How does acclimatization work in mountainous areas? Acclimatization. Mountain sickness Altitude of development of mountain sickness

Yesterday I gave a lecture at the MAI Mining School. I hope it will be useful to climbers and mountain tourists, and indeed to all mountain lovers.

Is maximum sportswear really necessary during security checks at the airport or during passport control? Or, perhaps, is it necessary when unloading expeditionary cargo from the vehicle at the beginning of the route? Of course not. You will need your maximum ability to withstand physical activity not at the beginning of a mountain sports event, but in its culminating phase, for example, during the days of the assault on the most important or most difficult peak.

The following figure shows a typical fitness versus time curve for a mountain sports event. This is not just a typical curve, it is a desired curve, because the implemented graphs may look more pessimistic. In this graph we see the growth of physical fitness to its maximum state in the middle of a mountain sports event and degradation towards its end due to exhaustion and accumulated fatigue.

Rice. 1. Typical fitness curve in a mountain sports event.

But this “training” may not take place, because in the mountains you will be under the influence of destabilizing factors that work to make you sick and, on the contrary, to degrade your form to zero.

2. Destabilizing factors. Destabilizing factors include: altitude, solar radiation, physical overload, hypothermia, dehydration, poor nutrition, poor hygiene, microorganisms brought from the city and local microorganisms.

Rice. 2. Destabilizing factors that impede the growth of sports form.

As for germs and viruses, you bring some of them in your body from cities. And they really want to multiply in your body. And the other part is made up of local microorganisms. Most often, these are various types of intestinal infections that can be picked up on the way to the mountains, or even in the mountains through water from mountain animals.

So, all these, as we say, destabilizing factors, work against the growth of physical fitness. Under their influence, it is easy to bend and not become physically stronger.

3. Fitness, experience and health. So how do you ensure a good alpha angle?

This angle depends on your experience, your organization and, if you like, your wisdom. And it very much depends on the amount of health (vitality) at the beginning of a mountain sports event.

As is known, and this has been published in many sources, peak athletic fitness does not correspond to maximum health. Athletes at the peak of their athletic performance, in particular, have reduced immunity. Therefore, the peak of sports form at the beginning of the event can result in its rapid degradation in the mountains under the influence of destabilizing factors. These are curves 2, 3 and 4 in Figure 3.

Rice. 3. Different types of sports form graphs in a mountain sports event.

To realize this wish, in the last month before leaving for the mountains, you should switch to a special regime of training and life in general.

4. Routine before going to the mountains. In order to increase the alpha angle in the last month before going to the mountains you need to:

1. Stop building up your fitness and switch to stabilizing training.

2. Refuse to participate in sports competitions.

3. Avoid stress.

4. Avoid emergency situations at work.

5. Don’t fall in love to the point of rut.

6. Get enough sleep.

7. Eat regularly and efficiently.

8. Don't overeat during the holidays.

9. Don't get drunk.

10. Cure teeth and other indolent diseases.

Now look at yourself, what are you doing in the last month before leaving for the mountains?

Obviously, this program may not be feasible for you. But it clearly shows, at least, what we should strive for. Now you have a choice. Either you seriously intend to achieve high results in the mountains, or you prefer to fall in love until the rut, which is perhaps no less valuable acquisition.

5. Effective, safe and non-debilitating acclimatization. Now let's move on to the question of how to resist the most important destabilizing factor - height. The following recommendations were developed based on the experience of managing teams (teams) from 1982 to 2009. During this time, I taught dozens of people how to climb at high altitude, and simply led hundreds of people through the stages of acclimatization. These recommendations do not apply to people with a special constitution, whose names and surnames are widely known. However, my experience is valuable because the conclusions derived from it are good for real teams. And in real teams there will always be weak links who, for example, did not manage to spend the last month correctly before leaving for the mountains. And these recommendations are good for everyone. When it comes to standing up to heights, you should not strive to become a superman. After all, none of the famous supermen have yet had their brains examined, as Vladimir Ilyich Lenin was done after his death.

By the way, the widespread belief that brain cells die at altitude is very superficial. Brain cells do not die from the realization that you are at a high altitude. They die from mountain sickness, in other words, from acute oxygen starvation. And this oxygen starvation is largely connected not with altitude, but with your behavior. Nothing prevents us from organizing a more intense extinction of brain cells at an altitude of 4000 m than at an altitude of 7000 m. To do this, just take the train, arrive in Nalchik in the morning, then take a taxi to Terskol, then climb the Shelter of Eleven and the rest of the day and all that follows spend the night at this shelter. I assure you, in this situation, you will die more brain cells than when climbing a seven-thousander, taking into account all my subsequent recommendations.

In earlier texts on this topic, I wrote about effective and safe acclimatization. At the same time, in the concept of efficiency, I included the speed of the adaptation process and its reliability, in the sense that you are confidently acclimatized and will feel good at altitude. And by safety I meant the low probability of getting acute mountain sickness during the acclimatization process. Now, taking into account everything that I have said about sports form, it is advisable to add that we are also interested in acclimatization that does not weaken the body. In other words, proper acclimatization should give you strength at altitude. Or, if you want, keep the alpha angle large for a long time.

So I want to separate the two cases. In the first case, a person, being at 7000 m, feels well, does not suffer from altitude sickness, but at the same time he is tired and weak to perform much physical work. And in the second case, a person at 7000 m is full of strength.

Now we will say that we need effective, safe acclimatization that does not weaken the body.

6. Mountain sickness. The higher the altitude above sea level, the lower the air pressure. Accordingly, the pressure of that part of the air called oxygen is lower. This means that oxygen molecules are less common, and they no longer hit any surface as often, and in particular lung tissue. Therefore, they bind less intensively to hemoglobin in the blood. The oxygen concentration in the blood drops. Insufficient oxygen in the blood is called oxygen starvation or hypoxia. Hypoxia leads to the development of mountain sickness.

We list the typical manifestations of mountain sickness, ordered by severity of the disease. At each new stage of development of mountain sickness, its previous manifestations at earlier stages, as a rule, are not excluded, but only aggravated.

1. Increased heart rate.

2. Shortness of breath on exertion.

3. Headache.

4. An excited state, which can be replaced by apathy to what is happening. Cheyne-Stokes breathing (periodic spontaneous deep breaths). Difficult transition to sleep. Restless sleep. Decreased performance.

5. Weakness. Nausea and vomiting. Increase in body temperature by 1-2 degrees.

6. Development of pulmonary edema or cerebral edema.

7. Coma and death.

The main treatment for acute mountain sickness is immediate descent.

Acclimatization, or more correctly, altitude adaptation is impossible without altitude sickness. Moreover, mild forms of mountain sickness involve mechanisms of body restructuring. But safe acclimatization should be accompanied by the first and second conditions and rarely by the third. And getting into the fourth state is already dangerous.

There are two phases of altitude adaptation based on the depth of changes in the body.

7. Short-term altitude adaptation. Short-term altitude adaptation is a quick response of the body to hypoxia. The mechanisms of such a response are activated “on the spot.” The body's first reaction is the mobilization of oxygen transport systems. The breathing rate and heart rate increase. There is a rapid release of hemoglobin-containing red blood cells from the spleen.

