A more uncommon practice that may be used in an attempt to increase performance is Erythropoietin. This substance is produced naturally in the body by the kidneys and is used to regulate red blood cell production. Patients suffering from anemia or chronic renal failure are legally allowed to use this form medically, however some athletes have decided to take advantage of this substance as well.
Due to medical advances, we can now inject EPO rather than blood doping, which was the common method in the past. EPO works by increasing the bloods ability to carry oxygen, thus serving as an ergogenic aid. Some studies have shown that athletes have had an 9% increase in VO2 max, 7% increase in power output, and a 5% decrease in max heart rate ((Juhn, M., 2003).
While the benefits of using erythropoeitin are unquestionable, there are serious side affects that an athlete needs to consider. After injection, the blood has a higher concentration of red blood cells and a thicker viscosity. This may lead to thromboembolic events that could be fatal.
Seizures and hypertension are also demonstrated in those athletes who are blood doping. Most athletic federations have banned this practice and a haemoglobin limit of 18.5 g/dL has been implemented.
The injection of EPO in the body is a practice that would be very beneficial to any athletes involved in endurance activities. It would allow them to carry more oxygen per unit of blood than before thus improving their performance. This is not a sound technique however as there are strict regulations around it and there are many adverse health consequences that have been reported.
Source - bodybuilding.com