HRM calorie calculation algorithms

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invisibubble
invisibubble Posts: 662 Member
in Fitness and Exercise
Posted a similar topic but after today's workout I'm still confused.
I put the following stats into MFP, my HRM and the Shapesense calories burned from heartrate thingy.
Weight
Height
Age
Sex
Activity duration

And the HRM obviously measures heartrate, which I plugged into the Shapesense thing also.

So MFP gives me 608 - no heart rate so meh, doesn't matter.

But my HRM gives: 329
Shapesense gives: 708

Exact same stats, wildly different equations used, it seems. What do I put in? I'm trying to manage my intake properly and an incorrect calorie difference that high either way is not okay. My HRM was a pretty cheap one. £35 on Amazon, brand I've not heard of. (Bought elsewhere cheaper.) My fault for not going with Polar or similar? Money's tight but if I've spent money on something I'll have to replace with something decent I've obviously wasted more going the cheap way.

Replies

  • Eats_With_A_Fist_Returns
    Eats_With_A_Fist_Returns Posts: 77
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    You had me at 'algorithm'. :p How does your HRM measure? Is it a chest strap with constant connection, or a watch/something else that keeps track of periodic readings?
  • SteveTries
    SteveTries Posts: 723 Member
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    Describe the workout also pls
  • invisibubble
    invisibubble Posts: 662 Member
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    Chest strap.

    Elliptical on 3/4 of Max resistance. Heels down. Hands free and hips stationary alternating with moving arm bars and hips mobile every 5 minutes. Pedalling forward for ten, back for ten. 60 minute workout total.
  • Eats_With_A_Fist_Returns
    Eats_With_A_Fist_Returns Posts: 77
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    When was the last time you replaced the battery in the chest strap? Mine cost roughly the same as yours (about $60 USD) and it rarely varies more that 60-100 more or less from MFP and Endomondo. The three are usually close enough that I average the three and assume that's closer to where it actually is. It may just be the brand of monitor unfortunately.
  • invisibubble
    invisibubble Posts: 662 Member
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    I only bought it last week :D
    I would split the difference if it were smaller, but honestly I'd rather risk undereating than overeat if I have to choose. Obviously I don't want to undereat, either...
  • IndianCat3
    IndianCat3 Posts: 158 Member
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    Sometimes my HRM goes outrageously high when I'm not even huffin and puffin..it can be a lil frustrating..so I have to play with it at times..hope u find ur answers
  • Eats_With_A_Fist_Returns
    Eats_With_A_Fist_Returns Posts: 77
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    One thing that might be wrong is how the sensor on the strap sits while you're exercising. If it shifts around a lot then the broken connections could mess with the reading. All of what I'm about to say sounds weird as crap...but I don't care. My first problems with mine were that the strap kept sliding down my chest so I bought some elastic, grabbed the sewing kit, and made straps. Now it looks like I'm wearing serious S&M gear when I put it on, but it stays in place. The second big issue was that I'm something of a grizzly man so I had to shave a swath of hair around my torso. After I dealt with these two things, it worked a whole lot better and the calorie count came up much closer to MFP and Endomondo. So my two goofy suggestions is shave any torso hair that might be getting in the way; (Seriously hope you know I'm kidding about that one. :p), and/or sew it into some random bondage gear. On a more serious note, you can also try some conductive gel for it. Look for electrode gel at a pharmacy or med supply store. It might help.
  • invisibubble
    invisibubble Posts: 662 Member
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    It fits really well and thankfully, no I'm not hairy :laugh: I'll try the gel thang. Thank you!

    And thanks, indiancat. Sometimes I think I was better off without a stupid HRM :grumble:
  • Prefessa
    Prefessa Posts: 90
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    Trust your HRM#'s....the numbers they quote on this site are from a fantasy land where everyone has a high metabolism.

    I "ate my exercise calories back" based on those numbers and gained a pound a week....until I bought a heart rate monitor(Polar FT40), measures and entered my V02 Max, HRM and BIO. Now I am loosing weight...its taken me another month to get back to where I started.

    For you to burn that many calories on a piece of gym equiptment you would have to be working in your anerobic threshold for the duration. I am 198 pounds and a 15 mile bike ride burns ~400 calories....MFP based on time, and pace quotes me like 793 calories. Unfortunately, the fitter we get the more efficient the body gets.
  • annahiven
    annahiven Posts: 185
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    I agree with Prefessa. Trust the HRM. I got an HRM last week and dang, the machines at the gym have overestimated my burn by 30%!

