Training for/coping with stomach issues?

Hi there,

I just recently completed Ironman Canada, and overall had a fantastic day. However, the biggest single issue I saw was stomach shutdown in the late bike/early run. Any ideas how someone can train for these issues? It happened to me and all my training partners, although we all raced with the same nutrition we trained with, and even had professional advice as to the amounts of carbs, etc, that we took in.

I didn't sign up for next year, but I can imagine doing such a race again. I am wondering, however, how people cope with this issue? Does it just happen every race and people just get used to it?

Any thoughts?

Thanks!