Add an algorithm for calculating kcal burned from running/walking/biking etc. based on distance travelled, instead of speed. Since the deciding factors for burning kcal in these exercises is WEIGHT and DISTANCE TRAVELLED, rather than SPEED and TIME.
It's true that if you know exactly how fast you run and exactly for how long, it should add up the same kcal burned, however it is much easier to just enter the distance travelled and have the app calculate how many kcal is burned with the users registered weight with the given distance.
I believe this would provide much more accurate results from these activities.

The most simple way to put this equation is weight*distance=kcal.
Example: weighing 80 kg * running 10 km = burning 800 kcal.

Naturally there are more factors to take into account when exercising, but this is an improvement. Speed, terrain and style can have an impact, but for most people who don't run 10+ km regularly the impact will be minimal.

Hope this gets added.