Setup Polar HRM for more accurate calorie burn for known BMR

heybales

Everyone probably has noticed that when you setup your Polar HRM, you enter in gender, age (birthdate), weight, and height (sound like familiar stats?). You probably can change max HR also, perhaps VO2max on more expensive models.

So why use most correct stats as possible? Especially for women, your accuracy is all over the place for calorie burn. And calorie burn was probably the only reason you got the HRM, so why not have it as accurate as possible?
http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

So Polar uses a BMR calc of stats as part of calculations for calorie burn.
So correcting any of those stats can improve what Polar estimates as your calorie burn. Because so many rely on that calorie estimate to tell them how many calories to eat back (very smart), more accuracy would probably be of benefit.

Which means if your estimated BMR based on body composition (Katch-McArdle formula) is different, or based on suppressed metabolism because of underfeeding it (NETting below BMR constantly), you could have a better estimate of calorie burn possible.

So probably the easiest method that doesn't require any self tests, would be adjusting your stats so Polar estimates with the same BMR you know is more accurate.
How to do it for body composition (Katch-McArdle BMR formula):
1 - Use the stats you entered into Polar (only sex, age, weight, height) here - http://www.gymgoal.com/dtool_bmr.html
________Note that BMR figure(that will not match MFP, which uses a slightly more accurate formula by Mifflin).
2 - Now get a decent estimate of your bodyfat% here - http://www.gymgoal.com/dtool_fat.html
________Use the Covert Bailey as accurate enough, and note it.
3 - Now take the BF% figure back to site in step 1 and use the optional % Body Fat stat.
________Note this more accurate estimate of your BMR based on your current Lean Body Mass (you are hoping this changes).
4 - Now remove the BF% stat, and adjust the age stat so the displayed BMR matches the estimate for BF% BMR.
________So that is the age of avg person with your BMR by Harris formula. That is what you enter into your Polar. When you drop 10 lbs, recalc your BF% and redo BMR calc based on it, to see if any need to change, hopefully you get younger biologically!

How to do it if your current daily goal has you NETting below your BMR on constant basis (per choice to lose weight slower):
1 - Get a decent estimate of what your BMR could be if fed (only sex, age, weight, height) - http://www.gymgoal.com/dtool_bmr.html
________This is not your true estimated BMR if netting below it for long enough to not be hungry anymore.
2 - Change the weight stat until the displayed BMR matches what you currently NET on constant basis (1200, 800, whatever).
________So that is the weight of avg person with your BMR running at full steam. That is what you enter into your Polar. When you drop 10 lbs or notice you are not netting so bad, recalc your BMR with what you are now netting constantly, or if you raise net goal at some point, hopefully you get heavier! Why not use age? You'd likely have to be 100 yrs old with metabolism that slow, but you can try it. Or change a little of both weight and age to show same slower BMR.

So the other reason for variance in the stats, is the MHR, and VO2max. Women again have big variance in true MHR, and resulting VO2max estimated from that.
And with the change to biological age above compared to chronological age, you may desire to adjust the MHR so the zones are correct, if that matters to you.

If you wish to get these as accurate as possible, here is a nice test to do if you have been exercising for a little while. With link if you are very aerobically fit for more serious test.
http://www.myfitnesspal.com/topics/show/466973-i-want-to-test-for-my-max-heart-rate-vo2-max

If you have not been exercising that long, submaximal step test for MHR estimate.
http://doctorholmes.wordpress.com/2008/11/20/determine-your-maximum-heart-rate-with-the-step-test/

And for submaximal step test for VO2max, just use HRM for top bpm at end of test.
http://www.brianmac.co.uk/stepvo2max.htm

So hopefully by getting your more biological age down for both BMR and MHR compared to chronological age based on calculations, you can have better HRM calorie burn estimates, and hopefully you are eating those back to feed your workout so your body can improve and continue to give you great performance.

