question about acclimatising to altitude

Where are you planning to do this hiking, John, and what will be your total number of days at altitude? What is the highest you will go? We could help if we knew exactly what your trip plan is.

http://www.chinatrekking.com/routes/adventure-tour/pilgrimage-of-meili-snow-mt

i'm spending a total of about 12 days, most of which should be above 3000m and sometimes 4500m or higher.

of course i could just drive through the <2000m location on the way up and spend time there on the way down. that would mean spending most of day 2 in a car above 3000m, with the full-day hiking still starting on day 3.

thanks for the advice

i've done extended hiking above 4000m before (in the same part of the world).

But last time I wasn't flying in, and from what i've heard the fact that you don't suffer altitude sickness on one occasion is no guarantee it won't affect you on another.

John, it seems that if you could manage to spend 2-3 days at 3000 M, you would be well on your way to adjusting to the elevation. But like you mentioned, altitude sickness can hit you differently (or not at all) on different trips. I couldn't really tell from the trip description what the different days' hiking will entail, but it seems like you will be above 3000-3500 M most of the time, with the passes being over 4500 M. I think that once you've spent 4-5 days on the trail, climbing high and sleeping lower down, that you should be OK. I would suggest for you to do a couple of days at that 3000 M elevation before you do any serious trekking.

We need for Bob Gross to offer his suggestions, as he has spent a lot of time doing that same sort of trekking. But it certainly appears to be an interesting trip you ahve planned.

Geez, I don't know. Everybody has their own elevation threshold, the point where you might get triggered into some high altitude problem. After their first trip or two, everybody should know what their own threshold is, or at least to be able to guess what it might be.

The old "climb high, sleep low" rule is awfully conservative, but it works.

The medical experts would all advocate that you take a very conservative approach and take layover days. But I don't know how that fits into the schedule.

Once you get above 6000 meters or so, you can throw out whatever rules you thought you understood. Up there, the least little thing can throw you off your game.

–B.G.–

One thing that needs to be discussed is what to do on a layover day for adaptation.

I think a big mistake is to do nothing. Similarly, a big mistake is to do some exhausting activity for hours. Personally, I've found the best thing is to do some very light activity, like at 25% of your limit, and only for an hour or so at most. This should act as a trigger to warn your body that some altitude changes are coming up, so your body needs to get with the program. For me, that means about an hour of easy walking.

A light dose of exercise like that should set you up for a good night of sleep. On the other hand, if you are mentally stressed out, you may not sleep well. But you probably do not want to fool around with serious sleep aids. The most that I take as a sleep aid is 3mg or 5mg melatonin.

Also, during that time, your body might be a little fragile, so you don't want to stress it with an excessively strange diet.

As a general rule, few people will fool around with Diamox for those kinds of elevations.

–B.G.–

FWIW, from Zubieta-Calleja, et al.’s article “Altitude adaptation through hematocrit change”:

Adaptation = Time/Altitude, where High altitude adaptation factor = Time at altitude (days)/Altitude in kilometers (km). The time in days required to achieve full adaptation to any altitude, ascending from sea level, can be calculated by multiplying the adaptation factor of 11.4 times the altitude in km.

http://www.ncbi.nlm.nih.gov/pubmed/18204195

So spend a month for 3,000 meters and two months for 5,000 meters? That's matchs what I've read and experienced for FULL acclimatization meaning your red blood cell count has fully adjusted to your new environment in addition all the quicker adaptations. Few of us, though, get to take that much vacation time.

And as Bob Gross mentioned, above 18,000 feet, all bets are off. Below 18,000, more time means gives you more acclimatization. Above 18,000 and you just get worse, your body doesn't heal and "climb high, sleep low" is the only way to go.

But for our more typical trips – going to 3 km or 4 km from sea level, your blood pH, beathing tidal volume, and an initial thickening of ones blood happens over the first few days. While it takes 6 weeks to be 100% acclimatized, I'd rate myself at 20% for having spent the night at the trailhead, and 40% at 3 days.

Two easy to remember data points on atmospheric pressure:

At 7,500', there's 75% of sea level air density.

At 18,000', half the atmosphere is below you (50% sea level pressure).

"Put your own oxygen mask on first. Then assist your companion."

"The time in days required to achieve full adaptation to any altitude, ascending from sea level, can be calculated by multiplying the adaptation factor of 11.4 times the altitude in km."

This muddies the water, because there are really two types of adaptation going on, short-term and long-term. Long-term can require two or three weeks, and that has to do with making more red blood cells to carry more oxygen. Hematocrit includes red blood cells, so an increase in hematocrit can normally measured over that time, but you don't promote hematocrit to aid adaptation. Some people try to take dietary iron supplements to help this, and it is mostly unnecessary.

