No, there isn't an additional run/sprint button. :)
The levels are specifically built for having multiple pathways between checkpoints. Generally speaking the easier paths are more obvious (but slower) while the less obvious paths are faster but harder to pull off. Balancing those paths is (in terms of level design) a bit tricky because i didn't want to have faster paths which are easy (or easier) to pull off compared to the more obvious paths. :P
So in order to get better times you will have to experiment a bit with the level geometry in each map and look for potential pathways to reduce your time even more. :)