Using slow-motion footage, scientists have discovered that experienced barefoot runners land very differently from runners who wear shoes.

The researchers showed that runners who have trained barefoot tend to strike the ground with their forefoot or mid-foot, rather than their heel.

The team described their findings in the journal Nature.

Barefoot runners, the scientists say, may be at less risk of certain types of injury than those who wear cushioned running shoes.

The question of how best to support and protect a runner's feet is something that has intrigued both scientists and sports shoe designers.

This analysis, the researchers said, took an evolutionary approach to that question.

The research team used a combination of highly sensitive scales, high speed cameras, and 3-D motion analysis to compare barefoot runners to those wearing running shoes.

Their results showed that "shod" runners tended to strike the ground with their heel first.

"This creates an impact; it's like someone hitting your heel with a hammer with up to three times your body weight," said the lead researcher, Dr Daniel Lieberman from Harvard University in the US.

"Those collision forces have been implicated, by several studies, in certain kinds of repetitive stress injuries.

"Shoes work because they cushion much of that force - slowing it down, mostly."

But experienced barefoot runners appear to have developed a different way to prevent the pain, striking the ground with the forefoot or mid-foot.

"By forefoot or mid-foot striking correctly, one can almost completely eliminate that collision, making barefoot running comfortable," said Dr Lieberman.

He explained that the style adopted by barefoot runners may, in some respects, be less damaging.

Dr Lieberman's footage also demonstrated the specialised anatomy of the human foot, and caused him and his colleagues to propose that modern sports footwear may have altered how people run.