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Acclimatization and Altitude Sickness
#46298 05/17/16 08:39 PM
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In this forum people often ask questions like, "Is there a hike you can recommend to help me adjust to the altitude of Mt. Whitney...", or similar questions. Good question. The flat answer is (take this from a former SAR member)that a one-shot hike to Mt. Baldy (or wherever) is not going to do much of anything toward prevent AMS (Acute Mountain Sickness - altitude sickness). It has been proven by medical research and by the experience of knowledgeable mountaineers, that sleeping at least several nights at intermediate altitudes, in stages, is the best way to stave-off AMS. Even the best of preparation and precautions are no guarantee that you won't get AMS.

Even youth and excellent physical condition will not guarantee that you won't get AMS. In fact, it is a medical fact that older people are less prone to AMS. At age 78 (the secret is out!) I haven't had AMS in over 30 years, and I'm a frequent mountain traveler in the Sierra Nevada, at high altitude, carrying a heavy pack.

The website below gives some good, factual information on AMS and how to prevent or lessen the affects.

http://www.altituderesearch.org/traveling-to-altitude/fast-facts

I know from past experience that there won't always be time for most "week-end" warriors to adequately prepare themselves for the rigors of high altitude (been there, done that as a former Bay Area resident). The fast drive from LA or SF on Friday night followed by an approach hike early Saturday morning, then the climb Sunday morning and then the retreat to the car Sunday afternoon, are the conditions under which most visitors to the Eastern Sierra will be forced to endure. (Sound familiar?) But it's all fun, right? Darn right it is! So do what you can to make it a more comfortable experience and, as an Austrian mountain guide once said to me, "Suck it up, princess!", and don't worry about it.

Re: Acclimatization and Altitude Sickness
Bob West #46301 05/17/16 10:15 PM
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Thanks for opening this topic, Bob. I see the Altitude Research Center is associated with long-time altitude researcher, Peter Hackett, MD, and they are located in Denver, CO. Their Fast Facts page is quite useful.

Just a note about their location: Being located at 5000' elevation, all the people around there who also climb peaks will not experience nearly as much altitude sickness as we see here with the sea-level-dwelling weekend-warriors. And I notice your note of 30 years without AMS: How long have you lived in Bishop, at 4k elevation? :-) That's a huge advantage over most Californians. You could probably go to 18k before AMS set in like it does for me at 14k.

Included in the Fast Facts recommendations:
* Avoid going directly to a sleeping altitude of over 9,000 ft in one day
* Consider adding a day at a modest altitude such as Denver (5,000 to 6,000 feet)


I would tell people to spend as much time as high as possible, with the idea that acclimatization will occur faster the higher you are ...so long as you don't go so high as to bring on serious symptoms. Most people here recommend sleeping at 8000 feet, places like Mammoth Lakes or Whitney Portal. My favorite is to use Horseshoe Meadows, at 10k. I like to plan a trip where I drive directly to HM, arriving at night, and get to sleep--even inside my car. Next day, hike or pick up permits, etc, and then spend a second night up high. After the second night, I feel I am acclimated enough to climb to the Whitney summit.

Re: Acclimatization and Altitude Sickness
Steve C #46308 05/18/16 07:47 AM
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Hi Steve,

Dr. Hackett worked in the Bishop hospital ER for several years before he went to Everest on a medical expedition. At a regional MRA conference in Yosemite he gave a lecture on his acclimation experiences. Yes, he's one of the leading experts in his field.

I've lived in Bishop since 1975, at 4100' which yes, does help somewhat. Yes, Mammoth Lakes residents have a distinct advantage living at 8000' plus. I've notice that after a long vacation (2-3 weeks) at sea level I start to lose acclimatization and need to regain it after coming home.

On SAR ops we often encountered hikers sick with AMS, who didn't know what was making them feel like hell. We would recommend they hike to a lower elevation, which helped, much to their relief and amazement. All too often their hiking companions hadn't a clue what was wrong with their friend, and then walked out to get help.

The point I was trying to get across is that a quick hike up a local (LA or Bay Area) mountain is not actually going to help the weekend hikers to acclimate. As you said, sleeping a couple of nights at altitude (or longer if they can) is a good idea which will give them a little advantage.

Last edited by Bob West; 05/18/16 07:55 AM.
Re: Acclimatization and Altitude Sickness
Bob West #46319 05/18/16 05:39 PM
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There is tremendous individual variation in what speed people acclimatize, at what altitude, and to what ceiling. The guidelines are like all guidelines, meant to be helpful for most people, not 100%. Some people are lucky, others not. Just like in all aspects of medical diagnoses.

Sleeping altitude is important for several reasons. Obviously one spends a lot of time in the tent, but more importantly what they are doing in the tent. Doing nothing? No, breathing while asleep is essential to life. During the day, you can voluntarily increase breathing, but at night, you depend on your autonomic nervous system, ie your brain, to sense and stimulate breathing while you are unconscious. It takes many days for your brain to get its central and peripheral oxygen and carbon dioxide sensors back in sync at the new altitude.

The above comments pertain to ventilation ( breathing), but other factors in acclimatization such as blood production and cellular metabolic changes take even longer, from many weeks to months, or some cases generations. For the average Sierra acclimatizer, the respiratory changes are the most likely as they are the ones that occur the quickest and in the time frame the person is visiting. The other changes take much longer, and occur in people who live at altitude, climb frequently, or stay for months. We are finding with more and more research in high altitude areas like Tibet that metabolic changes probably outweigh the others


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