Acclimatisation Process – What it involves and why it is important

Vic climbing on Spantik in 1987

Trying to climb a 6,000m Himalayan peak without getting the body used to the altitude is very unlikely to lead to success and is dangerous because of the risk of life threatening conditions such as pulmonary or cerebal oedema.
The body needs time to adapt with the general advice being along the lines of climb high, sleep low.
Individuals acclimatise at different rates. Some seem to find it impossible to satisfactorily acclimatise. Fortunately Victor and I have a long experience of climbing at altitude so we know we don’t fall into the latter category.
Over the years I have found out what works best for me. For Sersank it will go something like this from the point of arrival at base camp:
Day 1. Arrive at base camp. For Sersank our base camp will be at around 4,250m and we will have gained that height gradually over 2-3 days of driving and 2 of walking. Even on the drive we will almost reach 4,000m when crossing the Rhotang Pass at 3978m. On arriving at base camp we can expect to feel breathless from the altitude and might experience some headaches. We will have been making a special effort to keep well hydrated and do not expect to take any medication such as headache tablets.
Day 2. While unpacking and generally sorting out base camp we will expect to feel breathless but know that this is perfectly normal as our bodies continue to adjust to the altitude.
Day 3. Leave base camp with the intention of both doing a reconnaissance of our intended route and acclimatising to the extent that we are in with a chance of success. We will carry enough food and gas to be away from base camp for about four days. On this day we will expect to get to perhaps 4,800m – the same height as Mt Blanc. Our sacks will feel very heavy and we will be moving very slowly.
Day 4. This day we expect to reach the Sersank La at 5,130m and continue to an altitude of about 5,200m. The Sersank La is a difficult historic pass between Pangi and Zanskar districts. It is rarely crossed (I think just once by a British group) and we do not expect to see anyone after leaving base camp. We will expect to feel exhausted and may take some medication for headaches. From our camping spot we hope to get a good view of the north face of Sersank. And we expect to feel so exhausted that we can’t ever imagine being able to climb it.
Day 5. We expect to spend the day reading and brewing (to keep well hydrated) and generally sucking in the thin air at 5,200m. At this height there is about half the amount of oxygen at sea level. While lying down in a well hydrated and relaxed condition the altitude will be hardly noticeable. But any form of activity will immediately lead to a shortage of breath. Taking a book to read is something that I find essential to pass the time pleasantly. Acclimatising can be very boring and it is important not to succumb to the temptation to cut short the process.
Day 6. Explore and climb to the summit of a 5,500m peak if possible. Return to the tent at 5,200m to sleep. We will expect to go very slowly with a lot of heavy breathing. Some headache medication may be necessary.
Day 7. Spend the day at 5,200m simply to make sure that our bodies have a good chance of adapting well to this altitude. The summit of Sersank is at about 6,100m and I generally work on the basis that if the intended route is technically difficult (as we expect Sersank to be) then acclimatizing to height of within 1,000m of the summit is sufficient. The advantage of climbing a technically difficult route is that progress on the climb is likely to be slow and the altitude gain no more than the generally recommended maximum of 300m per day.
Day 8. Return to base camp at 4,250m. This should feel ridiculously easy and relaxing now that our bodies are well into the acclimatisation process. And at altitude you really notice how much easier it is to go down than up. We will hope for a good nights sleep at base camp which will be a relief as I don’t sleep well whilst acclimatizing.
Day 9. Rest and eat and drink lots at base camp. Declare ourselves acclimatized and ready to climb.
Day 10. Leave base camp to attempt the north face of Sersank.

Read Micks previous blog on acclimatising on Mt Fuji