Usain Bolt - file

MIAMI, Florida (CMC):

World renowned coach Clyde Hart, a man labelled as perhaps the best 400-metre coach ever, believes Jamaican sprint phenomenon Usain Bolt has the potential to run faster than 43 seconds in the 400 metres.

Bolt, the Olympic champion and world-record holder in the 100 and 200 metres, has been sidestepping the quarter-mile to concentrate the shorter distances, which have been fruitful for him.

However, Hart, who conditioned American great Michael Johnson to the 200 and 400-metre world records in 1996 and 1999, is confident Bolt is capable of running a world-record 42 seconds in the one-lap event.

The Jamaican has a personal best of 45.28 seconds - achieved last season - but after looking back at his 19.30-second world-record run in Beijing, Hart believes the sprint star can take quarter-mile to another level, should he apply himself to the right programme.

"Yes, I think certainly if he (Bolt) had the right programme, with his speed, he could run under 43 seconds, but whether he would ever do that is a whole different ball game," Hart was quoted as saying on the Spikes - the New Heroes of Athletics website.

Current world record

The current world record is 43.18 seconds by Johnson.

"When we talk about potential, I always use a formula. You double a person's best 200m and add 3.5 to it and that should give you what you are able to run in the 400 metres. If they have the work ethic, motivation and all the condition to go with it, you could see that Bolt would be running in the 42s," he added.

In the wake of his inspiring comments, Hart, who also guided American Jeremy Wariner to World and Olympic titles, also took time to be cautious in pointing out that achieving this feat will take more than "physical ability".

"You need to recognise there is more to running the 400m than physical ability because in the past there have been some very fast people that have tried the 400m and didn't run very spectacular times," he noted.

Hart said Johnson could have gone sub-43 seconds had he not waited until the later stages of his career to attempt the world record.

"The same thing was true with Michael, although he had (a 400m best of) 43.18. I still think his potential was down in the 42s.

"He would probably have done this had he ran the pace he was running (in the 1999 World Championship 400m semi-finals) but he didn't attempt to go for the world record until he was well on into his career," Hart said.