Calorie usage variation on Garmin Connect

[tlittlefield]

OK went on two rides over the weekend, both were 41 miles give or take a couple of tenths and average spd was 18.5 and 18.3. Each ride was a completely different route.

Saturdays ride when downloaded to Garmin Connect from my Edge 500 showed I burned 2200 calories. Sunday I used my OEM Garmin HR strap and when I downloaded my ride it only showed 880 calories burned.

I have seen charts that state at an average 18 mph you burn appox 500 calories per ten miles, so it would seem with the HR strap is more accurate.

Has anyone else experienced this?

[MattTuck]

All I can say with regard to calorie estimations with any electronic device, is that they're estimates. Probably within 40% of the real calorie expenditure. Things that go into these calculations are population wide averages and may have very little to do with the particulars of your ride.

If you want to know the actual work you did, get a power meter. That will give you a better sense of the energy you put into the pedals. That is still not perfect because every person has different efficiency (how well you can convert 1 calorie of food input into 1 calorie of muscle energy output).

If you're interested for weight loss purposes, I'd say to just use the low end estimate.

[tlittlefield]

Thanks Matt, but the extreme variation is always there when I use the HR strap as opposed to when I do not. So it def does have something to do with that.

Not concerned about weight loss (weigh 144 lbs) I am just a stat nut (-;

[shovelhd]

Get a power meter then. Garmin estimates are way off.

[nooneline]

I have seen charts that state at an average 18 mph you burn appox 500 calories per ten miles, so it would seem with the HR strap is more accurate.

That is, at best, a ballpark figure. And it's a very big ballpark. Any time you have software estimating how much work you're doing without measuring how much work you're doing, you're not really going to get reliable information.

I have a GPS computer and I upload data to Strava. It offers me estimated power. It might approach reasonable accuracy on a steady, sustained cilmb (based on my weigh tinput), but in any other conditions it's useless.

[Black Dog]

If you are riding reasonably hard then expect a conservative estimate of 20 Cals/km. Anything beyond this and you will need a lot of data about the power output, heart rate, and details about your physiology to get a higher resolution estimate. YMMV.

[brian_d12]

I use my Garmin 800 as an estimate only, because I do see the same differences with and without the HR monitor - though not as drastic. I see ~1000 cals/hour on a flat ride without the HR strap, and ~600 cals/hour with. Here is a great reference:

http://www.dcrainmaker.com/2010/11/how-calorie-measurement-works-on-garmin.html

[SoCalSteve]

I cannot imagine the algorythms work well without the heart rate component...I do know that Garmin has had some software glitches over the years that have messed it up pretty badly.

The newest firmware update on my 510 seems to be pretty accurate ( while using a hrm)... YMMV