Blood is redistributed in the body. Cerebral blood flow increases because brain tissue consumes many times more oxygen than muscle tissue. This leads, by the way, to headaches.

At this stage of acclimatization, a poor supply of circulating blood to other organs disrupts the body’s thermoregulation and increases sensitivity to cold influences and infectious diseases.

Short-term adaptation mechanisms can only be effective for a short time. The increased load on the heart and respiratory muscles requires additional energy consumption, that is, it increases oxygen demand. Thus, a positive feedback effect or “vicious circle” occurs, which leads to the degradation of the body. In addition, due to intensive breathing, carbon dioxide is intensively removed from the body. A drop in its concentration in arterial blood leads to weakening of breathing, since carbon dioxide is the main stimulator of the respiratory reflex. This is a second additional mechanism that aggravates degradation.

Thus, in the short-term adaptation phase, the body works for wear and tear. Therefore, if the transition to the second phase - to long-term high-altitude adaptation is delayed, then acute forms of mountain sickness develop.

8. Long-term altitude adaptation. This is a profound change in the body. This is exactly what we want to get as a result of acclimatization.

In contrast to short-term adaptation, this phase is characterized by a shift in the main field of activity from transport mechanisms to oxygen utilization mechanisms, to increasing the efficiency of using the resources available to the body. Long-term adaptation is already structural changes in the body in the systems of transport, regulation and energy supply, which increases the potential of these systems. Conventionally, the nature of structural changes can be represented as follows:

Tab. 1. Restructuring of the body in the phase of long-term adaptation.

The blood system undergoes a complex of changes. The number of red blood cells and the content of hemoglobin in them increases, increasing the oxygen capacity of the blood.

In addition to the usual adult hemoglobin, embryonic hemoglobin appears, capable of attaching oxygen at a lower partial pressure. Young red blood cells have a higher level of energy metabolism. And young red blood cells themselves have a slightly changed structure; their diameter is smaller, making it easier to pass through the capillaries. This reduces blood viscosity and improves its circulation in the body. Reducing blood viscosity also reduces the risk of blood clots.

The increase in the oxygen capacity of the blood is complemented by an increase in the concentration in the myocardium and skeletal muscles of muscle protein - myoglobin, which is capable of carrying oxygen in a zone of lower partial pressure than hemoglobin. An increase in the power of glycolysis in all tissues during long-term adaptation to hypoxia is energetically justified and requires less oxygen. Therefore, the activity of enzymes that break down glucose and glycogen begins to increase, new isoforms of enzymes appear that are more suitable for anaerobic conditions, and glycogen reserves increase.

At this stage of acclimatization, the efficiency of the functioning of tissues and organs increases, which is achieved by an increase in the number of mitochondria per unit of myocardial mass, an increase in the activity of mitochondrial enzymes and the rate of phosphorylation and, as a consequence, a greater yield of ATP at the same level of oxygen consumption. As a result, the heart's ability to extract and use oxygen from flowing blood at low concentrations increases. This allows you to ease the load on transport systems - the respiratory and heart rate decreases, and the cardiac output decreases.

With prolonged exposure to high-altitude hypoxia, RNA synthesis is activated in various parts of the nervous system and, in particular, in the respiratory center, which makes it possible to enhance breathing at low concentrations of carbon dioxide in the blood, and improves coordination of breathing and blood circulation.

9. Gradual and stepwise acclimatization. We can now describe the step-by-step process of acclimatization through two phases of altitude adaptation. You rise to heights. There is not enough oxygen, and short-term adaptation mechanisms are activated. Outwardly, this manifests itself as mild mountain sickness. After some time, long-term adaptation mechanisms are activated and the symptoms of mountain sickness disappear. The height has been mastered.

Now you can rise to even greater heights. There is not enough oxygen again, and short-term adaptation mechanisms are activated again. Increased heart rate, mild shortness of breath, possible headache. And again, after some time, further structural restructuring of the body takes place, and the symptoms of mountain sickness disappear. The height is mastered again, etc.

The result of the structural restructuring of the body in the long-term adaptation phase can be assessed by the maximum height H a, at which the heart rate does not exceed the usual values ​​for the plain, say, 70 beats per minute.

Now the described process of step-by-step acclimatization can be conventionally displayed in the form of a graph, see Fig. 4

Rice. 4. The process of gradual acclimatization.

The blue line on the graph is the height H a at which the heart rate does not exceed the usual values ​​for the plain; this line characterizes the result of the structural restructuring of the body.

The yellow-colored area between these graphs characterizes the amount of load that the body receives under the influence of hypoxia. The larger the yellow area, the more the body weakens, the worse for the growth of athletic form.

Three gamma angles characterize the intensity of the long-term adaptation process. These angles decrease because the athlete’s body gets tired from the effects of hypoxia, from a long stay at an ever-increasing altitude. A large and long-lasting yellow area after the third ascent characterizes the risk of getting mountain sickness with serious consequences.

Thus, if you only go up all the time, then the body gets tired and exhausted. As a result, the restructuring of the body takes place less and less intensively.

This is a very bad way to acclimatize. Much more effective is stepwise acclimatization, which involves a sequence of ascents and descents with ascents each time to higher and higher altitudes. It is important that between these rises there are intervals of recovery at low altitudes. These recovery intervals allow the body to accumulate strength, due to which the mechanisms of long-term adaptation will take place more intensively.

An altitude graph is usually called a line reflecting the life of an individual or group in the mountains, which is drawn in the T [time] and H [altitude] axes. So, the altitude graph during stepwise acclimatization has a sawtooth shape. We will call each tooth an exit to the highlands, and the depressions between the teeth will be called restoration intervals. The lower the height of the recovery intervals, the better. At altitudes above 5000 meters, the body’s recovery practically does not occur.

Acclimatization must be planned. The most important part of such planning is the construction of the desired altitude schedule. When constructing altitude graphs, we will operate with the altitude of overnight stays and obey two rules (rules of 500 and 1000 meters):

1. At an undeveloped height, you should not rise more than 500 meters per day from overnight stay to overnight stay.

2. The altitude of overnight stays in the next trip to the highlands should not exceed the maximum altitude of overnight stays in previous trips by more than 1000 meters.

The first rule limits the yellow area by limiting the height of the riser step. And the second rule regulates the recovery process and guarantees large values ​​of the gamma angle, excluding the situation shown in Fig. 4 after rising to height H3.

Now let’s build a high-altitude climbing schedule for a team of climbers who arrived at an altitude of 3200 and rest in the base camp at an altitude of 4200. When constructing the schedule, we will not take into account restrictions from the relief and will add only one day of rest between climbs for recovery (this is not at all a lot ).

Rice. 5. Stepped acclimatization according to the rules of 500 and 1000 meters.

Of course, rules 1 and 2 are to a certain extent arbitrary and replacing the numbers 500 and 1000 with 600 and 1200 will not lead to much trouble. But a gross violation of these rules risks disrupting the acclimatization of the weakest link in your team.

By the way, the transition to the standards of 600 and 1200 does not bring much acceleration, reducing the 19-day program to 18 days.

Rice. 6. Stepped acclimatization according to the rules of 600 and 1200 meters.

