Its pretty obvious that he used. Look at him in the terminators, commando, ect, then compare it to movies like the one he was pregnant in (Junior), he had a shirt-less pic in it and he was small as hell.
It is even rumored Will Smill used for the Ali movie, and Nicolas Cage did in Con Air...
Other point, he was cut in T3, then that pic of him above, small. He used have worn a shirt! haha. I know he is busy, but damn, at least do 50 push ups a day.