Acclimatization at high altitude

Acclimatization is a key to successful and safe mountain climbing. The keyword here is safe. Since many people die or get into accidents every year because of incorrect, imperfect acclimatization. According to some researches people mostly die in Everest due to cerebral or pulmonary edema, in the “death zone”. Not taking into account individual cases, for example individual inability to adapt or bad weather, the reason for this is mainly incorrect acclimatization.

The main reason of altitude sickness is hypoxia, or in simple words, oxygen starvation. Acclimatization process is a totality of complex biochemical processes in the body. But the main one is the release of a large number of red blood cells into the blood, which is an increase in hemoglobin level. Red blood cells “grab” oxygen molecules in the lungs and transport them throughout the body. Since the partial amount of oxygen in the mountains is less, more red blood cells are needed to increase the efficiency of gas exchange in the blood.

Preparation

Preparation should begin long before your trip to mountains. In previous articles about Mount Kazbek and altitude sickness we partially talked about this topic, but in this article we will talk about acclimatization in more detail. An important component is cardio training. During cardio training, the volume of heart and lungs increases, which helps to save energy in the mountains.

The problem is that your body experiences great stress during physical activities. Cells need more oxygen, especially brain cells. Add to this the oxygen starvation at high altitudes, and the heart will be forced to beat very fast, to manage to pump enough blood. The person also starts to breathe faster in order to manage to absorb enough oxygen. Very often, even at low altitudes, an untrained person starts to feel the shortness of breath. And at high altitudes, even a trained person experiences shortness of breath. The indicators of your training level should be your pulse and shortness of breath.

You need to train on the verge of shortness of breath and heart rate of 120-130 beats per minute. For different people these indicators may vary, but on average in can be considered like this. While running or walking, you should be able to talk calmly, without shortness of breath, and your heart should not jump out of your chest. If you feel this way, then your physical shape is lower than the load that you give to your body. It is necessary to slow down and gradually increase the shape and load. But it is also important not to over-train before going to mountains. You should not be at peak of your physical shape because after this comes a decline.

Let’s not go into details, not to complicate the task. Just imagine a sinusoidal graph, where the curve is the state of your shape. It can’t stay at the peak for too long. If you go to the mountains at your peak shape, the moment of decline can come in the most crucial section of the trail. Therefore it is necessary to stop intensive training one week before the climbing program, and maintain the body with easy evening walks and jogs of 2-3 kilometers. You need to reach your peak shape on first or second day of ascent.

Negative factors

Next, we need to take into account the effects and factors that negatively affect physical shape and acclimatization. These factors are: altitude, solar radiation, physical overload, hypothermia, dehydration, poor nutrition, poor hygiene, microorganisms brought from the city, and local microorganisms, food poisoning, stress. Very little attention is paid to stress.

I remember that the first time at Kazbek was too difficult for me, I was physically exhausted. After that, we trained hard for two years, read a bunch of articles and works on nutrition, acclimatization, equipment, cardio training, etc. But we forgot one important thing – the routine. Personally, I was completely unprepared for a camp life in a tent. It took me a lot of time and energy to put up a tent, flatten the rug and sleeping bag. I didn’t have mountain sickness, I felt fine, slept good and ate a lot. In the end, we successfully and fairly quickly reached the top and went down. But disorganization led to stressful situations that had a negative impact on our general condition. We reached the top in 6 hours and 50 minutes. But maybe without this stress, we would do it in 6 hours?

Okay, back to the topic of acclimatization. Acclimatization on the mountain occurs gradually. Altitude is gained a maximum of 1000 meters every day, followed by a descent of 300-400 meters for an overnight stay. Sleep is the key factor, because during sleep our body adapts best.

 

Let’s analyze the types of acclimatization. There is short-term and long-term acclimatization.

Short-term acclimatization

This is a quick response of the body. Available resources are mobilized to suppress hypoxia. The hemoglobin supply in the spleen is released into the blood, and the bloodstream goes to the brain, since the brain tissues consume the most oxygen and are the most important organ, at least for most people. By the way, because of this headaches occur in the mountains.

