Training at altitude


Hi. I live in miami fl and i  have an altitude question.
I’m racing las vegas half ironman 70.3 world championship on sept 8 2013, however I’m planning on going to Bogota
Colombia (27000mts/ 9000feet) between august 23 to sep 2 and then sep 2 go to las vegas for the race.
How do you think will that affect my race?? what can i do to prepare for my race in terms of altitude?
Thank you so much for any thoughts on the subject.

Thank you for your questions about exercise in relation to high altitude.

Training in a high altitude environment to improve athletic performance at sea level (or close to sea level)
is a popular technique amongst athletes from many different disciplines, particularly those involved in
endurance sports. However, despite the many people using altitude exposure as a means of gaining a competitive
edge, the scientific justification for altitude training is limited. In particular, there are no high quality
studies of altitude exposure comparing this with the same training at sea level altitudes.

Regarding the research that has been published, in some studies people living and training at altitude improved
their subsequent athletic performance at sea level, although this has not been replicated in all studies.
There may also be some people who will respond to altitude exposure whilst others will not. However, the
duration of exposure to altitude in these studies was usually around 3-4 weeks; some would suggest that at least
2 weeks would be required to obtain any physiological benefit from altitude exposure. Therefore the duration of
time for which you are in Bogotá may be too brief to provide you with any significant benefit.

It is difficult to predict how your time in Bogotá will affect your athletic performance at the 70.3 in Las Vegas.
The altitude in Bogotá is not so high that you are likely to suffer from altitude illness (although this is
possible). However, the reduced amount of oxygen in the atmosphere will mean that your maximal exercise efforts
will be reduced. Further, you will also have to work harder to achieve the same absolute work rate compared to
undertaking the same session at sea level. This can result in a slower pace for a fixed work rate training
session, something which is worth bearing in mind when undertaking training sets at altitude. Heart rate will
also be increased during submaximal exercise, which should also be taken into account if you use heart rate
monitoring during training.

I will also be racing in Las Vegas; I hope you have a
great time.


Dr Alistair Simpson MBChB MSc FRCA

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Chronic Obstructive Pulmonary Disease and altitude


Hi doc,

I currently live in pennsylvania and am wanting to move to Colorado. altitude of 8,747. My delima is, I have COPD. I have medicine for it but since i quit smoking i haven’t had to take it. My pulmonologist said that my breathing is better. I have never had to be on oxygen either. Is it possible for me to live in that altitude? Even if I took different meds to do it?    Thank you for your time.



Thank you for your question. At 8747ft, there is only 74% of the oxygen that is available at sea level.  For a person with any kind of lung disease, this can pose both short and long term problems.  As for anyone ascending to altitude, initially there will be a drop in your blood oxygen content.  However, for people with lung disease ascent to relatively modest altitudes can lead to more significant shortness of breath and a reduction in how far you can walk or how much you can exercise. During short term exposures to altitude (or on board aircraft) some people may even require supplemental oxygen.  This is something your pulmonologist can assess as it will depend on the severity of your condition.  With very mild lung disease supplemental oxygen may not be required and after a period of acclimatisation you may find your symptoms are similar to what they were at sea level.


However, longer term health problems also need to be considered. There are published studies which suggest that people with COPD who live at altitude don’t live as long as those living at sea level.  A possible explanation for this is the recognised consequence of lung disease causing strain on the heart. With less oxygen available in the air, blood vessels in the lung tend to constrict and this increases the workload of the right-hand side of the heart. Over time this can lead to a form of heart failure. Again your pulmonologist can arrange tests to assess your heart. If there is evidence of high pressure in blood vessels supplying the lungs, the safest approach is to avoid travel to altitude.

Dr Roger Thompson

Please remember Any answers we give are general: since we do not have access to your own health records we are unable to make specific recommendations about your health or treatment. All enquiries or concerns about your own health should be directed to your physician. Your email and any answer will be published at altitude.org/mountain_doc.php. If you do not agree to this then please to not post a question here.

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Altitude and Migraines


I have a friend who is training to climb Mt. Rainier (14,410’) next month.  She has pre-existing migraines.  We have trained a few days on the mountain – up to 10,188’ this past week.  Every time she goes, it triggers a migraine.  She is even taking some migraine meds as a preventative before she goes.

Do you have any advice?