Short-term can require just a day or two, and that has to do with increasing your natural respiration rate and depth, and possibly an increase in heart rate. It has nothing to do with red blood cells or hematocrit. There are several minor factors that help this out, like adapting to a better sleep pattern, adapting to a better diet, etc.

–B.G.–

I have a couple additional questions on this topic….

Let's say you hike up to around 12,000 feet and then spend a few days there before hiking over an 18,000 foot pass over the following two days. Then over the next 3 or 4 days you hike back down to around 3,000 feet. If you plan to continue on from there to reach about 13,500 feet do you have to restart the acclimatization process?

Also, in the scenario above, is it unusual to show no symptoms of AMS the first full day at 12,000 feet, but then feel the symptoms late in the second day (around 48 hours after arriving at that altitude)?

This muddies the water, because there are really two types of adaptation going on, short-term and long-term.

The article referenced treats it as three stages rather than two types. The abstract follows:

Adaptation takes place not only when going to high altitude, as generally accepted, but also when going down to sea level. Immediately upon ascent to high altitude, the carotid body senses the lowering of the arterial oxygen partial pressure due to a diminished barometric pressure. High altitude adaptation is defined as having three stages: 1) acute, first 72 hours, where acute mountain sickness (AMS) can occur; 2) subacute, from 72 hours until the slope of the hematocrit increase with time is zero; here high altitude subacute heart disease can occur; and 3) chronic, where the hematocrit level is constant and the healthy high altitude residents achieve their optimal hematocrit. In the chronic stage, patients with CMS increase their hematocrit values to levels above that of normal individuals at the same altitude. CMS is due to a spectrum of medical disorders focused on cardiopulmonary deficiencies, often overlooked at sea level. In this study we measured hematocrit changes in one high altitude resident traveling several times between La Paz (3510 m) and Copenhagen (35 m above sea level) for the past 3 years. We have also studied the fall in hematocrit values in 2 low-landers traveling once from La Paz to Copenhagen. High altitude adaptation is altitude and time dependent, following the simplified equation:

A complete and optimal hematocrit adaptation is only achieved at around 40 days for a subject going from sea level to 3510 m in La Paz. The time in days required to achieve full adaptation to any altitude, ascending from sea level, can be calculated by multiplying the adaptation factor of 11.4 times the altitude in km. Descending from high altitude in La Paz to sea level in Copenhagen, the hematocrit response is a linear fall over 18 to 23 days.

There is no actual answer that is going to help you. Every one is different. After a day or two at 10,000 feet, I can run a regular three mile as I do at home. And hiking around at 12 or 13 is no big deal. But, I have seen other fellows who have been in better shape than I who have to be almost sedentary for 4 days. You are just going to have to hit the ground and see how things go, you may be able to achieve your expectations, you may not.

Crap, I didn't realize how old this post was. Sorry.

Yes, it is an oldie but goodie thread.

Back around 1981, there was a U.S. medical expedition to Mount Everest. Sure, they had people trying to focus on bagging the peak. Also, they had researchers in physiology and related sciences, and they had research subjects for experiments in altitude adaptation. The subjects were broken up into three groups. Group A were the serious sea-level athletes, e.g. marathoners. These were typically people with a rest pulse of about 35-45! Group B were the weekend athletes. They were backpackers, skiers, climbers, and such. Typically they did some jogging or cycling to try to stay in shape. Group C were the couch potatoes. They were typically medical students and such who had no particular sport or exercise plan. The researchers had bicycle ergometers set up at different camps in order to measure physical output and to measure who was adapting and who was not. They even took the test gear up to the South Col (26,500') for tests! I believe that test was disrupted by weather. However, which group do you think adapted to elevation best?
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It was Group B who adapted the best. Their output was good at the lower elevations and did not degrade too terribly as they got higher. I would guess that many readers here fall into that category. Most had been to moderately high elevations before, and they seemed OK with going again.
Next best was Group C, the couch potatoes. Their output was only moderate at the lower elevations and degraded somewhat as they got higher.
Worst was Group A, the marathoners. Their output was odd. It was almost as if their bodies were perfectly tuned for sea level air pressure, and as soon as they went up higher and higher, it was like an old car with a carburetor that got vapor lock. They could not adapt much at all. Go figure.

There is a message here.

–B.G.–

Edit: 1981, not 1980

Bob: Interesting. That matches my experience with a smaller sample size – the people I've hiked with.

The only people I've treated for AMS were quite atheletic – sea-level cross-country runners, a guy who could do a one-armed pull-up (1 in 5,000 of the population), etc.

