Athletics: It used to be in athletics you could believe in the impossible. Believe when great barriers were broken, when new limits were reached in human speed and endurance. Over the years that belief was often shaken by the powers of pharmacy.

But the belief largely survived. And then came 2003. A year when athletics was dragged through so many dirty tales of new drugs and plain old cheating it seemed there was nothing left to believe in. Nothing remotely ground-breaking, and least of all the impossible. It takes a strong preacher now to keep that belief alive.

It was for sure a year when athletics made headlines for mostly the wrong reasons. For the first time since the Ben Johnson scandal in 1988 it proved truly hurtful for admirers of the sport. At one point it all went totally crazy. So on reflection you can't avoid the negativity. Maybe it can be put down as the year when cheats, the great minority, discovered their days might be numbered.

It started when the belief in even our own was shaken, as one of the first big, bad drug-related stories of the year involved an Irish athlete. On the first Monday of March news emerged that an out-of-competition test on Geraldine Hendricken had revealed traces of the banned anabolic steroid nandrolone. The previous summer she had run 4:02.08 for 1,500 metres and was ranked 10th in the world. Hendricken proved her food supplements were contaminated with the drug but the athlete is liable and she's serving a two-year ban. She was the first Irish athlete to test positive for a steroid.

In April the world took notice of the next big athletics story of the year. Carl Lewis, winner of nine Olympic gold medals, was found to be among some 100 American athletes involved in a cover-up of drug abuse back in 1988, testing positive for three types of banned stimulants.

Lewis was cleared at the time for "inadvertent doping" and the American Olympic Committee kept the whole thing under wraps. He admits now his samples were positive, but he successfully appealed, and "everyone was treated the same". Yet there was no disguising the damage done to his legacy.

In late August Paris hosted the ninth IAAF World Championships, and like the Olympic Games, athletics was brought to the centre of the sporting stage. Belief was damaged there when American sprinter Kelli White, winner of the 100 and 200 metres, tested positive for the stimulant modafinil. Not a particularly upsetting scenario, but nonetheless cheating, and White is set to be stripped of those titles.

In the immediate aftermath of Paris came yet further damage. Days after winning the 400 metres another American, Jerome Young, was revealed as the athlete who tested positive for nandrolone before competing at the Sydney Olympics, where he helped his team win gold in the relay. Another cover-up that didn't last.

But to say the World Championships in Paris were spoiled by these stories of cheating (not to mention Jon Drummond) is unfair. It was a brilliant week of athletics. And so much of it believable, like the 18-year-old Kenyan Eliud Kipchoge beating Hicham El Guerrouj to win the 5,000 metres. Or the 21-year-old Kenenisa Bekele beating fellow Ethiopian Haile Gebrselassie in the 10,000 metres.

Or the race of the entire week - the men's 3,000 metres steeplechase and the speed over the barriers of Saif Saeed Shaheen, a Kenyan bought up by Qatar. It was impossible running, but wholly believable.

Ireland had its moment in Paris, too, when Gillian O'Sullivan carried her consistent progression in 20km race walking onto the medal podium, taking silver behind Yelena Nikolayeva, the vastly experienced Russian.

It's probably true O'Sullivan's achievement was somewhat overshadowed by the massive disappointment later that week when Sonia O'Sullivan trailed home a distant last in the final of the 5,000 metres. No one can explain that performance, not even O'Sullivan herself, and it has left a question mark over her ability to still compete with the best on the world stage.

Yet typical of O'Sullivan, the future is all that matters and the Athens Olympics beckons. In December she helped the Irish women's team win silver medals at the European Cross Country in Edinburgh, but her own fourth-place finish was ultimately a few steps short of a return to old form. It might be her great career has run out of track.

Despite the struggle to keep the sport alive at grassroots level, much hope emerged over the year. There were five major track championships outside of senior competition and Ireland won medals in them all. So taking a bow after 2003 are the following: Ann Loughnane, silver medallist in the 5km walk at the World Youth Championships; Robert Connolly, bronze over 5,000 metres at the European Under-23s; Joanne Cuddihy, silver over 400 metres at the European Juniors; Colin Costello, silver over 1,500 metres and bronze in the steeplechase at the European Youth Olympics; and finally Paul Hession, silver over 200 metres at the World University Games.

Not all those medals came as a surprise, at least not as much as Paul McKee's bronze at the World Indoor Championships in Birmingham back in March. No Irish male had won a major medal over 400 metres on the flat, and yet there was McKee - the affable 26-year-old from Belfast - on the medal podium after a race you could truly believe in.

But it was as the athletics year wound down that the greatest damage was done to what is still believable. On a slow day in mid-October word came through that several high-profile athletes had tested positive for tetrahydrogestrinone. What is tetrahydrogestrinone? It sounds better as THG, and turned out to be a designer steroid, specifically fashioned to be undetectable. A lucky tip-off from an anonymous American coach back in June started the process whereby a new test was developed, and old samples retested. When the results came back all hell broke lose.

When the new drug was traced back to the California laboratory of Victor Conte, its use seemed limited to certain American athletes, such as 1,500 metre runner Regina Jacobs and shot putter Kevin Toth. Then Britain's 100 metre champion Dwaine Chambers got caught with THG in his system and suddenly no one could be trusted. So the IAAF retested around 400 samples from Paris, although no new names have yet been added to the list of THG abusers. For now THG appears to have been a small operation. Other designer steroids are sure to exist and might not be. Be careful then what you believe in.