Try the one at the end of PUB. It is pretty tough. Only I try to remember to do it first before the rest of the workout. If I do the ab section AFTER working my upper body, my arms are shaking with planks on the ball!
I used to think it was Muscle Max, but now I have to say that it's PUB. I've never thought to do the ab portion at the beginning like so many of you mentioned - I'll have to try that. Anyway, they're both tough ab workouts!
Paula
ME abs!!!! Gets me every time!! I do like using the medicine ball to work my abs though. The next hardest for me is Muscle Max abs. Tough, but effective.}(
I think PUB is not that bad except for the pikes. With ME, on the other hand, I think Cathe and crew must have necks of steel. If I did all that stuff I'd be in the hospital in traction. Ouch.
I find PUB core tough due to the arm fatigue during the pikes. I typically take a quick break after the roll-ins, and then after the first round of pikes/leg lifts. I keep my form better for the pikes that way.
The hardest end-of-workout ab workout, IMO, is Muscle Max. The bicycles straight into 16 jacknifes, straight into 16 oblique crunches just about kills me. In a good way
PUB is tough, but which one is it that has those explosive crunches where you're supposed to reach the soles of your shoes? I think it's MM. It destroys me.