    For several months I thought I was burning 400-500 calories, but I was barely getting to 300-350. And I also ate my calories back, so... I never actually created the proper deficit thanks to those stupid overestimated numbers. Grr!

    I definitely trust the HRM more since it is actually measuring my heart, which the machines don't.
  • invisibubble
    invisibubble Posts: 662 Member
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    Mmmr, I still don't think it's accurate. Of course, there's no way in hell I think I'm burning 700 or anywhere near, either. I don't think any of the methods I listed are accurate, but I'm not comfortable splitting the difference, either.
    I just don't think it makes sense that for an hour in the 160-170 HR zone, sweating my *kitten* off and breathing like a dog on that high resistance would only burn 300 and change.
  • heybales
    heybales Posts: 18,842 Member
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    Mmmr, I still don't think it's accurate. Of course, there's no way in hell I think I'm burning 700 or anywhere near, either. I don't think any of the methods I listed are accurate, but I'm not comfortable splitting the difference, either.
    I just don't think it makes sense that for an hour in the 160-170 HR zone, sweating my *kitten* off and breathing like a dog on that high resistance would only burn 300 and change.

    I'm going to go the opposite direction, because I haven't seen what your HRM asks for as to stats.
    I had a Timex that had great HR training features on it, but only asked for weight and age, and from testing the age was only used to set the zones, not used in the calorie calc's. And it was double cal estimates what the later Polar gave as counts. And it was higher than what other formula's gave.

    Very good reason not to trust it, some don't ask for enough info to be even close.
    Shoot, even the Polar, the epitome of accuracy for HRM's, can be off 33% for women if stats not correct!
    http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

    What personal stats does yours have you enter, and what is the brand?

    You are probably correct on more than 300. Even if it set and uses a maxHR figure using 220-age, 165 of 194 (my tested max) is 85%, typically estimated to be around your lactate threshold burning almost total carbs, that would burn min 600/hr for me, true, at more weight of course.

    So here is a formula based on a study that had great accuracy results, the study link is there too.
    http://www.braydenwm.com/calburn.htm

    Sadly, the accuracy is improved when you know your VO2 max. Not so sadly, you can get a pretty decent estimate of that! Read through this post and in the middle is method, based again on study showing great accuracy, for getting VO2max. Then you can use that on the site.
    http://www.myfitnesspal.com/topics/show/577839-hrm-s-with-vo2max-stat-improve-calorie-estimate&nbsp

    I used this site for a long time with the Timex. Just got the avgHR at the end of the session, plugged it in, there's my count.
  • heybales
    heybales Posts: 18,842 Member
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    Posted a similar topic but after today's workout I'm still confused.
    I put the following stats into MFP, my HRM and the Shapesense calories burned from heartrate thingy.
    Weight
    Height
    Age
    Sex
    Activity duration

    And the HRM obviously measures heartrate, which I plugged into the Shapesense thing also.

    So MFP gives me 608 - no heart rate so meh, doesn't matter.

    But my HRM gives: 329
    Shapesense gives: 708

    Could only find one model of WiKi HRM around. It appears the battery in the strap is not replaceable, since it says one is required. So perhaps keep using until battery is dead on strap.

    So it is interesting it asks for so many stats, when cheaper ones usually don't.
    Now, is that for the purpose of using in calorie estimates, or the fact the watch tells you your BMI? Which I think is rather hokey "feature", seeing as how easy it is to get BMI from many places.

    Now interestingly, BMI is used as optional value in that estimate of VO2max in above post. But unless they ask for athletic performance rating, they aren't using it.
    Those values also let you estimate the BMR of course, which is another method of calculating calories.

    Since you don't trust the calorie count right now, I think you should have fun experimenting. It does mean trying to hit the same avg HR as you have before. May just discover it is more trustworthy than you thought. Shoot, than I think.

    I'd start with changing the age by 40 yrs older first, and see what kind of change that causes. Same HR for older person should indicate more effort/calories.
    See if you can find a field referencing maxHR that is not related to a workout you just did. See if it changes after changing the age. See if you can change that maxHR stat yourself. Might allow better accuracy when you are done testing.
    If a big change to calories when you maintained the same AHR, then correct it back.

    Now change the gender, and test again. That should make a decent difference too.

    Height would matter to BMI estimate, and to BMR if they truly do use that in calorie estimate. Would need to increase it by probably 20 inchs for significant change to value.

    I'm very curious too. And then you can write the first review on Amazon for the watch and describe the proof of how nice it is. Because if they really do use all that, then that is decent competition to Polar. Because cheapest Polar has less actual training features, very simple in that regard.

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