Where I live we have the Ironman (gruelling triathlon). My husband and friends all work in the restaurant business, and they've told me that the night before the triathlon all the athletes eat tons of carbs. Some have gone so far as to ask if they can order the pasta water along with their pasta dish. Most of those athletes have told me that they eat loads of carbs the night before (race starts at like 7am, goes all day) to stock up on energy. Seems to work for them, they should know as they train for the race all year.