Exercise log miscalculation?

[theoairplane]

I hope I'm posting this under the right category. 

I have a regular distance I bike and an average time it takes me to do it. There are days when it is more and days when it is less. Tonight I was able to cut my minutes per mile down by 34 seconds. When I very excitedly put in the information into the exercise log I noticed that despite doing the same distance in much less time than my average, I am only logging 3 more calories burned than I would with my average time. Now I'm not a mathematician or a doctor, but should I not be burning more when doing the same distance in less time? Given the state I was in after doing it I would assume I burned a solid amount more, so why is it not showing this when I calculate on the app? I know it's an imperfect science but I found this confusing. 
Has any one else noticed this?

[TandemWalker]

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@theoairplane wrote:

I hope I'm posting this under the right category. 

I have a regular distance I bike and an average time it takes me to do it. There are days when it is more and days when it is less. Tonight I was able to cut my minutes per mile down by 34 seconds. When I very excitedly put in the information into the exercise log I noticed that despite doing the same distance in much less time than my average, I am only logging 3 more calories burned than I would with my average time. Now I'm not a mathematician or a doctor, but should I not be burning more when doing the same distance in less time? Given the state I was in after doing it I would assume I burned a solid amount more, so why is it not showing this when I calculate on the app? I know it's an imperfect science but I found this confusing. 
Has any one else noticed this?

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In the absence of the exact duration and distance, I can only surmise that the 'loss' of calories burned due to the shorter duration of your run offset most of the additional calories due to your incremental effort. Another way to look at it is that you achieved the same burn as you normally do, plus 3 calories, in a lesser amount of time; so that's good, no? Say your normal run is 30 min. and you did in in 15 because of a much higher intensity -- had you gone on for the same 30 min at the same intensity, your caloric burn would likely be double or more your normal burn. Here is an example:

Hope this helps. Have a nice day.

    TW     

(If this tip solved the problem for you, please mark this post solved, as this will be helpful to other users experiencing similar issues.)

[Heybales]

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@theoairplane wrote:

I hope I'm posting this under the right category. 

I have a regular distance I bike and an average time it takes me to do it. There are days when it is more and days when it is less. Tonight I was able to cut my minutes per mile down by 34 seconds. When I very excitedly put in the information into the exercise log I noticed that despite doing the same distance in much less time than my average, I am only logging 3 more calories burned than I would with my average time. Now I'm not a mathematician or a doctor, but should I not be burning more when doing the same distance in less time? Given the state I was in after doing it I would assume I burned a solid amount more, so why is it not showing this when I calculate on the app? I know it's an imperfect science but I found this confusing. 
Has any one else noticed this?

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You are indeed correct.

An additional issue that can happen.

Despite Fitbit asking for exact distance and time to see that better speed, the database entries are still grouped in ranges. When you type in biking you can see those ranges.

So if your speed fell within the same range, it uses the same METS multiplier for all speeds in that range, it doesn't from what I've seen take any original formula and apply it to any speed.

The METS database that most sites use just doesn't provide that info.

In your case, it may have slipped in to the higher range for slightly more calorie burn per minute - but you did less minutes overall.

So only slightly more calorie burn.

If you want a much better estimate to compare to - try this:

http://www.bikecalculator.com/

One comparison with better details - and you may discover that for your speed the estimate from the database is close enough.