There is very little objective evidence on this subject. It has been reported that those people who suffer from migraines have an increased risk of high altitude headache but there are no studies to prove this. There is possibly a similar mechanism behind the two conditions.
One study has shown that migraines can be triggered by low levels of oxygen leading to dilatation of vessels. Other evidence points to both altitude headache and migraine being linked to the activation of a particular neuro-vascular system (the trigemino-vascular system).
It is important to distinguish a migraine headache from an altitude headache. Altitude headaches do not usually have any neurological type symptoms like an aura, sight problems or being unilateral however they can cause vomiting, significant incapacity and irritability.
There is no contraindication for taking migraine prophylaxis at altitude. The UIAA recommends those who suffer from migraine should carry analgesic drugs that have previously proven effective for their migraines as well as preventatives.
Please remember Any answers we give are general: since we do not have access to your friend’s health records we are unable to make specific recommendations about her health or treatment.I would suggest your friend sees her physician. Your email and any answer will be published at altitude.org/mountain_doc.php. If you do not agree to this then please rsvp. 
I hope this helps.

Dr Kitty Duncan

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Kilimanjaro Advice


Hi – I’m climbing Kilimanjaro in January for Alzheimer’s Society and went to see my doctor last night re jabs etc. We discussed Altitude Sickness and she gave me your website. 15 years ago I suffered with altitude sickness whilst skiing at Breckenridge in the US  – short of breath, headaches – still skied and used an oxygen machine in the evenings. Question is should I use Diamox prior or take some with me. Any guidance you can give me would be greatly appreciated.

I’m 52 and generally fit. – but know that means nothing


My suggestions would be:
Check out the altitude experience of the doctor who is coming with you or how they are backed up from home.
Check out the flexibility of Discover Adventures team…can it be split up if some people are slower than others? How do they deal with anyone having an issue with altitude?
I would certainly suggest you carry Diamox. It is not actually licensed for use at altitude, so you may find your GP is not willing to prescribe it – some will and some wont. Before you go out, you should try out a test dose on yourself, to check you don’t have any reaction and also so you have experienced the side effects that you might get, like tingling in hands and feet. You can find out more about it on the internet. A useful little booklet is the Medex booklet.  For prevention the recommended dose is 250mg ie 1/2 tablet twice a day and treatment is one tablet twice a day. Staying hydrated is extremely important.
If you have a chance to go to altitude again, either in the Alps or in the USA before you go it might be worth seeing how you feel.
Everyone is always feeling a big psychological push to get to the summit, especially when you are doing it for charity, but remember safety and your health comes first.
Dr Kitty Duncan

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Acclimatisation and HAPE


Hi Doctor,
I read your on-line blog about Altitude Sickness of your website Altitude.org. I am in my mid 40’s and practice Mountaineering, about 2 expeditions a year. I grew up in Mexico city 2200 m over sea level and was never affected by altitude. However I moved to Michigan, just about 300m over sea level and have been living here for about 15 years and now I feel the effects of high altitude. But the only problem I have, is usually over 4000m when I have a hard time breathing, but only when I am making a physical effort. If I am resting I feel fine. I have tried getting acclimatized spending a couple of extra days at high altitude before pushing for the summit, but I still get the same issue.

Is this related to HAPE or to AMS?


Even though you spent many years living at a reasonable altitude, since you have been living at near sea level in the last 15 years, any acclimitisation you once had will be long gone.

Effects of altitude, in the forms of both HAPE and AMS can start occurring over 3000m

AMS cannot be diagnosed unless you have a headache after ascent plus at least some of the other symptoms of poor appetite, sleep, fatigue or dizziness. If you are suffering from breathlessness alone then it is more likely that you are possibly developing an early form of HAPE. Recent studies have used ultrasound scans to show that some people develop “sub clinical pulmonary oedema”. This means that, although they do not have the classic symptoms of HAPE, they are carrying extra fluid in the lung tissue. These studies also show that exercise increases this fluid. This is the most likely possible cause for your symptoms. If this is the case you are likely to suffer the same symptoms every time you go above 3000-4000m.

As per the Wilderness Medical Society, slow ascent is really the only safe way to try and prevent these symptoms. You should ascend no more than 300-500m per day once over 3000m and rest every third day or 1000m. HAPE can take up to 48hours at a new altitude to develop.

Nifedipine is a drug that lowers blood pressure and can be used to prevent HAPE in known susceptible individuals, but it does have significant side effects and you would need to discuss the possibility of using this with your own doctor or mountain medicine specialist in the US. 

Dr Kitty Duncan

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Prophylaxis and treatment of AMS

Hello there,
I’m emailing with questions about altitude medicine for the Himalaya trek. I live in Denver, Colorado and we are trekking to EBC at the end of this month. I think the most we will ascend is about 2000 ft at a time with a rest day the next day.
It is with the Wilderness Medicine group.

Of course I am concerned about atlitude illness, so I have prescriptions for acetazolamide, decadron, and am considering an emergency Lasix prescription.

I understand that altitude illness is difficult to predict, but I am wondering since we have hiked the Inca Trail to Machu Picchu (not as high as EBC by any means) but we had no problems on that trek, what your opinion is on the likelihood of altitude illness.

