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EPO Blood Doping May Cause Stroke in Bikers and Runners

Tim Boyer's picture
Morning Running

EPO blood doping to enhance performance in bikers and runners during competitions may put the athletes at risk of death from a stroke. Researchers recently reported their discovery that both acute and long term use of EPO blood doping results in an increased blood pressure in the brain’s blood vessels, which could result in a cerebral vascular accident such as a stroke.


Blood doping is the illegal practice of some athletes—notably bikers and runners—who increase the number of their red blood cells in their bloodstream in order to enhance their athletic performance during competition. An increase in the number of red blood cells improves both the aerobic capacity and endurance of an athlete, thereby giving him or her a physical advantage over competitors during a race.

Blood doping originated with the practice of using blood from either a compatible donor or from blood drawn by the user himself that was then stored away for later use. Typically, the blood was processed to increase the concentration of red blood cells and then stored away. Just before an event takes place, the concentrated blood is then transfused “doped” into the bloodstream of the athlete.

Blood doping today refers more commonly to erythropoietin (EPO) blood doping. Erythropoietin is a hormone that acts as growth factor that stimulates the production of red blood cells. Medically, EPO is used for the treatment of anemia, renal failure and during cancer chemotherapy. EPO doping involves injection of the hormone into the body, which will then raise the hematocrit. The hematocrit is the percentage concentration of red blood cells in the blood, which in women and men is normally 40% and 45% respectively.

One of the dangers of EPO blood doping is that an excessive hematocrit of 70% or more can result in polycythemia. Polycythemia basically is a thickening of the blood that results in decreased blood flow and increases the risk of forming blood clots that can cause a stroke, heart attack, pulmonary embolism or deep vein thrombosis in the legs.

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However, according to a recent article in The FASEB Journal, researchers have discovered that EPO blood doping has other dangers aside from raising hematocrit levels too high. They found that EPO also raises the blood pressure in the blood vessels that feed the brain.

In the study, researchers from the Zurich Center for Integrative Human Physiology at the University of Zurich in Switzerland looked at the effects of EPO on two groups of healthy males. One group was administered high doses of EPO for three days and other group received much lower doses for 13 weeks. Blood vessels in the brains of both groups were analyzed for their response to EPO under conditions of normal oxygen levels and hypoxic levels while at rest and during exercise.

What the researchers found was that the 3 days of high doses of EPO did not increase the one group’s hematocrit levels, but that the 13 weeks of low levels of EPO did raise the hematocrit levels for the other group. More significantly, however, both groups showed an increase in blood pressure related to the increase in blood vessel constriction in response to both the short term-high and long term-low levels of EPO administered.

In a response to the researchers’ findings, Gerald Weissmann, M.D. and Editor-in-Chief of The FASEB Journal states in a press release, "EPO is used by doctors to increase red blood cells in sick people who can't make enough of them: it's called honest medicine. When EPO is used by healthy bikers and runners to boost their performance, it's called cheating. Now we know that folks who use EPO covertly are cheating not only the time-clock, but themselves," says Dr. Weissmann. "Not only is EPO likely unsafe in healthy athletes, but there are many other ways to build up stamina without drugs."

Reference: The FASEB Journal
Image reference of runners: Wikipedia