Friday, 15 May 2020

Sherpa people's physical endurance in oxygen-starved environment on Mt. Everest!!

Sherpa of the Himalaya
For any mountaineering team to scale the tallest peak in the world or any peaks in the Himalayas, the untiring help of Sherpas is quite indispensable. It is quite unthinkable to ascend the tall peaks above the dangerous zone without the guide of a team of Sherpas who have been adopted to  climbing  high altitude mountains. Unlike other mountaineers, these people  climb the oxygen-deficient  zones on the high mountains with considerable ease.  No person from any other ethnic group  can match them in this respect!!
The Himalayan mountain
Long before their genetic variants were discovered, the Sherpa people were admired for their ability to easily cope with high altitudes.  The moot question is: How is it possible for them to achieve this great feat?   What inbuilt physio-biological  mechanism do they possess? 

A research expedition to Mount Everest has thrown light on this unexplained riddle by studying the  physiological basis of amazing adaptations seen in the native Sherpa people, which make them a class apart in the area of mountaineering; they  far better suited  to high altitude life unlike others. The scientific advantage we get from this rare and unique research is a  good understanding of Sherpas'  adaptation to oxygen poor environment  will  help improve the treatment of patients with conditions related to reduced levels of oxygen in the blood and tissues.

Being high  altitude dwellers, Sherpas  are known to have the rare  ability to live and climb  high Himalayan mountains  where oxygen level  is low.   No doubt genetic inheritance and natural selection have played a vital role in the development of  special  traits that help the natives  survive  at high altitude. However, scientists are yet to understand  the physiological basis underlying their  far superior  endurance power in a fatal environment.  In the case of Lowlanders and other high-altitude populations (e.g. Andeans and Ethiopians),  they try to cope with the reduced oxygen levels at high altitude by increasing the amount of oxygen carrying cells (hemoglobin) in the body. But in the  case of Sherpa it is quite surprising that they do well with less oxygen in their blood.  How come they have this unique trait?

The investigation on the physiology of the Sherpas and their adaptation at high altitude  was undertaken by a team from  University College London's Center for Altitude, Space, and Extreme Environment Medicine on Xtreme Everest 2, a transnational research program undertaken on Mount Everest.  The team researched on two different groups one from the Sherpas, and the other naive population of Lowlanders. They took the 
baseline measurements in London (50m altitude) and Kathmandu (1300 m altitude) for the Lowlander and Sherpa participants respectively, and then  they took repeated  measurements  from participants as they ascended to the base camp of Mount Everest (5300 m altitude).
The highlight is participants  followed an identical ascent profile to each other,  and this was done to ensure that the physiological challenge, environmental oxygen content and temperature (which affects the constriction of blood vessels) were matched for all participants. Thus, any differences detected between participants would be attributable to their individual physiology rather than variation in the magnitude or duration of exposure to low levels of oxygen at high altitude.
Sherpa people, the great heroes of the Himalayas youtube

The team observed  Sherpa people  were able to maintain a greater degree of blood flow and oxygen delivery to the working tissues in a changing environment at high altitude on the ascent of Everest.  The emerging factfrom this study is Sherpas (in comparison to Lowlanders), are able to deliver more oxygen around their bodies. These unique  findings  clearly explain as to how  Sherpas survive at altitude without increasing hemoglobin content. Little do we realize that high levels of hemoglobin will  make the blood thick and viscous. Obviously this will  slow down its flow around the body,  causing unwanted risk of   side effects such as blood clots to the lung.  With  favorable  increased blood flow and oxygen delivery over high oxygen content, Sherpa folks  still  have the natural ability to provide their tissues with enough oxygen and, at the same time,  minimize the risk of potentially fatal side effects.

The low levels of oxygen at high altitude can simulate the reduced oxygen faced by critically ill patients in hospital. A good understanding of the  physiology behind Sherpas' ability to  survive in a  low oxygen environment  will help the doctors  improve intensive care of patients through  new  diagnostic and treatment strategies to promote easy flow of blood.  There is a small hitch in terms of physiological mechanism that the hospital environment on the ground level is different from the oxygen-poor high mountain environment.  Yet another problem is in the hospital doctors deal with heart patients with different heart conditions and they may be ill for a number of  reasons. This research study  looks at the normal function of the body in  an oxygen poor situation as in the case of Sherpas. 

Dr Edward Gilbert-Kawai, a co-author of the research is of the opinion, "The mechanisms identified in this study, such as increased blood flow and oxygen delivery to working tissue, feasibly describe an alternative means to aid oxygen delivery in critically ill patients.''  Better  new critical care strategies and medicines, besides the underlying cellular mechanisms behind the response  may improve the  condition of heart patients who experience low oxygen delivery.  Such patients can function normally if we come up with right strategy and drugs. 
A new study says,  ''Sherpas have evolved to become superhuman mountain climbers, extremely efficient at producing the energy to power their bodies even when oxygen is scarce''
“Sherpas have spent thousands of years living at high altitudes, so it should be unsurprising that they have adapted to become more efficient at using oxygen and generating energy,” says Dr Andrew Murray from the University of Cambridge, the study’s senior author (Proceedings of the National Academy of Sciences (PNAS).  “When those of us from lower-lying countries spend time at high altitude, our bodies adapt to some extent to become more ‘Sherpa-like’, but we are no match for their efficiency.”  .....(……

Journal Reference:
Thomas Davies, Edward Gilbert-Kawai, Stephen Wythe, Paula Meale, Monty Mythen, Denny Levett, Kay Mitchell, Michael Grocott, Geraldine Clough, Daniel Martin. Sustained vasomotor control of skin microcirculation in Sherpas versus altitude-naïve Lowlanders-experimental evidence from Xtreme Everest 2. Experimental Physiology, 2018; DOI: 10.1113/EP087236