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Old 06-29-12, 05:41 AM   #1
krobinson103
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Endomondo and calorie use calculations

Is it just me or does the calculated calorie use of any given ride seem a bit high on these smart phone apps? I rode for 1:40 at about 16mph average for a distance of 27 miles with an average pace of 3:43 for a mile and a best pace of 2:23 for a mile. It tells me that I used 1519 calories, That seems a bit excessive when you weigh 180 pounds.
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Old 06-29-12, 07:40 AM   #2
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Check out my reply to the calorie thread just below the one you posted.. The numbers you get from endomondo are general averages based on assumptions you provide it, but i'm willing to bet, they're not that far off when you figure in your ride burn + BMR which endomondo probably does.

go to http://www.wolframalpha.com and do a query adjusted for your ride/averages such as

"cycling 180 min, 3.7 min/mi, 36yo male, 5'10", 178lb" (my stats)

and you get:

2440 calories burned
.7 lbs fat burned
128lbs of oxygen consumed

You can also then input windspeed and direction (split your time into two queries, one with headwind or vice versa)

Also, use WOlfram alpha to calculate your BMR so you know what your calorie burn is just being alive.

BMR 36yo male, 5'10", 178lb

Again, these are just averages/assumptions but of all places, WolframAlpha is using the most standard formulas since its the same calculations implemented in mathematica and their built in research tools.

of course none of this includes outside temp, hills, bicycle gearing blah blah blah
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Old 06-29-12, 08:15 AM   #3
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Quote:
Originally Posted by krobinson103 View Post
Is it just me or does the calculated calorie use of any given ride seem a bit high on these smart phone apps? I rode for 1:40 at about 16mph average for a distance of 27 miles with an average pace of 3:43 for a mile and a best pace of 2:23 for a mile. It tells me that I used 1519 calories, That seems a bit excessive when you weigh 180 pounds.
What type of bike are riding? Tires? Elevation? In any case, 1519 sounds high and would require 250W average power. Most of the on-line calculators, including Wolfram, overestimate caloric expenditure.
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Old 06-29-12, 09:30 AM   #4
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Originally Posted by gregf83 View Post
What type of bike are riding? Tires? Elevation? In any case, 1519 sounds high and would require 250W average power. Most of the on-line calculators, including Wolfram, overestimate caloric expenditure.
Wolfram uses what they call the "Riegel model" of which they do show a little concept of their model thoughts here:

http://blog.wolframalpha.com/2010/07...-and-cyclists/

apparently they figure in exertion and other factors, i'll see if i can't find a released paper speaking more directly on the model itself.
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Old 06-29-12, 11:16 AM   #5
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The Riegel model is just an exponential formula for predicting performance over a range of times given measured performance on one time.

Their caloric expenditure overestimates if you are riding a standard road bike in a reasonably aero position. It might work for a hybrid bike with bigger tires ridden in an upright position.
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Old 06-29-12, 12:25 PM   #6
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That's an interesting use of wolfram alpha. But I concur that numbers it produces are too high. Comparing wolfram's numbers against kreuzotter, there's reasonable agreement for a 40 lb upright roadster (though wolfram still overestimates the power below 15 mph), wolfram alpha overestimates the cost of riding a MTB by 30-70%, and the cost of riding a road bike (on the tops) by 50-100%.

For example, wolfram alpha says that its default male (5'9"/159) burns 668 calories/hour riding at 15 mph. That's around 185 W. Kreuzotter says that the same male requires 170 W to ride a roadster, 133 W to ride a MTB, and 111 W to ride a road bike on the tops.
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Old 06-29-12, 01:25 PM   #7
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Ok, I got it. It includes the basal metabolic rate. In their model, it costs you around 150 calories/hour (depending on your weight) just to sit on the bike without moving. Subtracting the BMR, what's left is a fairly clean model of a bicycle with low-to-average frontal area (Cd*A 0.5 m^2, about right for a road bike on the hoods), high rolling friction (C_r ~ 0.01), and no dynamic rolling resistance. The model completely ignores your height and uses a fixed value Cd*A in all cases.
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Old 06-29-12, 02:38 PM   #8
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Ok, I got it. It includes the basal metabolic rate. In their model, it costs you around 150 calories/hour (depending on your weight) just to sit on the bike without moving. Subtracting the BMR, what's left is a fairly clean model of a bicycle with low-to-average frontal area (Cd*A 0.5 m^2, about right for a road bike on the hoods), high rolling friction (C_r ~ 0.01), and no dynamic rolling resistance. The model completely ignores your height and uses a fixed value Cd*A in all cases.
That's about what i figured, i emailed the person who has repsonded to requests in the forums to ask for more details, see if they respond i'll i'll post more details here if they agree
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Old 06-29-12, 05:11 PM   #9
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The bike is a 30 pound MTB with dual purpose tires. You do get a decent amount of air resistance at speed.
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