My sister lives at sea level -- Baltimore and Chicago. She is coming to visit me in Denver (5280 ft or 1600m). She wishes to climb Mt Bierstadt (14,065 ft or 4200m) the same day she arrives.

I have read over the answers to "What are some proven methods of training for week long backpacking trips at high altitude?", which covers coming to Colorado for a hiking trip across several 14-ers. My sister is in excellent physical condition, however, and I am mostly concerned about the adjustment in altitude given the very short period of time involved.

  • Will the effects and onset of altitude sickness exacerbated by the short time-frame involved and the drastic change in elevation given what her body is acclimated to?
  • Most questions relating to altitude sickness agree that the best way to acclimate yourself is to go to high altitude regularly. Given that this is not an option, is there any way to mitigate the risks somewhat?
  • If she climbs the mountain the day after she arrives, will this make much of a difference?
  • Is she in good shape?
    – AM_Hawk
    Commented Aug 1, 2014 at 19:20
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    A lot of what people interpret as AMS is actually sleep deprivation and caffeine withdrawal. Re caffeine, see Hackett, "Caffeine at high altitude: java at base camp," High Altitude Medicine and Biology 11 (2010) 1, and this question: outdoors.stackexchange.com/questions/5820/… . Diamox is a good idea if there's time for her to get a prescription and test it at home to make sure she doesn't have a bad reaction to it. It's rare to get dangerously sick at 14,000'. Most unacclimatized people will simply feel lousy to some degree. That's all AMS is.
    – user2169
    Commented Aug 1, 2014 at 19:44
  • @AM_Hawk Yes, she is in excellent shape. She is a long-distance runner and also participates in amateur bouldering, rock climbing, and spelunking. Commented Aug 1, 2014 at 19:52
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    I wrote some infos for altitude sickness here: outdoors.stackexchange.com/a/5023/2653 What might help you in that situation is the last part: Don't panic if you are getting headaches in higher altitudes. They are not unusual above e.g. 4000 m. If they are occurring together with other symptoms you should start to worry a bit more. Be cautious, listen to your body and ask your mates because sometimes you aren't able to judge by yourself anymore.
    – Wills
    Commented Aug 2, 2014 at 12:23
  • Shouldn't be a problem if she's in good shape. Just think of all the tourists coming to Mauna Kea directly from the beaches of Big Island.
    – Phab
    Commented Dec 18, 2015 at 6:58

4 Answers 4


The other answers already gave lots of information about altitude adaption, so I will focus on one certain point:

AMS (acute mountain sickness) evolves when staying at high altitudes. It is a pathologic disease with potential severe consequences. This should not be mixed up with the immediate influences of high altitude on the body like decrease of physical performance, fast breathing or even headaches.

These symptoms can be very troublesome and prevent a successful ascent, but as long as you descent the same day, they will vanish. So it is very important to take the possibility of a need to turn back on the ascent into account when planning. But going fast to high altitude does not put you at risk for AMS and thus long term medical problems.

I live at 600m altitude (~2000 feet) and climbed mountains of up to 4200m (14000 feet) several times. In my case I always did an ascent to a mountain cabin the first day and climbed the peak the next, so there was a certain "acclimatisation". I never had any headaches, just the normal decreased physical performance. A friend of mine ones made a trip from 600m (2000 feet) by train to 1500m (5000feet) and then an ascent to 4400m (<15000 feet) in one day. He had a nasty head ache when reaching the summit, but absolutely manageable, and by the time he was home he was fine. The next day we went multipitch climbing.

So in my opinion it is perfectly save to do day trips to high-altitudes as long as one can turn back when experiencing problems. Of course this is all considering a healthy and fit person, if one has a history of heart or lung problems, it is obvious this does not apply.

  • Most questions relating to altitude sickness agree that the best way to acclimate yourself is to go to high altitude regularly. Given that this is not an option, is there any way to mitigate the risks somewhat?

While the above answers the other questions, I want to address the implication in this question:
I understand the statement put in the question about acclimatisation the following way: By going to high altitudes many times (but not staying up high) you build a lasting resistance against high altitude sickness. This is not the case.

How long the effects of high altitude acclimatisation after getting back down to low altitudes lasts is an ongoing subject in research and kind of controversial. But many findings suggest, that you loose the effects of acclimatisation to high altitude faster than you build them up.

