What is "blood doping," and why does it matter?

Any time someone breaks a record, people inevitably bring up the possibility that they had some illegal enhancements. Just yesterday, gold medalist Ye Shiwen was accused of "blood doping" to improve her performance. You may be familiar with steroids and other drugs — but what on Earth is "blood doping?" And why would injecting yourself with your own blood be such a problem?

Blood doping is the act of adding red blood cells to an individual's bloodstream. Why red blood cells? Red blood cells carry oxygen, and an increase of oxygen in the bloodstream raises the supply of oxygen available to muscle.

By increasing the volume of oxygen available to one's muscles, muscles perform more efficiently. With this increased efficiency comes an increase in athletic endurance, allowing blood doping to benefit cyclists, swimmers, and long distance runners. Athletes regularly underwent doping procedures prior to events before the banning of blood doping in Olympic competition in 1985. The red blood cells come from two very different methods — one is gory and old school, while the other involves hormone injections.

What is "blood doping," and why does it matter?

The oldest form of blood doping involves obtaining fresh blood and extracting the oxygen carrying red blood cells. The extracted red blood cells are then frozen and stored. Prior to competition, the athlete undergoes a clandestine intravenous infusion to add the red blood cells to their circulatory system.

The blood can come from the athlete desiring to dope, but if it does, he or she will likely become anemic for a short period after donation. The concentrated red blood cells can also come from compatible third party donors. This method allows for a larger storied supply, more opportunities to dope, and negates the possibility of anemia in the athlete. Using an outside donor, however, introduces the risk of obtaining a communicable disease or undergoing a transfusion rejection.

Red blood cell transfusions are detected in tests looking for the presence of organic molecules known as plasticizers in blood samples. These molecules are commonly sloughed from IV bags, bags used to store and transfer concentrated red blood cells. Biochemical markers detecting the presence of red blood cells from multiple individuals in an athlete also tip off officials to blood doping.

What is "blood doping," and why does it matter?

Erythropoietin (EPO) is used by athletes to increase red blood cell counts in a less gruesome manner. Erythropoietin is a protein that stimulates the production of red blood cells. The use of erythropoietin eliminates the problems that come along with obtaining and storing red blood cells, as well as clandestine operations to infuse one's blood with the red blood cells prior to an event.

Erythropoietin is normally produced by the kidneys, with the hormone binding to receptors in the blood marrow and increasing red blood cell production. The protein can be created and purified through recombinant methods, with erythropoietin created in this manner available for purchase as a pharmaceutical for treatment of anemia. The use of erythropoietin, however, is outlawed in most sports.

Catching blood dopers who use erythropoietin is tricky, as increased levels EPO can only be detected in the first few days after injection. Urine tests looks for differences between pharmaceutical EPO and the athlete's own EPO, as the mass of the two proteins slightly differ.

Checking total red blood cell counts within an athlete's blood is another common test. The red blood cell levels for males and females are well established. Spikes in red blood cell count are often an indirect signal that an athlete is doping.

Increasing the amount of red blood cells in one's circulatory system is not without risks. Blood doping brings with it an increase in blood viscosity, making blood clots much more likely and increasing the risk of stroke. The communicable diseases and risk of blood contamination inherent in transfusion of red blood cells will always be problem, but one that can be eliminated with proper screening of donors.

Doping with erythropoietin is linked to several amateur cyclists who died from cardiovascular complications, as well as New York Rangers draft pick Alex Cherepanov. The 19-year-old Cherepanov died when his heart stopped after he accidentally collided with teammate Jaromir Jagr during a hockey game.

Top image: Picture of Ye Shiwen from Adam Pretty/Getty Images. Erythropoietin structure courtesy of the Protein Data Bank. Additional images from mikecogh/Flickr. Sources linked within the article.