Shannon Rowbury eclipsed one of America's most venerable track and field mileposts last month, breaking Mary Decker Slaney's 32-year-old record in the 1,500 meters.

But the historic performance has been something of an afterthought in a sport undergoing another crisis of conscience over the use of performance-enhancing drugs.

Rowbury opens the World Championships on Saturday in Beijing unable to escape the credibility question, underscoring the predicament athletes in sports such as track and cycling face because of a history of drug scandals.

"I'd rather quit the sport than cheat or do something dishonest," she said recently by phone from Japan.

To some, Rowbury has been victimized by cheaters after finishing sixth at the 2012 London Games in a race in which two women who finished ahead of her have been banned for drugs and a third is suspected of using them.

To others, the fourth-generation San Franciscan is part of the problem as a member of the Nike Oregon Project team. Former athletes and others have alleged that Oregon Project coach Alberto Salazar gave runners banned drugs and manipulated the rules to provide some medications solely for a competitive edge.

None of the allegations have involved Rowbury, but the public has become jaded after hearing so many heartfelt denials from Lance Armstrong and Marion Jones, among many others.

Rowbury, 30, accepts the added scrutiny as the reality of a sport that is experiencing eroding popularity a year before the Rio Games.

"It is something that has haunted anyone in the sport," said Rowbury, a Sacred Heart Cathedral alum. "The women's 1,500 in particular -- and the 800 -- seem so highly susceptible to cheating and dishonest people."

This week, Asli Cakir-Alptekin of Turkey was stripped of her 1,500 gold medal from London and given an eight-year suspension after drug tests showed abnormalities in her blood.

Her Turkish training partner Gamze Bulut, who won the silver in London, also is under suspicion although she never has been publicly cited for failing a drug test. Russian Tatyana Tomashova, who finished fourth, served a two-year ban for manipulating drug samples on the eve of 2008 Olympics.

It took Rowbury time to get over the London results.

"As much as I think it is horrible that anyone could stoop to such a low level and cheat to succeed, I can't change their actions," she said.

In the meantime, Rowbury has steadfastly defended Salazar, a former marathon great who has become one of America's leading track coaches. She also has denied breaking any rules, or subverting the system to gain an edge although she didn't break the 4-minute barrier until after joining with Salazar in 2013.

"I've had to come to terms with that no matter how genuine I am and no matter how truthful I am, there are people who want to believe the worst and will find a way to spin anything that I say into something negative," the two-time Olympian said.

She hopes to change the narrative in Beijing, where Rowbury is among six U.S. athletes with Bay Area ties competing. The former Duke standout is expected to advance through preliminary heats Saturday and the semifinals Sunday to reach the final Tuesday at the Olympic stadium.

So far, nothing has stopped her this summer.

She lost a shoe during a qualifying 1,500 heat at the U.S. Championships in June and ran barefoot the rest of the way. She ripped skin on the bottom of her foot but eventually finished second to rival Jenny Simpson in the final to make the World Championships.

Then came her towering run July 17 at the Diamond League meet in Monaco. The performance partially was overlooked because Ethiopia's Genzebe Dibaba won in a stunning world-record time of 3 minutes, 50.07 seconds. Rowbury was third in 3:56.29, breaking Slaney's long-standing mark of 3:57.12. It was Rowbury's best time in the event by more than three seconds.

"You start to realize just how much has to go right for that big successful race," she said. "You can be in the best fitness of your life, but if you don't have a great racing opportunity it's hard to force it to happen."

Now she has landed in China feeling fitter than ever.

"What more can I hope for?" she asked.

Well, another fast race might be nice.