HRM Calorie Burns Too Low??

nkayyy
nkayyy Posts: 46
in Fitness and Exercise
I recently bought a HRM (Polar FT4) and decided to test it out on a walk tonight. I want to use it primarily for running, but I'm currently recovering from an ankle injury and trying to take it easy.

The walk took about 1.5 hours, and I covered about 4 miles at a moderate/fast pace. I expected to burn at least 300 calories, but it only displayed 160 burned!

So now, naturally I'm concerned that I've been overestimating my calorie burns this whole time... but at the same time, I wonder if tonight's numbers are inaccurate.

It's highly possible that I made a mistake operating the HRM, since it was my first time using it. I put the chest strap directly beneath my bra (sorry if tmi) and made sure the battery part was right in the center. Everything seemed pretty good. But then again, I could be mistaken.

If it helps at all, I'm an 18 year old girl, 5'9" and about 138 pounds. I'm in pretty good aerobic shape; I can run a half marathon at about a 9.5 minute pace. My goal is to tone up, get down to 130, and run a marathon some time before I graduate college.

Thank you in advance for your support. I love MFP and the awesome community here!

Replies

  • kellehbeans
    kellehbeans Posts: 838 Member
    Did you set up your user information in settings to your correct height, gender and weight?
  • nkayyy
    nkayyy Posts: 46
    Did you set up your user information in settings to your correct height, gender and weight?

    Yep. One of the first things I did after I bought it.
  • weightlossdiva1219
    weightlossdiva1219 Posts: 283 Member
    Hmm. i also think you should have burned much more....don't get discouraged
  • nkayyy
    nkayyy Posts: 46
    Hmm. i also think you should have burned much more....don't get discouraged

    Glad I'm not the only one! There's a part of me that wants it to be wrong, so that I'm burning more calories. But I also don't want a defective HRM. I'll probably have to experiment more to see how well the numbers match up with my expectations, etc.
  • TavistockToad
    TavistockToad Posts: 35,719 Member
    The walk took about 1.5 hours, and I covered about 4 miles at a moderate/fast pace. I expected to burn at least 300 calories, but it only displayed 160 burned!

    4 miles in an hour and a half is actually about 2.6mph, which is a fairly slow speed when 'average' walking speed is 3mph
  • EdTheGinge
    EdTheGinge Posts: 1,616 Member
    Sometimes the strap requires a little bit of moisture to start with, I was having a similar problem but since wetting it a bit before I head out it seems to be much more accurate.
  • luvtcuk
    luvtcuk Posts: 69 Member
    I found it is low like that too. I wear it all day and do my normal activities. And it show me that I burn about 100 cals an hours even when I walk. So MFP is way over estimate for me. I did cardio circut MFP said I burn 356 cals, but the HRM said only a little over 200 cal burn. So I end up eating too much.
    So after that I find my TDEE and eat 10-20% less and not log in my work out.
    It work for me.
  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    If you use Runners World's suggested formula of:

    .53 x your body weight in lbs x distance in miles (gross) .30 x body weight x distance (net)

    you'd expect to be burning approx 80 cal gross or 40 cal net per mile walking

    http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning?page=single

    Is it possible that the FT4 reports net cals? (I couldn't find a definitive answer in their forums)

    For anyone interested in weight loss it's important to know as gross includes calories that would have been expended while lying in bed (hence my preference for a TDEE based approach rather than MFP's net calories approach)
  • nkayyy
    nkayyy Posts: 46
    If you use Runners World's suggested formula of:

    .53 x your body weight in lbs x distance in miles (gross) .30 x body weight x distance (net)

    you'd expect to be burning approx 80 cal gross or 40 cal net per mile walking

    http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning?page=single

    Is it possible that the FT4 reports net cals? (I couldn't find a definitive answer in their forums)

    For anyone interested in weight loss it's important to know as gross includes calories that would have been expended while lying in bed (hence my preference for a TDEE based approach rather than MFP's net calories approach)

    Very interesting article! Maybe, like the man who wrote it, I'm just learning the hard way that walking burns way less than running does. Thank you for sharing!

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