The scientific findings, which were presented on a British television documentary last night, explain black runners' world domination of track and field and come amid an ongoing academic controversy over whether racial differences influence athletic and intellectual ability.

The documentary, on a Channel 4 show titled The Difference, examined new research from the Danish Sports Science Institute, which compared the running style of Kenyan athletes with Danish runners of similar physique.

The researchers spent 18 months in Eldoret, a town in northwestern Kenya that is home to the Kalenjin tribe, which has produced 12 of the world's top 20 runners.

Kalenjins of the Great Rift Valley represent 1/2,000th of the Earth's population, yet win 40% of the top international distance-running honours. A single tiny district of the region, Nandi Hills, sweeps 20% of the major international distance events.

The Danish researchers found that the Africans' heart rates were extremely slow, even when running over long distances, a factor that was attributed to the fact the Kalenjin live on a plateau 7,000 feet above sea level, which increases the number of red blood cells carrying oxygen around the body.

But beyond the benefits gained from geographic circumstances, the researchers also found other genetic advantages.

The scientists reported that the Africans had "birdlike legs, very long levers that are very, very thin" enabling them to "bounce and skip" over the ground, with their legs taking off after each footfall far faster than the Europeans.

The Kenyan athletes "flowed through the running motion" compared to the Danes, who "landed heavily and sunk into the ground and almost had to pull themselves forward," according to the research team.

The scientists concluded that the Danish runners were "pullers," while the Kenyans were "bouncers."

The research even pointed to differences within the Kenyan athletes that showed how members of the Kalenjin tribe from Nandi Hills consistently outperformed their countrymen.

Bengt Saltin, of the Danish Sports Science Institute, said the study proved that the Nandi Hills Kalenjin had a clear genetic advantage over other athletes.

"There are definitely some genes that are special here," he said.

The scientific tests pitted three groups of schoolboys at random -- one from Denmark, one from Nandi Hills and one from Eldoret, all of them with no prior athletic training.

The boys were given three months of training and then raced over 10,000 metres. The Nandi Hills boys beat the Danish runners and also the boys from Eldoret.

In further tests, two of the Nandi Hills boys then beat one of Denmark's top-ranked distance runners, Thomas Nolan, in a race.

"I could not catch them up, they were getting longer and longer away," said Mr. Nolan.

Mike Boit, a Kenyan who won gold at the Commonwealth Games in 1978, said, "The genetic inheritance is there."

But Kip Keino, a fellow Kenyan who won Olympic gold in 1968 and 1972, condemned the latest research as racist: "There's nothing in this world unless you work hard to reach where you are and so I think running is mental."

Earlier this year, researchers in South Africa comparing black and white distance runners found that black runners had greater fatigue resistance, greater activity of enzymes related to consuming oxygen and less accumulation of lactate in the blood.

Other studies comparing Kenyan and Scandinavian runners found that black athletes were better able to clear lactic acid from their muscles, and thereby sustain longer periods of intense exercise.

In Canada, Philippe Rushton, psychology professor at the University of Western Ontario, has been vilified for his controversial "racial sandwich" theory that puts Orientals at the top, whites in the middle and blacks at the bottom. His theories use head size to prove biological determinants of behaviour, and link race to intelligence, crime rates and athletic ability.

In the decade since he first introduced his theories at a major science conference, he has been investigated by the Ontario Provincial Police and the province's Human Rights Commission and the Premier of Ontario has called for his dismissal.