Oh, how did I come up with Polar is using BMR calc in their calorie estimates? Several online forums discussing. Tests people (and myself) did changing the values, doing exact same workout level for HR, and seeing the variance in estimate matches the variance in BMR changes.
Why could BMR calcs be that different? Because the BMR calcs are based on studies of people ALREADY at healthy weight, with avg LBM / BF ratios. If you have higher BF% at overweight compared to study partipants, then BMR is overestimated. At least with Katch BMR formula using LBM, while it was based on healthy weight subjects too, it will slightly underestimate at overweight, not as bad a deviation though.

Natihilator

bump for later

Tina180130

Bumping and doing some research now.,....I own a Polar FT7 and use it for the Max & Min HR which I have worked out based on my age etc....this sounds interesting so will investigate further ) - thank you Heybales

TheMiddlePath

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zzzzia

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surferfreak07

bump! Hm I apparently require the same amount of calories as an 11 year old, I feel young again!

kristy6ward

I've been driving myself insane trying to get my ft7 calibrated correctly.. rather hard when I don't know my mhr. I'll give this a shot.

Effy826

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c8linmarie

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heybales

bump! Hm I apparently require the same amount of calories as an 11 year old, I feel young again!

That's excellent if your Katch BMR estimate was that far over the Harris BMR estimate.

That means you have much more muscle than average study participant, excellent!
And potentially much higher metabolism.

Here's to not slowing it down!

LoveLiveLift

ETA: Oops! No wonder I was getting a ridiculous number. I put that I was 7 lbs. :blushing:

surferfreak07

bump! Hm I apparently require the same amount of calories as an 11 year old, I feel young again!

That's excellent if your Katch BMR estimate was that far over the Harris BMR estimate.

That means you have much more muscle than average study participant, excellent!
And potentially much higher metabolism.

Here's to not slowing it down!

I actually just ordered a Polar FT4 so I will be using that age on it I'm really excited for it to come, I've been thinking of getting one for a while and this post inspired me so thank you

BelMckenzie

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kristy6ward

According to my results, I'm a 7 year old?? That's a 21 year difference. I find that a bit crazy. This is the age I'm supposed to enter into my ft7?

Bmr before: 1729, BF%: 28.97, bmr after: 1828

salxtai

Bumpity

HarlowS

Fantastic info! I have been looking around for all of this and I appreciate how you were able to get all the components together. I have a Polar FT4 and have been using it for 2 weeks. Something wasn't adding up with my net and cals burned. Hopefully this does the trick.

Thank you!

katydid25

My Polar is in the mail! Great info at the perfect time! Thank you!

Starbec

Bump - for when my Polar HRM arrives

heybales

According to my results, I'm a 7 year old?? That's a 21 year difference. I find that a bit crazy. This is the age I'm supposed to enter into my ft7?

Bmr before: 1729, BF%: 28.97, bmr after: 1828

Count yourself very fortunate!

Usually with greater weight comes greater fat % too, which means the LBM is not that great.

So just enough stats to totally duplicate, because I backed into it.
I found the weight that made 1828, found the height that made 1729 - 63".

So you are exactly correct. With that much current muscle mass, well above avg for someone your age/height even at goal weight, you would have to enter 7yrs old. Now at that extreme, obviously a real 7yr old can't have your metabolism (actually, I'm not sure about that, think of kids running around and active), but for the math that occurs in the HRM, that would be correct.

As long as you did the BF measurements correctly! Hinges on that.

I will comment, if that truly is a correct BF%, and you have that much LBM, as you lose weight, you will lose LBM.
If you take 71.03% x current weight, that would be your LBM currently. Which if you lost none of it, you could obviously never get to that weight, as you'll always carry some fat on the body. And even if at 20% BF, I bet you want to lose more than 30 lbs from current weight.

Now here's the kicker though, the second set of instructions might actually apply.

Meaning, if you have been NETing below 1828, then that is not your current true BMR.
What ever you have been eating, minus whatever real exercise has been using first, leaving NET calories for BMR, that is your true BMR if you are no longer hungry eating at that low level.

Now, if you have been eating at about 1900, and eating back exercise calories, than that second setup does not apply, and good for you!

Eve1972

According to these steps I should input my age as 58 and weight at 55lbs?? Explain to me how this is going to give me a correct reading on the calories I am burning? *lol* My brain does not like math...

Smuterella

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