Why are Sherpas excellent high altitude mountain climbers?

Sherpas. The Himalayan Times

Among the outdoor adventure sports activities, mountaineering is the most dangerous and challenging one.  Also refereed to as  mountain climbing, the ultimate aim of this unique sport  is to climb the highest  points in mountainous regions, mainly for the pleasure of the climb. This  may be true of mountains with moderate height where the climbers may experience less difficulties that can be overcome easily. This kind of mountain climbing is often clubbed with hiking in the mountainous terrains. 

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In the strict sense, mountaineering refers to  the high altitude rock climbing that is beset with all kinds of hurdles. The rugged terrain, ever-changing weather conditions, sometime blizzards, etc may  present  hazards for the prospective climbers. Unless they  are well trained and have gained vast experience to face any eventuality-  dangerous situations  that may be unfolding before them they should not risk their lives. For the  poorly trained, mountaineering is a dangerous pastime. High altitude climbers should be well-versed in advanced techniques that deal with challenging vertical rock faces, wide crevasses, etc that are common in glaciated terrains.

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In the area of high-altitude mountain climbing, no ethic group is more adopted to this dangerous  pastime than the Sherpas of Nepal who are well known for their innate climbing skills, amazing strength and endurance on the high mountains and the knowledge of  snow-covered terrains. For any mountaineering expeditions from teams world over the role of Sherpas is indispensable. For the new mountain climbers, Sherpas' invaluable expertise, years of experience and advice come quite handy.  They get engaged in many activities, right from  carrying the loads up hill to setting up  camps, securing climbing routes, fixing lines, ferrying  supplies and guiding  clients to the top of Everest and other Himalayan peaks.

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 Scaling Mt. Everest, the tallest peak in the world, is the ultimate challenge of any professional climbers, a dangerous endeavor that requires lots of preparations; physical as well as mental prowess  is essential. For the Sherpas rock-climbing comes easy - something like climbing a flight of steps in a tall building.

For a few decades, researchers are baffled by Sherpas' long endurance  and physical and mental agility on high mountains. They are admired for their natural physical endurance  and ease with which they tackle physical challenges of scaling the world's tallest and dangerous peaks in the Himalayas.  How come the Sherpas do it with considerable ease,  while  other able-bodied, strong and robust climbers from many countries fail to achieve one third of what these simple people achieve? What is the biological reason for their  ability to function in oxygen-starved environment without getting fatigued? 

In the case of high altitude challenges when scaling a tall peak like Everest above 18000 feet, the prevalence of oxygen-starved atmosphere is a major and dangerous road block. According to Levett (2013), a researcher on 'human body functions at high altitude' oxygen levels at the summit are one third of those found at sea level and, fewer than 6% of humans are capable of making the climb without supplementary oxygen.

Oxygen sickness may occur if your are up above a few thousand meters and further up you may feel sick as if you had a hangover. Being natural climbers, having been adopted to living in  high mountain terrains for generations, Sherpas do not experience this physiological disorder.  From the physical and biological data collected from 116 low land people and 64 Sherpas during their 5300 meters climb, she focused her attention on  human cells  that respire to generate energy -- known as mitochondria and correlated their activities between Sherpas and other people. ''The Sherpas' mitochondria were much more efficient at using oxygen.They're like a fuel-efficient car," said Levett. 

Levett and her team studied the microcirculation of the climbers to find out how the small blood  circulation takes place in small vessels and how well the oxygen  reaches muscles, tissues and  organs as the body functions depend on them.  The team studied

Scaling Mt. Everest. Red Bull

blood vessels under the tongue and other locations in the body and she  found out at  high altitude the blood flow within these small blood vessels was found to be normal among Sherpas; but it is not so in the case of other volunteers  whose blood flow slowed down considerably.The secret in the case of Sherpas's ability to be agile at high altitude is their blood flow is quick enough to deliver oxygen to other organs, tissues, etc and this makes them energetic. At high altitude blood vessels in the brain swell because of more blood  goes in to tackle oxygen and its inability to drain out quickly as it gets in. 
 According to Levett  one Sherpa descended  2,000 meter from the top  in just two hours and had a cup of tea on the way down but  her team members  took almost a day.

This study by Denny Levett an others will be helpful in the future to figure out  to tackle oxygen-starved environment. For example when planes experience change in cabin pressure, hospitals experience limited oxygen supply and patients in critical state experiencing shortage of oxygen.  This study is also useful in the case of people with head injuries.

Note: Denny Levett is  a founding member of Xtreme Everest and a consultant in clinical care at University Hospital Southampton, England. It was in  2013 she took part in Xtreme Everest 2 -- a scientific expedition to the top of Everest to study human body's endurance on the high mountains in  an oxygen-deficient environment.

https://edition.cnn.com/2015/11/11/health/sherpas-superhuman-mountaineers/index.html