Do you have to take Acetazolamide/Decadron prophylactically or can you wait and take it if you get sick. I am worried about prophylaxing in the case that I do get sick there won’t be much to do for myself other than descend.
Thank you for your help

Thanks for your question to altitude.org.

Please remember any answers we give are general: since we do not have access to your own health records we are unable to make specific recommendations about your health or treatment. All inquiries or concerns about your own health should be directed to your physician. Your email and any answer will be published at altitude.org/mountain_doc.php.

The difference between the Inca Trail trek and the EBC trek, as you rightly point out, is the maximum altitude you attain on the Inca trail is 4215m and this is a pass – the highest trekkers sleep is usually 3800m. So, EBC is a different proposition as you will be trekking up to 5300m. The fact that you did not experience any altitude problems on the Inca Trail is a hopeful sign, but every time you go to altitude your body can react differently, especially if you have been unwell in any way (for example if you get any infection). One thing you could do in the week before you go to Nepal is to get up into the mountains in Colorado, not only to keep hiking fit but to expose yourself to some relative altitude before you go.

I’m sure that, if you are trekking with the Wilderness Medicine group, they will be ascending according to their guidelines – ie only increasing sleeping altitude by 300-500m/day with a rest day every 3 days or 1000m. All my advice is based on these guidelines (as well as the UIAA ones) which are available to download from the Web.

Regarding prophylaxis; As recommended by the WMS guidelines, slow ascent is the best way to prevent Acute Mountain Sickness (AMS) which is the most common form of altitude illness. Acetazolamide is the best drug for both prophylaxis and treatment of AMS so it is good to carry some with you. Another important way of helping prevent illness is to stay well hydrated (so that you are peeing clear urine regularly) to keep yourself warm, take plenty of rest and to eat regularly.

One recommendation I would make is to take a dose of Acetazolamide at home before you leave on your trip, to make sure firstly you don’t have any reaction to it (this is unusual ) and also so you have felt some of the side effects it may give you before you are already at altitude. The most common side effects are having to urinate more (which is actually one of the way it works) and tingling in your hands and feet. Some people feel this and some don’t. When I take Diamox I usually get quite electric tingling which comes and goes in my feet but usually only lasts for a short time. The prophylactic dose is 125mg (usually ½ a tablet as tablets usually contain 250mg – please check this on your tablet information).

In terms of if or when you should take Acetazolamide (also known as Diamox), I would not take it unless you start feeling the early signs of AMS, for example getting a headache in the evening after ascent which is gone by the morning or if you are not sleeping well (in this case you can take a dose of 125mg about 2 hours before bed just as a sleeping aid). You can then start a prophylactic dose – 125mg twice a day – and if this helps the symptoms carry on taking this until you are descending again. Taking this will not mask any worsening symptoms so you will know if you are getting sick, in which case you should be upping the dose to 250mg (one tablet) twice a day and certainly not going any higher, probably descending. All these decisions should be taken in conjunction with the Medic on your trip.

It is not recommended to use Decadron/Dexamethasone as prophylaxis for AMS unless you do find that you have a reaction to Acetazolamide. It should be in the first aid kit for your group but I would not recommend that you need to carry it in your own personal kit.

Lasix is not recommended and has no place in prophylaxis or treatment of AMS or any other altitude illness. It is a diuretic like Acetazolamide but it works in a different way and can cause significant dehydration which can actually worsen symptoms as people tend to be dehydrated already when unwell at altitude.

I hope this helps.

Dr Kitty Duncan

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Illness after return from altitude.


I returned from a hiking trip to the summit of Mt Whitney day before yesterday. This was my 4th trip up Whitney and my third successful summit. I had altitude sickness each of the other three trips, the last being 10 years ago. I had no ill effects this time and felt great the entire climb. I attribute this to two factors: First, even though I am 57 years old I am in much better physical condition than in previous climbs, and secondly, I took 400mg of ibu 3 times a day for three three days prior to the climb and on the day of the climb.

However, yesterday I experienced shortness of breath and mild fatigue. Today those symptoms have been more intense following a three mile run this morning. This afternoon the symptoms seem to be subsiding. I also have body/joint aches today and loss of appetite. I am wondering if I could have a delayed reaction to the altitude or even if ibuprofen could mask symptoms on the mountain and some residual symptoms appear later.

I suspect this is a virus but thought I would run the question by you. Any thoughts?



Thanks for your question to mountaindoc.

Congratulations on your fourth ascent of Mt Whitney.

Even the same person ascending the same mountain at the same speed can be affected differently by the altitude at different times. There could be a number of reasons that you felt better this time. Fitness in itself is not a protective factor for altitude illness.

