Jamaica's Asafa Powell and Sherone Simpson, each former Olympic medalists, said they were surprised by their positive drug tests, according to reports by Reuters and the Jamaica Gleaner (via NBCSports.com's Nick Zaccardi).
The two sprinters face lengthy bans if their "B" samples also test positive. The runners said they tested positive for oxilofrine - an amphetamine - at the Jamaican national championships in June.
Powell was once the world record holder in the 100 meters and has won Olympic gold with Jamaica's 4 x 100-meter relay team.
“I have never thought about (retiring),” Powell told the Gleaner. “I was just shocked by the news. I have been thinking a lot but never once thought about giving up...
“At first I thought it was joke, you know. I thought I was being pranked because that was the first something like that has ever happened. I was confused after and just in disbelief.”
Simpson won a silver medal in the 100 in 2008. She had qualified for a spot at this year's world championships but seems unlikely to compete.