10. Night is the moment of truth. When mountain sickness occurs, a person is most vulnerable at night. At night, he relaxes, mobilization on the part of the nervous system disappears, and the tone that is maintained through volitional efforts disappears. At the same time, self-monitoring of the participant’s condition and monitoring of his condition by teammates ceases.

If a positive feedback (vicious circle) occurs, for example, of this nature - the heart weakens because it lacks oxygen, it pumps blood weaker and weaker, and from this the oxygen deficiency increases even more. So, if such a vicious circle occurs, a person can degrade overnight to complete morning incapacity or death.

At the same time, a successful overnight stay at altitude allows you to adapt to this altitude to the greatest extent. Therefore, night is the moment of truth.

A very good indicator is heart rate. The evening pulse can be quite significant and exceed 100 beats per minute in mild forms of mountain sickness. But the morning heart rate should drop to 80-90 beats per minute. If the morning pulse exceeds 105 beats per minute, this means that the person has not mastered the altitude overnight and must be escorted down. Further ascent from the overnight stay upwards at such a morning pulse is very likely to lead to severe mountain sickness and the group will only waste time descending the victim from an even higher altitude.

It is necessary to properly prepare for bed. Sleep must be sound.
First of all, you can't tolerate a headache. It is especially typical when the head hurts in the evening after completing the daily plan. This is explained by the fact that muscle work during physical activity stimulates intense work of the lungs and heart. Since a person has two circles of blood circulation, blood is automatically pumped through the brain by the same contractions of the heart. And the brain does not experience oxygen starvation. And in the evening in a tent with little physical activity, oxygen starvation of the brain develops.

So, it has been noticed that headaches destabilize the body. If you tolerate it, it will only intensify, and your overall health will continue to deteriorate. Therefore, if you have a headache, you must immediately take the pills. This is citromon 500 or even 1000 mg. Soluble solpadeine has an even stronger effect, which not only relieves headaches, but also relieves the general state of inflammation or, as it were, “restlessness” in the body. If you have a fever, it will relieve that temperature too.

It is in this normalized state that you should approach sleep. Naturally, you should not get drunk on coffee. Make sure that the tent is well ventilated so that you do not burn out oxygen at night, exacerbating oxygen starvation. Before going to bed, coat your lips with sunscreen (it contains ingredients necessary for the skin) or special lipstick. And put a layer of onions saved from dinner behind your cheek. Keeping onions in your mouth for a long time will protect you from the proliferation of microbes in the mouth and throat. If you have a runny nose, put a star under your nose, but I even like to put it in my nostrils. All the things you need to go to sleep should be in your personal box near your head. There should also be a flashlight nearby.

Now the next typical phenomenon. You can't sleep. This is very bad. Try to relax while listening to the player. If you have already lost an hour of sleep, then you need to use the tablets immediately. I love diphenhydramine. It not only has the effect of a sleeping pill, but is an antihistamine and relieves inflammation in the body. Sometimes you have to take two tablets.

A typical mistake is to suffer from insomnia. Some people say that sleeping pills will make them groggy in the morning. As a result, they do not get enough sleep, and this makes them even more lethargic than from sleeping pills. But the worst thing is that they do not spend the night effectively in terms of long-term altitude adaptation (small gamma angle). A sleepless night is very dangerous for the development of altitude sickness.

In 2005, Yu.M. When I first reached 5500 I couldn’t fall asleep. He said that he was bothered by the wind and the flapping of the tent. In fact, he had altitude sickness. For some reason, spending the night at 5250 on the previous trip to altitude did not restructure his body properly. He refused to take the pills. In the morning he was lethargic, but efficient. We continued to climb and stood around lunch at an altitude of 5900 so that Yu.M. I was able to rest and sleep for half a day.

The next day he woke up lethargic again. On the climb he was already 200-300 meters behind. He complained that his legs couldn’t move, but otherwise “everything is fine.” We spent the night on the top of Kyzylsel at an altitude of 6525 meters. I was very afraid that he would deteriorate overnight and we would have to save him. However, everything worked out well, and we completed the traverse, descending from the top along another ridge. Even below, after this traverse, he felt an absolute lack of strength and went home.

I'm 90 percent sure that a couple of diphenhydramine tablets taken in the evening at 5500 would have absolutely changed the course of events.

So, the overnight stay is the moment of truth. It’s good when the overnight stay is lower than the maximum altitude of the previous day, at least 300-400 meters. The same Yu.M., being an experienced high-altitude climber, likes to take a walk in the evening, gaining at least 200 meters above the tent (if the terrain allows it).

11. Mistakes and tragedies. Now let's plot some real events. The red line, as before, reflects acclimatization according to the 500 and 1000 m rules.

Rice. 12. Erroneous altitude charts of real expeditions.

Then there was an acclimatization trip. The height is not indicated, but it is written like this:

"...We went on our first acclimatization hike on August 8. There was a lot of snow on the glacier and, especially, on the ridge. Where last year we climbed almost 1000 m in one day, we walked a maximum of 200 m, raking the trench in front of us with avalanche shovels And the snow kept falling and falling... On August 13, all groups returned to base camp..."

Based on this text, I drew a climb to 5200. Then the climbers spent 5 days in the base camp and began climbing to the top. The ascent took place on the 8th day of this high-altitude climb. As you can see, the 1000-meter rule was violated - after reaching 5200, the climbers immediately went to 7400.

Morning of the 9th day of release. Height is about 7300 meters.

"...We get ready slowly. We help I. get dressed, and he is the first to get out of the tent to bask in the sun. After 15 minutes, D comes out. He called out to I., but he does not respond. He sits on a rocky ledge and seems to be sleeping. We all jump out of the tent, and it becomes clear to us that this is not a dream, but the quiet death of our wonderful comrade..."

This is such night degradation! Then, on the descent from the summit, two more exhausted climbers fall off and die.

Guess what famous tragedy I wrote about?

Second, purple graph. On the graph we see very sharp and bold climbs in acclimatization trips, between which the team recovers for 3-4 days. And this is no wonder. Overcoming altitude sickness wears down the body.

The training process is slowed down. At altitude, due to excessively severe mountain sickness, strength is depleted, training does not occur, and at the bottom, climbers sit in the base camp for several days, and training again does not occur.

After going out to 6400 with an overnight stay in the area of ​​6000 meters, we immediately go out to 7700. This is a bit abrupt. The 1000 meter rule was violated.

As a result of mistakes made, the speed on the day of the assault is extremely slow. Instead of returning to the assault camp at 7200 at 3 pm, the climbers return late at night. One of them falls from an ice break in the dark and injures his hand. Another comes in such a debilitating condition that he cannot come down the next day. Then the climbers arrange a day at an altitude of 7200 m. On this critical day, with a 50/50 probability, the exhausted participant could die or recover. As a result of a heroic struggle for his condition, using all his enormous high-altitude experience, he manages to stabilize his condition, and over the next two days the climbers descend safely to base camp.

And this is about a very recent story.

12. Driving to high altitudes. Starting acclimatization at an altitude of more than 4000 meters leads to wear and tear on the body. Such acclimatization does not give strength later. All subsequent stages at high altitudes will also occur sluggishly. And the already acclimatized team will work with low power, still sluggishly.

