MILWAUKEE - Ryan Braun certainly doesn't fit the image fans conjure up when they hear that a baseball slugger has been accused of using performance-enhancing drugs.

Since he joined the Brewers in 2007, Braun has belted big home runs not with cartoonishly large muscles, but with a sweet swing and an ultra-quick bat. Last season, he helped drive Milwaukee to the playoffs and was voted the NL's Most Valuable Player.

Now Braun finds himself fighting a 50-game suspension after news leaked that he tested positive for a banned substance. He maintains his innocence.

A spokesman for Braun said in a statement issued to ESPN and the Associated Press that there are "highly unusual circumstances surrounding this case which will support Ryan's complete innocence."

ESPN cited two sources Saturday in first reporting the result, saying Braun tested positive for elevated levels of testosterone, adding that a later test by the World Anti-Doping Agency lab in Montreal determined the testosterone was synthetic. Braun is appealing, according to people familiar with the case.

And fans may be inclined to believe Braun, given his clean-cut image and that he hasn't tested positive or even been suspected of using banned substances in the past. And, perhaps above all, is the fact that he doesn't look like a human science experiment.

But there is a long history of athletes accused of taking banned drugs insisting they did so to recover from injuries. Sports medicine experts acknowledge the drugs may help, raising the possibility Braun might have been doing just that.

Norman Fost, a professor of pediatrics and director of the bioethics program at the University of Wisconsin, said vigorous exercise breaks down microscopic muscle fibers.

"One theory is that anabolic steroids hasten the repair of those muscle fibers, and allow you to work out harder," Fost said.

According to a document on the Mayo Clinic's website, the potential injury recovery benefits of performance-enhancing drugs are part of their appeal to athletes.

"Besides making muscles bigger, anabolic steroids may help athletes recover from a hard workout more quickly by reducing the muscle damage that occurs during the session," the document says. "This enables athletes to workout harder and more frequently without overtraining. In addition, some athletes may like the aggressive feelings they get when they take the drugs."

Braun has dealt with nagging injuries in recent years, and other players have acknowledged they used performance enhancers to help them recover from injury.

One of the most well-known is pitcher Andy Pettitte, who said he used human growth hormone to recover from an injury, not to enhance his performance. Given the generally positive public reception to Pettitte's admission, Fost wonders why more athletes accused of using banned substances don't just follow his lead.

And Fost doesn't necessarily see anything wrong with athletes taking a substance that helps them recover from their injuries. He believes health concerns about steroids haven't been sufficiently proved, and blames the media and Congress for creating an atmosphere he likens to the Salem witch trials.

"That's the big question - why is it 'cheating?' " Fost said.

Braun did not respond to a request for comment from the AP.

"We are dealing with an incomplete set of facts and speculation," Brewers chairman and principal owner Mark Attanasio said in a statement. "Before there is a rush to judgment, Ryan deserves the right to be heard. We are committed to supporting Ryan to get to the truth of what happened in this unfortunate situation."