What is glycogen?
Glycogen is a carbohydrate reserve accumulated in the muscles and liver that can be used as needed. By its structure, glycogen represents hundreds of interconnected glucose molecules, so it is considered a complex carbohydrate . The substance is sometimes referred to as “animal starch”, because in structure it is similar to ordinary starch.
Recall that the storage of glucose in its pure form is unacceptable for metabolism - its high content in the cells creates a highly hypertonic environment, leading to the influx of water and the development of diabetes . On the contrary, glycogen is insoluble in water and excludes undesirable reactions¹. A substance is synthesized in the liver (it is there that carbohydrates are processed), and accumulates in the muscles.
If the level of glucose in the blood decreases (for example, after a few hours after eating or with active physical exertion), the body begins to produce special enzymes. As a result of this process, the glycogen accumulated in the muscles begins to break down into glucose molecules, becoming a source of fast energy.
Glycogen and glycemic food index
The carbohydrates consumed during digestion are broken down to glucose, after which it enters the bloodstream. Note that fats and proteins cannot be converted to glucose (and glycogen). The above-mentioned glucose is used by the body both for current energy needs (for example, during physical training), and to create reserve energy reserves - that is, fat reserves.
The quality of processing carbohydrates into glycogen directly depends on the glycemic index of food. Despite the fact that simple carbohydrates increase the level of glucose in the blood as quickly as possible, a significant part of them is converted to fat. In contrast, the energy of complex carbohydrates, obtained by the body gradually, is more fully converted into glycogen contained in the muscles.
Where does glycogen accumulate?
In the body, glycogen accumulates mainly in the liver (about 100-120 g) and in muscle tissue (from 200 to 600 g) ¹. It is believed that approximately 1% of the total muscle weight falls on it. Note that the amount of muscle mass is directly related to the content of glycogen in the body - an unsportsmanlike person can have reserves of 200-300 g, while a muscular athlete can have up to 600 g.
It should also be mentioned that liver glycogen stores are used to cover the energy needs of glucose throughout the body, while muscle glycogen stores are available exclusively for local consumption. In other words, if you perform squats, the body is able to use glycogen exclusively from the muscles of the legs, and not from the muscles of the biceps or triceps.
Muscle glycogen function
From the point of view of biology, glycogen does not accumulate in the muscle fibers themselves, but in the sarcoplasm - the surrounding nutrient fluid. Fitseven already wrote that muscle growth is largely associated with an increase in the volume of this particular nutrient fluid - the muscles are similar in structure to a sponge that absorbs sarcoplasm and increases in size.
Regular strength training has a positive effect on the size of glycogen depots and the amount of sarcoplasm, making the muscles visually larger and more voluminous. Moreover, the number of muscle fibers is determined primarily by the type of physique and practically does not change during a person’s life, regardless of training - only the body’s ability to accumulate more glycogen changes.
Glycogen in the liver
The liver is the main filtering organ of the body. In particular, it processes carbohydrates coming from food - however, at a time the liver is able to process no more than 100 g of glucose. In the case of a chronic excess of fast carbohydrates in the diet, this figure rises. As a result, liver cells can convert sugar into fatty acids. In this case, the stage of glycogen is excluded, and fatty degeneration of the liver begins.
The effect of glycogen on muscle: biochemistry
Successful training for muscle building requires two conditions: firstly, the presence of a sufficient content of glycogen reserves in the muscles before training, and secondly, the successful restoration of glycogen depots at its end. Performing strength exercises without glycogen stores in the hope of "drying out", you first force the body to burn muscle.
For muscle growth, it is important not so much to consume protein as to have a significant amount of carbohydrates in the diet. In particular, a sufficient intake of carbohydrates immediately after training in the “ carbohydrate window ” period is necessary to replenish glycogen reserves and stop catabolic processes. In contrast, you cannot build muscle on a carbohydrate-free diet.
How to increase glycogen stores?
Muscle glycogen stores are replenished either with carbohydrates from foods or with the use of a sports gainer (a mixture of protein and carbohydrates in the form of maltodextrin ). As we mentioned above, in the process of digestion complex carbohydrates are broken down into simple ones; first they enter the bloodstream in the form of glucose, and then are processed by the body to glycogen.
The lower the glycemic index of a particular carbohydrate, the slower it gives its energy to the blood and the higher its percentage of conversion is to glycogen depots, and not to subcutaneous fat. This rule is especially important in the evening - unfortunately, simple carbohydrates eaten at dinner will go primarily to fat on the stomach.
What increases the glycogen content in muscles:
- Regular strength training
- Low glycemic carbohydrate intake
- Weight gain after training
- Restorative muscle massage
The effect of glycogen on fat burning
If you want to burn fat through training, remember that the body first consumes glycogen reserves, and only then goes to the fat reserves. It is on this fact that the recommendation is based that an effective fat-burning training should be carried out for at least 40-45 minutes with a moderate pulse - first, the body spends glycogen, then goes to fat.
Practice shows that fat burns fastest during cardiotraining in the morning on an empty stomach or using interval fasting . Since in these cases the level of glucose in the blood is already at a minimum level, from the first minutes of training, muscle glycogen stores (and then fat) are spent, and not the energy of glucose from the blood.
Glycogen is the main form of storing glucose energy in animal cells (there is no glycogen in plants). About 200-300 g of glycogen is accumulated in the body of an adult, which is stored mainly in the liver and muscles. Glycogen is spent during strength and cardio workouts, and for muscle growth it is extremely important to properly replenish its reserves.
- Fundamentals of glycogen metabolism for coaches and athletes, source