I to stick with stuff that' s not going to put alot of stress on my body when I'm try to put on mass. Running I believe is too catabolic, unless it's at a very slow pace. I surf, but not alot during bulking phases because it just burns way too many cals. I like to walk on the treadmill at a 15%incline at 3.0 miles per hour and keep my heart rate between 120-130b/min. It's great for tightening up your ass and melts the fat off...try it out.