Ahh.. figured it was hollywood bull$hit. It seems like every movie still has dudes lifting weights in a court yard.

I have no doubt about doing one arm pullups making you strong. I just recently accomplished this myself but I had to loose a ton of weight to do so (from 198 -> 168). When I lost the weight I got a lot weaker and less powerful (albeit I certainly look better). I have feeling my old fat self could take more physical abuse.