Carbohydrates consist of sugar molecules that the body converts into energy. They are the body’s main source of fuel, stored in the muscles and liver as glycogen. Broken down into glucose, carbs power both your muscles and brain. They are found in many types of foods.

Why are carbs so important for endurance sports?

At moderate to high intensity, your body prefers carbohydrates over fat. The harder you go, the more dependent you become on carbs, as they are the primary fuel for your muscles.

The glycogen stored in your muscles typically lasts for about 90–120 minutes of continuous, moderate-to-high-intensity exercise before being significantly depleted. This duration can be shorter depending on factors such as exercise intensity, fitness level, body mass, and diet. Once depleted, you “hit the wall.”

Consuming carbohydrates during exercise spares muscle glycogen and keeps blood glucose levels steady. This helps you maintain pace, power, and focus for longer. Carbs fuel not only your muscles but also your brain—low carbohydrate availability leads to reduced concentration and slower decision-making.

Lastly, carbohydrates support recovery. After training, they are essential for replenishing glycogen stores. Faster recovery means better performance in your next session.

Carbs in sports nutrition

In sports nutrition, not all carbohydrates are created equal. Different forms are used depending on how quickly they digest, how they feel on the stomach, and how much energy they deliver.

The most commonly used forms of carbohydrates in sports nutrition are maltodextrin, fructose, sucrose, and dextrose.

• Maltodextrin is technically a complex carbohydrate but digests very quickly and is gentle on the stomach.

• Fructose is a simple sugar. When combined with glucose or maltodextrin, it allows greater carbohydrate absorption per hour.

• Sucrose (table sugar) is a disaccharide composed of 50% glucose and 50% fructose. It is absorbed quickly because the body rapidly splits it into its two components.

• Dextrose is the simplest carbohydrate—essentially glucose itself. It is absorbed extremely fast and spikes blood sugar quickly. It is not very popular among serious athletes because, in higher amounts, it can cause energy crashes and gastrointestinal discomfort.