I'm going to Colorado to visit a friend and we will be going on a week long trek across a couple of 14'ners. I'm looking for some ways to help prepare my body for trip.

  • If you haven't, you might like to check out 14ers.com for current conditions and trip reports.
    – xpda
    Commented Jan 26, 2012 at 5:10

6 Answers 6

  1. Aerobic conditioning will help a little with the altitude.
  2. You can practice walking / running on a treadmill at 15% incline.
  3. You can practice walking with a loaded backpack. Bonus points for doing it on an inclined treadmill.
  • 6
    I would definitely combine the elements of both answers. Good health is vital, but you can't really "train" for the effects of high altitude - you just have to try it. Acute Mountain Sickness (AMS) can set in at surprisingly low altitudes, particularly if you haven't given yourself adequate acclimatization time, and it can be deadly. Know the signs and take care of yourself.
    – Greg.Ley
    Commented Mar 11, 2012 at 5:13
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    Aerobic conditioning will only help with the part of "altitude" where you're getting less oxygen with each breath. It won't help in the least with all of the other physiological effects of low atmospheric pressure. Don't disregard the other answers which talk about the necessity of allowing your body to acclimatize by spending time at altitude - it's the only thing that works for the headache, nausea, mild edemas, rapid pulse, nosebleeds, etcetera. People who are in extremely good aerobic shape can be very, very fragile at altitude, if not acclimatized.
    – Beanluc
    Commented Jun 8, 2018 at 23:23

[Edited after comments and additional research.]

Aerobic training will not prepare you for altitude

Some of the answers here are misleading. According to the Altitude Research Centre:

Being physically fit does not prevent you from experiencing AMS (Acute Mountain Sickness) symptoms. There does not seem to be a link between fitness level and susceptibility to altitude illness.

Altitude sickness is a significant risk at 14,000 feet (4,200m)

At 14,000' (4,200m) you're only getting 60% of the oxygen at sea level. Altitude medics classify 14k as "Very High Altitude" which is a strong hint that the dangers are significant.

Susceptibility to AMS appears to be genetic and varies widely between individuals. Estimates of incidence levels are all over the place in the literature, but we can safely say that a significant percentage will experience quite severe physical and cognitive issues if they ascend rapidly to 14k.

Don't underestimate the impact. Even mild AMS is extremely unpleasant and can affect your ability to move safely on technical ground. Severe symptoms can be pretty much paralysing. I'm very susceptible to AMS and know this from experience.

So it's important to follow the Golden Rules and not push on if you experience symptoms. Rapid descent will always resolve early symptoms - the problem is that denial is extremely common as people are keen to reach their goal and not disrupt the rest of the party. This is how the serious issues occur.

Currently, the only way to know your own response to altitude is to suck it and see. So it's important to be cautious on your first high ventures, and pick routes with an easy retreat. Even people with known low susceptibility can suddenly experience problems, so always be prepared to descend if you feel unwell.

How to acclimatise before ascending to 14,000 feet (4,200m)

It's very important to distinguish between two scenarios:

  1. The typical alpine trip where you make day-climbs to the peak, but descend to sleep below 8000 feet (2400 meters). That is what we are discussing here.
  2. A trip where you will be progressively sleeping at higher altitudes. This is a whole different ballgame and life-threatening problems are quite common. Do your research and understand the proper protocols for gaining height.

Traditional acclimatisation

The only proven way to acclimatise fully is a programme of training climbs at increasing altitudes. If you know you are one of the lucky ones, you can head straight off to your 14 thousander. For the rest of us, you'll need 1-4 days to acclimatise depending on your physiology.

I'm prone to sickness, so personally I find it best to be conservative and climb up to around 9,000' (2,700m) on the first day while sleeping low. Even this can be quite uncomfortable. Then I'll add 1,000' (300m) or so a day if things go OK. If I'm relatively symptom-free on an 12,000' training climb, I'd feel ready for 14,000' (4,200m). If you're less susceptible, you can accelerate the process. Only experience will tell.

Altitude tents and masks

This is quite an expensive and disruptive process. The equipment can be hired or purchased if you don't have a suitable facility nearby. US Army Research suggests that tents are better than nothing, but are far from a full substitute for traditional acclimatisation. For a 14 thousander, it's unlikely that this will be the way to go.


The only recognised medication is Diamox (Acetazolamide).

Diamox is far from risk-free, with many unpleasant but benign side-effects and occasional life-threatening reactions. And recent research suggests that it is not measurably effective for countering the effects of strenuous exercise during rapid ascent.

In the UK, the clinical authorities recommend against using Diamox prophylactically, so you won't get a prescription. It's available in the US, but the risk/reward ratio doesn't look good and you certainly shouldn't rely on it preventing AMS at 14k.

Edit: I've adjusted the broken Golden Rules link with some that I searched up. I'm not the OP, who knows way more, but they look fairly in line with what previous casual research showed me.

