Carb-Loading
Endurance athletes have long been told they must carb-load to fuel themselves before a difficult endurance activity. If you’re a runner, a swimmer, or a cyclist, you might have found yourself downing a huge plate of spaghetti the night before your competition. How does carb-loading work? How much does this nutrition strategy help athletes improve their performance?
What is carb-loading?
Carb-loading, or carbohydrate loading, is a method athletes use to increase their body’s stored glycogen above the usual amount. Glycogen comprises various of linked glucose molecules, allowing the body to store the carbohydrates you eat as energy. To carb-load, athletes begin to consume more carbohydrates multiple days prior to the activity while simultaneously decreasing exercise to prevent the body from burning through those carbs.
Is carb-loading effective?
According to registered dietitian Monica Bearden, it does. In an article with Houston Methodist, Bearden explains that “tapering workouts and increasing carbohydrate intake 1-3 days before a race helps to maximize muscle glycogen, which is the form of energy stored in muscles” (McCallum). Later on, during a race or competition, “your muscles will turn to this muscle glycogen to sustain effort and performance after the carbohydrates from your pre-exercise snack or meal run out” (McCallum).
However, its effectiveness has a limit. Carb-loading has a profound impact on events longer than 90 minutes but does not make much of a difference with activities shorter than 90 minutes. Research has found that higher glycogen content in the muscles “will postpone fatigue by approximately equal to 20% in endurance events lasting more than 90 minutes” (Hawley). Additionally, short, high-intensity exercises such as weight-lifting and sprinting, will not benefit from the glycogen increase obtained through carb-loading (Vandenberghe).
Pros and cons of carb-loading:
While carb-loading has great utility for those who partake in exercise lasting for 90 minutes or more, there are some pitfalls to the strategy. The biggest pro of carb-loading is delayed fatigue, helping athletes persist through long stretches of activity. However, consuming a higher amount of carbs can lead to digestive issues such as constipation, diarrhea, and bloating. How beneficial carb-loading is varies from athlete to athlete.
How to carb-load:
Athletes looking to carb-load need to plan out their diet in the days preceding their event. There are several carb-loading programs around (discussed later in this article) that you can choose from. All these types involve exercising less and eating more carb-rich foods. Increasing carb intake doesn’t mean you need to consume more calories or strictly eat carbs. Instead, you can replace some of the other components of your meals with carbs, increasing the percentage of carbs in your diet. Vitamins, minerals, and protein should not be neglected.
Types of carb-loading:
Here are four different types of carb-loading you can try for your next competition:
6-Day: For the first three days, follow a moderate-carb diet where 50% of the calories come from carbs. In the next three days, increase the percentage to 70% for a high-carb diet. Throughout the six days, slowly decrease the amount of exercise you do.
Classic 3-Day: At the start of the three days, do a workout session that gets your body to exhaustion. For the rest of the three days, don’t exercise at all and follow a 70% carb diet.
Modified 3-Day: This type is the same as the classic 3-day, minus the exercise session at the beginning.
1-Day: For one day before your event, do not exercise. Follow a diet that contains 4.5 grams of carbs per pound, or 10 grams of carbs per kilogram, of body weight.
Conclusion:
Carb-loading, a strategy that involves inflating carbohydrate intake to build up glycogen stores before an athletic event, is a useful tool for endurance athletes looking to maximize their performance in a race. However, for shorter activities at higher intensities, carb-loading is not a viable option for athletes to improve their performance.
Sources:
de Moraes, Wilson M. A. M., et al. “Carbohydrate Loading Practice in Bodybuilders: Effects on Muscle Thickness, Photo Silhouette Scores, Mood States and Gastrointestinal Symptoms.” PubMed Central, PubMed, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873117/. Accessed 20 June 2024.
“Glycogen: What It Is & Function.” Cleveland Clinic, https://my.clevelandclinic.org/health/articles/23509-glycogen. Accessed 16 June 2024.
Hawley, J A, et al. “Carbohydrate-loading and exercise performance. An update.” PubMed, 1997, https://pubmed.ncbi.nlm.nih.gov/9291549/. Accessed 22 June 2024.
McCallum, Katie. “Does Carb Loading Really Work? (& More Questions About Running Nutrition, Answered).” Houston Methodist, 4 October 2023, https://www.houstonmethodist.org/blog/articles/2023/oct/does-carb-loading-really-work-more-race-training-nutrition-questions-answered/. Accessed 16 June 2024.
Stockton, Teresa. “The Pros and Cons of Carb-Loading for Athletes.” PTandMe, 15 September 2021, https://ptandme.com/blog/carb-loading/. Accessed 22 June 2024.
Tinsley, Grant. “Carb Loading: How to Do It + Common Mistakes.” Healthline, 5 July 2023, https://www.healthline.com/nutrition/carb-loading. Accessed 17 June 2024.
Vandenberghe, K., et al. “No effect of glycogen level on glycogen metabolism during high intensity exercise.” PubMed, 1995, https://pubmed.ncbi.nlm.nih.gov/8531626/. Accessed 22 June 2024.