As for David's comments on weight training, simply incorrect. Proper weight training brings the entire body into play. Exercise physiologists have found, for example that Olympic style weight lifters are, on the indexes of strength, power, flexibility and joint stability to be the best athletes in the world. Yes, if you exclusively do isolation exercises for body building, one can exercises for form, not function. But that is not weight training, per se.
An interesting aside is that these guys have some of the highest verital leaps of any athletes with some of them reaching the mid 30 inches. Just a meaningless tidbit that surprised the heck out of me when I learned it.
Anyways, virtually every high caliber athlete in the world trains with weights. I'd bet it's something on the order of 95%, or more, of Olympic athletes which leaves me to wonder why folks in this art can be so rigid in their resistance to it.
A link to some shoulder exercises