Yeah, I'm taking a guess on this, but I think when you exersise the sweat and clean air going constantly through your lungs, somewhat 'refreshes' then and clenses them.

When this happens to me, I take a mental note of how 'heavy' my lungs feel, and then I'll wait a week and compare how they feel now. Good luck, dude!:thumbsup:

(And don't think about sneaking in a one-hitter every here and there!)