I just came across this article from the NY Times about this subject. Very interesting. Real Thought for Food for Long Workouts
Here is a small sample of what's in it:
"Here is what is known about proteins, carbohydrates and performance.
During exercise, muscles stop the biochemical reactions used to maintain themselves such as replacing and resynthesizing the proteins needed for day to day activities. It’s not that exercise is damaging your muscles; it’s that they halt the maintenance process until exercise is over.
To do this maintenance, muscles must make protein, and to do so they need to absorb amino acids, the constituent parts of proteins, from the blood. Just after exercise, perhaps for a period no longer than a couple of hours, the protein-building processes of muscle cells are especially receptive to amino acids. That means that if you consume protein, your muscles will use it to quickly replenish proteins that were not made during exercise.
But muscles don’t need much protein, researchers say. Twenty grams is as much as a 176-pound man’s muscles can take. Women, who are smaller and have smaller muscles even compared to their body sizes, need less.
Dr. Rennie said that 10 to 15 grams of protein is probably adequate for any adult. And you don’t need a special drink or energy bar to get it. One egg has 6 grams of protein. Two ounces of chicken has more than 12 grams.
Muscles also need to replenish glycogen, their fuel supply, after a long exercise session — two hours of running, for example. For that they need carbohydrates. Muscle cells are especially efficient in absorbing carbohydrates from the blood just after exercise.
Once again, muscles don’t need much; about one gram of carbohydrate per kilogram of body weight is plenty, Dr. Tarnopolsky said. He weighs 70 kilograms, or 154 pounds, which means he would need 70 grams of carbohydrates, or say, 27 ounces of fruit juice, he said."