Take-home points

  • The dangers of rapid ascent to 14k are significant
  • Only experience will tell you how long you take to acclimatise
  • If you do need acclimatisation, the only proven approach is traditional training climbs
  • Tents and masks only provide modest benefits, while medication has significant side-effects and may well not work in this scenario.
  • 2
    Without acclimatisation, most people will experience mild altitude sickness from around 8,000' Citation needed. At 8000', the air pressure is the same as in a passenger jet. Almost nobody gets AMS in a passenger jet. If you want to climb fourteen-thousanders, you only have two proven alternatives - either you allocate 3-4 days to training at lower altitude, or you pre-acclimatise with altitude tents and masks.* This is not accurate or realistic. I've done half a dozen fourteeners, and for almost none of those did I acclimatize for 3-4 days.
    – user2169
    Commented Aug 31, 2016 at 23:01
  • 2
    @BenCrowell - attitudes to medication seem to be different in the US. In the UK, Diamox would only be used for prevention if normal acclimatisation was not possible: nhs.uk/Conditions/Altitude-sickness/Pages/Prevention.aspx . Side effects are common and can be distressing: drugs.com/sfx/diamox-side-effects.html. UK policy states: "The routine use of acetazolamide before ascent is not recommended." and it is not licensed for this use. Your physician must have their reasons, but I would prefer to take a drug-free approach unless there was a very specific requirement. Commented Sep 1, 2016 at 0:17
  • 1
    @BenCrowell - airline cabin altitude isn't really relevant here - it's the combination of reduced oxygen and strenuous exercise that causes AMS. No one is lugging a pack up a slope in an airline cabin... Commented Sep 1, 2016 at 1:27
  • 4
    @BenCrowell - you can't argue from a sample of one - we know that 20% of people will be relatively symptom free if they ascend quickly to 14k. Other people will be at risk of death, as in the case-study above.. I've been to that altitude with a number of people, and we all needed training climbs before we could be remotely safe at 14k. General citations would include the CDC : wwwnc.cdc.gov/travel/yellowbook/2016/…. The specific stats are from US army research:livescience.com/… Commented Sep 1, 2016 at 1:34
  • 1
    Great answer, fully agree. Some rejection might arise because it is possible to ascend a 4000m peak (and then descend) safely without previous acclimatisation if you follow certain rules. It means that you have to turn back if you develop symptoms (nausea, headache, vertigo, ...). This is commonly done in the alps (friends and myself do it often), just that many people do not turn back when they should, but that is another problem. From the limited and not representative sample known to me turning back due to AMS was necessary in much smaller numbers than stated in this answer.
    – imsodin
    Commented Sep 1, 2016 at 11:48

There isn't necessarily a way to prepare your body for the altitude. You should however:

  1. Be in good condition overall, i.e. able to handle at sea level more than you are planning to do at altitude.
  2. Try to spend several days at a lower altitude (like 7000 feet) doing some aerobic activity before trying to go higher.
  3. Drink more water than usual.
  4. Take regular doses of aspirin during your trip (or starting before your trip, ideas on this vary).

There is a lot of general information at hiking, skiing, and sports conditioning sites (ex. Wilderness Sports Conditioning).

Finally, know the signs of altitude sickness and make sure your hiking partners do too, so that if anyone starts getting sick, there are people there to make sure that person descends immediately (altitude sick people are sometimes too confused to realize they are in trouble).

  • 1
    What benefit does thinner blood (aspirin) give to being at altitude? Commented Mar 13, 2012 at 22:43
  • 4
    I've heard that aspirin is a bad idea when at high altitude. It can mask the onset of a headache, which is one of your first warning signs that you're encountering altitude issues. Usually you take something like Diamox.
    – Eyal
    Commented Nov 4, 2012 at 14:35
  • 4
    Highly doubtful you should be self-proscribing diamox for a 14k peak. If you have already given your body sufficient opportunity to acclimatise and you have severe altitude sickness during the climb, then you should descend or at least give yourself a day's rest without further exertion.
    – Richard
    Commented Sep 10, 2013 at 16:05
  • 1
    Is there any evidence for any of the items on this list? I suspect that all four are either partially or completely incorrect.
    – user2169
    Commented Aug 28, 2016 at 19:58
  • 3
    -1 for the suggestion of taking Aspiring as a precautionary measure. Please provide solid scientific sources for this. Generally it is not a good idea to suppress/ignore the warning signs which your body gives you (like a headache can be for AMS or dehydration).
    – fgysin
    Commented Aug 29, 2016 at 8:34

Find an area with a large stairway (football field bleachers work great), then power-walk/run up and down them while taking a break every few runs. Keep doing this until the trip, while increasing the number of "laps" when you think you're improving.

When it starts becoming easier, pack up your backpack with your gear or simulate the weight with something heavy, and go at the stairs again (you'll want to power-walk with the backpack). You want to build your endurance, so practice breathing thoroughly while climbing.


Altitude adjustment is primarily conditioned through acclimation. Remember to travel high, sleep low. If you can, go earlier and spend some time acclimating to the higher altitude by going up to a higher altitude and then descending after a period of time. Perhaps a couple hours at the higher altitude before descending to a somewhat lower altitude. From what I am familiar with, physical conditioning is not directly related to the sensitivity to altitude changes.

Its also recommended to train your general hiking skills, get your backpack in order, work in your boots.

Enjoy your trip.


As for raw cardio stairs or stair trainer. Or running, walking, bicycle. Include some walking with a fully loaded pack to get you body used to bearing the weight.

Search on "altitude training".

There are altitude training masks but not everyone agrees they are effective.

There are altitude training tents, rooms, and even sleep tents. A gym near you may have an altitude training tents, rooms

They reduce the oxygen to simulate altitude. The idea is to get your body to produce more the oxygen carrying red blood cells.

There are drugs to produce more red blood cells but not something I would advise. Don't - it can kill you. Before cyclist got good at it many died.

If you can spend just a one or two days at elevation with some light excise before going high your body will adjust.

Look up signs and treatment of high altitude pulmonary edema before you go. If you are crossing a pass maybe sleep in the valley rather than on top of the pass.

  • Come on down vote. What is the problem?
    – paparazzo
    Commented Sep 19, 2017 at 13:37

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