April 30 (Bloomberg) -- Golfer Tiger Woods enhanced his vision to 20/15 with laser eye surgery. Football wide receiver Terrell Owens recovered more quickly from injuries by sleeping in a high-pressure chamber. And Olympic distance running hopeful Dan Browne extended his stamina by living in an altitude house that increased his oxygen-carrying red blood cells.

While athletes including the sprinter Marion Jones have lost gold medals, championships and eligibility for taking drugs, neither Woods nor Owens nor Browne was investigated by Congress or labeled a cheat by any U.S. sporting group. Their training and medical treatments are permitted under current rules.

Discoveries in genetics, physiology and nanotechnology are creating new challenges to definitions of cheating. Sports executives including Atlanta Falcons President Rich McKay and former World Anti-Doping Agency chief Dick Pound say a reconsideration of what's fair may lead to more-invasive testing, rules designed for emerging technologies and even legalizing banned substances if they become so commonplace they confer no advantage.

``We have become a fusion of humanity and technology,'' said Julian Savulescu, Uehiro Professor of Practical Ethics at Oxford University in England. ``We're not living in the kind of ideal world where we wrestle naked in oil and the strongest man wins. That is just not what professional sport is about today.''

Doping has gotten some of the world's most famous athletes in trouble. Jones returned five Olympic gold medals and went to jail this year after admitting to using steroids. Cyclist Floyd Landis lost his 2006 Tour de France title after testing positive for testosterone. And more than 80 Major League Baseball players were identified in Senator George Mitchell's report for using steroids or human growth hormone.

Fair-Unfair Line Blurred

The New York Yankees pitcher Andy Pettitte may have been unfairly tarred, according to at least one university study. Pettitte was named in the Mitchell report after saying he used human growth hormone in 2002 and 2004 while recovering from an elbow injury. A Stanford University study published in March found the substance would have little effect on a top athlete's performance.

Athletes themselves say medical advances are blurring the line between fair and unfair.

``You are taught from the time (you) are little to take any possible advantage you can get to make yourself better,'' said Chicago Cubs pitcher Kerry Wood in an interview. ``You are always trying to look for an edge.'' Wood hasn't been linked to any cheating.

Laser Eye Surgery

Tampa Bay Devil Rays pitcher David Price, the first selection in the 2007 draft, doesn't want competitors to use performance-enhancing drugs to offset any advantage he has on the mound. And yet he says he does plan to have laser eye surgery to improve his vision.

``Just because you are born with 20-20 you (get) an upper hand?'' he said. ``No. I think you are born with a disadvantage because everyone else is born with 20-20.''

Woods had Lasik surgery, which uses a laser to reshape the cornea, in October 1999.

Mike Adams, a 6-foot-8, 315-pound offensive tackle from Dublin (Ohio) Coffman High School, is the third most-talented high school football player entering college this year, according to rating agency Rivals.com. It would be wrong for a player as big and strong as he to take steroids, he says.

``Maybe you are not big enough to play a certain sport no matter how hard you work at it,'' said Adams, who graduated from high school early and has started taking classes at Ohio State University in Columbus, where he plans to play football on scholarship. ``I think it's different for smaller guys who can't compete without it. It's still wrong, but at least you can understand.''

Rules May Evolve

Pound, who was an Olympic swimmer and is the former president of the World Anti-Doping Agency, said more than 1,600 scientists, doctors and sports officials review WADA's list of banned substances every year to consider adding or removing drugs from the banned list. Sports are built around rules designed to ensure fair competition, Pound says.

``One of the things we agree upon is that we won't take the drugs that we've agreed will give us a competitive advantage,'' he says. The central principles are ``whether what you are going to do is performance enhancing, is it dangerous to the health of the athlete and is it contrary to a defined term of spirit of sports,'' he says.

At the same time, Pound acknowledges that rules have to change in response to medical advances and new practices.

``If it evolves to the point where everyone takes anabolic steroids and that's regarded as normal, then maybe the rules can change,'' he said.

Gene Doping

The anti-doping agency says the greatest cheating threat in the next decade is the emerging science of using cells, genes or other genetic elements to enhance the body. WADA Science Director Oliver Rabin has spent more than $6.5 million developing tests for gene doping, which he says athletes may try by the 2012 Olympics in London.

Lee Sweeney, chairman of the physiology department at the University of Pennsylvania's School of Medicine and a member of WADA's medical board, gained fame in the late 1990s when he injected mice with a synthetic gene that increased their muscle by 30 percent, even without exercise.

``If genetically, one day down the road we will be able to design people, then sports will be done, because how are we going to determine who is best?'' said Texas A&M University track coach Pat Henry.

The Falcons' McKay, a member of the National Football League's Competition Committee, said the burden is on sports' rule makers.

Non-Athletic Competition

``When there's a written rule and the written rule is violated, then in my mind it's cheating,'' McKay said. ``When there's no written rule, or someone is seeking an edge that isn't otherwise prohibited, that's competitive edge.''

As technology and medicine change, regulators need to be agile in determining when an advantage turns unfair, he said.

``It might turn into cheating, because somebody might have to go back and say, `You know what, we need a rule for that, because we hadn't thought about that,''' McKay said.

The issue spills over into non-athletic competition. Musicians take the blood pressure-lowering drug Inderal to calm their nerves before a tryout or performance, according to composer Stuart Dunkel. College students take the attention- deficit drugs Adderall and Ritalin to help them focus for exams, said Dr. Joji Suzuki of Boston University Medical Center.

`Spirit of Sport'

``Stock deals where people have inside knowledge are illegal, but in sports, having inside knowledge that the other team likes to run the fast break is fine,'' said National Collegiate Athletic Association President Myles Brand. ``The rules that apply to sports aren't necessary applied to other enterprises and conversely. But everyone knows the rules of their own game.''

The Oxford ethicist Savulescu dismisses the idea that athletes are competing on natural ability and that performance- enhancing substances violate the ethic of sport. He argues it seems arbitrary that marathoners are allowed to live in a low- oxygen chamber to increase stamina and Tour de France riders can prepare for races using intravenous nutrition and hydration.

``There is this harking for a spirit of sport I think is long gone,'' he said.

To contact the reporters on this story: Curtis Eichelberger in Washington at at ceichelberge@bloomberg.net; Aaron Kuriloff in New York at akuriloff@Bloomberg.net.

Last Updated: April 30, 2008 11:11 EDT