After a day’s work, we all get tired. Similarly, we get tired after running, swimming or doing exercise. Why we get tired after doing some work? Do you know?
When we do some work at with fast, our muscles do not get as much o2 (oxygen) as they need. In such a situation to provide some extra energy to the body, the glycogen stored in our muscles is transformed into lactic acid through the process of fermentation. The lactic acid reduces the working capacity of the muscles. This state of the body is known as muscle fatigue.
In our muscles, Lactic acid (CH3CH(OH)COOH) acts as a poison. If we can expel the lactic acid from the muscles by some process, they can again become fit for working.
As a result of the muscular action, some other substances (fatigue toxins) are also produced in the body. Blood circulates these acids and toxins throughout the body because of which both the body and the brain we get tired. Even when we do some mental work lactic acid and fatigue toxins are produced in the body and we get tired. Scientists conducted many experiments in this field. A dog was made to work hard. And when it got tired and went to sleep its blood was transfused into an active dog’s body. This active dog also became tired and then fell asleep. Similarly, if the blood of an active dog is transfused to the body of a tired dog, it immediately becomes active.
Fatigue is not only a chemical process but is a biological process too. It is a defense mechanism. This tells us as to when to stop work and give rest of the body. Fatigue cannot be removed fast. It is essential to give rest to the cells of the body to remove it. Sleep is a very effective means to remove fatigue. This repairs the damaged cell of the body. With the arrival of the proper quantity of oxygen in the body through breathing, the lactic acid is reconverted into glycogen and we again start feeling fresh. Little rest also removes fatigue to some extent. The loss of glycogen due to fatigue is replete to some extent by our food also. That is why a tired person feels very hungry.