while on you get even more ATP loading in the cells then normal which would equate in theory to more muscle mass do to more cell units recruited, fatigued and replenished while under anabolism
i'm a big fan of running it afterwards starting during PCT. the strength loss from coming off pisses me off, and i find that 10g of creatine is a good way to keep it up a little.
I use them while running pct and off.. thats whats works best for me, helps me keep gaining mass and giving me good pumps while off.. I use kre-alkalyn tabs from EFX. The best creatine ive ever tried.