UKC

May I kindly ask, what is the rule of thumb regards the length of time acclimatization lasts at altitude.

Is there one?

In reply to The Ice Doctor:

once you have acclimatiset to say 4500m, then there is no time limit to this. If there, was then communities could not live in elevated villages etc.

In reply to Mountain Llama:

But above about 5100-5200m long term living is not possible. I think in general it is possible to live a year or so at that height before a descent to lower altitude is needed for health, I guess it will be something like 2 to 3 months above 6000m, a matter of a few weeks above 7000m, and, as is well documented, only a matter of days or hours above 8000m.

In reply to Andes:

I agree, the reason people cannot remain at the attitudes you have mentioned is because they cannot become fully acclimatised.

The OPs question was how long does acclimatisation last. Once you are fully acclimatised it lasts indefinitely.

In reply to The Ice Doctor:

What about, if you are 'acclimatized' to say 4500m, and then you go back down to 'normal altitude' - how long does the acclimatized state last - could you go back up a week later and be ok?...2 weeks?....a month?

In reply to RuthW:

That's what I am driving at with the OP....

In reply to The Ice Doctor:

I think what you are asking about is "carry-over acclimatisation". As with most things medical you will not get a definitive answer. One has to understand that acclimatisation is a complex series of different physiological processes involving breathing rate, heart response, kidney and fluid balance, production of red blood cells, genetic components and most likely some other things we have yet to even comprehend. Full acclimatisation is a balance of all these factors and they in turn will vary from individual to individual.

Obviously just as acclimatisation is very variable the same is true of loss of acclimatisation and even less work has been done on this carry over phenomena. One early study showed that a degree of acclimatisation was maintained for at least 8 days after a group spent three weeks at 4300m. Some people believe that there is some residual effect even after a month or two at low altitude. Of course the more experienced one is at altitude the more experienced one is at slowly reacclimatising. Many professional guides will arrive a bit early in the season to climb or ski in the European Alps to adapt and then maintain their acclimatisation throughout the season.

At extremely high altitude it has become normal practice to spend time acclimatising and then dropping down for good food, good sleep and a rest prior to a summit attempt. How much of this is due to physiology and how much due to the rest and nutrition has not been investigated.

I hope this typically vague medical answer is of some help and am happy to hear from others of more hard evidence.

David Hillebrandt

In reply to The Ice Doctor:

David is, of course, correct. In addition, an old rule of thumb was that it took you as long to lose it as it took to get it - so if you spent a week around 4000m and were fine there after the first few days, then went to sea level, you'd be fine to go back up to 3500-4000m a few days later, but a week after coming down you would be back to normal.

There are so many variables in any situation - dehydration, sickness, diet, logistical methods - on top of the subjectivity in reporting of so many different individuals with different physiologies, that anecdotal knowledge is extremely unreliable. People are very subjective and unreliable witnesses to their own crimes, particularly when sick.

Personally I think I lose it faster than this, based on experience.

In reply to Damo: FWIW, a couple of years ago I had a summer alps trip that culminated with Dent Blanche (4300m from memory). I went back to work in my office for 6 weeks, then had a week in Chamonix in September and went straight up and did the Rochefort arête (4000m) in reasonable time. So I think acclimatisation is retained for a bit longer than a week. Again, FWIW, I'm not a particularly great acclimatiser.

In reply to David Hillebrandt:

I'm intrigued by the 8 days. If you were fully acclimatised and your red cell count was raised, would it not follow that it would take time for it to reduce? Given the life of an average red cell is 120 days and the body would "adapt" back to normal height given time for hormonal changes to take effect, this seems a short period. Certainly, after spending 6 weeks in Tibet where the base level is 10000 ft or higher, I was bouncing for a few weeks.
Chris

In reply to cannichoutdoors:


I think making a general claim like that based on your single personal experience demonstrates my point about extrapolating from anecdotes. You might be right, but not based on what you have written.

I spent six weeks in Ladakh this past June-July, almost all of that time above 3300m, and up to 6050m, with considerable time around 4500m, but not with so much actual climbing or trekking that my physical fitness was much improved. I flew home to Australia and several days later did the walk-in to an area (at 1600-2000m) I've been to a lot and was at least 15% faster than my best previous time. It was like I was floating. I went back about 10 days later and was back to normal.

In reply to cwarby:
Agreed, if you were physiologically adapted to altitude then the increased red cell count and haemoglobin density would last for a significant period possibly 8-12 weeks.
However as others have said its more than just about the oxygen carrying capacity, it's psychological and physiological in terms of breathing rate, depth, general fitness etc. There may be generic figures but each individual responds differently and perhaps unpredictably to altitude

In reply to Damo:
The results you experienced are the same As' blood doping' but done safely

In reply to Damo:

I think that for me personally some acclimatization lasts quite a long time. I've several times been to sea level after a month or more at altitude, down low for 1-2 weeks , then gone back up to altitude. With just 1-2 weeks at sea level I'd say that I have always done better at altitude than I would normally expect coming from an extended spell at sea-level (i.e. being at home). Obviously enough the longer spent at sea-level the more acclimatization is lost, but the first 2 or 3 nights always seem to be beneficial (better sleep/appetite/oxygen)

I've spent years wondering if there is any research out there on "de-acclimatization" or "carry-over acclimatization".
Do fast acclimatizers lose it fast or retain it longer? ...and vice-versa for slow acclimatizers?
Is there any correlation at all between the speed of acclimatizing and speed of losing acclimatization?
If only doctors would do some research on well people at altitude for a change instead of obsessing with the ill people!

In reply to Andes:



Well your experience would correlate with the theory of "it lasts as long as it took you to get it". And one month up, two weeks down is weighted in favour of a good experience returning high.

As to researching the good acclimatisers, yes, it would help. There was a relatively mainstream article recently that looked at Sherpa physiology but I can't find it right now.

In reply to The Ice Doctor:

I asked a very similar question to our experienced guide when doing Kili this year. He'd done numerous peaks all over the world and said "about a week or two". Haven't really had a chance to test it after tho.

In reply to Andes:
"If only doctors would do some research on well people at altitude for a change instead of obsessing with the ill people!"

If you study the literature on mountain medicine and acclimatisation I think you will find the vast majority of studies are done on fit climbers. This was true on the 1960s Silver Hut research expedition and on to the recent Xtreme Everest 1 and 2 trips. These research trips produce top quality research data. You are, however, right that more should be done on carry over acclimatisation and this thread may prompt that.

David Hillebrandt

In reply to Damo:


http://theadventureblog.blogspot.com.au/2015/11/researchers-explain-why-she...

http://edition.cnn.com/2015/11/11/health/sherpas-superhuman-mountaineers/in...