When on a regular diet, the body is able to store between 1,500 and 2,000 calories in the form of glycogen. About 75 percent of the glycogen is stored in the muscle tissue. This amount, however can be increased greatly through carbohydrate loading.

Glycogen Depletion

Heavy training over several consecutive days leads to glycogen depletion faster than it can be replaced through the diet. Glycogen depletion with athletes is very common during heavy training. Signs of depletion include chronic fatigue, difficulty maintaining training intensity, and lower performance.

Overcoming Depletion

On consecutive days of exhaustive physical training (several hours daily), a carbohydrate - rich diet - 70 percent of the total daily caloric intake, or 8 grams of carbohydrate per kilo of body weight (2.2 pounds) is recommended. This diet will often restore glycogen levels within 24 hours.

Along with the high carbohydrate diet, a day of rest is often needed to allow the muscles to recover from the glycogen depletion following days of intense training. For athletes who train less than an hour a day, a 60 percent diet, or 6 grams of carbohydrate per kilo of body weight is enough to restore glycogen levels.

Accelerate the Process

Following an exhaustive workout, eating a combination of carbohydrates and protein (example: tuna fish sandwich) within 30 minutes of exercise appears to speed up glycogen storage at even a faster rate. Protein intake increases insulin activity, thus enhancing glycogen replenishment. A 70 percent carbohydrate intake should then be maintained throughout the rest of the day.

Maximizing Glycogen Storage

By following a special diet/exercise plan for five days before a long distance event, highly trained (aerobic) athletes are capable of storing two to three times the amount of glycogen found in the average person. Athletic performance may be enhanced for endurance events or more than 90 minutes by eating a regular balanced diet along with intensive physical training the fourth and fifth days before the event, followed by a diet high in carbohydrates (70 percent) and a gradual decrease in training intensity the three days before the event.

Pre-Event Diet

On the day of the long distance event, high carbohydrates are still the recommended choice for food intake. As a rule of thumb athletes should consume 1 gram of carbohydrate for each 2.2 pounds of body weight (1 kilo) one hour prior to exercise. The amount of carbs can be increased to 2, 3, or 4 grams per 2.2 pounds of body weight - 2, 3, or 4 hours, respectively before exercise.

During Competition

During the endurance event it is recommended that 50-60 grams of carbohydrate (200-240 calories) be consumed every hour. This is best accomplished by drinking 8 ounces of 6-8 percent carbohydrate sports drink every 15 minutes. This also lessens the chance of dehydration during exercise, which hinders performance and endangers health.

NOTE: The percentage of carbohydrate drink is determined by dividing the amount of carbohydrate in grams by the amount of fluid in ml, and then multiply by 100. (example: 18 grams in 240 ml (8 oz.) of fluid yeilds a drink at 7.5 percent (18 / 240 x 100 = 7.5%).

REFERENCES:

Coleman E, Eating for Endurance, Palo Alto, CA: Bull Publishing, 1992