The human body was not really designed to absorb food during exercise, but in an Ironman race the body must defy its nature and absorb food anyway. Completing an Ironman is a 10,000-calorie task. Without refueling on the go, it could be done only at a crawl. Some bodies absorb food energy during exercise better than others, and in Ironman this ability is almost as important as speed and endurance. Many a successful short-course triathlete has failed to make the jump to Ironman because his gastrointestinal system wasn’t up to the challenge, even though his lungs and muscles were.
