What Is Carb Loading?

Carb-loading, or carbohydrate loading, is a dietary strategy used by endurance athletes to maximize glycogen stores in muscles before an endurance event. The goal is to ensure that the body has enough readily available energy to sustain prolonged physical activity, especially for events lasting over 90 minutes like marathons, triathlons, or long-distance cycling.

The process typically begins about 3-4 days before the event. During this time, athletes increase their carbohydrate intake to about 8-12 grams per kilogram of body weight per day, while reducing the intensity of training to minimize glycogen depletion. Foods rich in carbohydrates, such as pasta, rice, potatoes, fruits, and whole grains, are ideal choices. These foods help boost muscle glycogen levels, which will be used as the primary energy source during extended endurance efforts.

The reason for carb-loading is to fill muscles with glycogen, which is the body’s stored form of carbohydrates. During endurance exercise, glycogen is a crucial fuel that helps maintain pace and prevent fatigue. When glycogen stores are depleted, athletes may experience a significant drop in energy and performance, often referred to as “hitting the wall.” Carb-loading helps delay this depletion and allows athletes to maintain a steady effort for longer periods.

Hydration is also critical during carb-loading, as glycogen binds with water in the body. Athletes should drink adequate fluids to ensure proper glycogen storage and avoid dehydration. Additionally, it’s important to avoid high-fiber foods during this period, as they may cause gastrointestinal discomfort during the race.

Carb-loading can significantly enhance endurance performance by maximizing glycogen stores, providing sustained energy, and delaying fatigue. For best results, it should be done in conjunction with a well-balanced diet and tailored to individual carbohydrate needs based on body weight and the specifics of the endurance event.