Fatigue can be considered as some kind of poisoning. When the muscles are overworked, the body produces lactic acid. When the acid is removed from overworked muscles, we are able to work again.
During the day we are getting “poisoned” by lactic acid. There are, also, other substances that the body produces during muscle work. These substances are called poisons of fatigue.
They are transmitted by blood through the body, so you do not feel tired just in your muscles but also throughout the body, especially in the brain.
Scientific experiments on fatigue gave some interesting results. If a dog gets tired to complete exhaustion and sleep, and then his blood is injected into another dog, another dog will also immediately become tired and he will fall asleep. If, on the contrary, we “fuel” tired dog with a blood transfusion of a rested, alert dog, he will immediately wake up and will not feel tired.
Fatigue is not just a chemical process, but also biologically. We cannot simply “remove” the fatigue because the cells need a rest, to be renewed and able to work again. Consequently, fatigue is a signal that indicates that the body needs rest to rejuvenate the body’s energy.
However, there is something particularly interesting in the process of resting. Someone who worked for hours at the office will not want to lie down when he gets tired, he will want to walk! Or, when the kids arrive tired from the school, they would not lie down to take a rest but will run out to play.
This can be explained in the following manner: if just one part of the body is tired, such as the brain, eyes, hands, or feet, the best way to refresh that part of the body is to activate other parts of the body. Movement enhances breathing, accelerates blood circulation and glandular activity, and pollutants leaving tired parts of the body. But if someone is completely exhausted, the best rest is sleeping.