Want to Improve Performance? Learn How to Manage Glycogen

Glycogen is a term often used in endurance sports.

But what is glycogen and why should it matter to you?

Read on to find out what glycogen is, how to manage glycogen, and why glycogen is crucial to improve your athletic performance.

What is glycogen?

In simple terms, glycogen is a form of glucose that your body stores for fast energy, primarily in the muscles and liver.

To fill your glycogen stores, you must consume carbohydrates.

Whenever you consume carbohydrates, your body digests them into glucose. The body uses glucose for energy and transforms extra glucose into glycogen to be used for energy later. This process is called glycogen synthesis or glycogenesis.

As your body's main source of energy, glycogen obviously takes an important role to sustain your body functions, which includes both physical and mental activity.

When glycogen stores become depleted, your ability to sustain exercise intensity can decline significantly. As an endurance athlete, this is something you should definitely keep in mind!

How much glycogen is stored in the body?

Your body can store about 100 grams of glycogen in the liver.

It can also store glycogen in the muscles, about 1 to 2% of the muscle mass, which on average means around 400 grams.

Glycogen is also stored in very small amounts in other tissues, such as brain, kidneys, and even blood cells.

Depending on your muscle mass and ability to store glycogen, your body may store from 500 to 600 grams of glycogen.

When will the body use glycogen?

When glucose is not available, your body will use liver glycogen to manage glucose levels in your blood. That's because only liver glycogen can be delivered to other parts of your body.

On the other hand, muscle glycogen can only be used to fuel the activity of the specific muscle it is stored in.

Also, as exercise intensity increases, your body generally relies more heavily on carbohydrates, including muscle glycogen, for energy.

If you want to increase your VO2 max, check out our training plan! 

Your body can store around 500 grams of glycogen in the muscles and liver to be used as fast energy when glucose is not available.

Glycogen during exercise

During exercise, especially intense endurance exercise, your body needs a lot of energy. As the intensity of your exercise increases and you approach your VO2 max, your metabolism goes up, while your digestion goes down.

This means that glycogen becomes increasingly important, as your body will rely on its glycogen stores to keep running.

During prolonged, intense exercise, glycogen stores can become substantially depleted, especially if carbohydrates are not consumed during the activity. As glycogen availability becomes low, your ability to maintain exercise intensity can decline significantly — the phenomenon endurance athletes often describe as “bonking” or “hitting the wall.”

For this reason, endurance athletes pay special attention to glycogen and use several strategies to keep glycogen stores as full as possible.

Consuming carbohydrates during prolonged exercise can help provide an additional source of glucose and reduce reliance on stored glycogen.

Since your glycogen stores are directly linked to your carbohydrate intake, most of these strategies revolve around nutrition.

Let's look into it.

How to manage glycogen with nutrition?

If you want to keep your glycogen stores as full as possible, you need to intake a sufficient amount of carbohydrates.

But simply intaking large amounts of carbohydrates is not the way. You must also respect your body's ability to digest carbohydrates and the natural limits of your glycogen stores. While both can be improved with training, there are limits to that as well.

To properly manage your glycogen stores, you should consume carbohydrates before, during, and after exercise.

Glycogen stores before exercise

Ideally, you want to begin your endurance exercise with your glycogen stores fully loaded.

To achieve that, athletes use a strategy named carbohydrate loading. Basically, this involves eating plenty of carbohydrates in the days (or hours) leading to the physical activity.

While there are several detailed strategies out there how to best perform carbohydrate loading, you can follow these simple guidelines.

• Eat primarily fast-acting, high glycemic index carbohydrates.
• Avoid eating too much dietary fiber, as it may cause digestive issues.
  
• Take at least one full day to properly fill your glycogen stores, but if that is not an option, eat a breakfast filled with fast-acting carbohydrates.
  

Fill your glycogen stores before exercise with carbohydrate loading.

Glycogen stores during exercise

During intense exercise, you want to preserve your glycogen stores as long as possible.

To achieve this, you need to sustain a sufficient intake of carbohydrates. The amount required depends on the intensity of your exercise and your physical preparation, but a rule of thumb is 60 to 90 grams of carbohydrates per hour.

The ideal source of carbohydrates is a combination of two simple sugars, glucose and fructose.

Glucose is rapidly absorbed and can provide an additional source of carbohydrate during exercise.

Fructose and glucose are absorbed through different intestinal transport mechanisms. Consuming them together can increase carbohydrate absorption compared with glucose alone, particularly when carbohydrate intake is high.

To sustain such a carbohydrate intake, athletes primarily use energy gels and isotonic drinks, but sometimes they also use other sources of food, such as gummy bears, bananas, or white bread.

Energy gels and carbohydrate drinks are convenient ways to consume carbohydrates during prolonged endurance exercise.

Glycogen stores after exercise

After several hours of intense exercise, glycogen stores may be substantially depleted, even when carbohydrates are consumed during exercise.

You should refill your glycogen stores as soon as possible.

Refilling glycogen stores is part of recovery, which also includes protein to support the maintenance of muscle mass and replacing fluids and electrolytes lost during exercise.

While you can achieve this with regular food, recovery drinks offer a convenient way to consume carbohydrates, protein, and electrolytes after exercise.

A recovery drink is a convenient way to consume carbohydrates after exercise.

Negative effects of glycogen depletion

The main negative effect of glycogen depletion is running out of energy. Whether you are an endurance athlete or working at the office, your body needs energy to sustain physical and mental activity.

Prolonged or demanding exercise can place physiological stress on the body, while also reducing muscle glycogen stores.

There are several negative effects of long-term stress, which is something that affects several endurance athletes.

• Insufficient recovery can reduce training quality and performance.
• Illness and injuries prevent you from training and progressing.
• This prevents you from realizing your full athletic potential.

Since depleting glycogen stores is a regular process in endurance sports, stress is a constant factor you should be mindful of. Additionally, you may suffer from stress because of your mental processes. In this case, check out these useful tips from a sports psychologist.

Conclusion

Glycogen is glucose stored as energy in your muscles and liver.

During intense exercise, glycogen stores can become substantially depleted over time, which can reduce your ability to sustain performance.

To support carbohydrate availability, consume carbohydrates before and during prolonged exercise, and after exercise as part of recovery.

Energy gels and isotonic drinks are convenient ways to consume carbohydrates during prolonged exercise. After exercise, a recovery drink can provide a convenient source of carbohydrates and protein.