Polar ft7 HRM calories burned overestimation?

CraigwQ

Hi all!

I'm new to MFP today and to kick start my journey decided to buy a Polar FT7 HRM.
I went for a little walk to work and back today, nothing amazing (18mins there, 18mins back) and decided to test out the HRM along side the RunKeeper app.
I'm aware that ultimately any method of tracking or calculating calories burned is an estimate, however I'm a bit confused as to why my HRM is giving me such a different reading to everything else, as I was hoping to rely on it more than anything else.

I've read on other message boards that other people's HRM's are giving them a lower estimate than MFP, or RunKeeper etc... which I would expect, however mine seems to be the opposite!

I've put together a little pic below detailing my walks to and from work, along with my current body stats etc.. which shows just how different a result I'm getting between my HRM vs RunKeeper vs MFP Exercise Log vs Free Dieting's Calories Burned Calc.

Note* I have used the exact same body/personal stats with each method.

Any opinions on how/what I should log my exercise as, or how I might go about using all this info to make the best estimation?
Any and all help is welcome and appreciated

CraigwQ

Just to add to my last post as some of the image is cut off! My average heart rate / max heart rates from my Hrm for walk 1 and 2 are as follows:

Walk 1 : Avg HR= 167 and MaxHR = 192

Walk 2 : Avg HR= 179 and MaxHR = 193

yarwell

One factor will be that the HRM tells you the gross calories including your BMR whereas the other estimates are the net / extra calories of the specific activity.

What data do you give an FT7 about yourself ?

If your HR is that high walking you are probably very aerobically unfit and unless you can convey this to the device it will overestimate. There's a post / spreadsheet by Heybales that tells you how to lie to it about your height and weight etc to get the right VO2max

But first you need to do a VO2max test or estimate - http://www.brianmac.co.uk/vo2max.htm

VO2 max 28.6  mls/kg/min from your data and http://www.brianmac.co.uk/rockport.htm - I was about the same.

afortunatedragon

You had a maximum heartrate of 192 from a walk? :huh:

Doesn't sound right.
I have a max. Of 110 from a walk on a straight road. With bit incline maybe 120 and a hike up a mountain at 150 max.

Sure it was a walk and not a sprint?

Otherwise would have the HRM checked out.

If that one is fine, get your heart checked.

disturbed_s

I recently bought the exact same HRM and I have found the opposite! While using treadmill/bike I get a significantly lower calorie amount from HRM so I use that one as I'm assuming it's more accurate. Also my HR gets up to 160ish (very fast pace and highest incline) after 30 mins or so, maybe yours isn't reading properly? Do you wet the sensor strips? Hope you sort it out anyway ????

CraigwQ

Hey yarwell, thanks for the reply!

I've input my age, height, weight, and gender into the hrm as I have with everything else to try and keep it all as similar as possible.

I have always had quite a fast heart rate as it is, and I do smoke occasionally along with being quite a nervous person when out which I understand will all contribute to a somewhat false reading.

The cals burned and avg/max heart rates did strike me as really high. The walk I did wasn't really difficult as its something I do most days anyway, so the readings I'm getting from the hrm really don't match up with how I feel; I'm not particularly tired or out of breath before/after the walks.

Il have a look into VO2max now thank you!

CraigwQ

Thanks for the replies so far guys!
My computers a little slow at the mo so getting back to people might take some time.

I think it might be worth having another look at the HRM again now I'm back home and wearing it around the apartment to see what kind of readings I'm getting while I'm resting.

Hey afortunatedra - Yeah it was just a nice easy walk as usual though the readings I got definitely make it look like a sprint. Hopefully it is just an issue with the HRM and not my heart / having got so unfit!

Hey disturbed_s - Yeah I wet the sensor strips a little before I put it on but it was a while before I set off out after doing it, so maybe they dried out too much?



I was planning on spending an hour on a dance mat I've got tonight so I may go do that with the HRM and see what results I get from that, as well as resting so I can compare these too.

Hopefully it's just me being a little dim and setting the watch up wrong or there's an issue with it :P fingers crossed!

Thanks again guys, really appreciate the help. I'l get back with some more results soon and hopefully figure it out

MyaPapaya75

I have a Polar hrm ft7 I get pretty accurate readings from it....I would say if your a smoker though it would be worth taking the hrm with you to a doc appointment and just getting heart health check up what can it hurt?..The hrm may not be off at all....Good luck!

shiec92

I also got a ft7 recently, I was wondering the same about accuracy.
When I use the treadmill, my HRM seems to give a higher number than the treadmill and activity tracking apps.
Although, if I use it with any other equipment the HRM seems to be lower

VERY CONFUSED!

CraigwQ

Hey MyaPapaya75 - I was just thinking the exact same thing, I think I'm going to book an appointment with my Dr tomorrow and take it with me, for all I know it might be giving me the right readings and it's just me needing to cut down / finally quit smoking!


