Stride length relationship with calories burned

[wicked_sticky]

Will a larger stride length increase or decrease calories burned?  (or does it not matter)

Increasing max heart rate to 220 get me realistic walking numbers, but then high intensity cardio exercises are only slightly higher than walking casually.  

For me, fatburn should start at 110 bpm, 100% is 180bpm, Fitbit only lets you fix one # not both, so Im trying to find a happy medium.

[JohnnyRow]

Calorie burn is a function of heart rate.  Stride length should make no difference.

I see you are age 40 which makes your max HR 180 (220 minus 40).

I question how you came up with 110 for start of fat burn.  I realize you are trying to adjust for a high resting heart rate but I doubt the usefulness of trying to fudge the numbers to fit what you think the zones should be for HR.  Unless you have had some medical test to determine the parameters, I suggest just sticking with what Fitbit says.

[wicked_sticky]

I did have my metabolic rate tested so I do have fairly accurate info. 
But even if I didn't, the 220-age formula is meant to estimate max heart rate, not metabolic effort/work/zone.   
50% effort for a 40y/o a resting heart rate of 90 is very different than 50% effort with a resting heart rate of 60.  
Karvonen formula is supposed to be used to determine fat burn/cardio calorie burn rates.  
((MaxHR - RestingHR)  x %intensity) + RestingHR 

I dont think fitbit is properly correcting for resting heart rate. 

EDIT: I'm not bashing on fitbit, I went off topic, I hate the 220-age x 50,60,70,80,90% formula thats being careless used on fitness sites. BUT that said, firbit is not going solely on heart rate, some movement is involved. A steady heart rate is never an equally steady calorie consumption. Some trackers dont even have heart rate and FB still gives a calorie burn.