Of course when going to high altitudes to do mountaineering often you will train some resistance to the symptoms described above as with every other training in sports. But this is no substitution for true acclimatisation and wears off if not trained, like everything else.

So you practically have to live in high altitude to really be acclimatised, not just go there regularly.

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    Thx a lot, also for clearing up the difference between AMS and the immediate influence of high altitude. Once again a nicely put answer with experience showing through. Do you know, why the first night is a problem? I could think of the horizontal position and the sleeping as itself. You might not be getting that much oxygen when you sleep. I saw tests where they had someone doing a workout in horizontal position and this was really stressful (also because of the limited blood circulation). Or is it the time, that after 12 or 24 hours the effects of the thin air hit you really bad?
    – Wills
    Commented Aug 2, 2014 at 20:15
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    No I actually don't and though I know the problem myself, never thought about why. Your inputs seem reasonable, I will ask a friend who did sleep studies related to altitude, he probably has some information about it. But that will take some time, I probably wont see him very soon.
    – imsodin
    Commented Aug 2, 2014 at 20:22
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    I recently covered this in my WFR course. During sleep, the respiratory rate naturally slows down. The leads to a decrease in oxygenation. As far as acclimation, I regularly moved between 5k (school) and 8k (summer internships). Even after spending a couple months at 8k, and hiking up to 10k, I lose acclimation after a couple of weeks at 5k.
    – KeithB
    Commented Nov 18, 2016 at 0:35

Here is a clip from this webpage - Acclimatization To Altitude:

Preparing for Competition at Altitude

How can athletes who live at sea level prepare for a competition at altitude?

One approach is to compete within 24 hours of arrival at altitude. Not much acclimatization will have taken place but most of the classical symptoms of altitude sickness will not have had time to manifest. After the initial 24 hours, dehydration and sleep disturbances become more prominent.

An alternative option is to train at a higher altitude for at least 2 weeks prior to competition. Although full acclimatization to altitude takes 4 to 6 weeks, many of the physiological adaptations occur in the first 2 weeks and the more severe disturbancs should have settled. It is important to remember that during the intial days at altitude work capacity is reduced, so athletes should train at 60-70% of sea level VO2 max and build up gradually over 10-14 days.

A third approach is to devote a greater percentage of training time at sea level to endurance training several weeks prior to competition. This is a strategy often adopted within many team sports, helping to raise players' VO2 max to a peak so that they can perform at a lower relative intensity without significant loss in performance.

Sleeping in altitude tents and hypobaric chambers may be able to adequately simulate the effects of altitude but these tend to be very expensive. Unfortunately, there is no evidence to suggest that spending 1-2 hours per day breathing hypobaric gases at sea level results in the same adaptations as living at altitude.

Conversely, a different webpage says this:

Prevention of Altitude Illnesses

Prevention of altitude illnesses falls into two categories, proper acclimatization and preventive medications. Below are a few basic guidelines for proper acclimatization.

  • If possible, don't fly or drive to high altitude. Start below 10,000 feet (3,048 meters) and walk up.
  • If you do fly or drive, do not over-exert yourself or move higher for the first 24 hours.
  • If you go above 10,000 feet (3,048 meters), only increase your altitude by 1,000 feet (305 meters) per day and for every 3,000 feet (915 meters) of elevation gained, take a rest day.
  • "Climb High and sleep low." This is the maxim used by climbers. You can climb more than 1,000 feet (305 meters) in a day as long as you come back down and sleep at a lower altitude.
  • If you begin to show symptoms of moderate altitude illness, don't go higher until symptoms decrease ("Don't go up until symptoms go down").
  • If symptoms increase, go down, down, down!
  • Keep in mind that different people will acclimatize at different rates. Make sure all of your party is properly acclimatized before going higher.
  • Stay properly hydrated. Acclimatization is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least 3-4 quarts per day). Urine output should be copious and clear.
  • Take it easy; don't over-exert yourself when you first get up to altitude. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
  • Avoid tobacco and alcohol and other depressant drugs including, barbiturates, tranquilizers, and sleeping pills. These depressants further decrease the respiratory drive during sleep resulting in a worsening of the symptoms.
  • Eat a high carbohydrate diet (more than 70% of your calories from carbohydrates) while at altitude.
  • The acclimatization process is inhibited by dehydration, over-exertion, and alcohol and other depressant drugs.

Altitude sickness really differs from person to person. If you're a very fit individual (distance runner, swimmer, cyclist, or other endurance athlete), the transition to altitude usually isn't as drastic. My personal experience tells me that the only real benefit of waiting a single day will be to give her a chance to recover from the jet lag (not the altitude acclimatization).

