My friends and I talk about the Tour and how guys get either disqualified or drop dead from taking EPO, steroids and/or other banned substances. I wonder what the percentage of people who do Ironman's are taking some sorta of magic powder??? gotta wonder............. Pura Vida, Dave skar :-)
I have wondered about it but at the Ironman races I'd think any stimulant would be bad, you'd just hurt yourself. About the only thing I could think of would be something to make you retain a bit of extra water and salt will do that in the days leading up to a race.
I'm not in the medical field (Cathy? A little help here?), but I'd think that anything that could boost you for 8+ hours would likely kill you once you got on that podium. I would tend to think that if any triathlete was abusing something, it'd more likely be in Olympic distance races.