Cycling: Expert calls Landis' 'natural' theory into question

As Floyd Landis, who tested positive for testosterone on his way to victory in the Tour de France, was waiting last night to discover if the counter-analysis he requested on the B sample confirms the result, a leading expert on doping in sport denied the American's claim that naturally occurring levels of the substance in his body caused the positive result.

If the positive test were confirmed, the American would be stripped of his Tour victory and Oscar Pereiro of Spain, who finished second overall in last month's race, would be declared the winner. His Phonak team said Landis would be dismissed if the B result was positive. The American, who has denied any wrongdoing, has said he intends to continue racing once he has had the hip replacement he needs.

Landis' hopes of proving that his own naturally elevated levels of testosterone caused his positive A test have been dealt several blows by experts, who have contradicted claims made by the Phonak rider and his legal team last week.

Speaking to Procycling magazine, one of the experts, Professor Michel Audran of the organisation, Sports and Industry Against Blood-Doping, said that Landis' A sample would only have been deemed positive after an Isotope Ratio Mass Spectrometry test had confirmed the presence in his urine of non-naturally occurring, or "exogenous" testosterone.

Landis had claimed on Friday that "there [was] no indication of an outside source of testosterone" in his urine sample - which would mean that his positive test would have been due to natural levels.

"When a sample shows a testosterone: epitestosterone ratio of more than 1:4, an IRMS test is now used to check for the presence of exogenous testosterone," Audran said, however. "If Landis' A sample was positive, it means that exogenous testosterone must have been found."

If the positive test is confirmed, USA Cycling, the American federation, would have a month to make a ruling, the most likely decision being a two-year ban. Landis' lawyers could then take the matter to the Court of Arbitration for Sport and a long procedure would begin.