I have written before about the science of adjustment to high altitude, but thought a brief recap might be in order, as it relates to part of the journey featured in my new book. So if you are considering a train trip to the Andes or the Tibetan Plateau, here are some thoughts from my experiences on the rails.
It’s about the profile of the climb, not just the absolute height
Human beings can succumb to altitude sickness from altitudes as low as 2500m, but the chances of this happening at over 3500m are much higher. To put this into context, the Qinghai-Lhasa railway goes briefly above 5000m and the Peruvian train between Cusco and Lake Titicaca tops 4700m. But what makes the biggest difference is how you acclimatise.
Climbers often stop and sleep lower than they have climbed. On a train you might not have that option. You will of course be able to try and rest, but the altitude will be dictated by the route and speed of your train. Fast ascents will always be trickier than slow ones. However, a train operator will be experienced in what is practical and adapt the service as much as possible to keep passengers healthy.
Be prepared to not feel as well as you normally do
You might have no symptoms at all, but knowing that it is common to feel a bit under the weather, even if just a headache and a loss of appetite, it’s worth bringing along comfort food and things that are easy to drink.
Carbohydrates are supposedly more effective to convert to energy at high altitude, but with no appetite you might prefer to have a supply of chocolate and goodies. If you don’t want to eat, be prepared to start adding sugar to your tea, and remember to keep hydrated, which significantly reduces the risks and effects of being at high altitude.
As I found out on the train to Lake Titicaca, even tying your shoelaces can seem hard at high altitude, so be prepared to take it easy. You may also find, as I did, that your brain sees colours that are far more saturated at altitude, creating a strange sort of height induced ‘high’.
Consider taking appropriate medication
Talk to your doctor and do some reading before you set off. There are specific drugs that can help minimise the effects of benign acute mountain sickness (AMS), the most well used being Diamox (acetazolamide). Climbers are well drilled on the fact that its purpose is not to help ignore the symptoms and keep climbing, but to manage the condition before going higher. On a train, this can be hard, so an understanding of the altitude profile of the trip is important.
Oxygen is useful in that it can simulate a lower altitude. For example, on the Qinghai-Tibet railway, O2 is pumped into the train as a matter of course, but people who are sick are given a higher flow rate with an oxygen mask. One advantage of being on a train, rather than climbing, is that it is easy to carry plenty of oxygen for sick passengers. It is not pressurised like a jet aircraft, but added to the ventilation system of the compartments to help simulate a lower altitude, perhaps 2000-3000m, rather than the 5000m outside.
The Tibet train has health officials or attendants on board who ensure every passenger has signed a form to say they are aware of the altitude and have no major health problems. I have also seen them dispense oxygen masks to people who are unwell. I don’t know if one of them is a doctor or not, but they are clearly used to helping passengers who become sick on the climb up to the Tanggula Pass – at 5072m, the highest railway station in the world.
Ibuprofen can also be helpful managing mild headaches. More serious AMS drugs should be prescribed by a doctor and not taken without a professional medical diagnosis.
Keep yourself occupied
It’s good to keep busy and not let your weakened condition get on top of you mentally. Get off at stops, enjoy the scenery and visit the restaurant carriage to drink tea and talk to people. If you feel too unwell to do this, then stick to your berth and read a book. Writing a diary or a blog with a record of your trip can be a useful distraction and creates a positive mental focus. Photography is also great to keep your brain engaged with your surroundings.
Sleep and eat when you can
It is hard to sleep at high altitude, as you often have rather weird dreams and can find yourself waking up panting. This is quite normal; it’s to do with acclimatising to the changes in the air content. Your body needs to rid itself of CO2 as much as to breathe O2. This can result in ‘periodic breathing’, when you wake up feeling that you have stopped breathing. If you feel tired, take a nap, and if you are lucky enough to feel hungry, have something to eat. You may not be able to do this throughout your journey, so take advantage when you can.
Finally, if you are really don’t feel well, you should tell someone. You are unlikely to get better unless you descend, and there is a chance you might get worse. The practicalities are different on a train to climbing a mountain, but officials will know what can be done. There will often be a doctor onboard the train or someone who is specifically trained in helping people with the symptoms of AMS.