Usain Bolt tells reporters ` ` I ' m clean '' ahead of London Diamond League meeting . `` I was the youngest person to win the world junior title at 15 , I ran the world junior record at 18 , the world youth record at 17 . Tyson Gay and Colin Powell failed drugs tests earlier this year . Gay and Powell both admitted knowingly taking banned substances . A Jamaican international footballer failed a drugs test during a World Cup qualifier .
Usain Bolt tells reporters ` ` I ' m clean '' ahead of London Diamond League meeting . Tyson Gay and Colin Powell failed drugs tests earlier this year . Gay and Powell both admitted knowingly taking banned substances . A Jamaican international footballer failed a drugs test during a World Cup qualifier .