What Are the Dangers of Blood Doping?

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Blood doping is one of the simplest way to improve your race time. By taking erythropoietin (EPO), a hormone usually produced by the liver and kidneys, you trigger your bone marrow to overproduce red blood cells, in effect boosting oxygen capacity. The result, as seven Tour de France titles show, is a boon for endurance, muscle recovery, and overall performance. It’s one hell of an enhancement—and it works fast too—but what's the downside?

“There are a few pretty substantial risks,” says Dr. Philip Friere Skiba, program director of sports medicine at Lutheran General Hospital. The most common is a blood clot that can lead to heart attack, stroke, or even sudden death in your sleep. “Increasing the blood count makes it more viscous,” says Skiba. “We call this ‘sludging,’ which can slow down your heart rate and cause clots.” To avoid the so-called sludging, you have to keep that heart pumping. There are stories of some doping athletes waking up in the middle of the night and doing jumping jacks to keep it moving. Others, at least anecdotally, weren’t so lucky, dying in their sleep.

Years from now, taking EPO to up your red blood cells will likely be considered as archaic as giving yourself a blood transfusion from saved bags of blood (like the first dopers did). Instead, we’ll turn to genetic tinkering for more oxygen. One study showed that by imparting such genes to monkeys, researchers could permanently up the amount of EPO that their bodies created. The problem for these unfortunate animals was the runaway blood cells caused their bodies to turn on the EPO hormone and fight it like a virus. The monkeys eventually died of anemia (or lack of red blood cells). If we learn how to give that gene an on/off switch, however—something that’s exceedingly difficult to do in genetic research today—we could regulate red blood cells for life. This would give you that untraceable edge for all your endurance sports.