Hey shiec92 - I know it's so confusing! I know it's not going to give an exact reading which I didn't expect, I just want a little more accuracy so that when I'm logging exercise I don't overestimate what I've done and end up eating back too much. I'm sure we'll figure it out though!

Again thank you all for the replies so far. In the mean time, how do you all think I should go about logging my cals burned?

I was thinking of either just halving what my HRM is telling me at the mo, or adding up all my results (e.g cals burned from MFP log, RunKeeper,Hrm and Cal Calc) and taking the average from that? Any thoughts? I'm not too concerned if I log a little bit under what I've burned off, just as long as I'm not logging over the amount I've burned off!

annziexo

Mine is always to same with walking always higher heart rate pm and always burn more calories however any other exercise it seems roughly the same to MFP so try something else?

I however think mine is due to being unfit... I never used to walk much!

happyfeetrebel1

My HRM was actually a titch below the treadmill, not as much as I'd thought it would be based on what I've heard here, MFP estimates were higher still, but I use the HRM for logging.

My HR is avg around 160 on a 5k RUN, I can't even imagine it being in the 190's. I'm uncomfortable around 175 which has me huffing and puffing, LOL, so I start walking.

I hope you figure it out thought, must be very frustrating

heybales

The cheaper Polar's like FT4/FT7 are lacking a key stat and a way to get it for estimating best calorie burn - VO2max. Your fitness level.

So the cheaper ones estimate it base on your BMI.
If BMI (height & weight) is in the bad range (gender and age) then it's assumed your fitness level (VO2max) is bad too.
That's a bad assumption.

It means when you first start out your fitness level is likely even worse than that, but then it can improve faster than you can lose weight and improve your BMI to good range.

The HRM is just like the treadmill and database entries though, it's giving total GROSS estimated calorie burn during that time. I've never seen one that gives NET, leaving out the resting metabolism that would have occurred anyway. I've only seen one site give that ability.

But guess what has been with 4% accurate of measured calorie burn?
Formula. Treadmill tests with measured calorie burn are the MOST used lab researched method of exercise, right above cycle ergometers.

And you can test your HRM to see how good or bad it is.
http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

Sadly Polar doesn't use a public study for the cheaper models so I can't figure out what stats to change to correct the device.
The better models do use public studies for getting the VO2max (still BMI, but also restingHR, and user selection of athletic level) in the self-test, so unless you've gotten lab measured, the self-test is best you'll get.

But test yours.

And if really doing that much cardio and trying to follow the MFP method correctly for exercise eat back that you want a best calorie burn estimate but don't want to pay for a VO2max/HRmax test, try this.
Background on why it works first, then the spreadsheet contains updated instructions.
http://www.myfitnesspal.com/blog/heybales/view/getting-your-personalized-calorie-burn-formula-663625
https://docs.google.com/spreadsheet/ccc?key=0Amt7QBR9-c6MdC10WXNweGI0ZGRNZHE4Wmc3UURaWVE&usp=sharing

And just so you know, any HRM and the formula's they use (including the spreadsheet personal one) are ONLY valid for aerobic exercise - that means all day non-exercise is invalid use of the formulas and useless calorie count. To see what your HR happens to do during the day - great if curious.

yarwell

The cals burned and avg/max heart rates did strike me as really high. The walk I did wasn't really difficult as its something I do most days anyway, so the readings I'm getting from the hrm really don't match up with how I feel; I'm not particularly tired or out of breath before/after the walks.

The most obvious check is that your pulse rate is similar to the HRM. Count pulse for 10 seconds and multiply by 6.

If it's measuring the correct heart rate then your aerobic capacity is low and the HRM assumes it's normal hence the overestimate. I'm anaemic so have a high heart rate when exercising but my HRM uses my actual VO2max data so doesn't overestimate so bad.

heybales

Just to add to my last post as some of the image is cut off! My average heart rate / max heart rates from my Hrm for walk 1 and 2 are as follows:

Walk 1 : Avg HR= 167 and MaxHR = 192

Walk 2 : Avg HR= 179 and MaxHR = 193

Do you wear synthetic/poly shirt and/or shorts, quick-dry type stuff?

The friction between them, even not between but by itself if humidity is low, can buildup static, and that can spike the HR.

Sometimes it's obvious, heading on up fast to 200's or above. But other times it's just enough to raise it 10-30 bpm.

Check for that - hold shirt against the strap and if it almost instantly lowers - there's your problem.

Spray static guard on shirt, and/or place where it meets shorts, especially across the strap. It's trying to read your body's reversal of electrical impulses and is pretty finely tuned, and static can ruin that ability.

Because that is some pretty high readings for something you do regularly, unless you've only recently set a time limit on yourself.