This system works for a short time, because our body simply turns on all its reserves, speeds up the heart rate. Other body functions suffer due to the blood flow to the brain, for example, limbs begin to freeze faster, and metabolism is disturbed. With a long stay in the mountains and rapid increase in elevations, the body gets exhausted and if you don’t slow down, then you can have quite serious consequences. These processes occur in the bodies of skyrunners. They must quickly go to the top and also quickly descent, before the body “realizes” everything.

Long-term acclimatization

This is what we need during the ascents. In this case, deep changes occur in the body. Vessels become elastic, embryonic hemoglobin appears, which is able to attach oxygen at a lower partial pressure. The density of capillaries in the lungs increases, and as a result the efficiency of absorption of oxygen molecules increases, and the blood viscosity decreases. All this is supplemented by the increase in the concentration of muscle protein (myoglobin) in the cardiac muscle and skeletal muscle. Myoglobin carries oxygen in the zone of lower partial pressure than hemoglobin.

So what are the phases of acclimatization?

First you go up a small height, short-term acclimatization is turned on. In this stage you may feel a minor mountain sickness, headache and dizziness, nausea. Then the body turns on a long-term acclimatization and you adapt to the height. The next day you gain a little more height, and the same processes occur. Usually people climb 800-1000 meters per day, then drop 300-400 meters for an overnight stay. It is not recommended to exceed the height of your overnight camp by more than 1000 meters per day. And if you’re not adapted to the height, then do not climb more than 500-600 meters per day.

To understand if you got used to the height, pay attention to the following things:

• At rest, your heart rate does not exceed the usual urban rhythm
• You have no shortness of breath during rest or easy physical work
• You sleep peacefully at night
• You have a good appetite, you don’t feel sick
• You have a clear mind, give correct answers to simple questions on logic or history, solve simple arithmetic problems (of course if you can do this in the city)

The key factor is the descent to a lower height for an overnight stay. During the day, you climb a new height, expose the body to stress, as it has to adapt to this height. Then you descent a couple of hundred meters for an overnight stay, and at rest the body copes better with this task. The point of such acclimatization schedule is not to fall into a “dead loop” of exhaustion. The body lacks oxygen – the heart beats faster to pump more blood – the heart gets tired and beats slower – the body lacks oxygen, hypoxia and exhaustion begin.

Reacclimatization

On the plain we do not need as much hemoglobin as on the mountain. Therefore, along with the descent, the body gets rid of acclimatization. At this time, disturbances in blood pressure, drowsiness, headache and dizziness are possible. I remember that after Kazbek we went to Batumi. On the first day by the sea, we felt worse than on Kazbek. This was a consequence of a rapid elevation drop. Almost in one day we went down from 4000 meters to 0. The next morning, we already felt better.

High altitude experience

As we’ve already said, with descent to the plain, acclimatization disappears, but the so-called high altitude experience remains. High altitude experience is a memory of our body from a past ascent. With each ascent the high altitude experience increases, and each time the body adapts faster and better and is ready for new undeveloped heights. Therefore, it is not recommended to increase the height of the next peak by more than 1000 meters. But there is no such dogma. Nothing catastrophic will happen if your next mountain is 1600 meters higher.

Also let’s not forget that in addition to the altitude, the geography of the mountain is important, too. For example, a person who climbed Elbrus should in theory calmly climb Aconcagua, because closer to the equator the atmospheric layer is thicker, and the climate is warmer.

High altitude experience can be divided into subconscious and conscious.

Subconscious

These are the processes that happen in the body in order to adapt. An experienced person adapts faster and more efficient. Also, subconscious experience includes emotional stability, stress resistance and comfort zone which expands each time.

Conscious

Conscious experience is the knowledge and experience that a person acquires each time. Knowledge of how to respond to various signals and symptoms of your body, how to better plan your ascent, how to deal with ailments, etc.

High altitude experience is developed slowly, throughout the life with each ascent. Sure we can read smart books and train ourselves with different hypoxic masks or even be in a special altitude chamber, but these synthetic trainings will never replace real experience in the mountains. That’s why it’s called experience.

We would not recommend going to an undeveloped height alone. If you don’t have any experience above 5000 meters, then it’s better to hire a guide, at least for the first time.

Go to the mountains wisely and safely. See you!

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