By Tom Geoghegan BBC News Magazine

On top of the world... for now

Asafa Powell broke the world 100m record by shaving one-hundredth of a second off the old mark. Savour the moment, because record-breaking is set to happen less and less.

Since the ancient Greeks began the quest to find the world's fastest runner, mankind has been getting stronger, faster and fitter.

But the progress seems to be slowing down if the 100m, the gold standard of modern racing, is any indication.

In 1968, US sprinter Jim Hines became the fastest man on Earth when he lowered the 100m mark to 9.95s.

Thirty-seven years later, Powell's achievement this week in Athens means the record has been lowered by only a further 0.18s - an average of 0.005s each year.

LITTLE BY LITTLE 9.95: Jim Hines 1968 9.93: Calvin Smith 1983 9.92: Carl Lewis 1988 9.90: Leroy Burrell 1991 9.86: Carl Lewis 1991 9.85: Leroy Burrell 1994 9.84: Donovan Bailey 1996 9.79: Maurice Greene 1999 9.78: Tim Montgomery 2002 9.77: Asafa Powell 2005

The 22-year-old Jamaican was so close to the previous record that his initial time was the same, only to be rounded down a few minutes after the race. That meant Powell was the 10th man to break it since Hines and he has vowed to break it again.

But has man "hit the wall" in his most prestigious race?

Not yet but he will soon, says British 200m record holder John Regis, who believes the 100m record will reach a point and almost stop.

"I think in my lifetime it will break 9.70s, maybe 9.69, somewhere in that area. And once you start to get down there, there's not much room for improvement, unless in the future they're seven feet tall with twice as much muscle as us. So it won't go down much below that."

Eventually every event will get to a breaking point John Regis

The races will be no less competitive as a result because athletes will still have an incentive to break the world record but it's unlikely to happen, he says. And the same pattern will be followed in the other track and field events.

"There's more scope with the longer distances but eventually every event will get to a breaking point. In the 200m, Michael Johnson's 19.32 is out there, but in five years that record will go and at some point, someone will break 19 seconds, which will be the ultimate record."

Diet, training and technique can still be improved, says Regis, and there's no predicting raw talent in sport like Tiger Woods, Michael Johnson and Michael Schumacher, who "keep raising the bar".

Never perfection

Track statistician and broadcaster Peter Matthews thinks the 100m record will fall to 9.6s.

"But we can never say that would be the end. Men and record-breaking is such that if there's a target, that's what we go for.

"You can never reach perfection, so although record-breaking is slowing up, it will never stop entirely."

Johnson's 200m: Unbreakable?

Huge improvements made in the 1950s, 60s and 70s, due to science and more nations racing, have slowed down now, he says, but conditions can still play a part. The maximum wind assistance allowed, of two metres a second, can make a difference of 0.15s in a 100m race.

So Maurice Greene would have run under 9.70s on a couple of occasions if the wind had been in his favour, says Mr Matthews. And if a major games was held at altitude, like in Mexico City in 1968, then that would also assist the athletes.

Soon officials may record times to one-thousandths of a second, says Kate Owen, physiologist with the British Olympic Association. But there are so many variables involved in preparation and the race itself, the record will continue to fall, although by smaller margins.

"We just don't know the limits of the human body yet," she says. "This is not an exact science and if you asked sprinters around the world, you would find there are differences in training and who's to say Asafa Powell has got it right?"