HRM users, do you factor in a margin of error?

nuttynanners

I am currently using a Polar FT4 to get a good estimate on my energy expenditure during exercise. I love it because it allows me to monitor my heart rate so that I can try to stay in the optimum zone for fat burning. And it gives me quantitave data at the end of my workout!

That being said, I sometimes think the numbers are a bit inflated (and yes, my stats are entered into the watch). I like to factor in a margin of error when I record my calories burned. I think shaving 10% off to be on the safe side might be a good precaution to take. Can anybody either confirm or deny the efficacy this method?

And no, before any concerned individuals come valiantly to my rescue, I'm not going to start wildly under-eating. I know my limits and I like to eat.

SLLRunner

Not I. My results tell me the numbers are accurate enough. I weigh all my food, though, and log everything I eat.

nuttynanners

I weigh my food sometimes. Meat, cheese, and starches mostly. I don't always bother weighing some things, like fruits and veggies. I kind of eyeball those, haha. And for "ingredients" i use measuring spoons. So I'd say I do okay....

But maybe it's not. Maybe I subconsciously want that margin just in case I am careless with my measurements. Hmmmm.

BWBTrish

yes i do.
I only eat a 1/4 back

Found 2 sites in the past ( just google overestimation of devices) that told that my polar FT7 could be off about 20 to 25%

Than take any underestimation of my calorie intake. So i have a bit of a buffer there for errors.

btw i log everything!

BWBTrish

btw this is why i weigh every solid food and measure all my liquids.

https://www.youtube.com/watch?v=JVjWPclrWVY

SarcasmIsMyLoveLanguage

Yes, I agree. An HRM is more accurate than the MFP database, but it's still not exact. I don't have a specific margin that I work with, but 10% sounds reasonable. I'd rather under-estimate my burn than over.

tbullucks2006

I have heard to shave 20 - 25% off for accuracy with HRM's.

Sued0nim

I should but I have been going with my burns on HRM (not steady state cardio) plus fitbit extra calories and averaging about a 500 calorie margin for error across the week (eg generally 300-600 under my weekly goal). My trend weigh loss shows it is working

When it stops working for a whole 6 weeks (because I stall for 2-3 weeks then whoosh) I will adjust

You have to use your results to judge and not just worry about the numbers

BWBTrish

Here are some for the Polar HRM

http://www.livestrong.com/article/490909-the-accuracy-of-calories-burned-in-polar-heart-rate-monitors/
Says about 12% overestimation.

Here one that say 86 to 93% accurate
http://www.heart-rate-monitor-specialist.com/polar-fitness-test.html


When you search you will find more articles/tests.

Hope that helps

enterdanger

I always feel like my garmin is high on calorie burn, so I only eat back part of my exercise calories unless I'm starving.

nuttynanners

I used to have an FT60, which went mysteriously missing during a move. That model monitored VO2 max, but the FT4 I have now does not.

Today I worked out and got a reading of ~750 calories burned for 1 1/2 hours activity (which included a few stops to distract my cat from attacking my legs mid-workout and changing DVDs). Between DVDs I tried to keep moving i.e. running/stepping in place.

I logged it as 600 cals instead, so like a 13% margin.

But as it has been said, numbers are just numbers...

Thanks, @TheOwlhouseDesigns‌, I will read those.

BWBTrish

yvw

I log it all ( i adjust the exercise to the calories my polar watch says i burned)
So means i have to log more minutes most of the time to get the right amount

From that amount i eat back 1/4 And when i am hungry or something extra i will

Mr_Knight

It depends on the exercise. If you're out of shape and doing something like Zumba, the HRM could be overestimating by as much as 10x. Yes, 10x. If you're in shape and running, it can easily be within 10%.

So...it depends.

higgins8283801

I just round down. If it says I burned 540, I log it as 500. I ran one day last week and it told me I burned 800 calories (5 miles) and I only logged it at 600.

krysmuree

Not technically, but I try not to eat more than half of my calories back.

aplcr0331

Yep, multiple my Polar results by .75 every time.

segacs

There's no specific margin or calibration factor that's going to apply to all people. What you have to do is monitor your actual results and then adjust by the factor that it's off for you in particular. Same as a TDEE formula.

kcjchang

Folks at Garmin did a real bang up job making everyone think HR monitor do something it can't. HR monitor record and display your heart rate, that's it. To draw any conclusions on calories expended verses heart rate you need to have a few testing done, develop a corresponding mapping, and that's still an appropriate. It's like expecting to draw conclusions on how fast your car engine is turning by reading the gas gauge; half tank of gas tells you nothing about the engine's rpm. Read this http://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472

The algorithm used is for an average male at some fitness level that they are loath to publish because it will dispell the myth and hurt sales. Use it as a matrix for tracking progress but don't get hang up on it. If your not where you want to be in a few weeks, adjust accordingly.