Carbohydrate loading
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In sports, carbohydrate loading, also known as carbo-loading, is a strategy employed by endurance athletes such as marathon runners to maximize the storage of glycogen in the muscles.
The protocol of carbohydrate loading was originally developed in 1967 in Sweden. The original theory of carbohydrate loading was that, if the body's glycogen stores were depleted, it would store more glycogen than normal when carbohydrate intake returned to normal. Consequently, the original carbo-loading regimen began one week before the event, and called for three days of minimal carbohydrate intake and exercise to deplete the body's carbohydrate stores. Then for the next three days, the athlete would consume primarily carbohydrates, and reduce the intensity of exercise to allow for maximum storage.
In the 1980s, further research led to a modified carbo-loading regimen that eliminates the depletion phase, instead calling for increased carbohydrate intake and decreased training for three days prior to the event. Most athletes now follow this modified regimen, and it is recommended by many coaches, although there are some athletes who still follow the original carbo-loading regimen.
Carbohydrate loading is generally recommended for endurance events lasting longer than 90 minutes. For many endurance athletes the food of choice for carbo-loading is spaghetti. Because of this, hundreds of marathons and triathlons have huge spaghetti dinners the night before the race.
However, there have been some more recent experiments with increasing glycogen storage. The most promising is one developed in Australia. Here is a snippit from an article that was published on several web pages, I copied this from the Leukemia & Lymphoma Society Team in Training web site:
The Western Australia method
The newest and perhaps the best of all the carbo-loading strategies was devised in 2002 by scientists at the University of Western Australia. It combines depletion and loading and condenses them into a one-day time frame.
The creators of this innovative protocol recognized that a single, short workout performed at extremely high intensity creates a powerful demand for glycogen storage in both the slow-twitch and fast-twitch fibers of the muscles. They hypothesized that following such a workout with heavy carbohydrate intake could result in a high level of glycogen supercompensation without a lot of fuss.
In an experiment, the researchers asked athletes to perform a short-duration, high-intensity workout consisting of two and a half minutes at 130 percent of VO2max (about one-mile race pace) followed by a 30-second sprint. During the next 24 hours, the athletes consumed 12 grams of carbohydrate per kilogram of lean muscle mass. This resulted in a 90-percent increase in muscle glycogen storage.
| The Western Australia Carbo-Loading Method
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Runners have cause to be very pleased by these findings. Doing just a few minutes of high-intensity exercise the day before a competition will not sabotage tomorrow's performance, yet it will suffice to stimulate the desirable carbohydrate "sponging" effect that was sought in the original Ahlborg protocol. This allows the athlete to maintain a normal diet right up until the day before competition and then load in the final 24 hours.
The Western Australia carbo-loading strategy works best if preceded by a proper taper -- that is, by several days of reduced training whose purpose is to render your body rested, regenerated, and race-ready. In fact, several days of reduced training combined with your normal diet will substantially increase your glycogen storage level even before the final day's workout and carbohydrate binge.
When you exercise vigorously almost every day, your body never gets a chance to fully replenish its glycogen stores before the next workout reduces them again. Only after 48 hours of very light training or complete rest are your glycogen levels fully compensated. Then the Western Australia carbo-loading regimen can be used to achieve glycogen supercompensation.
Having said all of this, I would like to note finally that carbo-loading in general has been shown to enhance race performance only when athletes consume little or no carbohydrate during the race itself. If you do use a sports drink or sports gels to fuel your race effort -- as you should -- prior carbo-loading probably will have no effect. But it doesn't hurt to do it anyway, as insurance.
So the morning before the marathon I'll be sprinting hard for just a few minutes before breakfast. This may seem odd training for an endurance event but this same recommendation is in Ellen Coleman's book, "Eating for Endurance."I should add that tapering is a part of the carbo-loading ritual and during the taper period it is important to maintain a low fat, high carbohydrate diet and increase hydration--for every gram of carbohydrate (glycogen) the body stores, it also stores 3-5 grams of water. I've been drinking one gallon of fluids per day during my taper phase. Basically, a quart of Hydralyte in the morning workout, a quart of water before lunch, a quart after lunch and a quart of Poweraid, which isn't ideal but is available at the commissary where I work, between 4-5pm. I don't gulp it down but sip throughout the day and try to stop before 6pm to avoid too many nightly bathroom breaks.
I've heard stories of how some endurance athletes get a "stuffy" feeling in their muscles during this taper/carbo-loading phase. Now I'm experiencing it--or is it just that lethargic feeling from cutting back the exercise? We'll find out soon enough.
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