THURSDAY, June 26 (HealthDay News) -- Tests designed to detect the illegal presence of a performance-enhancing drug that boosts blood oxygen levels in elite athletes are likely to miss those who decide to cheat, a new study claims.
The researchers recommend that the test, currently accredited by the World Anti-Doping Agency (WADA), be either improved or scrapped for an alternative test. However, they acknowledged in a statement that this "seems unlikely to occur before major events scheduled for 2008 like the Tour de France or the Olympic Games in Beijing."
The performance enhancer in question is recombinant human erythropoietin (EPO), and it's believed to give added stamina to athletes such as cyclists and distance runners. The current test is run on urine samples, but, in recent years, the procedure has been criticized by some, according to the study authors, who are from the Copenhagen Muscle Research Center in Denmark.
For their study, which is reported online Thursday in the Journal of Applied Physiology, the researchers took eight males who were recreational athletes, injected them with EPO, and took urine samples before the injections and on eight more occasions. They then sent two identical sets of samples to two separate, WADA-approved testing labs. The results were wildly divergent, with one lab detecting numerous positive results and the other detecting no positive results.
"The implication -- if applied to athletes -- is that there is only a small 'risk' of being tested positive" for blood doping, the researchers added.
However, WADA told the New York Times that it stands by the test and questioned the study.
"I have never seen such a drastic situation as the one reported in this article," Olivier Rabin, scientific director at WADA, told the newspaper.
This study is only the latest to look at the issue of performance-enhancing drugs.
Just last week, Australian researchers reported that when athletes think they are taking a performance-enhancing drug, their performance tends to get better -- even if they never really take the drug.
That study also used recreational athletes, half of whom received human growth hormone supplements, while the other half took a placebo.
Human growth hormone (HGH) is produced naturally, and it is a key player in the regulation of muscle, skeletal and organ growth.
As an injectable supplement for the purposes of boosting athletic performance, the use of HGH has been on the rise in recent years. But the WADA noted that its use has also been linked to an increased risk for heart disease, diabetes, muscle, joint and bone pain, high blood pressure and osteoarthritis. WADA has therefore classified HGH as a banned substance. Since 2004, a blood test has been in place to screen out those athletes engaged in its surreptitious use.
The Australian researchers wanted to explore whether the physical boost athletes attribute to HGH might be more psychological in nature.
To do so, they focused on 64 healthy recreational athletes, men and women between the ages of 20 and 40, who had been exercising at least two hours per week in the six months before the study.
After testing the participants for their athletic ability, the men and women were randomized into two groups. One group got growth hormone for eight weeks, and the second received a placebo. Neither the researchers nor the athletes knew which one they were getting.
At the end of the two-month trial, all the participants were asked to guess whether they had been taking HGH or a placebo, and whether their sporting performance had changed during the study period. Athletic ability was then re-tested on a range of performance parameters.
The team found that about half of the participants who received a placebo incorrectly assumed they had been given HGH.
What's more, these "incorrect guessers" actually did improve, albeit minimally, in all measures of performance, including endurance, strength, power and sprint capacity. In one category -- high-jumping ability -- the improvement was significant.
People in the placebo group who correctly guessed that they had taken a placebo improved their performance by about 1 percent to 2 percent, but those who mistakenly thought they had taken HGH showed twice that level of improvement -- about 2 percent to 4 percent.
There's more on EPO at the World Anti-Doping Agency.
SOURCES: June 26, 2008, statement, Applied Physiology Society; June 15-18, 2008, presentation, Endocrine Society annual meeting, San Francisco