The watch looks huge, I doubt very much his wrist is much larger than mine if at all. When you lift weights / body build, you can enlarge your biceps, chest etc. but you don't increase the bone structure of your body. I'm 6'5" 240 pounds, not as pumped as Arnold but not wasted away (at 65) and my wrist is a little over 7.5", always been the same size regardless of my strength or muscle mass.
I wouldn't wear a watch that size, a 41mm looks big on my arm...…..