normal activities and see approximately how many calories you burn.
  • GetSoda
    GetSoda Posts: 1,267 Member
    You're right, the hrm doesn't know if you're sitting or jogging, but even at rest your body is burning calories to keep itself functioning.
    An interesting experiment is to wear the monitor all day, through all your normal activities and see approximately how many calories you burn.

    Except that number is meaningless, because the formula the HRM uses to figure calories is based on steady state cardio. Not anaerobic activity or resting. Your resting heart rate has little to nothing to do with your basal metabolic rate.
  • phjorg1
    phjorg1 Posts: 642 Member
    Depending on how much you weigh... this could be pretty accurate for 30 min of running. I also have the polar FT4, and i think its pretty much in line with MFP exercise database and if i use other apps like Runtastic, they are all pretty close. As long as your resting heart rate is close to normal when you start the session.

    Because I mostly use it for running/jogging I pretty much know what to expect, roughly 100 cals a mile.
    it's very unlikely. she said she did first day c25k. which i'm taking to mean she is a beginner runner..

    840calories an hour is a LOT. Like you have to be going advanced level intensity pace to be able to hit those sorts of numbers.

    Whats actually happening here is her HRM is giving a way over inflated number due to not being able to input proper settings. When someone is new to cardio, their cardio system sucks. So what happens is the heart has to beat a crapton faster to provide lower amounts of oxygen the body is demanding. The HRM does not know her VO2MAX numbers and mistakenly assumes the increased heart rate is from work being done, rather than a very poor cardio system, so gives a very inflated calorie burn number.
  • LydsVille77
    LydsVille77 Posts: 126 Member
    Depending on how much you weigh... this could be pretty accurate for 30 min of running. I also have the polar FT4, and i think its pretty much in line with MFP exercise database and if i use other apps like Runtastic, they are all pretty close. As long as your resting heart rate is close to normal when you start the session.

    Because I mostly use it for running/jogging I pretty much know what to expect, roughly 100 cals a mile.
    it's very unlikely. she said she did first day c25k. which i'm taking to mean she is a beginner runner..

    840calories an hour is a LOT. Like you have to be going advanced level intensity pace to be able to hit those sorts of numbers.

    Whats actually happening here is her HRM is giving a way over inflated number due to not being able to input proper settings. When someone is new to cardio, their cardio system sucks. So what happens is the heart has to beat a crapton faster to provide lower amounts of oxygen the body is demanding. The HRM does not know her VO2MAX numbers and mistakenly assumes the increased heart rate is from work being done, rather than a very poor cardio system, so gives a very inflated calorie burn number.

    Makes sense.... good to know.
  • __Di__
    __Di__ Posts: 1,658 Member
    Bump. Anyone?

    What was your average and maximum heartrates OP - this has a bearing on calorie burns.

    Also, I presume you put all your relevant personal info into the watch beforehand, not being funny or anything, but that is very important to get accurate readings x

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