raining for High Altitude
Regardless of the intended extremity of the altitude, whether it is Mera Peak (6,476m) or Everest (8,848m), people are always surprised by my response that to train for high altitude, swimming is the key. Initially, this doesn't seem like an intuitive answer since swimming apparently has very little in common with high altitude mountaineering, or indeed climbing in general. The benefits of swimming for high altitude life however aren't brought about by the type of movements involved but by the difficulty in breathing whilst underwater.
You will hopefully notice that when you are underwater, it is generally considered impossible to breathe. This is mainly because the breathable oxygen molecules are less dense than the surrounding water, and so you have to break the surface to take your next breath. Of course every water molecule (H2O) is made up of one breathable atom of oxygen, however this is covalently bonded to two atoms of hydrogen, meaning any attempt to breathe whilst underwater usually results in drowning.
In comparison, at the summit of the highest mountains on the planet, whilst there is some breathable oxygen, there is only a very small percentage of what you would expect at sea level. For example, at the summit of Everest, there is 33% of the oxygen available at sea level. This is certainly not enough oxygen to survive on without any form of adaptation, and this is why the process of acclimatisation is so important. If you were flown straight from sea level to the summit of Everest, a lack of oxygen would cause you to lose consciousness within minutes, and death would follow not long thereafter.
It is clear to see therefore that acclimatisation plays a vital role in ascending to extreme high altitudes, but what of the training whilst you are still at sea level? Whilst many climbers embarking on high altitude adventures concentrate on long walks in the hills and fast runs across the countryside, training for extreme high altitude needs to be much more specific than this, and oddly enough, there is a way to replicate conditions on Everest at sea level and in your local pool through what is known as 'apnea training', or 'dynamic apnea' to be more precise.
Apnea is a Neo-Latin term which simply means 'without breathing', and is the basis of many elite athlete training programmes due to its place in sports science literature. To simplify this literature somewhat, over a number of years scientists have found that the lungs generally exceed the requirements of their function, however it is nearly impossible to improve lung capacity with conventional training methods, unlike every other structure in the mammalian respiratory system.
In general, the lungs comfortably meet their demands, but when faced with extreme demands such as the need to breathe at high altitude, the lungs are often the limiting factor in a system which has otherwise adapted through acclimatisation. Whilst comparing sports though, scientists noted extreme growth of lung capacity in competitively trained swimmers, and eventually reasoned that it was the case due to the restrictive breathing associated with swimming and to some extent the added pressure found underwater. This is where apnea training comes in.
Studies have shown that swimming is the only sport where a physical increase in the capacity of the lungs can take place. This phenomenon is exaggerated when forcefully restricting the ability to breathe whilst swimming, and hence, apnea routines have been developed to exploit this unique growth. As previously mentioned there are two main types of apnea training, the first is 'static apnea' where an athlete will remain in one spot and simply hold their breath; this is common practice for free divers. The second is dynamic apnea, where athletes will perform routines which limit the ability to breath whilst swimming, with the aim of gradually stretching the athletes ability to perform with less and less oxygen over time.
But why is this important for mountaineers? Well this again is all down to being specific with your training. When you are standing on top of Everest or any high mountain, your performance is limited by how much oxygen you can deliver to your organs and working muscles. There are many unknowns to high altitude travel which science is yet to uncover, but simply put for now, if you can increase your lung capacity and become accustomed to working in restricted oxygen environments, the greater the chance that you will be able to perform well once you start venturing in to the thin air of the high mountains.
So what should you actually do? Well that's all down to personal preference, but I usually advise the use of a pyramid type routine. In any length of swimming pool, warm up as usual, then with your preferred stroke (preferably front crawl), do one length breathing every two strokes. Then with your second, aim to breathe every four strokes, and so on, up to 10 strokes per breath, then make your way back down. If you can breathe bilaterally, then you can go up in individual strokes, but this isn't important. All that is necessary is to stretch the time you spend underwater before breathing gently.
Once you have mastered this, it's time to get creative. There are an infinite number of routines and tests that you can do to expand your capacity to cope with 'hypoxic' (low oxygen) body states with a restriction of breathing. Equally, as you learn which routines really test you, you'll begin to understand what effect this will have on your ability to climb at high altitudes, and eventually, you'll be able to push the distances and time that you can go without oxygen which will greatly improve your ability to keep plodding up a seemingly never ending snow slope surrounded by that awful 'empty air' which surrounds the tops of all but the smallest Himalayan peaks.
So mix things up! Instead of just running or walking or cycling, add some swimming to your training programme, and reap the benefits when it becomes time to test yourself on your next big adventure.
Of course swimming always carries a risk of drowning, and so just like you wouldn't cross crevassed terrain without a qualified guide whilst you were learning, it is best to practice apnea training under close supervision until you start to learn the limits of your own ability underwater.