I'm trying to focus on my weak areas, mostly the upper body in general. The problem is that if I work my legs too hard then they'll get huge. I'm serious it doesn't take too much and my legs get thicker and thicker and my upper body looks small by comparison. Fricken hate this shit, but it could be worse I guess. So i'm focusing my attention on my upper so to balance things out. Anyhow I'm doing alternating wind sprints and hill sprints 3x a week with a heavy upper body routine (heavy weights 3 sets of 5 reps). That's about all I want to do to keep proportional.
I'd like to do more core work such as squats and deads but again I don't want to build legs up. Is there a set and reps scheme that would help build core but not legs?