COLORADO SPRINGS, Colo. -- Olympic gold medalist runner LaShawn Merritt has been banned through July 2011 for using a banned substance found in an over-the-counter male enhancement product.

Merritt won Olympic golds in the 400 meters and 400 relay in Beijing. He accepted a provisional suspension earlier this year and received a 21-month suspension from arbitrators Monday.

The suspension is retroactive to last October and he'll be eligible for the 2011 world championships next August.

The 24-year-old from Virginia tested positive for testosterone prohormones three times between October 2009 and January 2010. He cooperated with doping authorities, and arbitrators took three months off the normal two-year ban for first-time offenders.

In finding Merritt's use of a product called Extenze, the arbitration panel wrote that Merritt's conduct "was exemplary and demonstrated tremendous character in making what had to be a painful and humiliating confession."

In a statement released through his attorney, Merritt said he appreciated the arbitrators' decision to cut the suspension by three months, which will allow him to defend his 2009 world title -- there are no world championships in 2010.

"While I acknowledge that I made a mistake, I appreciate that the Arbitration Panel listened to all of the evidence, and agreed that I have never taken any substance to gain an advantage on the track," Merritt said.

International Olympic Committee rules state that any doping offense carrying a suspension of at least six months will result in a ban from the next Olympic Games, regardless of whether the games fall within the suspension period. No decision has been made on Merritt's status for the London Games in 2012.