18

I have a Polar heart rate monitor chest strap, and a compatible Android phone on which I can run a number of different apps for recording my heart rate. My primary interest is in how many calories I am burning during any one exercise. I play a variety of sports and run regularly.

What concerns me is that just about every app I've tried comes with an option to select a type of exercise, and then it will calculate different calorie burn rates.

Worse, these different calorie burn rates seem to be derived from a lot of assumptions about how much a person would burn doing these activities, not what I'm actually doing. As a test, I've tried connecting the heart rate monitor, choosing an activity, like "team sports" or "rock climbing", and then just standing there without moving. Regardless of the fact that I'm not actually doing anything, each app shows me burning calories fairly aggressively, as if I were engaged in that activity.

What I really want is an objective measure, something that doesn't try and make guesses based on the type of workout I'm doing, and lets me know what the most likely minimum calorie burn I am doing given my current exertion level, as measured by my heart rate. And, of course, taking in some known measurements about me, such as my height, weight, and age. Maybe GPS and pedometer as well, but whatever measurements it uses, it should be objective and not assumed.

I saw this related question, which leads me to believe that it should be possible to only use heart rate, and yet I can't find an app for Android that does that.

Is it actually not possible? Is there a reason why these apps are all making up numbers and not just going with the heart rate input?

  • 3
    The answer with the formulae is excellent, however unless you are directly measuring via spirometry or other similar procedure, ANY formula is basically a guess. I would also hesitate to put too much reliance on heart rate based guesses since there is so much variability to heart rate. For example, say your normal exercising HR is 150, but today because you were tired you drank an energy drink and now your exercising HR is 180 due to the caffeine. Does that mean you're suddenly burning 20% more calories? (That answer is no, btw). – JohnP May 8 '13 at 14:43
  • 1
    @JohnP: Any measure of calorie burn is an approximation, but that doesn't change that it's worth having at least some measurement. No one's asking for perfection, just questioning what assumptions are made in the calculations. – Questioner May 9 '13 at 4:02
  • 1
    I think picking the type of exercise is mainly a variable that determines how calories scale with your heart rate. Certain exercises involve more muscles, with different ranges of motions and movement frequencies and thus work your muscles differently. So as soon as you tell the app you're doing a type of exercise, it'll have to assume that's what you're doing. I can't reliably determine whether you're actually doing it. So yes, they use your heart rate, but in a pretty naive way – Ivo Flipse May 9 '13 at 10:08
  • I'm seeing an opposite problem, though maybe related to Ivo's comment above mine. My heart rate watch doesn't know what exercise I'm doing other than "Other", so try rock climbing with it and it reports very low. 30 minutes quite intense autobelay and bouldering scored 57 Calories! Despite a heart rate averaging 150 peaking over 180. – Richard Corfield Feb 26 '16 at 19:18
  • this calculation says I burn over 300 calories sitting at my computer for 2 hrs and less than 275 calories burned walking 2.5 miles an hr for an hr. Its crap. With this calculation I would burn nearly my entire calrie intake sitting at a desk. – Bernadette Ezakovich Sep 24 '18 at 15:52
13

Yes it is, this is the Formula when you dont know the VO2max (Maximal oxygen consumption)

Male:

((-55.0969 + (0.6309 x HR) + (0.1988 x W) + (0.2017 x A))/4.184) x 60 x T

Female:

((-20.4022 + (0.4472 x HR) - (0.1263 x W) + (0.074 x A))/4.184) x 60 x T

HR = Heart rate (in beats/minute)

W = Weight (in kilograms)

A = Age (in years)

T = Exercise duration time (in hours)

With VO2max known you can calculate the calories burned like this:

Male:

((-95.7735 + (0.634 x HR) + (0.404 x VO2max) + (0.394 x W) + (0.271 x A))/4.184) x 60 x T

Female:

((-59.3954 + (0.45 x HR) + (0.380 x VO2max) + (0.103 x W) + (0.274 x A))/4.184) x 60 x T*

Source: http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.aspx

You have a online Calculater Tool on this Website if you dont want to calculate everything on your own.

On the bottom of the Website you also have some calculations about the Equation for determination of the maximal Heartrate based on age and the equation for Exercise Intensity Conversion from %MHR to %VO2max. But I don't know what to do with these 2 Formula so i didn't post them.

  • 1
    IMO this tends to be more accurate than those 'Calories Burned' meters on the treadmills. – MDMoore313 May 8 '13 at 14:43
  • 3
    These formulas are copied and pasted all over the place. Anyone who's tried the female calculation will know that it's utter nonsense. – Daniel Wood Dec 11 '14 at 11:12
  • When excited, your heart rate can increase a lot without moving a finger and you burn much less calories during that than during exercise. So you can't calculate calories burnt just from heart rate. – Jan Aug 27 at 17:34
  • These formulas are linear regressions of a normally distributed population. That means that if you fall within 1-2 standard deviations of the entire population, it would most likely be generally acceptable. However, because fit and active people are NOT the norm, they will usually fall outside that scope. For example, when I ride my bike an hour, my heart rate monitor says I’ve burned around 800 calories. Measured by my power meter, it’s closer to 500. Since watts and calories are almost identical, the power meter is way more accurate. The difference: A slice of pizza. That’s significant! – Frank Aug 28 at 22:04
6

Some guys at Stanford did some actual experiments on this :) Got people to do various forms of exercise, such as sitting, running, and cycling. They measured the oxygen and carbon dioxide in breath, strong proxies for the actual underlying metabolic rate; whilst also measuring heart rate using one of five consumer wrist devices. They then ran a whole bunch of statistical analysis. On the team were Trevor Hastie, who is pretty big on stats :)

Example image from the notebook linked above:

enter image description here

3

I'm sorry but I don't see being able to calculate without the vo2 max or at least the persons resting heart rate. I use my bmr + (average heart rate - resting heart rate)*6 and it comes out very close to my calorie burn for the day. The 6 is just a variable that works for my body and could just as easily be a 5 for a overweight female or a 7 for a male athlete. There are flaws to this also but it does not come out with outrageously high numbers like that formula

1

You might be able to calibrate it using a rowing machine, which I assume calculates calories based on force x distance, and/or treadmills which you can set at different gradients to separate out the assumptions about how much you expend running from the part due to gain in height (gain in height x your weight = energy used).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.