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Carbohydrate loading helps athletes improve performance

Maggie McDaris is a dietetic intern at MUSC
Athletes training for a big endurance event should develop a strategy for carbohydrate loading to enhance performance.

Carbohydrate loading involves the  increased consumption of carbohydrates, which means making them a greater percentage of the total calories, in preparation for an endurance event. It also involves a gradual decrease of training in the days and weeks before competition. Carbohydrate loading ensures that the body’s glycogen stores are topped off before an event. Glycogen is the storage form of carbohydrate found in the liver and skeletal muscles that provides energy during exercise.
While performing high-intensity exercise, the body can deplete between 38 percent and 88 percent of its muscle glycogen stores, according to Nancy Clark’s “Sports Nutrition Guidebook.” Glycogen also helps maintain normal blood glucose levels and hydration status during an endurance event. Three grams of water (about 0.1ounce) are stored per gram of glycogen stored.

Carbohydrate loading is not for everyone or every type of athletic event. Carbohydrate loading is most beneficial in well-trained athletes competing in endurance events lasting 90 minutes or more. Marathon runners (full and half), distance swimmers, triathletes, cyclists, cross-country skiers, and professional soccer players are examples of athletes who would benefit from carbohydrate loading. Football, basketball and volleyball players, weight lifters and recreational runners would not benefit from carbohydrate loading strategies.

Current research has shown that an athlete training for a high-endurance event should consume a high carbohydrate diet (55 to 60 percent of total calories from carbohydrates) on a daily basis in order to replace muscle glycogen lost in training. The actual carbohydrate loading process should begin three days before an event accompanied by a tapering of training that begins two weeks prior to the event. During the three-day loading period, carbohydrate consumption should increase to about 70 percent of total daily calories.  When carbohydrate loading, focus on whole grains instead of refined sources of carbohydrate such as sugary breakfast cereals, white rice, tortillas, and French fries.

Below are seven steps to successful carbohydrate loading
1. Carbohydrate load daily to replenish stores lost in training. A general rule of thumb is to consume 55 percent of total daily calories from carbohydrates (or three to five grams of carbohydrates per pound of body weight).

2. Taper training. Current research suggests that a 10 to 13 day taper is more effective than a seven-day taper.

3.Eat enough protein. Athletes should consume between 0.8 and 1.0 grams of protein per kilogram of body weight.

4. Choose carbohydrates wisely. Avoid foods that are high in both carbohydrate and fat. Don’t load up on refined bread products or fruit and avoid alcohol and unfamiliar foods.

5. Plan meals and meal times carefully. Consume a light, familiar breakfast on event day to maintain blood sugar and prevent hunger.

6. Choose fiber-rich foods. Carbohydrate loading on low-fiber foods can increase the likelihood for constipation and gastrointestinal distress during an event.  Instead, consume more complex carbohydrates such as whole grain breads, fruits and vegetables and oatmeal.

7. Drink more water. Proper carbohydrate loading should be accompanied by a two-to-four-pound water-weight gain. This practice is also important as fiber intake increases to avoid bloating and constipation.

Friday, Oct. 1, 2010

The Catalyst Online is published weekly by the MUSC Office of Public Relations for the faculty, employees and students of the Medical University of South Carolina. The Catalyst Online editor, Kim Draughn, can be reached at 792-4107 or by email, Editorial copy can be submitted to The Catalyst Online and to The Catalyst in print by fax, 792-6723, or by email to To place an ad in The Catalyst hardcopy, call Island Publications at 849-1778, ext. 201.