Carb loading, or muscle glycogen supercompensation, is a process used to increase glycogen storage in the muscles beyond normal levels. It is hoped that this extra storage will then allow athletes to maintain their exercise for a longer period of time before exhaustion starts to kick in. While this is may seem like great news, there are still a lot of misconceptions out there about carb loading, how to do it, and who will profit from it.
Who: Carb loading is mostly beneficial to long distance and endurance athletes who are competing for 90 minutes or longer and need the extra energy in order to continue at the same pace for the whole event. This is because the extra glycogen does not allow athletes to workout harder or with more intensity, but rather it will only be used once normal levels have been depleted.
How: I have heard from many coaches and athletes refer to eating a heavy carbohydrate meal the night before the big race as carb loading, but this may not be enough. Taking in extra carbs after and intense (glycogen depleting) practice the day before the competition will help more efficiently restore muscle glycogen, and may be able to increase storage above the normal amount, but it might not be enough to maximize glycogen storage completely. This one day carb loading process is simple and easy, and the research so far looks promising, but it has yet to show the same results as the standard six day approach to muscle glycogen supercompensation.
In the more traditional approach to carb loading, the process needs to be started an entire week before competition. During the first three days of this method, exercise and training should be slowly reduced each day, while the carbohydrates in the diet are lowered (to 5 g/kg) in order to deplete muscle glycogen. During days 4 to 6, training continues to be tapered off to about 20 minutes a day until day 6, which should be a rest day. During this second phase, days 4-6, daily carbohydrate intake is doubled (to 10 g/kg) so that by day 7, the day of the competition, muscle glycogen stores will be as high as possible.
Clark, Nancy. “Carbohydrate to Fuel Muscles.” Nancy Clark’s sports nutrition guidebook. 4th ed. Champaign, IL: Human Kinetics, 2008. 114-119. Print.
Dunford, Marie. “Carbohydrate and Exercise.” Sports nutrition: a practice manual for professionals. 4th ed. Chicago, Ill.: American Dietetic Association, 2006. 19-21. Print.