Acclimatisation – factors under our control

* Education, Planning & Prevention are key in aiding acclimatisation *

The first time high altitude affected me with an impact that made me sit up and take notice was just at around 14,000 ft., an altitude in the Himalaya touched by thousands each year. It was 1989, and I was at our base camp (B.C.) on the expedition to climb Mt. Gangotri-I (6,672 m./21,885 ft.). We had arrived at the site typically in the afternoon and set up camp close to a shelter of shepherds who had their flock grazing on the slopes around our site. After setting up our tents we had laid out all gear and made ready for the next day’s move up towards the first camp up on the mountain. It was after I had retired for the day and snuggled up inside my sleeping bag that the nausea started which soon had me retching. Finally I scrambled out and had just managed to move away a decent distance before all undigested stuff from my tummy projected out of my mouth violently. So there I stood leaning against a convenient rock, shivering in the cold, my stomach making repeated attempts to empty itself of everything via the oesophagus. Back in the tent, I slept cold – there was no fuel for body heat – and fitfully, worried about my ability to continue to move up the next day or even later if I did not acclimatise well.

The next day morning, two more team members reported sick with splitting headache. The three of us stayed back at B.C. along with our base camp manager while the remaining three members went up to scout out the route along with our two guides, local mountaineers hailing from nearby villages. Fortunately I recovered and could keep my food down the whole day while the condition of the other two worsened with additional symptoms cropping up. The day after that they moved down to the lower camp to acclimatise before coming back to B.C.

From then on I was super worried about acclimatisation and took extra care to stay fit and healthy, going almost by the book in terms of pacing myself while walking, hydrating appropriately, layering up to keep warm at all points of time and getting enough sleep. It all worked out well and eventually, accompanied by a team member and our two guides, I reached the summit.

I was in my mid-twenties (I have touched upon the vagaries of that age in my post high-drama-on-a-glacier), and I was planning to spend a lifetime hiking in regions like the Himalaya. My experience of that night spent sleeping cold due to non-acclimatisation made me determined to find out everything I could about life at high altitude. I read whatever I could lay my hands on to help me understand the world of high altitude and its effects on human beings. That, my experience of managing acclimatisation on subsequent trips (sometimes I used to be in the Himalaya for more than 3-4 months every year) and my later training in wilderness first aid gives me the confidence to state some key aspects about high altitude related safe practices as given below. Needless to say, a simple blog post can never cover all the existing knowledge about human adaptation at high altitude, a subject that doctors continue to research. The content in this post also does not cover everything that I address in my sessions on acclimatisation that I conduct for individuals and groups who are planning to go on high altitude hikes.

Key message

As one gains altitude, one’s body starts adapting: certain changes are initiated.

We have to support our body by undertaking certain actions and giving it enough time to adapt.

To be able to ‘support’ we should

1. Prepare in advance; e.g., choose route wisely (e.g., match your goals with your level of conditioning), choose appropriate gear and food, walk wisely (e.g., do not over exert by rushing along a trail)
2. On trail: stay alert to changes undertaken by the body, state of wellbeing, control own actions
3. Adopt conservative, proactive & preventive approach
4. Take early action in response to discomfort & illness

Critical to acclimatisation

1. Appropriate hydration – adequate quantity, ‘sipping at regular intervals’ method of drinking
2. Appropriate nutrition – understand what to eat and when
3. Gradual elevation gain – elevation gain on overall route, daily elevation gain, gentle pace of walking
4. Ensure fresh air at all times: e.g., keep tents ventilated
5. Layering – manage layers of clothing in such a way that you are warm at all times
6. Physical fitness as matched with the requirements of your activity helps since ‘exercise exhaustion’ is a stress factor that can hinder acclimatisation

Form your own checklist to help you assess factors like the ones listed above. With the first signs of discomfort and altitude illness, check each factor in the checklist and address any lacuna or lapse that you spot in aspects like water and food intake, layering and ventilation in tents.

Note: this blog-post can never replace information that is given in a wilderness first aid course, and experience gathered over years of functioning at high altitudes.

For my posts on managing layers in cold weather conditions click here, (staying warm in cold climes), here (warm layers for outdoors), and here (examples of layering scenarios).

This link here is to a discussion that I participated in where I recount two intense incidents at very high altitudes, one of which was on Mt. Gangotri-I.