calorie burn calculations (Garmin vs Polar)

ironmanwannabe
ironmanwannabe Posts: 81 Member
in Fitness and Exercise
So I recently purchased the Garmin 910xt. I have been a Polar user forever. One drastic thing I noticed is that the Garmin calorie count for the same exercise is WAY lower than the Polar. It is in the ballpark of 30% lower. To test I wear both my Polar and Garmin at the same time (yeah I know I am anal that way) :)

Examples:

My last computrainer bike ride I rode 2hrs 45mins at a steady pace (50.5 miles) avg HR of 146.
Garmin calculated my calories as 1342.
For the exact same exercise, Polar calculated my calories as 1954.

Running 3.17mile run 150HR polar=415 garmin=355
Running 8.49mile run 149HR polar=1036 garmin=879

By adjusting my fitness level in the Garmin to say I am less active, I can get the numbers closer. But by answering these questions truthfully the difference is huge. Anyone else look into this? comments? thanks in advance!

Replies

  • scottb81
    scottb81 Posts: 2,538 Member
    Mine is usually 20 to 30% lower also.

    Garmin uses a second generation Firstbeat algorithm that calculates calories differently. It is supposed to be the most accurate short of a metabolic test. Here is a Firstbeat White Paper on how they do the calculation: http://www.firstbeat.fi/userData/firstbeat/download/white_paper_energy_expenditure_estimation.pdf
  • ironmanwannabe
    ironmanwannabe Posts: 81 Member
    Thanks for confirming that! I did find out some more about the Garmin. Without the newleaf testing (I heard all the testing centers are now closed) that is supposed to be the most accurate way of determining calorie burn on the new 910xt watches, you have to rely on the 2nd method which takes into account age, sex, weight, heart rate, "lifetime athlete" parameter and a parameter called "activity level". This activity level is a number from 1-10 and is determined by how many times you work out and how long you work out per week. This makes no sense. A better method would be to allow the user to put in a VO2 max number. I got into a reasonable ballpark by lowering my activity level to something that is totally non-reflective of how much I do workout.

    Anyways, I do understand that calorie burn is an estimate on any HRM. It would be nice if the default on the Garmin was at least reasonable...

    Having said that I am enjoying the watch and it's various features. :)

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