"Simple, wholesome, real food—not too much, and consumed at exactly the right intervals before & after workouts—is the key to boosting athletic performance."
The key on race day is to get as much water as your stomach can handle -- one coach (Benji Durden) recommends about a quart of water 1-2 hours before the race, and then almost a half bottle every 6 miles or so. That's a lot of water when you're trying to run 5:30/mile pace!
Be extremely careful if following this advice. Hyponatremia--dilution of the blood resulting in low levels of sodium--is a serious concern for marathon runners. Dehydration during a race won't kill you; hyponatremia might.
Absolutely, positively do not "get as much water as your stomach can handle". Your stomach can handle enough water to kill you.
