The blood booster at the heart of the Lance Armstrong doping scandal does not improve real-world cycling performance, according to the most rigorous study yet of how the protein EPO affects athletes.
The results, published Thursday in the journal Lancet Haematology , may convince some to pay more attention to the harms of supposed performance-enhancing drugs by punching holes in the myths surrounding them, researchers said.
Dutch scientists staged a bike race up a mountain to study whether erythropoietin (EPO) lives up to its reputation, transporting a large group of avid cyclists to southern France in a tour bus and putting on a grueling day of cycling for them.
''It was hectic and stressful, but also a lot of fun and exhilarating,'' said Jules Heuberger of the Centre for Human Drug Research in Leiden, Netherlands, who led the effort and describes himself as ''an active, fanatic cyclist.''
Previous studies of EPO in sports have been flawed, Heuberger said. Participants weren't trained athletes, knew they were getting EPO, or testing was limited to short bursts of strength and endurance.
EPO is among more than 300 substances banned by the World Anti-Doping Agency. Cycling's anti-doping unit is again gearing up for comprehensive testing at this year's Tour de France, planning an average of eight tests per day, always including the race leader and winner of each stage, plus six others. The race starts Saturday in Duesseldorf, Germany.
One support rider already has been dropped from his team after an out-of-competition test was positive for EPO. In 2012, Armstrong was stripped of his seven Tour de France titles for doping and he later admitted to using EPO and other banned substances.
The anti-doping agency's science director, Olivier Rabin, said he would read the study with interest, but doubted it would change the group's ban on EPO.
''We would need much more than this,'' Rabin said. ''The scientific community will receive this with a lot of skepticism.''
EPO, produced naturally in the body, enhances the ability to carry oxygen to the muscles and is thought to increase endurance. Doctors use a manufactured version to treat anemia related to cancer or kidney disease. It thickens blood, too, which can raise the risk for heart disease and stroke.
For the test, the Dutch scientists used gold-standard methods as if they were studying a new drug for a medical condition.
''The medicine is EPO and the disease is slow cycling,'' Heuberger said. ''Can you really improve cycling performance with EPO?''
Professional athletes were impossible to study because they're barred from taking EPO. Instead, the scientists recruited 48 amateur, but well-trained male cyclists willing to take shots for eight weeks then race up a mountain in southern France.
None knew whether he was getting the real stuff or dummy injections. Researchers gave the EPO group enough to increase their levels of hemoglobin, the part of blood that carries oxygen.
To nobody's surprise, the EPO group did better on a short, high-intensity test in the lab where they pedaled on an incline until they were exhausted. But the two groups performed equally on a 45-minute endurance test inside.
Researchers and cyclists traveled from the Netherlands to France for the main event. On race day, the cyclists rode for 110 kilometers (68 miles) together, then raced for 21.5 kilometers (13 miles) up Mont Ventoux, a peak that's often part of the Tour de France.
Those who'd had EPO injections were 17 seconds slower on average compared to cyclists who got dummy injections. Most of them guessed wrongly that they got the fake shots. ''They couldn't feel the effect and we couldn't measure it either,'' Heuberger said.
Besides debunking claims for EPO, the study shows it's possible to do research that mimics competitive racing conditions.
''They did a great job,'' said Dr. Don Catlin, a retired University of California, Los Angeles professor and pioneer of anti-doping tests in sports. ''Their paper will stand as a model for future research studies.''
Robin Parisotto, an Australian sports scientist who helped develop a test to detect EPO, said he commended the researchers' motives. But scientists can't ethically investigate high, dangerous doses with human subjects so it may be impossible to mimic real sports doping, Parisotto said in an email. EPO does ''provide a very powerful benefit'' in shorter events such as 400-meter or 800-meter races, he said.
AP Sports Writer John Leicester contributed from the Tour de France, in Duesseldorf, Germany.
Follow AP Medical Writer Carla K. Johnson on Twitter: (at)CarlaKJohnson