Garmin Calories burned calculation?

n1ckster

Good morning,
Can anyone offer any sort of explanation as to why 2 not dissimilar rides and efforts have produced such different Calories Burned figures? Below is a screenshot of a ride yesterday and one this morning, along with a number of other metrics.



Thanks in advance,
Nick

JackPozzi

I think it does use heart rate somewhere in the calculation and the fact you've hit 115% and 118% of your maximum might have confused it?

NeXXus

The numbers are largely junk.

davidof

RPM of 190 looks quick too.

n1ckster

NeXXus wrote:

The numbers are largely junk.

Hmmm, so at what point or level of technology do figures become more trustworthy??

NeXXus

n1ckster wrote:

NeXXus wrote:

The numbers are largely junk.

Hmmm, so at what point or level of technology do figures become more trustworthy??

When there is a constant like power, not a wild variable like HR which can be affected by multiple things.

Alex_Simmons/RST

n1ckster wrote:

NeXXus wrote:

The numbers are largely junk.

Hmmm, so at what point or level of technology do figures become more trustworthy??

When you use a lab grade metabolic cart with people who know what they are doing to assess your typical gross mechanical efficiency and a quality power meter on your bike.

bahzob

Alex_Simmons/RST wrote:

n1ckster wrote:

NeXXus wrote:

The numbers are largely junk.

Hmmm, so at what point or level of technology do figures become more trustworthy??

When you use a lab grade metabolic cart with people who know what they are doing to assess your typical gross mechanical efficiency and a quality power meter on your bike.

Garmin calories are basically a lookup of hr vs calorie usage. As such the default will be very hit and miss since they will be an average based on a few gross metrics like sex/age/weight/RHR/MHR i.e. wrong for 99% of folks, (e.g. not everyone does the same amount of sex )

You can however make it more accurate. If you have the results of a test like the above you can download them to Garmin and then xfer to your device. It's a bit of a pfaff as Garmin only officially support tests done by New Leaf which is a bit stupid given they are meant to be a global company while New Leaf is US only and New Leaf have gone bust anyways.

However it can be done, details can be found in the comments to this DCrainmaker post
http://www.dcrainmaker.com/2012/01/look-at-testing-with-new-leaf-fitness.html

> "Joseph LeBlanc
January 14, 2012 at 7:36 pm #31

I've whipped up a crude but working Windows app that can generate a New Leaf data file that Garmin Training Center will accept and upload to your device.

The app is written in C# and requires .Net 4.0. I've included both an exe and the source code in this zip file.

link to fixedvancouver.com "

I've done this and the results are quite consistent. By this I mean that the calories estimated tally with sums of calories burned vs eaten in terms of weight management which is what I use the information for.

term1te

It looks like the ride on the left is the outlier, 154C for a 24 mile ride seems somewhat low, whereas 661C seems more realistic. Did you get any odd readings on your heart rate, clearly 115% or your maximum is an oxymoron. My Garmin doesn’t' record calories if the HRM signal goes haywire, e.g. wind flapping a lose top causing a ridiculous heart rate. Maybe on the first ride it just didn't record many calories as your HRM signal was just wrong? Whereas on the second ride you spent more time with a good HRM signal, so it recorded more of them?