Glycogen is a reserve of carbohydrates accumulated in the muscles and liver, which can be used as the metabolic requirement increases. In its structure, glycogen represents hundreds of interconnected glucose molecules, so it is considered. The substance is sometimes referred to as "animal starch" because it is similar in structure to regular starch.
Recall that the storage of glucose in its pure form is unacceptable for metabolism - its high content in cells creates a highly hypertonic environment, leading to an influx of water and development. In contrast, glycogen is insoluble in water and eliminates unwanted reactions¹. The substance is synthesized in the liver (this is where carbohydrates are processed), and accumulates in the muscles.
In the event that the level of glucose in the blood decreases (for example, after a few hours after eating or during 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 index of food
Carbohydrates eaten during digestion are broken down into glucose, after which it enters the bloodstream. Note that fats and proteins cannot be converted into glucose (and into glycogen). The aforementioned 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.
At the same time, the quality of processing carbohydrates into glycogen directly depends on food. Despite the fact that simple carbohydrates increase blood glucose levels as quickly as possible, a significant part of them is converted into fat. In contrast, the energy of complex carbohydrates, obtained by the body gradually, is more fully converted into glycogen contained in the muscles.
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 the liver glycogen stores are used to cover the energy needs of glucose throughout the body, while the muscle glycogen stores are available exclusively for local consumption. In other words, if you do squats, then the body is able to use glycogen exclusively from the muscles of the legs, and not from the muscles of the biceps or triceps.
Functions of glycogen in muscles
From the point of view of biology, glycogen does not accumulate in the muscle fibers themselves, but in the sarcoplasm - the nutrient fluid surrounding them. Fitseven has already written about what is largely associated with an increase in the volume of this particular nutrient fluid - 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. At the same time, the number of muscle fibers is set first of all 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 body's main filtering organ. In particular, it processes carbohydrates supplied with food - however, the liver can process no more than 100 g of glucose at a time. 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.
Effects of Glycogen on Muscles: Biochemistry
Successful training for muscle recruitment requires two conditions - firstly, the presence of sufficient glycogen stores in the muscles before training, and, secondly, the successful restoration of glycogen depots at the end of it. By doing strength exercises without glycogen stores in the hope of "drying out", you are forcing the body to burn muscle in the first place.
For muscle growth, it is not so much protein intake that is important, but the presence of a significant amount of carbohydrates in the diet. In particular, a sufficient intake of carbohydrates immediately after the end of the workout during the “ ” period is necessary to replenish glycogen stores and stop catabolic processes. In contrast, you can't build muscle on a carbohydrate-free diet.
How to increase glycogen stores?
Glycogen stores in the muscles are replenished either with carbohydrates from food, or by using a sports gainer (a mixture of protein and carbohydrates in the form). As we mentioned above, in the process of digestion, complex carbohydrates are broken down into simple ones; first they enter the blood in the form of glucose, and then they are processed by the body to glycogen.
The lower the glycemic index of a particular carbohydrate, the slower it releases its energy into the blood and the higher its percentage of conversion is into glycogen depots, and not into subcutaneous fat. This rule is of particular importance in the evening - unfortunately, simple carbohydrates eaten at dinner will go primarily to belly fat.
What increases the amount of glycogen in the muscles:
- Regular strength training
- Eating low glycemic carbohydrates
- Reception after training
- Revitalizing muscle massage
The effect of glycogen on fat burning
If you want to burn fat through training, remember that the body first uses glycogen stores and only then moves on to fat stores. It is on this fact that the recommendation is based that the effective one should be carried out for at least 40-45 minutes with a moderate pulse - first the body spends glycogen, then switches to fat.
Practice shows that fat burns fastest when doing cardio in the morning on an empty stomach or using. Since in these cases the level of glucose in the blood is already at a minimum level, from the first minutes of training, glycogen stores from the muscles (and then fat) are spent, and not glucose energy from the blood at all.
***
Glycogen is the main form of glucose energy storage in animal cells (plants do not have glycogen). In the body of an adult, approximately 200-300 g of glycogen accumulates, stored mainly in the liver and muscles. Glycogen is wasted during strength and cardio training, and for muscle growth it is extremely important to properly replenish its reserves.
Scientific sources:
- Fundamentals of glycogen metabolism for coaches and athletes,
Full recovery depleted glycogen- it's not easy. This often takes days rather than the seconds, minutes or hours needed to restore the metabolic phosphagen system and lactic acid. The figure shows the recovery process under three conditions: (1) in people on a high carbohydrate diet; (2) in people whose diets are high in fat and protein; (3) in people without food.