Therefore, if you want to be strong at high altitudes, do not skip the acclimatization stage at an altitude of 3200-3700 meters.

13. Containment. The point of the 500 and 1000 meter rules is containment. It is containment that is the main leitmotif of effective, safe and non-debilitating acclimatization. You should not get ahead of the pace of body restructuring in the long-term adaptation phase. Phases of mountain sickness from the 4th onwards weaken the body and hinder the growth of athletic fitness. Don't tear your claws, and you will have great athletic shape, and everything will be easy and safe for you.

Containment does not only refer to the construction of desired altitude schedules and their implementation. The leitmotif of deterrence permeates everything and, in particular, the behavior of each participant in a mountain sports event.

You trained all year, competed in all sorts of running and skiing competitions, and took part in marathons. You are a lifelong athlete. But as soon as you arrive in the mountains, you should forget about your sportiness.

In the first days, I categorically do not recommend straining. And I want it so bad! Finally, the long-awaited season has begun, alpine meadows are illuminated by the morning sun, high snow-white mountains are in the distance! Ahead on the path there is a 10-meter rise. How great it is to lightly grit your teeth and playfully fly up onto it with your strength, especially since then the path is flat and you can catch your breath. Don't do this, control yourself. All those little tears tend to add up and you'll get too tired. But you are gaining altitude, and at night you have to overcome the load from hypoxia, from the yellow spot in Figure 4.

At night, your tired heart will beat faster, pumping oxygen-depleted blood. It will get more and more tired. Now there is not enough oxygen even for its effective operation. The heart weakens, oxygen becomes even less, the heart weakens more and more - a vicious circle! In the morning, nausea, vomiting, blue lips, weak and rapid pulse. Instead of continuing the hike, the group goes down. It’s good if it walks, worse if it carries.

What happened to your luckier friend that night? He, too, began to develop this destructive process, but its pace was slower, since he was much less tired during the day. At the same time, a revolution began in his body. The metabolism changed, hemoglobin and hundreds of other necessary and still unstudied compounds began to be produced at an accelerated pace. The oxygen concentration in the blood increased. The heart began to beat calmer, it could finally rest. In the morning, my friend woke up cheerful with a moderate pulse - 86 beats per minute.

This kind of restructuring began for you too, but you didn’t have time to help. It's all about the speed of both processes. The rate of degradation must be less than the rate of adaptation.

When I was still young, my uncle, the USSR champion in the high-altitude class, taught me this: “When you go uphill with a backpack, your heart rate is inevitably high. But walk in such a way that your breathing does not falter, so that your breathing is calm and uniform.” And this should be applied to the weakest link of the team. Otherwise, what is the point of your successful personal acclimatization if you have to waste time, weakening the movement schedule, taking unplanned days or rollbacks with the descent of a sick participant downstairs.

Since we’re talking about the first days in the mountains, I’ll give you altitude graphs before the first climb to 6000, implemented by my teams over the past three years. And next to it there are three more schedules, the implementation of which led to negative consequences. All these graphs are built taking into account the race, since acclimatization also takes place during the race. Long rides in the high Asian mountains explain the apparent effect that in Asia the heights are tolerated “easier” than in the Caucasus.

Actually this is not true. There is no such harmful gas "Caucasin" and oxygen substitute "Asian". The composition of the atmosphere is the same. As for humidity, which is often cited to explain this apparent effect, when precipitation condenses, the humidity is the same everywhere and is close to 100%. Therefore, drizzling rain or wet snow in the Pamiir occurs in the same humid air as drizzling rain or wet snow in the Caucasus. And everything becomes completely the same, but the Caucasus and Asia do not exist. Well, of course, there are more sunny days in the Pamirs, but I have never noticed that when the weather suddenly deteriorates, the manifestations of altitude sickness get any noticeably worse.

So let's move on to the charts.

A sharp peak of up to 4700 on the 4th day of acclimatization in 2008 was achieved without backpacks in a radial climb to the peak of 4713. With overnight stays on these days, everything was divine.

Colors close to red reflect graphs with unfavorable consequences.

Raspberry chart 2003 An experienced high-altitude climber, having several ascents of seven-thousanders behind him, including Pobeda (7439), arrives at an altitude of 3600 m on the first day. The next day he climbs to the base camp at an altitude of 4600 m. He spends another day at base camp, and only in the evening he begins to develop altitude sickness so severe that he almost dies. Fortunately, in a state of “near death”, they manage to transport him down.

Red schedule 2007 A group of tourists drove to an altitude of 3500 meters and on the same day rose to 3750. The next day they passed a simple pass with an altitude of 4200 m and spent the night at 3750. On the third day of acclimatization, they spent the night at 4300 m. And on the fourth day they crossed pass 3A altitude 4800 m, after which we spent the night at 4400. In the morning, cerebral edema was diagnosed in one of the participants.

Here's what they write about his condition: "...Symptoms: inadequate, unstable, severely inhibited, cannot walk independently, without assistance, attention quickly depletes, makes mistakes when performing simple tasks...". After this, rescue operations were organized using a helicopter.

Orange schedule 2009 For two days, tourists traveled to the Pamirs and drove to an altitude of 4400 m. Over the next 3 days, they crossed a pass at an altitude of 5200 meters. How many people vomited and how often - I have no data about this. After the pass, many in the group had a temperature of 38-40.

With some delay, as in the case of 2003, at an altitude of 4100 m, the participant in the hike became especially ill. At night she experiences weakness, fever and shortness of breath (while lying down). Then tourists arrange a day trip, during which the patient’s condition stabilizes.

The victim was very lucky that she was able to stabilize her condition at an altitude of 4100 m. If her condition had required a drop in altitude, say, to 3300 meters, she would have died. Because there was nowhere to drop the altitude. The height of 4100 corresponded to the bottom of the huge valley of the Eastern Pamirs.

14. Be careful, athlete! But look at an excellent athlete, a first-class skier. He remained cheerful when everyone else was sick at 3900. But what was happening? At an altitude of 4500, when all the recovered participants felt quite tolerable, he began to lag behind. And the higher, the more
stronger. After spending the night at 4800 he has nausea, vomiting, a pale face, blue nails - it’s time for him to go down.

The fact is that his powerful heart responded to the challenge of 3900 in the usual way for an athlete - a high pulse. Athletes can endure high-pulse work for a very long time. This is business as usual for them. Therefore, the restructuring in his body did not begin.

Just, for God's sake, don't get me wrong, I'm not at all urging you to quit all training. You need to train. First, to be broadly healthy. Then the adaptation mechanism will better turn on. And only, secondly, to be powerful in order to quickly, quickly hang the rope at 5800 under a threatening ice break.

But on grass at the very beginning of a mountain sports event, the athlete does not have a noticeable advantage, moreover, he is at risk. After all, everything happened because neither he, nor the leader, nor the group paid attention to his special story: “So healthy - what will happen to him? So..., some kind of malaise.”

Of course, this does not apply to those who already have solid high-altitude experience. And this is because one of the main components of high-altitude experience is a quick reaction to the first signs of lack of oxygen, to the sight of snow-white peaks, to the smell of wormwood, finally! The mechanism of long-term adaptation is activated clearly, to the fullest, and does not depend on whether the first days in the mountains are easy or difficult to bear.

