Cycling and its most famous race the Tour de France have long been embroiled in doping scandals. American Floyd Landis was stripped of his 2006 Tour title after admitting that he used performance-enhancing drugs. Landis has also accused many others in the sport of using drugs, including seven-time winner Lance Armstrong. Armstrong has maintained his innocence, though federal prosecutors continue to investigate the charges.

Major league baseball has been plagued in recent years with reports that potential Hall-of-Famers such as Barry Bonds and Roger Clemens used steroids to enhance their performance. A 2009 poll found that one in ten retired NFL players admitted to using now banned anabolic steroids while playing.

Doping charges have not been limited to the U.S. A major doping scandal is brewing in South Africa involving a former East German head coach who allegedly administered suspicious drugs to the country’s top sprinter.

Women have also been involved in doping scandals. Most recently, Nigeria’s Oludamola Osayomi, the women’s 100-meter champion in the 2010 Commonwealth Games, tested positive for the stimulant methylhexaneamine. A second Nigerian athlete, Samuel Okon, who finished sixth in the 110m hurdles, tested positive for the same drug. Nine Australian athletes also tested positive and are facing two-year suspensions. Sydney 2000 Olympic Games star Marion Jones has tearfully admitted that she used drugs.

Swimming has not been immune to drug scandals. French swimmer and two-time European champion Frederick Bousquet was recently handed a two-month ban following a positive test for the banned stimulant heptaminol.

Now comes the admission from Eddy Hellebuyck, the men’s winner of the 2003 Twin Cities Marathon, that he took injections of the banned substance EPO, which increases endurance. He was forty-two years old when he easily won the race, breaking away from a pack of runners at the twenty-three mile mark. He is the only Olympic-caliber American marathoner to have been found guilty of a major doping violation, according to Runner’s World.

Despite the expanded testing and repeated warnings, athletes in many sports continue to risk their careers and their health in order to maximize their performance. With the London Olympics less than two years away, it will be no surprise if even more athletes find themselves banned from competition for using performance-enhancing drugs.