High altitude and how are bodies react to it

The purpose of this material below is to be aware of how our bodies react to high altitude as and when we gain.

As humans our bodies are used to a certain temperature, level of oxygen and atmospheric pressure depending upon the altitude at which we stay. Our bodies get used to it and it happens naturally that we don’t even realise it happening. It is only when we gain altitude; we feel and observe these changes.

Our bodies tend to feel the altitude change a little over 6000 feet as the air pressure gets lower and the air gets thinner. It is now that our bodies tend to behave differently as it tries to make up for the oxygen levels.

As we trek higher and higher above the 10,000 feet altitude mark, each breath we take means less oxygen for our bodies. Oxygen in our atmosphere gives us the energy to continue moving. The nervous system, digestive system, muscular system and all the other functions the body does without our knowing (realising basically) happens well with proper acclimatization. As we gain altitude our body has the tendency to adjust naturally. Our breath tends to get faster and deeper than normally. This deep breathing that happens naturally helps the red blood cells carry oxygen all throughout. These changes tend to take time. Going slow (in terms of gaining altitude) means going healthy. Going faster increases the chances of an acute version of mountain sickness.

Below mentioned is a chart that indicates the high altitude along with a few treks to have a better idea;

Altitudes zones Height (In feet) Treks/Expeditions
Death Zone 23,000 feet and above Nun, Kun, Nanda Devi, all the 14 - 8000 metre peaks
Extreme High Altitude (16,500 - 23,000 feet) Pangarchulla summit, Markha Valley, Everest Base Camp, Kanamo Peak, Stok Kangri
Very High Altitude (12,500 - 16,500 feet) Roopkund, Rupin Pass, Great lakes Kashmir, Goechla, Tarsar Marsar
High Altitude (6,000 feet - 12,500 feet) Nag Tibba, Prashar lake, Kheerganga, Triund, Har Ki Dun, Kuari Pass, Chadar Trek, Valley of Flowers, Kedarkantha Summit
Sea level  (up to 6,000 feet)  

Acclimatization – The process in which the body adjusts to the lower levels of oxygen is termed as Acclimatization. Different hikers, trekkers and mountaineers acclimatize at different speeds, so no one rule works for all, there are just good guidelines. The idea is to trek and reach at the campsite and rest. For any forced ascend (more than 1300 feet in one day) it is important to go for acclimatization walks.

Acclimatization walks – 13,500 feet and above, any forced ascend generally calls for a height gain walk for better acclimatization. After reaching the campsite and post some rest, we trek approx 300 to 500 feet higher, spend about 20 to 30 minutes and return. While getting down, the bodies feel the oxygen gain of this 300 to 500 feet descend instead of the oxygen loss during the forced ascend done a while ago. This is one natural way of speeding the acclimatization process – Height gain walks. Generally a rest of about 24 hours is also done post these height gains to be safe at campsites that are in the very high altitude zones.

For some of the treks we might have to drive or take a flight, for instance Leh. Taking a drive instead of a flight (if option available) is better than taking a flight as the body gains the altitude gradually. However, even if a flight is taken to a city like Leh, it is advisable to rest well and hydrate for at least 24 to 36 hours before exerting physically. Acclimatization in Leh is very important as the Leh airport itself is in the high altitude zone.