Richard stated it well. However personally I feel like I don't get sh*t out of high reps abs and when doing my lifting they are being worked for their stabilizing role as well as when I'm running. I don't really do max sets of 10 with extreme weight but I am a fan of Kneeling cable pulldowns, Weighted Decline situps, Decline MB Throws against the wall, Body curls!!, hanging leg raises, Landmine Rotations and Russian Twists. All done anywhere from 10-20 Reps.