Story highlights Researchers explain why Sherpas are so good at dealing with extreme altitude

Xtreme Everest expedition tested Sherpa physiology

Sherpas are more efficient at using oxygen and have improved blood flow in their organs

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(CNN) Mount Everest is the ultimate test for adventurers trying to test their boundaries, but when it comes to climbing this natural monument, one group of people excel -- Sherpas.

The Sherpa people are an ethnic group from Nepal who have lived in the high altitudes of the Himalayas for generations. They have long served as guides and porters, whose local expertise has been invaluable for foreigners attempting climbs in the area.

But while they are admired for the ease with which they deal with the physical challenges of scaling some of the world's biggest peaks, the biological reasons for their mountain-climbing prowess have remained unknown -- until now.

Denny Levett is a founding member of Xtreme Everest and a consultant in clinical care at University Hospital Southampton, England. In 2013 she took part in Xtreme Everest 2 -- a scientific expedition to the top of Everest -- which explored the biology behind human endurance at high altitude.

She still recalls the exploits of one particular Sherpa who was part of the expedition.

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