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Recent interviews with cyclist Lance Armstrong made headlines around the world. He admitted to the use of performance-enhancing drugs to win the Tour de France. Scientists have overcome many hurdles to develop the drug testing that underpins this revelation.

Among other things, Lance admitted to using recombinant human erythropoietin (rEPO) during his cycling career. Erythropoietin (EPO) is a hormone produced naturally by the kidneys, and is responsible for red blood cell production. Red blood cells carry oxygen around the body. Having more red blood cells increases an athlete’s endurance.

Everyone has some EPO in their body, so detecting rEPO abuse by athletes is not easy. rEPO that has been injected is almost identical to EPO that naturally occurs in the body. To test for rEPO, an athlete is required to give a urine sample. Roughly a tablespoon of urine is concentrated down to about one drop. The sample will contain EPO, rEPO (if the athlete has been using it) and other proteins.

The sample is placed on a gel, and an electric current run through it. The electricity causes the large protein molecules to separate and spread out. Like a cloth absorbing a spill, a membrane is then used to blot the gel. The membrane contains antibodies that bond to proteins. After a second blotting, just rEPO and EPO molecules will stick to the membrane.

The membrane is then treated with other chemicals. If rEPO is present on the membrane, this treatment will cause it give off light in a particular pattern, where it is detected and measured. For an athlete to test positive to rEPO, additional confirmation tests are undertaken and another of their samples (a B sample) can be tested to confirm the initial results.

Since the introduction of a test for rEPO, its use appears to have dropped significantly. Anti-doping officials are now concerned about the use of blood transfusions, where blood is removed from an athlete, stored and then reinjected later in order to give a performance boost. This is even harder to detect than EPO because it is the athlete’s own blood that is the performance-enhancing substance.

The Lance Armstrong case shows how important science continues to be in monitoring drug use in sport.