Calories calculation based on? (quite different from Polar)

Zones are tools for you to help you in your training, and don't influence calories calculation.

Every vendor uses a different algorithm (Garmin uses Firstbeat) and the usual parameters used in high end devices are: age, HRmax, HR at rest, weight, height, VO2max and Firstbeat also uses heart rate variability, but if I understand that correctly, heart rate variability for the 235 is only available when you pair a chest strap.

Did you already get a VO2max estimate from the 235? Is there a VO2max setting in the polar beat app and is it close to the 235 estimate?

Also, check that all the other parameters are the same.

Supposedly the 235 calories accuracy will also further improve over time once the VO2max estimate stabilizes (also Garmin clearly states that VO2max estimates obtained while using a chest strap are more accurate than VO2max estimates obtained with the optical heart sensor)

EDIT: I looked ad the polar beat app. There is no setting for VO2max, but there is a "training background" setting that is used in the energy expenditure calculation, that doesn't seem very scientific to me... Also they don't use resting heart rate (other dedicated higher end Polar units use both VO2max and resting heart rate).

The bottom line is that they are only estimates, so there's no way to know which one is closer to reality, but the Polar beat app seems to use a simplified method vs other higher end HRM watches, like the 235. There's no reason to think that the 235 estimations are any less accurate (provided that the heart rate readings are similar). If anything I would probably trust the 235 more, because of the more advanced algorithm and because Garmin stands by their VO2max estimate saying that is 95% as accurate as a lab test.

Zones are tools for you to help you in your training, and don't influence calories calculation.

Every vendor uses a different algorithm (Garmin uses Firstbeat) and the usual parameters used in high end devices are: age, HRmax, HR at rest, weight, height, VO2max and Firstbeat also uses heart rate variability, but if I understand that correctly, heart rate variability for the 235 is only available when you pair a chest strap.

Did you already get a VO2max estimate from the 235? Is there a VO2max setting in the polar beat app and is it close to the 235 estimate?

Also, check that all the other parameters are the same.

Supposedly the 235 calories accuracy will also further improve over time once the VO2max estimate stabilizes (also Garmin clearly states that VO2max estimates obtained while using a chest strap are more accurate than VO2max estimates obtained with the optical heart sensor)

EDIT: I looked ad the polar beat app. There is no setting for VO2max, but there is a "training background" setting that is used in the energy expenditure calculation, that doesn't seem very scientific to me... Also they don't use resting heart rate (other dedicated higher end Polar units use both VO2max and resting heart rate).

The bottom line is that they are only estimates, so there's no way to know which one is closer to reality, but the Polar beat app seems to use a simplified method vs other higher end HRM watches, like the 235. There's no reason to think that the 235 estimations are any less accurate (provided that the heart rate readings are similar). If anything I would probably trust the 235 more, because of the more advanced algorithm and because Garmin stands by their VO2max estimate saying that is 95% as accurate as a lab test.

Thanks for your extensive answer. Polar has a "fitness test" which gives a so called OwnIndex, which should be something like VO2max. From the FR235 I got a VO2max just above 40, which is also what I got from the Polar Fitness test. Polars test however is taken during rest in a laying position. Polar says in research for its fitness test, deviation from mean was 12%. So it might not be bad but apparently not as good as firstbeats algorythms.

However you're right, that there is no personal setting for resting HR and neither for Vo2max in the app. Maybe when using a Polar watch you might have the VO2max and HRrest in personal settings.

So I would guess that it makes sense to trust the firstbeat numbers more. I also checked out the firstbeat website, they seem to have an extensive background in this area.

I also have looked into the details of the walk I mentioned and compared the HR from the Fr and Polar H7. I found out, that the FR had somewhat of a big drop in HR over some time. I guess that would explain why the difference for this specific activity was so big.

What I really don't like about Polar is that you cannot adjust the HR Zones. Those are always 50-100% from HRmax. When doing a normal easy run and by feel in Zone 3, Polar would always put me in Zone 4 maybe even on the upper end. With Polar Zones a recovery run in Zone 1 is impossible for me, I have to walk to be in that zone. With the Garmin Zones, having them calculated as %HRR, Walking doesn't put me in a zone and a slow run will much more likely put me in Z1 :)

Calorie calculations (and indeed things like VO2 Max) on all Garmin devices are sourced from Firstbeat - see http://www.firstbeat.com/consumer-products/garmin/

I have a relatively old Polar watch (RS300X) and it has all the features and settings that you are talking about (VO2max, resting heart rate, ownindex, customizable zones, etc...). It is just the Polar Beat app that is watered down. BTW, the ownindex test result is heavily influenced by how you input some settings in the watch (activity level and resting heart rate), while the more modern 235 is great because you just have to run outside and it calculates almost everything (you still need to have a good idea of what your max heart rate is). I'm not sure how equivalent level Polar watches have evolved in the past few years.