If you like, it's a conditioned reflex. Pavlov taught dogs to secrete gastric juice when the bell rang. So why can’t an experienced high-altitude climber learn to produce hemoglobin immediately upon arrival in Osh, from the Asian heat, from the crowd at the market, from the anticipation of a quick trip to his favorite mountains?

I know that my altitude sickness is already kicking in in Osh or Kashgar. I feel it.

15. Reacclimatization. After returning from the mountains, acclimatization disappears as quickly as it appeared. The body does not need an excess of oxygen. It is harmful. Hence the feeling of poor health in the first days of city life after descending from a high altitude. After 10 days, your hemoglobin will drop to normal levels and you will feel better. Therefore, May trips to Elbrus are absolutely useless for the summer in terms of acclimatization. But they are useful for gaining high altitude experience.

However, why May? Winter ascents are no less useful for high-altitude experience.

In general, the rapid loss of acclimatization is often forgotten, and this becomes the cause of many tragedies. MAI climbers probably remember the consequences of being imprisoned in Dushanbe between the peaks of Korzhenevskaya and Communism in 2007. This did not lead to tragedy. But the imprisonment of the May mountaineer Valentin Suloev in the Alai Valley between the peaks of Lenin and Communism may have become one of the main reasons for his death at an altitude of 6900 meters in 1968. At the peak of Communism he also fell ill, and these two factors, acting together, ensured him night degradation. Now, if he had gotten sick, being perfectly acclimatized, he would not have died.

A similar story happened with the famous “Himalayan” Vladimir Bashkirov. Before climbing Lhotse, he took a break and spent a significant amount of time in the city of Kathmandu after his previous ascent. On the descent from Lhotse he died.

16. High altitude experience. High-altitude experience is a person’s ability to adapt to high mountains, acquired as a result of repeated trips to the mountains in the past. High altitude experience has subconscious and conscious components.

The subconscious component of high-altitude experience includes the body’s memory of triggering adaptive reactions at altitude. The body of an experienced person carries out the acclimatization process faster and more efficiently. The subconscious component also includes unconscious stereotypes of correct behavior at heights.

The conscious component of high-altitude experience includes the knowledge acquired by a person about the reaction of his body to altitude, about how to carry out acclimatization more gently, about the inadmissibility of overload during the acclimatization process, about individual symptoms that precede the exacerbation of not only mountain sickness, but also other diseases typical for an individual , for example, sore throat, bronchitis, furunculosis, hemorrhoids, gastritis.

Thanks to conscious high-altitude experience, the climber monitors the condition of his body and takes measures to prevent the development of diseases at altitude.

When planning climbs to peaks and passes, it is necessary to take into account the high-altitude experience of the event participants. For example, in the rules for conducting sports mountain hikes, a participant is not recommended to exceed his altitude experience by more than 1000 or 1200 meters (this threshold was set differently in different years).

It is more consistent, however, to limit the height of overnight stays to such a threshold. For example, after climbing Elbrus from “barrels” or from the Shelter of the Eleven, in the next event do not plan overnight stays above 4000 + 1200 = 5200 m.

High altitude experience is acquired slowly over several years. But it lasts for a long time. The loss of two or three seasons for already acquired high-altitude experience is not critical. For example, after climbing Aklangam (7004) in 2002, I had a break. In 2003, I only climbed up to 5975 m. And in 2004, I broke my leg and managed to visit 5000 m only once. This did not stop me from carrying out a magnificent hike in 2005 with a traverse of three peaks with heights of 6525, 6858 and 7546 meters. And I felt great there.

This lecture is intended to help increase your high-altitude experience, I mean its conscious component.

Additional literature.

3. A.A. Lebedev.

For fans of the scientific approach, I can also recommend this book. It was published in large numbers and is available in many libraries.

Contains several sections dedicated to preparation for Everest-82

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Ilya, thanks for the useful additions.

So I did a little research. Source data taken from
table kindly suggested by Comandante

That's why weak Caucasus and Asian exist :-))

But the physiological effect, I’m sure, is explained by the acclimatizing effect of long rides. This influence is much stronger.

The key to a successful climb to the top is proper acclimatization of the body. The nature of the high mountains is harsh and merciless; anyone, even a physically very strong person, can be affected by mountain sickness, the outcome of which can be anything... In order to prevent an accident in the mountains and to be confident in one’s abilities, acclimatization must be completed.

Acclimatization is the physiological adaptation to a new environment or situation. Acclimatization in mountainous areas is one of the common phenomena. The main factors that negatively affect the body in mountainous areas are a decrease in the concentration of oxygen in the air and low barometric pressure, as well as the high intensity of ultraviolet radiation from the sun. During adaptation to these conditions, there is an increase in hemoglobin content and the number of red blood cells and blood, a slowdown in the speed of blood flow, increased pulmonary ventilation, an increase in cardiac output and a more economical expenditure of energy resources.

Acclimatization, symptoms

Unfortunately, many monstrous stories have survived to this day when strong, physically fit people died from the effects of altitude sickness, the so-called “miner’s disease.” Mountain sickness, as a consequence of improper acclimatization above 2000 meters above sea level, has the following symptoms, which you should immediately stop and contact your ascent leader:

dizziness;

• acute headache;
• noise in ears;
• drowsiness;
• darkening of the eyes, temporary blindness;
• violations of correct distance assessment;
• pain in various parts of the body;
• shortness of breath, feeling of suffocation, chest tightness, hemoptysis;
• pulmonary hemorrhage;
• heavy sweating;
• chills (fever);
• increased urination;
• pale face, blue lips;
• nausea, abdominal pain, vomiting, intestinal upset;
• fainting.

Most often, these symptoms result in cerebral edema or pulmonary edema, the outcome of which is often fatal.

To avoid all these terrible situations, you need to seriously prepare for the climb in terms of acclimatization. At altitudes of 1500-2500 meters, the likelihood of altitude sickness is low, but physiological changes can already be observed. At 2500-3500 altitude sickness develops with rapid ascent. Above 3500 meters, a significant decrease in the concentration of oxygen in the blood during exercise begins, and the likelihood of altitude sickness is high.

Acclimatization tactics in the mountains

The level of training and experience of tourists and climbers is so great that it is not possible to propose any universal scheme. Climbers can afford to use in its pure form a very effective method of “stepped” acclimatization, or as it is called in Western Europe, the “saw teeth” method, in which climbers make acclimatization trips, organizing intermediate camps and again descending to the base camp for 2-4 day. When climbing upward, fatigue accumulates in the body and performance decreases. To recover, the altitude is reset, descending to base camp. The greater the load a climber performs, the longer the period given to him for recovery. A simple conclusion follows from this: tourists’ daily loads should completely eliminate overload. Of course, proper rest and days off are extremely important. During the day, it is necessary, if possible, to adhere to one of the most important rules of mountaineering: “ Work high - sleep low»

Some people quickly adapt to altitude, others have a very difficult time, it all depends on the individual characteristics of the body. Gaining altitude in the mountains must be done with great caution, especially for older people. Before a large climb, it is recommended to make an acclimatization trip, and then, after descending, rest and spend the night. A person does not always feel the changes that occur during such a maneuver, but at this moment the body is just going through the stage of adaptation: the heart, lungs, brain - all this adapts to the work of the body at a new height. Only with good acclimatization can you be confident in the success of the ascent and safe return. Neglect can cost the climber the most precious thing - his own life.

