Image 1 of 5 Clara Hughes Image 2 of 5 Canadian time trial champion Clara Hughes finished second in the women's time trial. (Image credit: Wil Matthews) Image 3 of 5 Clara Hughes (Canada). (Image credit: Daniel Simms) Image 4 of 5 Big things are expected of Clara Hughes in 2012 (Image credit: VeloDramatic) Image 5 of 5 All the jerseys (l-r): Andrea Dvorak (Colavita/Forno d'Asolo), Heather Logan-Sprenger (Colavita/Forno d'Asolo), Clara Hughes (Pactimo Cycling Team) and Lex Albrecht (Team Juvederm-Specialized) (Image credit: Mitch Clinton)

In an autobiography to be released September 8, Canadian Clara Hughes details the cover up of a 1994 positive test for ephedrine at the World Championships in which she finished fourth. Hughes went on to win two bronze medals at the 1996 Atlanta Olympic Games in her road racing career, also riding the Sydney and London Olympic games. Hughes also competed as a speed skater during her cycling career, winning gold at the Turin 2006 Winter Olympic Games.

Hughes reveals in Open Heart, Open Mind that she was contacted months after the Sicily Worlds by national team director Pierre Hutsebaut regarding the positive test and the information was "intentionally kept quiet among Clara and the three people specifically named by her" according to a release from Cycling Canada.

The governing body further added that "While the practices in relation to the disclosure of anti-doping rule violations are substantially different today compared to 1994 when neither WADA (World Anti-doping Agency) nor CCES (Canadian Centre for Ethics in Sport – Canada’s National Anti-doping Organization) existed, Cycling Canada cannot condone how this matter was handled at the time by any of those involved," the statement read from Cycling Canada regarding Hughes admission.

"To this day, I don't know how that happened. I have never talked about it," Hughes told CBC News of the positive test. "I have no reason for it. I have no excuse for it. But it is real. And it makes me sick. It actually makes me sick because I know I didn't do anything, and it is so empty to say that 21 years later."

Hughes explained to CBC News she did not deliberately take the substance and is still unsure how she tested positive for ephedrine.

"My bottle was on my bike when I went to the porta-john and I remembered going and leaving my bike there. Whether someone did something to my bottle, I will never know. Or whether something [happened] in the lab, I don't know," she said.

"I still actually don't know how to talk about this. But because I wrote this book, I did feel that I had no choice. Definitely. Maybe that's in some small way part of the motivation [for] writing this as well… finally being completely honest."

A Cycling Canada statement announced Hughes had contacted the cycling body on August 27 and provided with it a manuscript excerpt detailing the positive test. The statement explained it welcomed the admission from Hughes but no action would be taken against the 42-year-old.

"Regardless of the practices of the day, Cycling Canada believes in full, fair and open disclosure of all doping related offences. We remain fully committed to the principles of fair play and rigid compliance with the WADA Code. Cycling Canada is proud of its current role as a leader in the anti-doping movement and remains committed to learning from the mistakes of the past so we don’t make them again."