SOME athletes have gone down in history for being drugs cheats rather than their achievements on the sporting field.
One of the most notorious cases involved Ben Johnson, who won the 100m final at the Seoul Olympics in 1988, breaking his own world record.
But just three days later he was disqualified after his urine samples were found to contain an anabolic steroid.
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Marion Jones became the golden girl of athletics after becoming the first woman to claim five medals in a single Olympics Games in 2000.
But in 2008, she was sentenced to six months in jail for lying to investigators after admitting her achievements were fuelled by steroid abuse.
Away from the athletics track, last year cyclist Lance Armstrong ended years of speculation by admitting he used performance-enhancing drugs during all seven of his Tour de France wins.
During an interview with chat show host Oprah Winfrey, he felt it was "part of the process" to win the Tour and did not feel he was cheating but competing in a "level playing field".
More recently, the news that 100m runner Tyson Gay - a rival to Usain Bolt - had tested positive for a banned substance rocked the athletics world.
Last month, he was been banned for one year and forfeited the Olympic silver medal he won as part of the United States 4 x100 metres team in London after testing positive for an anabolic steroid last summer.
Six athletes failed tests during the last Commonwealth Games in Delhi and four were sent home.