Erythropoietine is a hormone produced by the liver and kindney as well as by genetic engineering. It stimulates the production of erythrocytes in response to oxygen deficiency. This is the definitino which we find in "Robert's Dictionary", Paris, 2000, page 908.

EPO augments the effects of intensive training. It is a hormone secreted naturally by the kidneys. When artificially administered, it increases the proportion of red blood cells and thereby increases the amount of oxygen transported by the blood. Suddenly, with an overabundance of oxygen, the body's endurance is increased and its muscular performance also improved.

EPO is used under medical supervision in the treatment of kidney disfunctions, anemia, or for the attenuation of secondary effects of certain treatments for SIDA.

The blood can thicken to the point where it is transformed into a gel-like substance. Racers using it can attain heartrates of up to 190 beats per minute, reduced to 30 beats per minute when resting. It is at this point that EPO can become fatal. The more the heart slows down, the more the blood thickens and the faster it coagulates. And it is at this point that the heart can just give out.