It is seen that people in food which are rich in carbohydrates, full recovery occurs in about 2 days. Conversely, people who eat a lot of fat and protein or don't eat at all show very little recovery after 5 days. This comparison suggests that it is important for an athlete to: (1) eat a high-carbohydrate diet before a debilitating sporting event; (2) not engage in exhaustive physical activity for 48 hours prior to the upcoming event.
In addition to a large number carbohydrates, used by muscles during physical work, especially in the early stages of exercise, as a source of energy, muscles use a large amount of fat in the form of fatty acids and acetoacetic acid, and to a much lesser extent - proteins in the form of amino acids. In fact, even under the best conditions during prolonged sports activities lasting more than 4-5 hours, muscle glycogen stores are depleted almost completely and further contribute little to providing energy for muscle contractions. In these cases, the muscle depends on other sources of energy, mainly fat.
The figure shows data on the relative use of carbohydrates and fats as an energy source during long-term exhausting physical activity with three types of diets: high-carbohydrate, mixed and rich in fats. It can be seen that in the first seconds or minutes of the load, carbohydrates are the main energy supplier, but by the time of depletion, up to 60-85% of the energy is extracted from fats, and not from carbohydrates.
Not all carbohydrate energy comes from muscle stores. glycogen. In fact, almost as much glycogen is stored in the liver, from where it can be released into the blood in the form of glucose and taken up by the muscles for use as an energy source. In addition, glucose solutions given to athletes during a sporting event can provide up to 30-40% of the energy needed during long-term exercise, such as marathon running.
Therefore, when presence of muscle glycogen and glucose blood, they are the main nutrients used as an energy source for intense muscle activity. Even so, to provide energy for a long-term heavy load, usually about 3-4 hours after the start of work, the source of more than 50% of the required energy is fat.
The importance of training with maximum load. One of the cardinal principles of muscle development during athletic training is as follows. The strength of muscles that function without load, even if they contract indefinitely, practically does not increase. On the other hand, if the muscles contract in excess of 50% of the maximum contraction force, their strength quickly increases, even if the contractions are performed only a few times a day.
Based on this principle Muscle development experiments have shown that a set of exercises consisting of approximately 6 muscle contractions with maximum load, performed 3 times a day, 3 days a week, gives an optimal increase in muscle strength without the development of chronic muscle fatigue.
The top curve in the figure shows percentage the increase in strength that can be achieved with this maximum load training program in a previously untrained young adult. It can be seen that muscle strength increases by about 30% during the first 6-8 weeks, but after that it practically does not change (plateau on the curve). Along with this increase in strength, about the same percentage increases in muscle mass, which is called muscle hypertrophy.
In old age, many people are so little are moving that their muscles are atrophying to an extreme degree. In these cases, muscle training often increases muscle strength by more than 100%.
Glycogen is a "reserve" carbohydrate in the human body, belonging to the class of polysaccharides.
It is sometimes erroneously referred to as "glucogen". It is important not to confuse both names, since the second term is a protein insulin antagonist hormone produced in the pancreas.
What is glycogen?
With almost every meal, the body receives, which enter the blood in the form of glucose. But sometimes its amount exceeds the needs of the body, and then excess glucose accumulates in the form of glycogen, which, if necessary, breaks down and enriches the body with additional energy.
Where are the stocks kept?
Glycogen stores in the form of tiny granules are stored in the liver and muscle tissue. Also, this polysaccharide is found in the cells of the nervous system, kidneys, aorta, epithelium, brain, in embryonic tissues and in the uterine mucosa. In the body of a healthy adult, there is usually about 400 g of the substance. But, by the way, with increased physical exertion, the body mainly uses glycogen from the muscles. Therefore, bodybuilders about 2 hours before training should additionally saturate themselves with high-carbohydrate foods in order to restore the reserves of the substance.
Biochemical properties
The polysaccharide with the formula (C6H10O5)n is called glycogen by chemists. Another name for this substance is animal. And although glycogen is stored in animal cells, this name is not entirely correct. The substance was discovered by the French physiologist Bernard. Almost 160 years ago, the scientist first found “reserve” carbohydrates in liver cells.
"Reserve" carbohydrate is stored in the cytoplasm of cells. But if the body feels a sudden shortage, glycogen is released and enters the bloodstream. But, interestingly, only the polysaccharide accumulated in the liver (hepatocide) is capable of transforming into glucose, which is able to saturate the “hungry” organism. Glycogen reserves in the gland can reach 5 percent of its mass, and in an adult body be about 100-120 g. Hepatocides reach their maximum concentration about an hour and a half after a meal rich in carbohydrates (confectionery, floury, starchy food).
In the composition of the muscles, the polysaccharide occupies no more than 1-2 percent of the tissue mass. But, given the total muscle area, it becomes clear that the glycogen "deposits" in the muscles exceed the reserves of the substance in the liver. There are also small reserves of carbohydrate in the kidneys, glial cells of the brain and in leukocytes (white blood cells). Thus, the total glycogen stores in an adult body can be almost half a kilogram.
Interestingly, the "reserve" saccharide is found in the cells of some plants, in fungi (yeast) and bacteria.
Role of glycogen
Basically, glycogen is concentrated in the cells of the liver and muscles. And it should be understood that these two sources of reserve energy have different functions. The polysaccharide from the liver supplies glucose for the body as a whole. That is, it is responsible for the stability of blood sugar levels. With excessive activity or between meals, plasma glucose levels decrease. And in order to avoid hypoglycemia, the glycogen contained in the liver cells is broken down and enters the bloodstream, leveling the glucose index. The regulatory function of the liver in this regard cannot be underestimated, since a change in sugar levels in any direction is fraught with serious problems, even death.
Muscle reserves are necessary to maintain the functioning of the musculoskeletal system. The heart is also a muscle that stores glycogen. Knowing this, it becomes clear why most people develop heart problems after prolonged fasting or anorexia.
But if excess glucose can be deposited in the form of glycogen, then the question arises: “Why is carbohydrate food deposited on the body as fat?”. There is also an explanation for this. Glycogen stores in the body are not dimensionless. With low physical activity, animal starch reserves do not have time to be spent, so glucose accumulates in a different form - in the form of lipids under the skin.
In addition, glycogen is necessary for the catabolism of complex carbohydrates and is involved in metabolic processes in the body.
Synthesizing
Glycogen is a strategic store of energy that is synthesized in the body from carbohydrates.
First, the body uses the received carbohydrates for strategic purposes, and saves the rest for a rainy day. Energy deficiency is the reason for the breakdown of glycogen to the state of glucose.
The synthesis of the substance is regulated by hormones and the nervous system. This process, in particular in the muscles, “triggers” adrenaline. And the breakdown of animal starch in the liver activates the hormone glucagon (produced by the pancreas during fasting). The hormone insulin is responsible for the synthesis of a “reserve” carbohydrate. The process consists of several stages and occurs exclusively during meals.
Glycogenosis and other disorders
But in some cases, the breakdown of glycogen does not occur. As a result, glycogen accumulates in the cells of all organs and tissues. Usually, such a violation is observed in people with genetic disorders (dysfunction of the enzymes necessary for the breakdown of the substance). This condition is called the term glycogenosis and belongs to the list of autosomal recessive pathologies. Today, 12 types of this disease are known in medicine, but so far only half of them have been sufficiently studied.
But this is not the only pathology associated with animal starch. Glycogen diseases also include aglycogenosis - a disorder accompanied by a complete absence of the enzyme responsible for the synthesis of glycogen. Symptoms of the disease are pronounced hypoglycemia and convulsions. The presence of aglycogenosis is determined by liver biopsy.
Glycogen, as a reserve source of energy, is important to restore regularly. So, at least, scientists say. Increased physical activity can lead to a total depletion of carbohydrate reserves in the liver and muscles, which as a result will affect the vitality and performance of a person. As a result of a long-term carbohydrate-free diet, glycogen stores in the liver are reduced to almost zero. Muscle reserves are depleted during intense strength training.
The minimum daily dose of glycogen is 100 g or more. But this figure is important to increase when:
On the contrary, people with liver dysfunction, lack of enzymes should be careful about food rich in glycogen. In addition, a high-glucose diet reduces glycogen intake.
Food for glycogen storage
According to the researchers, for adequate storage of glycogen, approximately 65 percent of calories the body must receive from carbohydrate foods. In particular, in order to restore stocks of animal starch, it is important to introduce bakery products, cereals, cereals, various fruits and vegetables into the diet.
The best sources of glycogen: sugar, honey, chocolate, marmalade, jam, dates, raisins, figs, bananas, watermelon, persimmons, sweet pastries, fruit juices.
Effect of glycogen on body weight
Scientists have determined that about 400 grams of glycogen can accumulate in an adult body. But scientists also determined that each gram of reserve glucose binds approximately 4 grams of water. So it turns out that 400 g of polysaccharide is approximately 2 kg of glycogen aqueous solution. This explains the profuse sweating during training: the body consumes glycogen and at the same time loses 4 times more fluid.
This property of glycogen also explains the quick result of express diets for weight loss. Low-carbohydrate diets provoke an intensive use of glycogen, and with it, fluids from the body. One liter of water, as you know, is 1 kg of weight. But as soon as a person returns to a normal carbohydrate diet, animal starch reserves are restored, and with them the liquid lost during the diet period. This is the reason for the short-term result of express weight loss.
For truly effective weight loss, doctors advise not only to review the diet (prefer proteins), but also to increase physical activity, which leads to the rapid depletion of glycogen. By the way, the researchers calculated that 2-8 minutes of intense cardio is enough to use glycogen stores and lose excess weight. But this formula is only suitable for people who do not have cardiological problems.
Scarcity and surplus: how to determine
An organism that contains extra portions of glycogen will most likely report this with thickening of the blood and abnormal liver function. In people with excessive reserves of this polysaccharide, intestinal malfunctions also occur, and body weight increases.
But the lack of glycogen does not pass without a trace for the body. Deficiency of animal starch can cause emotional and mental disorders. There is apathy, depression. It is also possible to suspect the depletion of energy reserves in people with a weakened immune system, poor memory, and after a sharp loss of muscle mass.
Glycogen is an important reserve source of energy for the body. Its disadvantage is not only a decrease in tone and a decline in vitality. Deficiency of the substance will affect the quality of hair and skin. And even the loss of luster in the eyes is also the result of a lack of glycogen. If you notice symptoms of a polysaccharide deficiency in yourself, it's time to think about improving your diet.
Suren Harutyunyan, head of the sports laboratory of the Trifit studio, launched your channel on Youtube, which clearly talks about scientific achievements for running and triathlon enthusiasts. Zozhnik arranged Suren's video into this text - about how to eat before and during running and other endurance competitions.
What is glycogen and how to increase its level
Glycogen is the carbohydrate operational energy reserves of the body - in the muscles and liver, there is also a small amount of glucose in the blood. At distances over 30 minutes, the main causes of fatigue are precisely the depletion of glycogen stores and dehydration.
Increasing the concentration of glycogen in the muscles and liver is an important condition for improving the result in competitions. For this purpose, the so-called “carbohydrate loading” can be used - it is needed in order to achieve the maximum concentration of glycogen in the muscles and liver by the start of the competition.
How to properly carb-load
The history of the study of this issue dates back to the 60s. In 1967, a group of Scandinavian scientists found that a low-carbohydrate diet leads to a decrease in the concentration of muscle glycogen stores. But if this low-carb diet is followed by a high-carb diet, muscle glycogen stores increase significantly - and even above the initial values. This is called the phase of supercompensation - excessive compensation for the lack of something, in this case - glycogen.
Since then, athletes began to use carbohydrate loading according to the scheme: first, they kept a diet low in carbohydrates for 3-4 days, then for 3-4 days - a diet with a high content of carbohydrates, thus achieving supercompensation of glycogen stores.
However, in 1981, another variant of carbohydrate loading was investigated: when the loading was performed without prior low-carbohydrate diet. And it turned out that this version of carbohydrate loading has exactly the same results.
In a new 2002 study, athletes took 3 days of 10 grams of carbohydrates per kg of body weight per day. A muscle biopsy showed that after the first day of such a high-carbohydrate load, the concentration of glycogen in the muscles increased from 90 mmol / kg to 180 mmol / kg. However, after the third day of high-carbohydrate loading, the achieved concentration of glycogen in the muscles remained at the same level as after the first day.
In order to complete a carbohydrate load, it does not take 3 days - to replenish glycogen stores, it is enough to consume a sufficient amount of carbohydrates within 36-48 hours after training. This means that before the competition, athletes do not need to sit on the classic weekly carbohydrate load (3-4 days of low-carb meals and 3-4 days of high). Enough 2 days before the competition to consume a sufficient amount of carbohydrates: about 10 grams per kilogram of body per day.
Meals during the competition
It is believed that the consumption of carbohydrates directly during the competition can increase both speed and endurance. However, studies have shown that such an effect is achieved if the exercise is done for at least an hour and at high intensity - at least 75% of the MIC - that is, when the operational energy reserves (glycogen) are exhausted. If the distance lasts up to 30 minutes, there is no point in eating during the race.
It is very important to decide how many carbohydrates you need to take during the competition. It used to be thought that the rate of absorption of carbohydrates was 1 gram per minute (or 60 grams per hour) - regardless of the type of carbohydrate. The body would be ready to accept more, but it is limited by the capacity of the intestines - a special transporter substance can transfer it from the intestines to the blood only at such a speed.
However, a 2004 study showed that if you use different types of carbohydrates: together with glucose, another type of carbohydrate - fructose, then it will be absorbed using a different transporter substance and the overall absorption rate of carbohydrates can be increased to 1.26 grams per minute.
In a whole series of studies, scientists attempted to determine the maximum rate of oxidation of carbohydrates obtained from the outside. Studies agree that using different transporters (and therefore different types of carbohydrates) can increase the rate of carbohydrate oxidation by 75% compared to 1 gram per hour.
With a duration of work from 30 to 45 minutes, you can consume any carbohydrates and only a small amount will be enough. But the longer the load lasts, the more carbohydrates per hour you need to take - due to the depletion of glycogen stores. If the activity lasts 2.5 hours or longer (such as a marathon or triathlon), 90 grams of carbohydrates per hour is recommended, and since the ability of the intestine to absorb is limited to 60 grams per hour, then various types of carbohydrates should be used. It is usually convenient to use sports gels, bars.
Incidentally, slower athletes will have lower rates of carbohydrate oxidation. For example, to overcome the Ironman cycling stage in 4:30, an athlete needs about 1000 kcal / hour. If you cover the same distance in 6 hours, the athlete will burn approximately 700 kcal per hour. Accordingly, recommendations for carbohydrate intake per hour should be adjusted depending on the intensity of the load.
Bowel training works
According to unofficial information from athletes - increased consumption of carbohydrates contributes to the training of the intestine - increases its ability to absorb carbohydrates.
There is a limited amount of research on this subject. In 2010, scientists investigated whether the daily consumption of carbohydrates affects the body's ability to oxidize them. Intestinal carbohydrate transporters are indeed activated by a high carbohydrate diet. The scientists found that the level of carbohydrate oxidation in the body was higher with a high-carbohydrate diet that included 6 grams per kg of body weight for 28 days compared to a diet that included only 5 grams of carbohydrates per kg of body weight per day.
In other words, carb speed can also work out, so if you're into an endurance sport, be friends with carbs.
Got an interesting question - But what if there was strength training on the upper body (chest / back / arms ...), that is, the legs were not involved, respectively, the glycogen reserve remained in them, and after the strength training you went on a treadmill, then the fat will not “burn”, t .to. glycogen is left in the legs, and that's what the body will use, right?»
What is glycogen?
Glycogen is the storage form of carbohydrates in the body. Glycogen is mainly stored in the liver and muscles. The liver is responsible for a large number of important functions, incl. and for carbohydrate metabolism. The concentration of glycogen in the liver is higher than in the muscles (10% versus 2% of the weight of organ tissues), but still more glycogen is contained in the muscles, since their mass is greater. By the way, other tissues and organs of our body - the brain, kidneys, heart, etc., also contain glycogen stores, but scientists have not come to a final conclusion regarding their functions. Glycogen in the liver and skeletal muscle perform different functions.
Glycogen from the liver predominantly needed to regulate blood glucose levels during fasting, calorie deficit.
glycogen from muscles provides glucose to muscle fibers during muscle contraction.
Accordingly, the content of glycogen in the liver decreases during fasting, calorie deficit, and the content of muscle glycogen decreases during training in the "working" muscles. But is it only in the "working" muscles?
Glycogen and muscle work.
There have been several studies ( at the end of the article I will leave a link to a full review of all sources), during which a skeletal muscle biopsy was performed after performing intense physical activity in a group of volunteers. It was found that in the "working" muscles the level of glycogen decreases significantly during exercise, while the level of glycogen in inactive muscles remains unchanged. By the way, endurance is directly related to muscle glycogen levels, fatigue develops when glycogen stores in active muscles are depleted ( so do not forget to eat before training for 2 hours to show the maximum result).
