Why are players given more carbohydrates a day before a game?

December 2, 2025 •

3 min read

Studies have shown that maximizing the body's glycogen stores can improve endurance performance by 2-3% in activities lasting longer than 90 minutes. This is the primary reason why players are given more carbohydrates a day before a game—a nutritional strategy known as carbohydrate loading.

Quick Summary

This article explains the physiological science behind carbohydrate loading, a crucial strategy used by athletes. It details how increased carbohydrate intake maximizes the body's glycogen stores, serving as a vital fuel source for sustained energy and peak performance during high-intensity exercise or endurance events.

Key Points

Glycogen Storage: Consuming more carbohydrates before a game fills muscle and liver glycogen stores, the body's primary energy reserve for exercise.
Fatigue Delay: Maximizing glycogen levels helps delay the onset of fatigue, allowing athletes to maintain a high performance level for longer durations.
Mental Acuity: A steady supply of glucose, fueled by carbohydrates, supports brain function, helping athletes maintain focus and make better decisions under pressure.
Hydration Connection: Carbohydrate loading requires increased fluid intake, as every gram of stored glycogen binds with several grams of water, further aiding performance.
Low-Fiber Focus: Athletes often switch to lower-fiber carbohydrates in the days before a game to prevent gastrointestinal discomfort and bloating during the event.
Strategic Timing: The timing of meals and snacks is crucial, with larger meals 3-4 hours before competition and smaller, easily digestible carbs closer to the start time.

The Science of Carbohydrate Loading

The practice of giving players more carbohydrates before a game is rooted in the body's energy-management system. When we eat carbohydrates, the body converts them into glucose, which is then stored as glycogen in the liver and muscles. This stored glycogen is the body’s primary and most readily accessible fuel source for high-intensity, prolonged exercise.

Maximizing Glycogen Stores: The Goal of Pre-Game Nutrition

During an intense game or endurance event, the body rapidly depletes its glycogen stores. As these reserves dwindle, the body begins to slow down, and the athlete experiences a phenomenon known as "hitting the wall" or "bonking". By significantly increasing carbohydrate intake in the 24 to 48 hours before an event, athletes can super-saturate their muscles and liver with glycogen, essentially topping off the fuel tank. This strategy ensures that players begin the game with maximum energy reserves, delaying the onset of fatigue and allowing them to maintain a high level of performance for a longer period.

Low-Fiber Carbs for Peak Performance

To effectively carb-load without causing digestive issues, athletes typically opt for low-fiber carbohydrate sources during the final day or two before an event. While whole grains and vegetables are important for overall health, their high fiber content can lead to bloating or discomfort when consumed in large volumes. White rice, pasta, and refined grains are preferred during this phase, as they are easily digestible and provide a concentrated source of carbohydrates. It is also crucial for athletes to increase their fluid intake, as every gram of stored glycogen also binds with 3-4 grams of water. This extra hydration is a bonus, further supporting performance during the game.

The Timing of Carbohydrate Intake

Proper timing is essential for effective pre-game fueling. The main, high-carbohydrate meal is typically consumed 3-4 hours before the game, allowing sufficient time for digestion. Closer to the event, a smaller, easy-to-digest carbohydrate snack can provide a quick top-up of energy. This strategy ensures the body has both a long-lasting fuel supply and immediate energy available.

Comparison of Carb-Loading Strategies

There are several approaches to carbohydrate loading, though recent research has favored simpler, more practical methods over older, more restrictive ones.


Strategy	Duration	Exercise Taper	Daily Carbohydrate Intake	Key Features
Traditional Method (e.g., Saltin Diet)	6 days	Initial depletion phase (3-4 days heavy exercise, low-carb diet) followed by taper (3-4 days light exercise, high-carb diet).	Very high (8-10 g/kg body weight) during loading phase.	Exhaustion phase can be detrimental to mood and training quality. Now largely considered unnecessary for trained athletes.
Modern Method (24-48 hours)	1-2 days	Reduction in training volume and intensity (taper).	High (10-12 g/kg body weight).	Effective, shorter, and less stressful for the athlete. Relies on the natural glycogen-storing capacity of well-trained muscles.
General Pre-Game Fueling	Day-of-Game	Standard warm-up.	High-carb meal 3-4 hours prior, followed by smaller snack closer to game time.	Appropriate for events shorter than 90 minutes or as a standard part of game-day nutrition for all sports.

Beyond Endurance: Brain and Skill Performance

While the primary benefit is energy for muscles, research also shows that ingesting carbohydrates can improve brain function and mental acuity during prolonged exercise. A study on soccer players found that those who consumed carbohydrates during a simulated 90-minute match performed better on skill-related tasks like agility and dribbling, especially toward the end of the game when fatigue typically sets in. This occurs because glucose is the primary fuel for the brain, and maintaining blood glucose levels helps sustain concentration and decision-making when the body is under physical stress.

Conclusion

In summary, the strategic increase in carbohydrate intake a day or two before a game is a fundamental sports nutrition strategy for maximizing performance. By topping up the body's glycogen stores, athletes can sustain higher intensities for longer, delay fatigue, and maintain mental focus throughout competition. While the specific approach may vary, the core principle remains consistent: a robust supply of readily available fuel is the key to unlocking peak athletic potential. For further guidance on sports nutrition strategies, athletes can refer to resources from authoritative sources like the National Institutes of Health.

Frequently Asked Questions

Carbohydrate loading is a nutritional strategy used by endurance athletes to increase the amount of glycogen stored in their muscles and liver before a competition by significantly increasing carbohydrate intake over a few days while reducing exercise volume.

Glycogen is the stored form of glucose and is the body's primary and most easily accessible fuel source during high-intensity exercise. Maximizing these stores is critical for maintaining energy levels and delaying fatigue during prolonged physical activity.

Effective carbohydrate loading typically takes place over 1 to 3 days, combined with a reduction in training volume (tapering). In this period, athletes consume a high-carbohydrate diet to build up their glycogen reserves.

Carbohydrate loading is most beneficial for endurance athletes competing in events lasting longer than 90 minutes, such as marathons, long-distance cycling, or triathlons. It is less necessary for shorter-duration or lower-intensity activities.

The best foods for carb-loading are high in carbohydrates and low in fiber to promote easy digestion. Examples include white rice, pasta, potatoes, bagels, and fruit juices.

Temporary weight gain of 2-4 pounds is common during carb-loading due to the extra water stored alongside glycogen in the muscles. This should not be a concern, as it is a sign that the body's energy reserves are being successfully built.

To prevent gastrointestinal issues, athletes should limit their intake of high-fiber foods, such as whole grains and fibrous vegetables, and reduce foods that are high in fat or protein, which can slow digestion.