Shiwen, just 16 years old, swam faster than a male champion during her 400m medley at 4m 28.43s, sparking rumors of her drug use.
Team China Olympic swimmer Shiwen has denied the use of drugs after winning the gold in the 400-meter medley Sunday with a world record time.
"My results come from hard work and training and I would never use banned drugs," affirmed Shiwen after her win, according to The Sun. "The Chinese people have clean hands."
"There is no problem with doping," she later added. "The Chinese team has a firm police so there is no problem with that."
Shiwen's feats were so incredible that her ability raised questions of doping, or using substances that enhance performance. The Olympic athlete bested her own time from last year's World Championship by seven seconds.
World Swimming Coaches Association's John Leonard was outspoken about his concerns over Shiwen's performance.
"We want to be very careful about calling it doping," said Leonard, according to the U.K.'s Telegraph. "Where someone could out-split one of the fastest male swimmers, that I think legitimately calls that swim into question."
London 2012 chairman Lord Coe defended Shiwen though, and explained that it would be "very unfair to judge an athlete by a sudden breakthrough."
"What you tend to forget is probably the ten years of work that's already gone in to get to that point," said Lord Coe, according to ITV News. "You need to look back through her career. I think you've got to be very careful when you make judgements like that but yes it is an extraordinary breaktthrough."
Shiwen refused to be pulled into the controversy over her 400m medley time.
"I have no idea, I mean I wouldn't want to get into that at all, but a 58 second (final 100) is an insanely fast swim," she said, the Telegraph reported.
American Olympic swimmer Ryan Lochte admitted the incredible feat made by Shiwen.
"If she was in there [the pool] with me, she might have beat me," said Lochte, according to the Telegraph.
This year's London Games have the most stringent drug checks in the history of the games. During the Sydney Olympics, 2,300 random drug checks took place, but in London, there will be 6,000.