Regardless of what you do, hydrate, hydrate, and hydrate. Also, if the altitude sickness happens, don't just try to climb through it, as it generally worsens with higher altitudes. Hopefully it won't happen, but if it does, realize that protecting her health is more important that puking on top of the mountain.

  • 2
    *Regardless of what you do, hydrate, hydrate, and hydrate. * "While symptoms of dehydration are similar to AMS, no compelling evidence suggests that dehydration contributes to AMS." -- Hackett, "Caffeine at high altitude: java at base camp," High Altitude Medicine and Biology 11 (2010) 1.
    – user2169
    Commented Aug 1, 2014 at 19:41
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    @BenCrowell regardless of whether dehydration exacerbates altitude sickness, it's important to stay hydrated. If you know you're hydrated, but you're feeling symptoms that could be either altitude sickness or dehydration, then you can deduce that you might be suffering from altitude sickness and ought to head down. If you think you're "just" dehydrated but really have altitude sickness, that could end poorly.
    – nhinkle
    Commented Aug 1, 2014 at 23:43

This is really funny because I am from Toronto (Sea Level) and flew to Denver a couple months ago and climbed Bierstadt the morning after arriving followed by Quandary Peak the next day.

Upon arriving in Denver I drove to sleep at 10,000ft then woke up early and climbed Bierstadt.

Will the effects and onset of altitude sickness exacerbated by the short time-frame involved and the drastic change in elevation given what her body is acclimated to?

Yes, I certainly felt it and I am a fit cyclist and rock climber. Towards the summit I had what felt like a belt around my head and it was slowly being tightened.

Most questions relating to altitude sickness agree that the best way to acclimate yourself is to go to high altitude regularly. Given that this is not an option, is there any way to mitigate the risks somewhat?

You can try Diamox, which is an epilepsy drug used by mountaineers to help acclimatize. I have used it before, just makes you pee a lot. From what I understand you do not take it to make a one day trip better, you take it for ten days while gaining 1,000ft elevation per day to prepare for a climb like Denali.

Her other option is to improve her cardio prior to coming. Run Run RUN! The fitter you are the easier it will be to acclimatize, but don't be fooled ,even the fittest coming from sea level feel it...

If she climbs the mountain the day after she arrives, will this make much of a difference?

Yes, every second at altitude the body is adjusting. Ideally she would want to sleep at 10,000ft the night she arrives. The climb will only feel worse if she sleeps at 5280ft. An alternative is on the day of arrival to do a small workout and then climb the next day. The small workout will help acclimatize.

Now for the disclaimer I am not a Doctor, everyone is different! Everyone's body reacts differently to altitude. This is only my personal guess based on my own experience and the fact that it's the easiest climb in Colorado. This also assumes she is in good shape!

There's no doubt she could summit on the same day of arrival, my guess is she will experience shortness of breath towards the top due to altitude and exertion, she will most likely have a headache towards the top and she will most likely wake up the next day with a bloody nose.

The best way to ensure success is to pace yourself, breathe every step, take it slow and steady, bring lots of quick carbs and 250ml water every 15mins and stay positive.

PS. Sorry if this answer seems like it was written for a beginner I have no idea what your experience or your sister's experience is, I just tried to provide a good answer for anyone who reads in the future...

  • 1
    I don't think it's true that you have to use diamox for weeks while gradually acclimatizing to ultra-high altitudes. I often take it the night before summit day if I'm going to ~14,000'. But you do have to be careful because diamox makes some people violently ill. It's a good idea to try it at home to make sure it doesn't make you sick.
    – user2169
    Commented Aug 1, 2014 at 19:38

The answers given already address almost all the issues well, but I'd like to add one final point which hasn't been given enough focus; ease of descent in case something goes wrong. If the OP's sister arrives, makes it up, and comes down before the AMS symptoms begin, that's great. But if something goes wrong and she's stuck at 4000+ meters, she is in some risk. Although high altitude pulmonary oedema (HAPE) only occurs after a few days, high altitude cerebral oedema (HACE) can occur after a few hours. If your sister is injured, trips, falls, etc - can she be safely taken back down quickly? In Mount Bierstadt, the answer appears to be yes, since it is an easy and popular climb, and other people will be able to help carry her. But this is not necessarily the case in all trips to this height.

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