General Discussion Triathlon Talk » Garmin 305 Forerunner Calories Rss Feed  
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2011-05-13 7:51 PM

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Subject: Garmin 305 Forerunner Calories
How accurate is the calorie counter on the Garmin Forerunner 305???


2011-05-13 8:17 PM
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Subject: RE: Garmin 305 Forerunner Calories
Very inaccurate. The relatively small errors of calculated elevation for each data point accumulate and result in many phantom climbs and descents.
2011-05-13 8:33 PM
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Subject: RE: Garmin 305 Forerunner Calories
The calorie counter is not accurate at all.  It can be somewhat close for the run for me but horribly off for the bike.  Ignore
2011-05-13 9:24 PM
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Subject: RE: Garmin 305 Forerunner Calories

Ditto - the bike is consistenly way off but the run seems resonable.

Kevin

2011-05-13 9:30 PM
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Subject: RE: Garmin 305 Forerunner Calories

dano-oly - 2011-05-13 9:17 PM Very inaccurate. The relatively small errors of calculated elevation for each data point accumulate and result in many phantom climbs and descents.

If you have the latest firmware updates, elevation is no longer used to calculate calories.

2011-05-13 9:39 PM
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Subject: RE: Garmin 305 Forerunner Calories
My 310XT is horribly wrong too. I can ride 100 miles and only burn 1400 calories, if I'm lucky lol


2011-05-14 4:46 AM
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Subject: RE: Garmin 305 Forerunner Calories
Not accurate at all. For athletes that are trying to track caloric expenditure, I suggest the following calculations as a staarting point and then watch what happens with your weight based on intake and training load.

Swim - 100Cal/400m
Bike - .35Cal/kgkm
Run - 1Cal/kgkm

Shane
2011-05-14 9:00 AM
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Subject: RE: Garmin 305 Forerunner Calories
gsmacleod - 2011-05-14 2:46 AM Not accurate at all. For athletes that are trying to track caloric expenditure, I suggest the following calculations as a staarting point and then watch what happens with your weight based on intake and training load. Swim - 100Cal/400m Bike - .35Cal/kgkm Run - 1Cal/kgkm Shane


I like these calculations, Shane.  Thank you for sharing.  Did you arrive at them yourself or are they from a scientific study.  I'd like to share these with others but I need to back it up with something. Smile

Regardless, I'm going to use them on myself and see what happens. 
2011-05-14 7:08 PM
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Subject: RE: Garmin 305 Forerunner Calories

At first I was going to say, well, it's made of plastic and silicon so I wouldn't count too many calories if you eat it. But then, I saw the reasonable question.

It tells me I burn 1400 calories on a hilly bike ride of 12 miles. Yeah I am 274, but come on - that's so absurd a figure. I will look into a firmware update as mentioned.

2011-05-14 7:14 PM
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Subject: RE: Garmin 305 Forerunner Calories
64 mile loop that I do with 4000' of climb my 305 said I burnt 4400 calories. When I did it another time with edge 800 and powertap, it said I had burnt 3400 calories. At least with the powertap, you know that you're measuring the actual effort output, so the number is likely closer to accurate....
2011-05-15 6:47 PM
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Subject: RE: Garmin 305 Forerunner Calories
owl_girl - 2011-05-14 11:00 AM

I like these calculations, Shane.  Thank you for sharing.  Did you arrive at them yourself or are they from a scientific study.  I'd like to share these with others but I need to back it up with something. Smile

Regardless, I'm going to use them on myself and see what happens. 


The swim and run I picked up from a few articles; the run seems to be a pretty standard rough estimate while the swim is highly dependant on form but I've found it is a good starting point. As they were culled from a number of sources, I can't provide you with the sources as I don't even remember where I picked them up at this point.

The cycling number I picked up from a blog post about fueling the TdF from Jonathan Dugas and Ross Tucker at the Science of Sport.

Shane


2011-05-16 1:25 PM
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Subject: RE: Garmin 305 Forerunner Calories

gsmacleod - 2011-05-14 5:46 AM Not accurate at all. For athletes that are trying to track caloric expenditure, I suggest the following calculations as a staarting point and then watch what happens with your weight based on intake and training load. Swim - 100Cal/400m Bike - .35Cal/kgkm Run - 1Cal/kgkm Shane

Different units, but these are almost exactly the same as my estimates:

swim:  0.25 x yards

bike:  0.25 x miles x wt (lbs)

run:  0.75 x miles x wt (lbs)

I converted your formulas into mine as we're within ~2% for bike and run, while the swim remains off by the yard/meter factor, so about 10%. 

Someone else asked about sourcing.  For swim and run, I went to a bunch of those websites with tables for various speeds, effort levels, weight, etc.  I dumped the tables into sport-specific excel tables and ran regression to solve for underlying relationship.  I got ~90%+ r-squared with the simple stuff above.

Biking is a bit harder because it is more strongly non-linear.  I saw estimates all over the place, but the one that sounded credible and matched my experience suggested the following: 

10 mph -- 0.17 calories/pound

15 mph -- 0.2 calories/pound

20 mph -- 0.25 calories/pound

25 mph -- 0.3 calories/pound

30 mph -- 0.38 calories/pound

I've seen that chart attributed to Edward Coyle.  Since I'm working to improve in the 15-20mph bucket I aspirationally give myself credit for 0.25.

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General Discussion Triathlon Talk » Garmin 305 Forerunner Calories Rss Feed