Blood doping is the use of various methods and substances to increase a person’s red blood cell mass. Higher levels of red blood cells in the blood result in more oxygen being transported to the muscles, resulting in increased stamina and performance. There are three main types of blood doping:
- erythropoietin (EPO)
- synthetic oxygen carriers
- blood transfusions.
All methods of blood doping are prohibited by the WADA.
Erythropoietin—more commonly known as EPO—has long been the drug of choice for endurance athletes. Although used in a wide variety of sports, it is most commonly associated with cycling—particularly with the disgraced former champion of the Tour de France—Lance Armstrong.
Produced naturally by the kidneys, EPO is also available as a pharmaceutical. EPO stimulates the production of red blood cells in bone marrow and regulates the concentration of red blood cells and haemoglobin in the blood. This is useful for athletes, since red blood cells shuttle oxygen to the cells, including muscle cells, enabling them to operate more effectively. EPO is a peptide hormone and can be produced synthetically using recombinant DNA technology. By injecting EPO, athletes aim to increase their concentration of red blood cells and, consequently, their aerobic capacity. EPO can also work to increase the body’s ability to buffer lactic acid.
Synthetic oxygen carriers
Synthetic oxygen carriers (SOCs) are purified proteins or chemicals that have that ability to carry oxygen. They are still under development and have not been approved for use outside of South Africa and Russia. SOCs were developed for use in crisis situations where blood transfusions are not possible or blood products are not available.
There are several different types of SOCs available. Two of the most common types include haemoglobin based oxygen carriers (HBOCs) and perfluorocarbons (PFCs). Like red blood cells, they work to deliver this oxygen to the muscles, increasing aerobic capacity and endurance. However, they also have some additional benefits. HBOCs are not only great at tissue oxygenation, they can deliver increases in blood serum iron, ferritin and naturally occurring EPO. They can also increase CO₂ production and curb lactic acid production.
PFCs, due to their size, are able to enter the body’s tiny capillaries, providing very efficient local oxygen delivery to greater areas of the body, while the makeup of the drug also allows it to deliver oxygen to peripheral tissues.
SOCs are still under development and testing, and have not yet been proven safe for human use. However, this has not stopped rumours of athletes using them to get an advantage.
Prior to the introduction of synthetic blood doping drugs like EPO, blood transfusions were common practice among endurance athletes. Even with these drugs available the practice still persists.
Blood transfusion is an effective and relatively simple method of allowing athletes to boost the number of red blood cells in their blood, improving their aerobic capacity and endurance.
Blood transfusions can be classified as autologous, where the athlete receives pre-prepared doses of his/her own blood, or allogenic, where the transfused blood comes from someone else. Athletes who choose to use this method generally begin undergoing blood withdrawals several weeks before a competition, building up a supply of blood between 450 millilitres and 1800 millilitres. The plasma is returned to the body during the withdrawal while the corpuscular elements—basically the red blood cells (RBCs)—are stored. These can then be re-infused in the patient directly before or during a high-endurance event.
The re-infused blood greatly increases the number of red blood cells in the blood, boosting the blood’s ability to bring oxygen to tired muscles.