Why is acclimatization in the mountains so important? Why are so many articles devoted to this concept?

To understand this, just look at the statistics of ascents to Elbrus. It is clear that the two main factors here are the weather and the body’s adaptation to altitude (acclimatization). In almost half of the cases of unsuccessful ascents, insufficient acclimatization in the mountains plays a role, and if this factor is eliminated, then the chances of climbing to the top will increase significantly.

It is precisely because of the need to get used to the altitude that all tours are extended in time; if this were not necessary, then to climb Kazbek, for example, it would take three days.

Most often, those who come to the mountains either ignore this moment (“Why do we walk here when we can go to the top”), or concentrate too much on it, begin to worry and doubt (“Will I get used to the height?”, “Will I be able to?” am I?"). Both options are not suitable for us. If you decide to approach the acclimatization process competently, then you need to follow a long-established and tested method. It works no matter where you come to climb, at 5000 meters or 7000.

What is acclimatization?

In general, these are adaptive-compensatory reactions of the body, as a result of which good general condition, normal performance and the normal course of psychological processes are maintained.

When the body adapts to a lack of oxygen (this is called hypoxia), it strives first of all to maintain the proper level of oxygen supply to the central nervous system (our brain), this occurs by reducing the supply to other, less important organs. Initially, the human body reacts to a lack of oxygen by breathing deeper, and then by increasing the frequency of breaths. People have different thresholds of sensitivity and tolerance to reduced oxygen consumption and can vary widely. Up to an altitude of approximately 2000 m, most people do not experience any signs of hypoxia. Starting from an altitude of 2000m and above, the body's adaptive reactions begin to appear more clearly. As a result of a lack of oxygen, the number of red blood cells (oxygen transporters) and the amount of hemoglobin in them begins to increase in the blood. All this leads to an increase in the oxygen capacity of the blood, that is, the quantitative parameters of the blood and the ability to supply oxygen to the body’s tissues increase. The number of red blood cells and hemoglobin content are usually higher if the ascent is accompanied by intense muscle work, that is, when the process of adaptation to altitude is active.

The period of partial acclimatization can be shortened if in advance, several months before going to the mountains, you start regular general physical training classes, paying more attention to endurance work: long-distance running (at least 40 minutes in time), swimming, skiing. Proper nutrition plays an important role in accelerating the acclimatization process. At altitude, the body needs more carbohydrates (10-15%) and twice as many vitamins. It must be said that after the mountains, in the conditions of the plain, the acquired changes in the body pass quite quickly. For example, the amount of hemoglobin decreases to normal in 2-2.5 months. That is, the body’s adaptation to altitude lasts for about three months. If trips to the mountains are repeated, then a “memory” appears in the body to adapt to altitude, the so-called high-altitude experience appears. Therefore, the next time you go to the mountains, the body quickly acclimatizes and adapts to the lack of oxygen.

What we can do?

The basic principles that should be followed for successful acclimatization of the body:

1) You have arrived in the mountains, if this is the Caucasus, most likely at an altitude of 2000 meters above sea level. We don’t run, we don’t jump, but we don’t lie down either. You need to take a light walk, explore the beautiful mountainous area and not overload your body.
The next days in the mountains will be entirely devoted to adaptation. First, a small climb and overnight. It is important to spend the night at an altitude; it is more effective than climbing to 3000 meters and then descending to spend the night at 2000. The optimal altitude for the first overnight stay should be no higher than 600-700 meters from the previous one. Next, there is a smooth ascent with overnight stays, adhering to the principle of a difference in overnight stays of 600-700 meters in altitude.

2) During acclimatization, it is important to do physical work, this is precisely what a problem often arises with. The group climbed on the third day to an altitude of 3400 and everyone was lying tired from the trek with backpacks. There is no need to lie down for a long time, rest can be 30 minutes, and then you need to get up and move. Prepare your tent, walk to the stream for water, walk up and take a few pictures with your camera. Movement at altitude is necessary; it helps the body quickly get used to difficult conditions. Yes, it is difficult to force yourself to work, but it is necessary. The ideal option is to set up camp and climb 300 meters higher, lightly, this will help you sleep better.

3) The importance of good nutrition when adapting to altitude is obvious. A week before a trip to the mountains and while staying at altitude, it is recommended to take multivitamins. No matter how hard climbers try to maintain the required diet, some foods cannot be carried with them all the time (for example, vegetables, herbs), so vitamins will help make up for their deficiency.

4) You can often see participants trying to cheer themselves up by drinking coffee (especially on the day of the climb) or energy drinks. Based on personal experience, as well as observations of other guides, we should disappoint those who like to quickly get a boost of energy - it doesn’t help. But at high altitudes, on the contrary, it even harms. More than once, guides witnessed when a participant climbed to the saddle of Elbrus, drank strong coffee or a special energy drink and after 300 meters of a vigorous climb sat down, then everything usually ended with his descent down. Drink weak tea, this will help better than coffee, especially since at altitude the body has an increased need for water.

In general, to simplify everything that has been written, let’s say: moderate exercise, normal nutrition, healthy sleep - everything you need for a successful climb. Well, we will try to provide all this for you.

Happy climbing.

• Trekking
• Climbing
• Rock climbing

Acclimatization. Altitude sickness

As you rise in altitude, air pressure drops. Accordingly, the pressure of all components of the air, including oxygen, drops. This means that the amount of oxygen entering the lungs when inhaling is less. And oxygen molecules attach less intensively to red blood cells. The concentration of oxygen in the blood decreases. Lack of oxygen in the blood is called hypoxia. Hypoxia leads to the development mountain sickness.

Typical manifestations of mountain sickness:

• increased heart rate;
• shortness of breath on exertion;
• headache, insomnia;
• weakness, nausea and vomiting;
• inappropriate behavior.

In advanced cases, mountain sickness can lead to serious consequences.

To stay safely at high altitudes you need acclimatization- adaptation of the body to high altitude conditions.

Acclimatization is impossible without altitude sickness. Mild forms of mountain sickness trigger the body's restructuring mechanisms.

There are two phases of acclimatization:

Short-term acclimatization is a quick response to hypoxia. The changes mainly concern oxygen transport systems. The frequency of breathing and heartbeat increases. Additional red blood cells are released from the blood depot. There is a redistribution of blood in the body. Cerebral blood flow increases, because the brain requires a lot of oxygen. This leads to headaches.

But such adaptation mechanisms can only be effective for a short time. At the same time, the body experiences stress and works for wear.

Long-term acclimatization is a complex of profound changes in the body. This is precisely the goal of acclimatization. In this phase, the emphasis shifts from transport mechanisms to mechanisms for economical use of oxygen. The capillary network grows, the area of ​​the lungs increases. The composition of the blood changes - fetal hemoglobin appears, which more easily attaches oxygen at low partial pressure. The activity of enzymes that break down glucose and glycogen increases. The biochemistry of myocardial cells changes, which allows for more efficient use of oxygen.

