Heard an old school trainer once say it had to do with testosterone levels. I don't really believe that. I thinks more about distractions and control. Once you get some, all you're thinking about is getting some more... which means you're not concentrating on what you should be doing. That and Thinking about it this way, who would you listen to? The girl that gave you some or the guy thats trying to keep you from getting any?

Personally, I find it better to let a fighter get rid of the itch (as long as its on their own time) and then get down to business. We think about sex about every 2 seconds, anyway. Let something like that build and a fighter gets no rest even when they are supposed to be relaxing.