I've always done well with altitude and am closest to the "weekend-warrior" – I've always been active every day but only do 1-2 days a week of bigger stuff. My pulse rate and body fat have certainly never been in the elite range. Which I suppose is good, because then I can help those elite guys off the mountain.

Hey, I can do that; I mean a one armed pull-up. Really. Used to be super strong, very athletic; now just jog three or so times a week. The pull up thing is still possible; it is usually used as one of the crazy bets to win a beer nowdays.

"There is a message here." Perhaps, but I'm not sure one could draw general conclusions from it. I had an interesting discussion one time back in my climbing days with a physician who had gone on an Everest expedition and run into some folks who were interested in the subject under discussion here, only their focus was on actual climbers. Their findings agreed with your study as far as marathoners are concerned. Climbers who also trained for marathons tended to experience more difficulty adjusting to high altitude consitions. However, they also found that those who trained for 10 K races tended to fare very well indeed. This in turn agreed with my own anecdotal experience: There was a guy up here in Seattle, name of Dave Hambly, who summited Cho Oyu in his late 40's without supplemental oxygen and went on to serve as a support climber on the expedition that put the first US woman on top of Everest. He reached 27,000' in that role. He was also an excellent masters 10 K runner. My own experience adds to this body of evidence as well. I ran 10 K's at about the same level as Dave, although we never went head to head, and was a support climber on a 1991 expedition to Ama Dablam at altitudes up to 20,000'. We were carrying loads up to 40# over technical terrain, and I never had any trouble with altitude sickness other than Cheyne Stokes Syndrome, which was merely a nuisance. I was 50 at the time. My point is that perhaps the experiment was not asking the right questions to get a more general idea about who and who does not adapt well to altitude.

>"Hey, I can do that; I mean a one armed pull-up."

Ty, That is impressive. And pretty rare. While I can do pull-ups and a fair number of them if I condition a bit, when I put myself on a bathroom scale under the pull-up bar, I can lift only little over half my weight with each arm. Meaning I'd have to be twice the arm strength to do what you do.

With all the hiking I do and very little upper-body work, I'm better equipped below the waist. Maybe I should put that on a T-shirt?

"Perhaps, but I'm not sure one could draw general conclusions from it."

One general conclusion is that just because a person is a world-class athlete at sea level, that does not make them a world-class climber at 20,000 feet.

For something a little closer to home (or a little more down-to-earth, literally), there is the 2008 Mount Whitney paper on the Determinants of Summit Success and Acute Mountain Sickness.

–B.G.–

David said, "I'm better equipped below the waist. Maybe I should put that on a T-shirt?" . . no, I wouldn't put that on a T-Shirt; as luck would have it, you'd most likely get offers from the exact opposite of who'd you'd like. That would be funny, (watching from a distance anyway.)

Marathoning is an activity that focuses purely on aerobic capacity. The body becomes finely tuned for maximizing the amount of oxygen intake and to convert that oxygen into energy. But what happens when you remove oxygen (ie altitude)?

I wouldn't be surprised if the weekend warriors and 10K runners, due to their more general performance makeup of both aerobic and anaerobic ability utilize more anaerobic processes to overcome the lack of oxygen. Sure marathoners have phenomenal aerobic capacity, but no matter what they will be operating in hypoxic conditions at altitude in the short term. Their bodies are not adapted to using anaerobic metabolism to overcome this.

Now given adequate time (say the necessary month or two) to 100% adapt to altitude, I bet marathoners with their increased aerobic capacity would do quite well at altitude. But in the short term it makes sense that anaerobic metabolism kicks in while adapting.

This is all conjecture and hypothesis, but it seems logically and worth a grant or two to investigate a vacation!

>"get offers from the exact opposite of who'd you'd like"

That'd be my luck.

I saw a vanity plate on a motorcycle that said, "7 uncut" and I was puzzled for a bit.

Then I considered that I was in SF (my hometown) and it all clicked.

"One general conclusion is that just because a person is a world-class athlete at sea level, that does not make them a world-class climber at 20,000 feet."

I wasn't aware from your previous post that we were talking about world class athletes. A pulse rate of 35-45 doesn't necessarily make one a world class athlete, myself being a case in point. My pulse rate was in the high 30's-low 40's when I was racing, is still in the high 40's occasionally, and I most definitely wasn't going to the Olympics. Same went for a lot of runners I knew. In any case, doing a test on an exercycle at 20,000', or whatever altitude they conducted the test at, does not make the weekend warrior a world class climber at 20,000' either. I will go so far as to speculate that a world class 10K runner would have a far better chance of becoming a world class climber than a weekend warrior. Too bad the test wasn't set up to include a broader spectrum of the high end aerobic community, e.g. 10 K runners, cyclists, etc. I think that would have told us a lot more about what predisposes to success at altitude.