In an effort to make these sub-topic posts on nutrition more digestible (ahem, sorry for that), I want to break them down sufficiently enough so that your interest does not wane in the middle of reading one. Any post about carbs and sports could get out of control long if I'm not careful.
From a performance standpoint, I don't think anyone will argue the fact that we need to ingest carbohydrate to continue to train and race in endurance activities. We've covered this before in these pages. Let's recap the salient points as a segue to this post's topic. First of all, training and racing is supported primarily by glycogen which is stored in a limited capacity in the liver and muscle cells. At race intensity, we can last between 90 and 120 minutes before this supply is exhausted. By ingesting carbohydrate (which is converted to glycogen) during exercise we can stave off exhaustion almost indefinitely. We seem to be able to process about 300 kcal/hour. Yes, I know, fat is part of this energy equation, too, but I want to keep things simple here for the sake of discussion. Some athletes use fat for energy better than others but glycogen and, thus, glucose is still the main player for most of us. Bottom line is carbs are are both good and necessary for athletes.