I tried to investigate a little on this issue.

Somewhere in an older forum post I read, that Polar is including bmr calories (calories burnt without moving) in their excercise calories output, whereas Garmin is only calculating exercise calories excluding bmr.

Don't know if that is true but it might explain to some extent why the Garmin numbers are always lower.

On todays 6k/45min run Garmin tells me 388, while Polar gives me 582 calories burnt.

EDIT: just checked VO2max on the FR again. While it was set around 40 after my first runs with the watch I now got downgraded to 35. Don't know when that happened.

Does less VO2max mean less calories burnt?

> Does less VO2max mean less calories burnt?
No - VO2 Max is a measurement of fitness level not calorie burn.

You could well have a point about "BMR" calories. Garmin does not include them in the calories it gives for actual runs.

> Does less VO2max mean less calories burnt?
No - VO2 Max is a measurement of fitness level not calorie burn.

You could well have a point about "BMR" calories. Garmin does not include them in the calories it gives for actual runs.

I'm sorry, but all the literature I read points to the fact that the VO2max does affect calories expenditure and all the equations I saw do calculate different energy expenditure of the VO2max is different, including the white paper from firstbeat that is the basis for Garmin calories estimation:
http://www.firstbeat.com/app/uploads/2015/10/white_paper_energy_expenditure_estimation.pdf

I think it make sense: for example if you have two people with same age weight and max HR that run at the same HR, the person with higher vo2max will be able to accomplish more work (run faster for example) and so his energy expenditure would be higher.

Another example is if a person improve his cardiovascular fitness over time. At the same % of max HR, this person will reach an higher speed, that means that he is spending more energy.

That is why energy expenditure calculations in higher end devices include VO2max

Well yes and no. In real terms VO2 Max is a measure of how much oxygen you can use. Obviously these devices can't directly measure that.

The faster you run the faster rate of calories you burn but equally you will get there quicker. So if you do mile very quick and then stop you probably won't use that much different calories to running a mile slower as you will be working for longer.

For instance on my run on Saturday I can see one mile which I did in 5:29 within an extended fast stretch and that was given as 100 calories.
Earlier on I did one in 7:15 and got nearly the same - 97.
Later on I did one in 7:04 and got 109 - maybe higher as tired by then and not as efficient.
So I was clearly burning calories at a far faster rate in the quicker mile but for the distance covered was not much in it.

Very interesting!

In the whitepaper it says:

In the described calculation model, energy expenditure is calculated on the basis of information on VO2 (or METs), respiratory quotient (RQ) and caloric equivalent.
...
Both exercise intensity and duration affect RQ and caloric equivalent, which is a well-known phenomenon established in literature. An increase in exercise intensity results in increased RQ and caloric equivalent due to the increased oxidation of carbohydrate and decreased oxidation of fat. Prolonged exercise duration, on the other hand, has an opposite effect due to the increased oxidation of fat and decreased oxidation of carbohydrate.

So let's say in my example Polar expenditure is calculated similarly. Excercise intensity was exactly the same, as it was the same run for the same person. VO2max would be the only different variable, assumed Polar was using my fitness test result (above 40) while Garmin was using 35. Then it would be true, that a higher VO2max would result in higher expediture. Of course it's just speculation if and how similar Polars and firstbeats approaches are.


Polar calls its calories calculation smart calories or ownCal. SOME devices also use VO2max. See here http://www.polar.com/en/support/OwnCal?category=tips&product_id=7882.

But as noted, the Beat app has not personal data setting for VO2max. They might just use an average maybe based on level of activity (in my case set up as 3-5h a week).

Well I could make many more speculations, so it doesn't really make sense :) I could try to do the same run again, but change some settings (raise the VO2max in my Garmin data* or decrease the activity level in the Polar app).

*however I think firstbeats whitepaper talks about "realtime RR" so not sure if changing personal settings would affect calculation at all.


Thats the only white paper from polar I could find: http://www.sciencetech.gr/Polar/PolarLoop_whitepaper_June2014.pdf

This is also an interesting 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

Confirmed: Garmin activities without BMR calories

After today's run I can confirm by experiment that Garmin does NOT include BMR calories in activities reported calories.

I wrote down the values for total and active calories before and after the run.

Total Calories
before: 1202
after: 1746
Difference: 544

Active calories
before: 37
after: 487
Difference: 450

Calories reported for my run (Garmin): 451

Calories reported for my run (Polar Beat): 583

From this point of view the difference between Polar and Garmin reported expenditure isn't that big anymore.

It's just good to know that the expediture you see for an activity is active calories only!