The main physiological function of excretory processes is to free the body from end products of metabolism, excess water, organic and inorganic compounds, i.e. maintaining the constancy of the internal environment of the body. With intensive muscle work, a large amount of lactic and phosphoric acid, creatinine, enters the blood, which are removed from the body by the kidneys and sweats of the glands. With muscle work, the blood supply to the kidneys is reduced due to the redistribution of blood and a sharp narrowing of the renal arteries. When performing physical exercises, athletes often have a decrease up to the complete (short-term) cessation of urination, due to a drop in pressure on the malpigian glomeruli.