What drug left unchallenged Usain Bolt in the 100 meters?

American sprinter Tyson Gay who recently gave positive doping tests, had taken "natural external steroids," so it could be removed from competition for two years, according to the British broadcaster BBC. It was the athlete, specialist in testing 100 meters, who announced last month that the U.S. Anti-Doping Agency (Used, for its acronym in English) was found positive in doping tests conducted in May, before the World Athletics Championships Moscow this year. Although he had not yet specified what the substance for which the athlete had tested positive, the BBC reported today an excerpt from the letter that he sent to the athlete Used, in confirming that Gay had taken steroids. "Through the carbon isotope test found that the sample offered anomalous analytical results, which reflected a natural external steroids making ", says the letter that the institution sent the athlete on 23 July. The letter also claims that failing a doping test for this type of "anabolic" -chemicals used to increase metabolism, is a violation of the World Anti-Doping Code (Wada, for its acronym in English). Under the provisions of this code, the maximum penalty that could be applied to a convicted athlete taking steroids is the prohibition to compete for two years. After being informed of the results in July, the 30-year athlete voluntarily retired team United States selected for the World Championships in Athletics held in Moscow between 10 and 18 August. Since then, the Used still investigating his case before subjecting the athlete to a disciplinary hearing in the coming weeks. Meanwhile, Gay guilt attributed to a member of his team , saying "never" taken "consciously any drugs to improve performance." "There is no question of sabotage. What happened is that I put my trust in someone and failed me , "said the sprinter, who was world champion in 100 and 200 meters in Osaka 2007 , the year he was elected best athlete worldwide. "I hope to run again soon, but accept whatever punishment they deserve, "he added when it was discovered athlete doping. In response to the confessions of Gay, a spokesman for the Used said since the institution appreciated "their voluntary withdrawal from the U.S. team in recent competitions," he said in a statement to the BBC. This year Tyson Gay had regained full strength after a year of injury and surgery on a rib. Its brands -9.75 season at 100 and 19.74 in 200 - had raised hopes in the U.S. team to beat Jamaican Usain Bolt at the World Championships in Moscow, which were played from 10 to 18 August.