Yeah, interesting point. I've read somewhere (can't remember where) that taking AAS while doing lots of cardio related exercise can increase the size of your heart, as your heart is a muscle too.
I suppose it makes sense.
An increase in heart size has got it's obvious health problems.
Though wouldn't Rugby be more stop start running?
I think this article related to longer distance runners. Still, be careful and don't take any advice from me - a Biology gcse dropout!