Until Sunday, it was almost possible to believe Tyson Gay. He’s a sprinter, and a damn good one—which means that a rational fan should know that he might be using performance-enhancing drugs. But Gay, the second-fastest man in history, doesn’t have the Popeye physique and crazy eyes of notorious dopers of the past; he’s calm, not manic; his head is of a normal size, in both the literal and clichéd sense of that phrase; his improvements over the years have come steadily, not wildly.

Now, though, he’s a drug cheat. Rumors on letsrun.com, a Web site known for accurate ones, started on Saturday. On Sunday, Gay revealed that he had tested positive for a banned stimulant. To his credit, he admitted what had happened. “I don’t have a sabotage story,” he said, “I don’t have any lies. I don’t have anything to say to make this seem like it was a mistake or it was on USADA’s hands, someone playing games. I don’t have any of those stories.”

Contrast that with Asafa Powell, a Jamaican and the fourth-fastest man in history, who also was busted on Sunday. He, as athletes typically do, proclaimed that he had no idea what on earth had just gone on. “My team has launched an internal investigation and we are cooperating with the relevant agencies and law enforcement authorities to discover how the substance got in my system,” he declared. “I assure you we will find out how this substance passed our rigorous internal checks and balances and design systems to make sure it never happens again.” He must have eaten a bad steak, drunk too much Jack Daniel’s, or had someone drop a tablet in his beer.

There is much that we don’t know about these positive tests. Apparently, other announcements about other Jamaican athletes are coming soon. The accused will mount their defenses, and those defenses may be convincing. Nonetheless, it’s clear that the sport’s problem is endemic and appalling. With Gay’s bust, men implicated in doping scandals now own the twenty fastest hundred-metre times ever run by Americans. Every American gold or silver medalist in the race since 1988 was eventually busted for doping. And Carl Lewis, the winner that year—after a positive test ejected Canada’s Ben Johnson—didn’t just leave a trail of wheat germ in his wake. He tested positive for stimulants three times in 1988, though the results were thrown out.

Where does this leave Usain Bolt, the one man faster than Tyson Gay? He’s never failed a drug test. But now many of his countrymen have: Powell; Steve Mullings, one of the ten fastest men in history; triple gold-medalist Veronica Campbell-Brown; gold-medalist Sherone Simpson. Bolt is in something of the same position that Lance Armstrong was in about 2003: a man dominating a dirty sport as his rivals and teammates fall. It wouldn’t be a surprise if one day this summer Bolt starts talking about misreading the label on an herbal supplement—or if, a decade from now, he ends up talking to Oprah.

The problem in sprinting has long been like the problem in cycling. People think they have to dope in order to be competitive. Athletes test positive every year and get suspended. But that doesn’t break the cycle: it may just accelerate it. What high-school sprinter is going to think he or she can be the best in the country without using drugs now? Here is the argument that Ben Johnson’s coach made when persuading him, as a young runner, to get with the program: “You only cheat if you’re the only one doing it. This means if the other guys are doing it, and you start doing the same thing, it’s not cheating.”

How can sprinting change? Cycling has cracked down and cleaned up. Times in the Tour de France this year are far slower than in years past. (Though some riders are still going suspiciously fast.) Major League Baseball, after investigations and bloodletting, seems far less juiced than it was a decade ago.

So here’s one idea for track and field: change the incentive structure. When a baseball player or a cyclist is busted, the penalty hurts his team. If your third basemen tests positive for drugs, the whole team has to suffer through the search for a new one. Runners don’t really have teams, but they do have countries. So what if, to borrow an idea from Daniel Yi, countries were punished when their athletes test positive?

Tyson Gay was scheduled to represent the United States at the World Championships next month. He’s not going to go and so the U.S. will replace him. But what if the U.S. wasn’t allowed to send someone else? His lapse would be his nation’s loss. Countries can send three athletes to the Olympics in each Track and Field event. What if, after a positive test of a medal winner, they only got to send two the next time? National drug-testing organizations would have further incentives to crack down. Peer pressure against drug use would pick up.

That might not be enough. The culture of the sport is broken, and it needs repairing. The hundred-metre dash is one of the purest sporting events there is: this is how fast human beings can move. That’s why we take such pleasure in Usain Bolt’s beautiful loping stride or Tyson Gay’s amazing upright posture and the strain in his neck. And it’s why it so disappointing when, with the regularity of hot days in the summer, news comes that yet another sprinter has tested positive.

Photograph by Andy Lyons/Getty.