What I can remember about Arnie is that he was forced to lose muscle mass prior to film Conan. He was too bulky to move quickly.
For me, it feels like those abs are working. It's much easier to hold all the guts back into its place, and after a few weeks you will be surprised on how everything recedes into the torso so easily. It's a quick exercise with good results, or so they say.
Im doing these three exercises on an almost daily basis: