Why does a person get tired during training? Why by the end of the training sometimes there is sluggishness, inhibition, reluctance to engage in? All this occurs mainly as a result of the accumulation of fatigue toxins in the blood.

"Toxins of fatigue" - a notion of collective. In medicine, "fatigue toxins" mean a whole group of substances that are intermediate or by-products of metabolism. These substances are formed in the body as a result of intensive and prolonged work. First of all, it is lactic and pyruvic acids - by-products of glucose and glycogen oxidation in the body. Normally, in the oxygen oxidation of glucose and glycogen, they are oxidized to the carbon dioxide of gas and water. At greater physical loads, the body's need for oxygen exceeds the capabilities of the respiratory, cardiovascular and circulatory systems to meet this need.

As a result, all the energy substrates are not completely oxidized. Some carbohydrates are oxidized only to lactic and pyruvic acid. Moreover, an increase in the blood content of lactic acid blocks the blood transport systems of oxygen and makes it difficult to penetrate into cells.

There is a vicious circle: the less oxygen, the more lactic acid, and the more lactic acid, the less the tissues absorb oxygen. Fatigue grows like a snowball. The curve of increasing fatigue is getting steeper towards the end of training), fatigue is growing faster).

The body seeks to protect itself from lack of oxygen by activating anoxic oxidation. In muscles, for example, anoxic oxidation can increase by a factor of 1000 compared to the baseline. If before the training the share of anoxic oxidation does not exceed 15% of all oxidative processes, then in a well-trained organism with high physical loads this proportion can reach 50%. However, in anoxic oxidation, both glucose and glycogen are oxidized only to the stage of lactic and pyruvic acids and the concentration of lactic acid in the blood increases even more.

In the event of even a small carbohydrate deficiency, the body begins to intensively oxidize fatty acids and glycerin. After 15-20 minutes of training, the fatty acid oxidation mechanism starts to work at full strength. Fatty acids are never oxidized completely with glucose deficiency. Oxidation occurs only up to the stage of ketone bodies (acetone, acetoacetic acid, B-hydroxybutyric acid, acetoacetic acid and acetobutyric acid and t.

All ketone bodies have an acidic reaction. Milk and pyruvic acids shift the pH of the blood in the acidic side. The so-called acidosis develops. The leading role in the development of acidosis belongs to lactic acid. It is lactic acid is the main fatigue toxin.

Drowsiness and retardation after large volume training are caused primarily by lactic acidosis, which causes inhibition in the central nervous system and peripheral nerve centers. Heaviness in the head and a sense of intellectual fatigue, which are after prolonged mental work, are caused mainly by the accumulation of lactic acid in the brain tissue. Naturally, any measures for the elimination (utilization) of lactic acid in the liver and muscles will help improve the performance and eliminate fatigue.

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