The link below gives a formula to more accurately calculate carbohydrate loading needs prior to racing.
“People think hitting the wall is inevitable, but it’s not,” says Harvard-MIT scientist Benjamin Rapoport, who has run 18 marathons, including a personal best of 2:55 at this year’s Boston Marathon. “In order to avoid it, you need to know what your capabilities are.”
See below for the full article:
An interesting running technique course published by James Dunne on form, technique and injury prevention is also available: Here