Ibuprofen has been shown to be useful for preventing and treating altitude headache and possibly also for Acute Mountain Sickness, although at higher doses than you took. Ibuprofen, like Acetazolamide (Diamox) will not mask symptoms of altitude illness only reduce your chances of getting symptoms. Also, altitude will not cause effects once you are back at lower levels if you have not been affected whilst at altitude. If you have symptoms they will usually clear up within hours of returning to sea level/your normal altitude. I would agree with you that this is probably a virus. Being at altitude and the exertion of climbing will both reduce your immunity and therefore make it more likely that you are susceptible to infection during that time and produce symptoms 24-48 hours later.

I hope this helps

Dr Kitty Duncan, DiMM



Please note:

Any answers we give are general: since we do not have access to your own health records we are unable to make specific recommendations about your health or treatment. All enquiries or concerns about your own health should be directed to your physician. Your email and any answer will be published ataltitude.org/mountain_doc.php. If you do not agree to this then please to not post a question here.

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Steroids and altitude illness



It was suggested to me by a doctor that taking Cortisone while climbing Aconcagua will prevent mountain sickness.

Although when I mentioned this to the Doctor at Base Camp, he said that this was definitely not a good idea as the mountain is too dry?

Please advise on which one is correct?



Thanks for your question to altitude.org.
There is no evidence for taking Cortisone at altitude, as far as I know. We were wondering if your doctor meant Dexamethasone? Both drugs are steroids, however there is some evidence for the use of Dexamethasone at altitude.
Of course, the best way and safest way to prevent altitude illness is to follow a safe ascent profile.
Dexamethasone is primarily used as a treatment for High Altitude Cerebral Oedema and it has been shown to work as a preventative agent for both Acute Mountain Sickness (AMS) and High Altitude Pulmonary Oedema. Importantly it is not recommended by either the Wilderness Medical Society (WMS) or the UIAA as a first line treatment because of it’s significant side effects. Diamox (Acetazolamide) should be the standard preventative medication for AMS.
WMS guidelines 2010:
“In low-risk situations, prophylactic medications are not necessary and individuals should rely on a gradual ascent profile. Above an altitude of 3000 m, individuals should not increase the sleeping elevation by more than 500 m per day and should include a rest day (ie, no ascent to higher sleeping elevation) every 3 to 4 days. Prophylactic medications should be considered in addition to gradual ascent for use in moderate- to high-risk situations. Acetazolamide is the preferred agent, but dexamethasone may be used as an alternative in individuals with a prior history of intolerance of or allergic reaction to acetazolamide.”
I hope this helps,
Dr Kitty Duncan

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Asthma at altitudes

Dear Mt Doc,
My wife and I have been planning a 7 day trek in Peru, which involves acclimating for 2 days at 11,500″ (Cuzco) before ascending to just over 15,000, then descending to Machu Picchu. She has been treated for asthma for years. She is 59 years of age and quite active and fit, and is keen to do this trip. Your advice would be appreciated.


Thanks for your question. There is no strong evidence that asthma itself is affected by altitude and anecdotally some asthmatics may actually improve.

If your wife’s asthma is well controlled then she will be running on a normal level of blood oxygen and therefore the asthma should not contribute to an increased risk of hypoxia.

What is you wife’s asthma triggered by? Cold? Exercise? Allergens?

There is a theoretic risk that, if it is triggered by cold/dry air then she may get more wheezy doing the same level of exercise at altitude than she would at lower levels, however if she exercises without problems on a cold, dry winters day at home then this is unlikely to be a problem. A lot of asthmatics wheeze is triggered by allergens and there are actually less of these at altitude – less dust, pollen etc   – so that theoretically these asthmatics might actually have an improvement in symptoms.


The key points are

– should make sure her asthma is as well controlled as possible – this includes medication and general fitness.

– she should keep her medication with her all the time – not carried with the porter.

– she should be aware of the signs of altitude illness or worsening asthma and should not hesitate to turn around and descend if any problems occur.


It is important that you stick to the guidelines of not ascending more than 300-500m/day sleeping altitude.


On a personal note I am an asthmatic whose asthma is triggered by cold, exercise and allergens. I have very well controlled asthma ( long term steroids and beta agonists) and I have never had any problems with my asthma at altitude (including in Peru) however I have had AMS!


I hope this helps



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Health certificates

I have been asked to provide a medical certificate for treekking in tibet to say I am able to walk at 6000 metres. However my gp will only write a general health status letter and says cannot be specific about altitude etc.  Just wanted to check if such a certificate is possible to obtain.

Many thanks



Your GP is correct that it is not possible to be specific about someones health at altitude. No one can guarantee how a person is going to deal with altitude no matter how fit and healthy they are at sea level, so what the trekking company is asking for is impossible. The only thing your GP can give is an honest general health assessment. I would be interested to know the name of the company?
  Dr Kitty Duncan. altitude.org

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