Doubtful of HRM accuracy vs treadmill!

sarahlove43
sarahlove43 Posts: 26 Member
in Fitness and Exercise
I just used an HRM for the first time today during my 30 min treadmill workout. According to my treadmill, which has my weight saved, I burned ~150 calories. I don't weigh a lot so I have come to accept numbers like this.
My Polar heart rate moniter gave me an average heart rate of 153 at the end. I used this in a calculator I found online and it told me I burned around 320 calories! Is this possible?? I have always gone by my treadmill and assumed because of my size I wouldn't be able to burn that many calories.

I did an interval workout of 7mph runs and 4mph jogs. I am 4'10, so is it possible that there is a big intensity difference for someone my height running 7mph vs someone much taller? And the treadmill doesn't take this into account, thus the smaller number?

Or is my heart rate moniter just faulty?

Replies

  • blues4miles
    blues4miles Posts: 1,481 Member
    What distance did you cover in the 30 minutes? For running, calories burned tends to be pretty well tied to pace. I generally assume an HRM to be gobs more accurate than a machine however.
  • sarahlove43
    sarahlove43 Posts: 26 Member
    I covered 2.12 miles. The calories I calculated from my HRM just seem crazy high since my entire life ive been used to seeing the number on the treadmill stay in the 100s.
  • sarahlove43
    sarahlove43 Posts: 26 Member
    bump
  • bostonwolf
    bostonwolf Posts: 3,038 Member
    You can check some online tools for calculating calories that might allow for more accuracy. I wouldn't worry about it too much. Just take both and split the difference and call it a day!
  • ValerieMomof2
    ValerieMomof2 Posts: 530 Member
    Does your treadmill have your height and weight? If you can't put your height, it's not going to be as accurate because a person at 4'10" and 115 lbs and a person at 5'7" 115 lbs they will calculate differently. My HRM has height, weight, resting hr, and activity level, so I personally go with the HRM
  • wolfchild59
    wolfchild59 Posts: 2,608 Member
    I'd say that it sounds like it could be pretty close. The usual "rule" to go by is typically about 100 calories per mile. But if you were doing intervals with dropping to 4MPH instead of a recovery walk, I think that you could have burned around 300 calories in the 30 minutes, even though you didn't cover three full miles.

    But, from the way you calculated it, it sounds like you have an HRM that you have to put your finger on and get it to read that way, so it wasn't just recording your up and down heart rate through the intervals and calculating based on that. So I'd recommend getting an HRM with a chest strap so you can get a more accurate estimate of your caloric burn because it will be monitoring all of the ups and downs as you go through the intervals.
  • lizjohnson2169
    lizjohnson2169 Posts: 25
    Trust your hrm.
  • sarahlove43
    sarahlove43 Posts: 26 Member
    My hrm does have a chest strap. But does not calculate calories for me, which is why I use a calculator online. And my treadmill only takes my weight into account. I only weigh around 90(I'm very short). I knew treadmill calories tend to be off but I thought they are usually higher than reality, not a lot lower!

    I don't want to really lose much weight or gain that's why this big calorie difference is of concern to me, since I'm not sure if I should be eating back 300 calories or not.
  • CkepiJinx
    CkepiJinx Posts: 613 Member
    I would say if you are not trying to lose weight and you have been using the number on the treadmill for a while, several weeks, and maintaining just continue what you have been doing. If you had been losing doing that and now want to maintain up your calories according to your hrm number.
  • cmriverside
    cmriverside Posts: 34,282 Member
    My hrm does have a chest strap. But does not calculate calories for me, which is why I use a calculator online. And my treadmill only takes my weight into account. I only weigh around 90(I'm very short). I knew treadmill calories tend to be off but I thought they are usually higher than reality, not a lot lower!

    I don't want to really lose much weight or gain that's why this big calorie difference is of concern to me, since I'm not sure if I should be eating back 300 calories or not.

    If you have a Polar HRM with a strap, it should figure your calories burned. Are you sure you know how to use it? Which model is it?

  • Melo1966
    Melo1966 Posts: 881 Member
    Did you put your height in your HRM? Your only 4'10" so you stride is shorter so it takes more effort to walk a mile than a taller person so the treadmill may not be accurate.
  • Alanakrahenbil
    Alanakrahenbil Posts: 811 Member
    Trust your HRM!
  • sarahlove43
    sarahlove43 Posts: 26 Member
    My hrm does have a chest strap. But does not calculate calories for me, which is why I use a calculator online. And my treadmill only takes my weight into account. I only weigh around 90(I'm very short). I knew treadmill calories tend to be off but I thought they are usually higher than reality, not a lot lower!

    I don't want to really lose much weight or gain that's why this big calorie difference is of concern to me, since I'm not sure if I should be eating back 300 calories or not.

    If you have a Polar HRM with a strap, it should figure your calories burned. Are you sure you know how to use it? Which model is it?



    I have a very old model, it's a Polar a1. It's been lying around our house for awhile, I just recently found it.
  • AriesOx
    AriesOx Posts: 66
    Not all HRM's calculate calories for you. The one I have doesn't, it only gives max heart rate and average heart rate over time (from reading with chest strap) It is a basic Polar model (T1 or something like that I believe). If you're using your max rate, or just an instantaneous value, the calculation may be too high. If you use the average heart rate, it might be more in line with what you expect. (This is why I want a new HRM for myself :)
  • sarahlove43
    sarahlove43 Posts: 26 Member
    Did you put your height in your HRM? Your only 4'10" so you stride is shorter so it takes more effort to walk a mile than a taller person so the treadmill may not be accurate.

    No my HRM does not have any of my personal stats, it just gives me an avg heart rate that I put into a calculator, which uses my age and weight. But I was thinking the fact that it takes more effort could be why the treadmill calories are lower than what I calculated with my heart rate
  • Azdak
    Azdak Posts: 8,281 Member
    In this case, the treadmill is likely the most accurate number. Based on your weight, and the amount of work accomplished, if you are using a commercial treadmill, then the calorie estimates on the machine are usually accurate for the type of workout you described.

    Most online sites that use only heart rate as a gauge will not be very accurate.
  • Azdak
    Azdak Posts: 8,281 Member
    Did you put your height in your HRM? Your only 4'10" so you stride is shorter so it takes more effort to walk a mile than a taller person so the treadmill may not be accurate.

    Not really. It may take more strides for a shorter person, but the energy cost of each stride is lower, so the actual effort involved will be similar. In fact, a quick glance at the average elite distance running field would suggest that, for the 10K and marathon, being shorter might actually confer a physical advantage.
  • Melo1966
    Melo1966 Posts: 881 Member
    I can run faster than my son whom is a foot taller than me but when walking the mall I struggle to keep up and am far more out of breath. So I do think that the calorie burn per mile is not the same with different heights, which is also why your height is in heart rate calorie burn calculators.
  • Bubbas12
    Bubbas12 Posts: 79 Member
    I got a treadmill from my dad that came with a chest strap. I wore both the strap and my watch HRM and my calories were the same. The calories on my watch HRM are about double of what the treadmill says with just my weight and age. It sounds like yours is also about doubled and I would go with your HRM.
  • Azdak
    Azdak Posts: 8,281 Member
    I can run faster than my son whom is a foot taller than me but when walking the mall I struggle to keep up and am far more out of breath. So I do think that the calorie burn per mile is not the same with different heights, which is also why your height is in heart rate calorie burn calculators.

    Height is included in HRMs for math reasons, not scientific reasons. It's necessary to compensate for the inherent inaccuracies of HRM calorie estimates.

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