Ultimate Fighting Question

[ewile]

I was just watching Ultimate Fighting on TV. I'd never seen it before. A question: Alot of the fights ended where one guy would get the other in an "arm bar" and the guy would submit in like a second.

Is there sick pain in that first moment or does the guy just know that he can't get out and his arm is about to be snapped like a chicken wing. In other words, is it the pain in the moment or the anticipation of pain that causes such a rapid submission?