Stepped acclimatization

When rising to altitude, the body experiences a lack of oxygen. Mild mountain sickness begins. Short-term acclimatization mechanisms are activated. For effective acclimatization, it is better to descend after the ascent so that changes in the body occur in more favorable conditions and the body does not become exhausted. This is the basis for the principle of stepwise acclimatization - a sequence of ascents and descents, in which each subsequent ascent is higher than the previous one.

Sawtooth graph of stepwise acclimatization

Sometimes the terrain features do not provide the opportunity for full step-by-step acclimatization. For example, on many treks in the Himalayas, where there is daily elevation gain. Then daytime transitions are made small so that the altitude does not increase too quickly. In this case, it is very useful to look for an opportunity to make even a small exit from the place where you spend the night. You can often take a walk in the evening to a nearby hill or mountain spur and gain at least a couple of hundred meters.

What needs to be done to make acclimatization successful

Before the trip

General physical training. It is easier for a trained person to bear the loads associated with height. First of all, you should develop endurance. This is achieved by prolonged low-intensity exercise. The most accessible means of developing endurance is run.

It is practically useless to run often, but little by little. It is better to run once a week for 1 hour than to run for 10 minutes every day. To develop endurance, the length of runs should be more than 40 minutes, the frequency should be according to your feelings. It is important to monitor your heart rate and not overload your heart. In general, training should be enjoyable, fanaticism is not needed.

Health. It is very important to come to the mountains healthy and rested. If you have been training, then three weeks before the trip, reduce the load and give your body a rest. Adequate sleep and nutrition are required. Nutrition can be supplemented with vitamins and microelements. Minimize, or better yet, abstain from alcohol. Avoid stress and overwork at work. You need to get your teeth fixed.

In the first days of being at altitude

In the first days, the body is subject to heavy stress. The immune system weakens and it is easy to get sick. Hypothermia or overheating must be avoided. There are sharp temperature changes in the mountains and you need to follow the rule - undress before you sweat, dress before you freeze.

Nutrition. Appetite at altitude may be reduced, especially if you ride immediately to high altitudes. There is no need to forcefully eat. Give preference to easily digestible foods. Alcohol should not be taken. In the mountains, due to dry air and great physical activity, a person needs a large amount of water - drink a lot.

Continue taking vitamins and microelements. You can start taking amino acids that have adaptogenic properties.

Driving mode. It happens that, having just arrived in the mountains, tourists, experiencing an emotional upsurge and feeling the strength overwhelming them, walk too quickly along the trail. You need to restrain yourself, the pace of movement should be calm and uniform. In the first days at high altitudes, resting heart rate is 1.5 times higher than on the plain. It’s already hard for the body, so there’s no need to drive it, "hold your horses", especially on climbs. Small tears may not be noticeable, but they tend to accumulate and can lead to failure of acclimatization.

If you arrive at your overnight stay and don’t feel well, you don’t need to go to bed. It’s better to take a leisurely walk around the surrounding area, take part in setting up a bivouac, or generally do something. Movement and work- An excellent cure for mild forms of mountain sickness.

Dream. Night is a very important time for acclimatization. Sleep must be sound. If you have a headache in the evening, take a painkiller. A headache destabilizes the body and cannot be tolerated. If you can't sleep, take sleeping pills. Insomnia is also something you can't tolerate.

Monitor your pulse before bed and in the morning immediately after waking up. Morning heart rate should be lower- This is an indicator that the body has rested.

With well-planned preparation and a proper climb schedule, you can avoid serious symptoms of altitude sickness and enjoy the pleasure of conquering high altitudes.

Based on the article by A.A. Lebedev "Organization of effective and safe acclimatization"

HEIGHT AND MAN

When rising to a height, atmospheric pressure, the partial pressure of oxygen in the atmosphere and pulmonary alveoli, as well as the saturation of hemoglobin with oxygen simultaneously decrease (98% O 2 in the blood is transported by red blood cells and only 2% by plasma). This may cause hypoxia(oxygen starvation) is a condition that occurs when there is insufficient supply of oxygen to tissues or disruption of its use in the process of biological oxidation. Close in meaning is the term hypoxemia– low oxygen content in the blood. Oxygen is necessary for the processes of oxidative phosphorylation (synthesis of adenosine triphosphate (ATP *); O2 deficiency disrupts the flow of all processes in the body that depend on ATP energy: the work of cell membrane pumps transporting ions against a concentration gradient, the synthesis of mediators and high-molecular compounds - enzymes, receptors for hormones and mediators.If this occurs in the cells of the central nervous system, the normal course of the processes of excitation and transmission of nerve impulses becomes impossible.

*The reason for the preference, under hypoxic conditions, for high-intensity exercise to obtain energy from carbohydrates rather than higher-calorie fats is the greater ATP yield: carbohydrates form 6.3 moles of ATP/molO 2 ; fats – 5.6 moles of ATP/molO 2

From the table above, a number of conclusions can be drawn:
– the decrease in partial pressure of air and, accordingly, oxygen from altitude occurs nonlinearly;
– the degree of saturation of the lungs with oxygen in relation to its content in the external air decreases (this may be due to an increase in the proportion of CO 2 in the lungs, and in the “death zone” breathing is already so intense that CO 2 does not have time to accumulate in the lungs);
– hemoglobin is capable of being almost 100% saturated with O 2 at its partial pressure in the lungs 13-14% (!) of atmospheric;
– the degree of oxygen saturation of hemoglobin is not linear: even when the partial pressure of oxygen in the lungs is halved, hemoglobin will still be 80% saturated.

Thanks to the amazing property of hemoglobin to greedily absorb oxygen, even at low pressures, it becomes possible for a person to move and live in the highlands.
The lungs respond to a lack of oxygen by first breathing deeper (increasing its volume):

Degree of saturation of human hemoglobin with oxygen depending on altitude
and a decrease in atmospheric pressure (respectively, the amount of oxygen) with altitude

and then by an increase in breathing frequency. With reduced air density, the mass of oxygen contained in it naturally decreases, i.e. there is a “decrease in the oxygen ceiling”.

Therefore, the oxygen supply to the body at high altitudes will be insufficient, and the theoretical power of the work performed will be determined by the degree of oxygen saturation of hemoglobin in the blood.
And ultimately determine the duration of acclimatization.

According to modern ideas of height before:
5300-5400 m – full acclimatization zone when rest and nutrition completely restore the expended energy of healthy people;
5400-6000 m – zone of incomplete acclimatization(no complete recovery even with rest);
6000-7000 m – adaptation zone(the body’s compensatory mechanisms work under great strain and a complete restoration of vitality, although difficult, is possible for a short time;
7000-7800 m – zone of partial, temporary adaptation(the body begins to use up its own reserves without the possibility of replenishing them. The climber can stay in this zone for up to 4-5 days;
over 7800 m – “altitude death zone”(staying in it for 2-3 days without an oxygen apparatus causes rapid deterioration (exhaustion).

