Glycogen is one of the most important compounds for energy storage in the human body and plays a fundamental role in physical activity, metabolism and sports performance. Although rarely mentioned outside the realm of physiology and nutrition, glycogen is essential for maintaining energy, especially during exercise and periods of fasting. But what really is glycogen and why is it so crucial for our body?
In this article we will explore in depth the role of glycogen, how it is produced and stored in the body, its importance for sports performance and how diet and exercise affect its levels.
What is glycogen?
Glycogen is a polysaccharide, that is, a molecule composed of multiple glucose molecules, a type of sugar that serves as the main source of energy for cells. When we consume carbohydrates, the body converts glucose into glycogen to store it mainly in the liver and muscles. This process allows the body to store energy for times when it is needed, such as during intense exercise or when there is no recent food intake.
An interesting feature of glycogen is its highly branched structure, which allows it to be broken down quickly and efficiently release glucose into the blood when the body needs it. In energy terms, glycogen acts as a rechargeable battery that fills and empties depending on the needs of the moment.
How is glycogen produced and stored?
The process of glycogen formation, known as glucogenesis, occurs primarily after eating, when blood glucose levels rise due to the digestion of carbohydrates. The hormone insulin, secreted by the pancreas, makes it easier for glucose to enter muscle and liver cells, where it is converted to glycogen for storage.
glycogen in the liver
The liver can store between 80 and 100 grams of glycogen, and its main function is to maintain stable blood glucose levels. When we go without food for several hours, the liver breaks down its glycogen into glucose and releases it into the bloodstream to ensure that other organs, such as the brain, receive a constant supply of energy. This is especially important during fasting or overnight, when the body does not receive energy from food.
Glycogen in muscles
On the other hand, glycogen stored in the muscles can represent up to 400 grams or more, depending on the person’s training level and diet. Unlike the liver, muscle glycogen is not released directly into the bloodstream, but is used exclusively as an energy source for muscles during physical activity. This reserve is crucial for activities that require sustained effort, such as running, weight lifting, or swimming.
The importance of glycogen in sports performance
For athletes and physically active people, glycogen is a key factor in performance. During high-intensity exercise, such as sprinting or weight lifting, the body primarily turns to glycogen stored in the muscles as a quick source of energy. Glycogen levels in your muscles can be depleted after approximately 90 to 120 minutes of intense activity, often leading to fatigue and a decline in performance.
Glycogen cycling: Endurance athletes, such as marathon runners and cyclists, have adopted “carbohydrate loading” techniques in their training plans, which involve consuming a higher amount of carbohydrates in the days before a competition. This method helps maximize glycogen stores in the muscle, improving endurance and delaying fatigue. Additionally, recovery after exercise is largely dependent on the body’s ability to restore glycogen levels through carbohydrate intake.
What happens when glycogen reserves are depleted?
Glycogen depletion is commonly known in sports as ‘hitting the wall’. When glycogen stores are depleted, the body has to rely on fats as its primary source of energy. Although fat provides a longer-lasting source of energy, it is not as quick as glycogen to meet the energy demands of intense exercise. This change in energy source usually causes a decrease in performance, as well as feelings of weakness and fatigue.
During prolonged or high-intensity exercise, athletes should consume carbohydrates in the form of gels, sports drinks, or carbohydrate-rich foods to delay glycogen depletion. Maintaining optimal glycogen levels allows muscles to remain active and maximizes performance during physical activity.
Diet and glycogen: how does diet affect?
The amount of glycogen that the body can store depends directly on the diet and the type of activity each person performs. Below are some important aspects to consider:
1. Carbohydrate consumption– Adequate carbohydrate intake is essential for glycogen storage. Diets rich in carbohydrates (60-70% of calories) can help maintain high glycogen levels, especially in high-performance athletes.
2. Effect of low carbohydrate diets: Low-carb or ketogenic diets limit the amount of glycogen in the body by reducing the amount of glucose available to be converted into glycogen. Although some endurance athletes have adapted these diets to optimize the use of fat for energy, other sports that require explosiveness often benefit more from a carbohydrate-rich diet.
3. Recovery and restoration of glycogen: After intense physical activity, the body needs to restore its glycogen levels to accelerate muscle recovery. Studies indicate that consuming carbohydrates and protein in a 3:1 ratio within the first two hours after exercise promotes glycogen resynthesis.
Glycogen and its relationship with health
Beyond athletic performance, glycogen also has implications for overall health. Maintaining adequate glycogen stores helps regulate blood glucose levels and prevent episodes of hypoglycemia, especially during periods of fasting. Additionally, liver glycogen is essential for proper brain function, which relies heavily on glucose as an energy source.
Glycogen-related disorders
There are some rare metabolic disorders, known as glycogenosis or glycogen storage diseases, that affect the body’s ability to properly break down or store glycogen. These conditions, such as Pompe disease and McArdle disease, are often genetic and can cause muscle problems, hypoglycemia, and other serious metabolic problems.
On the other hand, in conditions such as type 1 diabetes, a lack of insulin affects the formation of glycogen in the liver and muscles, which can destabilize blood glucose levels. For people with diabetes, controlling glycogen storage and breakdown is a critical part of managing the disease.
Glycogen is much more than just an energy reserve; It is a crucial resource for the functioning of the body, especially in situations of physical effort and fasting. In sports, glycogen makes the difference between optimal performance and fatigue, while in the context of health it is essential for energy balance and metabolic well-being.
Through proper diet and training strategies, we can optimize our glycogen levels to improve both physical activity and our overall health. Understanding the importance of this compound and how to manage it in the daily diet allows people to make the most of their energy and stay active in a healthy way.
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