Himalayas Callenge V2

939x397 Mera Icewalk

Altitude in the Himalayas

Understanding it...

& being prepared!

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Most of our Himalayas Challenges will take you above 5,000m, and as such are classed as high altitude treks. Complex physiological changes take place in the body once above 2,500m and this is because the air becomes thinner with less oxygen. When we breathe, your body recognises this and reacts in several ways to ensure esssential oxygen gets delivered to your organs. To put it into context, at 5,500m, the air contains half as much oxygen than at sea level. 

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The Acclimatisation Process

The process of ‘acclimatisation’, which is often referred to when talking about trekking at high altitude is a temporary change within the physiology of the body to cope this lack of oxygen. It is not possible to ever totally acclimatise to high altitude, particularly above 5000m, as there simply isn’t enough oxygen to maintain our body for a prolonged period of time. We can however, acclimatise temporarily in order to reach our summit goal.

  • We breathe faster, which is a natural and normal reaction. Our body is trying to get as much oxygen into its system as possible.
  • Our heart beats faster even at resting pace. This is because it is working harder to pump oxygen around our body.
  • We start to produce more red blood red cells to increase oxygen carrying capacity.
  • We excrete bicarbonate through our kidneys and urine which makes our blood more acidic, in turn driving our ventilation of air to take on more oxygen (and help us to acclimatise).
  • Because our brain requires 15% of all oxygen intake, it responds by limiting the body’s physical activity to preserve energy and so you will find you walk at a slower pace at altitude and become tired and breathless if accelerating movement, e.g. running to find a toilet spot!

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Helping your body...

Go slow:  It is impossible to fully acclimatise on a Himalayas Challenge. However, all of our altitude treks include an acclimatisation day to allow our bodies to adjust to the ever changing altitude. Climbing higher and sleeping lower allows for acclimatisation to take place gradually. Our 7 day itineraries also give you more time to do  this and so increase your chances further of making it to the summit.

Pace yourself:  Our guides will set a deliberately slower and steady pace to aid the acclimatisation process.

Eat:  The body needs as much energy as it can get to pump oxygen around your body and so it is important to eat little and often, even if you feel you have lost your appetite.

Keep hydrated:  It is important to keep drinking water to keep hydrated; adding electrolytes will also help replace vital body salts lost though perspiration during the day.

Sleep:  Shortness of breath at higher altitudes can make it more difficult to sleep, but it is important to get plenty rest to recover after the day’s walk. NB: Sleeping pills should not be used to aid sleep at altitude!

Positive attitude: A Himalayas Challenge is as much a mental challenge as it is physical. It is important to mentally prepare and arrive with a healthy mind.

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What is Acute Mountain Sickness?

Acute Mountain Sickness (AMS) or Altitude Sickness can occur when the human body is exposed to high altitude. It affects everyone differently and some more severely than others. Of course it helps to be fit and healthy, but AMS has total disregard for experience and fitness. You may have trekked previously at altitude and not been effected, but another time you may experience symptoms. 

Mild AMS 
Symptoms include headaches, feeling tired and fatigued, loss of appetite, shortness of breath, swelling of hands and feet, stomach upset, nausea, dizziness, pins and needles, inability to sleep – generally feeling a bit rough!


Moderate AMS 
Severe headaches that are not relieved by medication, nausea and vomiting, increasing weakness and fatigue, shortness of breath, decreased coordination (Ataxia).

Severe AMS 
Shortness of breath at rest, inability to walk, decreasing mental status, fluid build in lungs or brain causing swelling. The only way to alleviate severe AMS is to receive medical attention and to descend to a lower altitude immediately.


High Altitude Pulmonary Oedema (HAPO) and High Altitude Cerebral Oedema (HACO) 
These are serious and life threatening conditions that are associated with altitude sickness and occur when an individual has not been able to acclimatise properly or has climbed too quickly. Symptoms that are not assessed or remain untreated can eventually result in either of these conditions, where lack of oxygen can result in leakage of fluid through the capillary walls into either the lungs or the brain causing swelling. Both conditions require immediate evacuation and hospitalisation.

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Don't panic!

You shouldn't be unnecessarily worried about altitude; you just need to be aware of how it can affect you and what you can do to help your body acclimatise. If you have any concerns about trekking at altitude and would like to speak to one of the team, please give us a call on +44 (0) 207 609 6695 or email Info@TheHimalayasChallenge.com and we'll be happy to respond to any questions regarding one of our Himalayas Challenges.

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