Many people know about this. And yet I would like to draw attention to the fact that the indicated conditions in these high-altitude zones imply climbers already have adequate acclimatization to these altitudes. By the way: the above graph explains why relatively complete rest is possible at altitudes of 4200-4400 m.

ACCLIMATIZATION FROM INSIDE

Scientists identify in the adaptation processes:
a) “urgent” (acute, emergency) phase and b) “long-term” phase.

Short-term adaptation - this is a quick response of the body to hypoxia as a stress factor in order to compensate for deviations from the equilibrium state that occur in the body. The mechanisms of such a response pre-exist in the body and are switched on “on the spot” when the oxygen content in arterial blood decreases from 80 to 50 mm Hg. Art. and below. Some authors call this period “respiratory acclimatization.” The body’s first reaction is to fight for oxygen, to maintain its normal concentration in the blood. The effect of hypoxia on interoceptors leads to the mobilization of transport systems. The respiratory rate, heart rate, minute volume of blood, and the amount of the main oxygen carrier - hemoglobin increase due to the release of red blood cells from the depot (primarily from the spleen). At the first stage, there is always a redistribution of blood in the body, an increase in cerebral blood flow (brain tissue consumes oxygen per unit mass 30 times more than muscle tissue), coronary blood flow (can increase 2-3 times during acute hypoxia) due to a decrease in blood flow in other organs It is known that an increase in cerebral blood flow is the cause of headaches. At this stage of acclimatization, a poor supply of circulating blood to other organs disrupts the body’s thermoregulation and increases sensitivity to cold influences and infectious diseases. Activation of transport systems is carried out by the sympathetic division of the autonomic nervous system. At the same time, the mechanisms of anaerobic glycolysis are activated: norepinephrine, acting as a mediator of the sympathetic nervous system, together with adrenaline, as a hormone of the adrenal medulla, through a system of intracellular intermediaries activates the key enzyme for the breakdown of glycogen - phosphorylase. Short-term adaptation mechanisms can only be effective at relatively low altitudes and for short periods of time. The increased load on the heart and respiratory muscles requires additional energy consumption, that is, it increases oxygen demand. Due to intense breathing (hyperventilation), CO 2 is intensively removed from the body. A drop in its concentration in arterial blood leads to a weakening of breathing, since CO 2 is the main stimulator of the respiratory reflex; acidic products of anaerobic glycolysis accumulate in tissues. The energy output of ATP is small. Many authors believe that the “acute acclimatization” phase ends by day 8-12. Therefore, in the future, mechanisms are activated in the body long-term adaptation , the strategy of which boils down to shifting the main field of activity from transport mechanisms to oxygen utilization mechanisms, to increasing the efficiency of using the resources available to the body. Long-term adaptation is already structural changes in the body associated with the stimulation of biosynthetic processes in transport, regulation and energy supply systems, which increases their structural potential and reserve power. Conventionally, the nature of structural changes can be represented as follows:

The expansion of the vascular network of the heart and brain creates additional reserves to supply these organs with oxygen and energy resources. Increasing the capacity of the vascular bed reduces its overall resistance. The growth of the vascular network in the lungs, combined with an increase in the diffusion surface of the lung tissue, provides the opportunity for increased gas exchange. A key role in the induction of erythropoiesis, angiogenesis and glycolysis is played by the iron-containing protein HIF-1 (Hypoxia inducible factor), which is activated during hypoxia.

Oxygen absorption and release curves
hemoglobin of highland animals

The blood system undergoes a complex of changes. It is well known that at the stage of long-term acclimatization, the number of erythrocytes and the content of hemoglobin in them increases, increasing the oxygen capacity of the blood (the dry matter of the erythrocyte contains up to 95% of hemoglobin). An increase in the concentration of erythrocytes begins from 2-3 days and can increase by 40-50% by the 4th week of stay in the mountains (reaches up to 8 million/mm 3, while among residents of the plain there are 4.5-5 million/mm 3). This is due to an increase in the secretion of hormones - erythropoietins in the red bone marrow. It is less known that at the stage of long-term adaptation, in addition to the typical adult hemoglobin (HbA), embryonic hemoglobin (HbF) appears, capable of attaching O 2 at a lower partial pressure of oxygen in the alveolar air (Fig. 2): young red blood cells have a higher level of energy exchange. And young red blood cells themselves have a slightly changed structure; their diameter is smaller, making it easier to pass through the capillaries. About changes in the quality of the red blood cells themselves also speaks of an increase in the content of 2,3-diphosphoglycerate (2,3-DPG), which promotes the release of oxygen from the complex with hemoglobin in tissues (it has been established that the concentration of 2,3-DPG in erythrocytes in athletes training endurance is 15-20% higher than non-athletes).
High-altitude adaptation also causes an increase in leukocytes, the maximum of which (+40%) is reached approximately by the 40th day of stay in the mountains.

The increase in the oxygen capacity of the blood is complemented by an increase in the concentration in the myocardium and skeletal muscles of muscle protein - myoglobin (Mb), capable of carrying oxygen in a zone of lower partial pressure than hemoglobin. An increase in the power of glycolysis in all tissues during long-term adaptation to hypoxia is energetically justified and requires less oxygen. Therefore, the activity of enzymes that break down glucose and glycogen begins to increase, new isoforms of enzymes appear that are more suitable for anaerobic conditions, and glycogen reserves increase. The danger of a pH shift with increased anaerobic glycolysis is prevented by increasing the alkaline reserve of the blood. At this stage of acclimatization, the efficiency of functioning of tissues and organs increases, which is achieved by an increase in the number of mitochondria per unit of myocardial mass, an increase in the activity of mitochondrial enzymes and the rate of phosphorylation and, as a consequence, a greater yield of ATP per unit of substrate at the same level of oxygen consumption. As a result, the heart's ability to extract and use oxygen from flowing blood at low concentrations increases. This allows you to ease the load on transport systems: the respiratory and heart rate decreases, and the cardiac output decreases. At an altitude of 3800 m, the tissues of a mountaineer extract 10.2 ml of O 2 from every 100 ml of blood versus 6.5 ml from a young healthy inhabitant of the plains who arrived in the mountains; at 4350 m, coronary blood flow and O2 consumption of highlanders are 30% more economical. Highlanders also have an increased mass of circulating blood, which causes an increase in its respiratory surface.

With prolonged exposure to high-altitude hypoxia, the synthesis of RNA and protein is activated in various parts of the nervous system and, in particular, in the respiratory center, which makes it possible to enhance breathing at low concentrations of CO 2 in the blood *; coordination of breathing and blood circulation improves. The power of hormonal components increases and their efficiency increases; the level of basal metabolism may decrease during the adaptation process. It has been established that the second phase of acclimatization is generally completed three weeks after the start of arrival in the mountains. However, for high altitudes this duration of acclimatization may not be sufficient.

* probably this reason was the reason for the attack of mountain sickness upon the first acquaintance with 7000 m by the author of the article, who at the same time had one of the lowest heart rates in the group - only 70 beats/min at night at 7200.

Compiled based on the article: “Problems of acclimatization in the mountains ̶ Oleg Yanchevsky, Kyiv //www.tkg.org.ua/node/11577. Editing and additions ̶ Ivanchenko Oleg.