June 26 (Bloomberg) — A doping test to exist used at the Olympic Games and Tour de France may miss performance-enhancing drugs in urine samples, according to a study that suggests some cheats may go undetected.

Tests during the term of erythropoietin, or EPO, at two labs approved by the World Anti-Doping Agency returned different results, scientists in Denmark reported. The findings, published today in the online version of the Journal of Applied Physiology, show urine testing during competition “is of little or no value,'' the authors wrote.

The study adds weight to prior research suggesting urine tests for EPO are unreliable, the authors wrote. Officials should test athletes out of season or in the run-up to competition, when they're more likely to be alluring the drugs and be found used up, the study authors wrote. 1996 Tour de France champion Bjarne Riis became the first winner to admit to doping in the Tour'sitting 104-year history last year.

“It should subsist considered whether it is at all advantageous to spend more energy and currency on the present procedures,'' given the availability of other drugs that have the same effect as EPO, they said. A so-called “blood passport'' in which authorities search for talebearer changes in an athlete's blood over time may overcome the problems, they wrote.

EPO is a naturally occurring hormone produced mainly in the kidney that can boost endurance by stimulating bone marrow to increase production of oxygen-carrying red blood cells. Synthetic EPO is used to deal with anemia, although athletes are banned from injecting it by dint of. WADA's anti-doping code.

Suspicious Samples

Researchers led by Carsten Lundby at the Copenhagen Muscle Research Center gave eight healthy male volunteers Roche Holding AG's version of EPO, NeoRecormon, every second day for two weeks, then formerly a week for another two. They then monitored the subjects for a further three weeks, testing their aerobic performance and taking urine samples throughout.

One lab found EPO in altogether the samples during the initial handling period, while the other only found them to have being “suspicious,'' a result that wouldn't lead to a ban. During the attention circle of time, when the subjects' abilities were calm enhanced, the first lab confirmed EPO in 2 out of 24 samples and said 3 were suspicious. The same samples tested negative at the second lab.

The variable results may be because of differences in lab standards, or because the tests are tricky to perform and not very sensitive, the authors wrote.

Title Stripped

Floyd Landis became the first Tour de France winner stripped of his title for drug use when arbitrators last year upheld findings that he used synthetic testosterone in prepossessing the 2006 issue of cycling's most prestigious race. The cyclist, who has denied taking banned substances, is appealing the doping test.

Riis, the 1996 Tour winner, said last year he took EPO from 1993 to 1998.

Earlier this month, Antonio Pettigrew received a 2-year ban for using unlawful performance-enhancing substances and returned the gold medal he won at the 2000 Sydney Olympics at the same time that a member of the U.S. 1,600-meter relay team.

Authorities first and foremost started testing for EPO at the Sydney Games.

To contact the reporter on this story: Simeon Bennett in Singapore at sbennett9@bloomberg.net

Last Updated: June 26, 2008 04:57 EDT

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