Calorie burn discrepancy, MFP/HRM

lthames0810 · December 2013

I have seen it posted here that MFP and excercise equipment overestimate calorie burns and that it's more accurate to use an HRM. This morning I had the opposite result. My HRM gave a reading that was far greater than MFP.

Numbers: Female, Age 59, 178 lbs, 30 minutes on the eliptical. MFP gave me 363, the eliptical machine gave me 303, my HRM gave me 545!!! Also from my HRM: average HR of 153 and max 167 (I know...redline...it was a really good song at the time.)

While I was excercising I compared the current HR on my monitor to the HR the eliptical displayed when I held the handles and the numbers were always close. So I think the heart rate was accurate and I rechecked my settings. It's just the calorie burn that seems way off.

I always assumed that the HRM included the calories burned by your BMR. For that reason I don't use the calorie burn from the HRM for a three hour bike ride, but over only 30 minutes I wouldn't expect that great a distortion.

I chose to put the middle number in my diary today, but my question is: Which number is more accurate?

agthorn · December 2013

545 sounds way too high for 30 minutes. That would be equivalent to running 6 minute miles, which if you're able to do that and still keep a HR under 170 you are in fan-freaking-tastic shape.

Does your HRM have a chest strap, and is your information entered correctly?

lthames0810 · December 2013

Yes it has a chest strap and I did check the age/weight settings, I did not, however, put these numbers in the eliptical.

agthorn · December 2013

I put your numbers into the calculator at shapesense (http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.aspx) and it spat back 303. I think your HRM is broken.

SJCon · December 2013

It can also vary by App, Company and what information is input. One of the apps that is advertised and pairs with MFP is Digifit. If you use it to track your HR it will overestimate your calories burnt by as much as 40%. Calorie burn will vary based on fitness level, gender, age, exercise being done and weight. Most references/machines make a lot of assumptions to give you a number. The closer you are to their model the more accurate the number will be for you. My experience is that Polar, Sunto, and Garmin are excellent brands and can give you good information. The less expensive the HRMs may be less accurate. Even among the "good" brands the "accuracy" can improve with the models that estimate VO2 max (how efficiently your body moves oxygen) and some even use more refined calculations on their more expensive models. How Chest straps fit can effect readings, body hair or ambient light can affect wrist models. Given all these variable it is hard to nail down what a "accurate" number is but your numbers sound high.

3dogsrunning · December 2013

A few good topics to read

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
http://www.myfitnesspal.com/topics/show/1044313-this-is-why-hrms-have-limited-use-for-tracking-calories
http://www.myfitnesspal.com/topics/show/773451-is-my-hrm-giving-me-incorrect-calorie-burn

If you have a Polar
http://www.myfitnesspal.com/topics/show/548645-setup-polar-hrm-for-more-accurate-calorie-burn-for-known-bmr

ETA - 500 calories is way too high for 30 minutes. There is an issue somewhere.

Mr_Knight · December 2013

I have seen it posted here that MFP and excercise equipment overestimate calorie burns and that it's more accurate to use an HRM.

Have you not also seen it posted that HRMs are also generally inaccurate for burns?

I chose to put the middle number in my diary today, but my question is: Which number is more accurate?

Pick the lowest number, and divide by 2.

ravinstar · June 2015

I am having similar issues with or without the HRM. I have decided to cut those calorie values in half. I am a cyclist using a Garmin Edge and a 20km bike ride at 23km/hr in 50mins = 946 calories burned. The same ride uploaded on Strava is calculated at 488 calories. I will keep using which ever is lower until I see better results.

gdyment · June 2015

My chest strap will go wonky sometimes and show 180+ when I'm just barely starting (even if I wet it sometimes). Usually settles down but of course the cal burn is skewed.

Calorie burn discrepancy, MFP/HRM

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