I have not been doing a bit of cardio so far but I am wondering if I should be doing some cardio or not at this point. I was going to kick off cardio in about a month to lean out for summer. Seems like I read somewhere that there was benefits to doing it on the off days at least at some level. I could be wrong.
I always heard not to do the cardio while trying to bulk up like I am because you want to rest as much as possible when not actually lifting.
I do it as just a warm up before lifting any weights. Just gets your body and blood going prior to goin crazy on some heavy weights. I especially like to do some before a leg workout. Normally I will just run on a treadmill or play some B-ball.
Sprints and other excercises can be great for helping to gain mass in the legs.
I was reading about it here http://www.bodybuilding.com/fun/satter2.htm on bodybuilding.com.
It got kind of technical and looked like the results would be hard to get (it would take a really special type of cardio program).
Just so you didn't think I was pulling that out of thin air or anything