"There are people whose job is to lie in the bathroom": how the effect of weightlessness on the health of astronauts is studied

There are people whose job it is to lie in the bathroom. Lie for hours, even days on end (and get paid for it). However, there is no need to envy them - we are talking about participants in complex scientific experiments, during which doctors from the Institute of Biomedical Problems of the Russian Academy of Sciences study the effect on the human body of conditions similar to conditions of weightlessness. By itself, this experience, like any long stay in space, leads to malfunctions in the body.

We asked Lyubov Amirova and Ilya Rukavishnikov, employees of the Institute of Biological and Biological Sciences, to tell us about how and why the method of "dry" diving was invented and what scientific results it allows to obtain. In addition, we suggest that you familiarize yourself with the diary of a participant in the "dive" that lasted five days, engineer and popularizer of astronautics Alexander Khokhlov. The recordings were made directly during the experiment.

Being in space, even on a well-protected spacecraft, has a negative effect on the health of an astronaut. In space flight, almost everything is unusual and hostile for the body - an increased background radiation, microgravity, isolation, an artificial atmosphere and lighting, and the monotony of sensory stimuli that drives you into homesickness. Among these factors, only microgravity is specific for space flight and is practically not reproducible in terrestrial conditions.

At the dawn of the era of astronautics, the main danger was not microgravity, but overloads, and it was for them that astronauts were actively trained. With the development of technology, flights became more and more prolonged, and in June 1970, Soviet cosmonauts Andriyan Nikolaev and Vitaly Sevastyanov make the first long 18-day space flight, set a record for the duration of a continuous flight, return to Earth and … cannot stand and walk. The state of the astronauts was depressing: muscle atrophy, negative reactions from the cardiovascular system.

This state of affairs led scientists to two conclusions. Firstly, it is necessary to develop a prevention system (so that this does not happen again!) And, secondly, to study the effect of weightlessness on the human body (in order to understand the fundamental laws of the influence of weightlessness). It became clear that, without a large amount of data on changes in each organ system, it was impossible to send astronauts into space. But how to study the effect of weightlessness on the human body without space?

Zero gravity immersion

Scientists have found a Solomon solution to this problem - an imitation of the conditions of weightlessness on Earth. Such experiments simulating space flight are called model (or models), and their effect on the body is similar to the effect of weightlessness. Since the main factors that influenced the state of the astronauts were physical unloading, fluid redistribution and lack of support, they formed the basis of model experiments.

In modern science, not a single model experiment can fully reproduce the conditions of weightlessness, therefore, depending on what scientists plan to study, the object of research and the experimental model are carefully selected. Quite often, laboratory animals such as mice and rats act as "test subjects", but the most valuable information is provided by model experiments on humans - volunteer test subjects.

Tester's Diary

We publish fragments of the records that were kept on Facebook by the design engineer of the space instrumentation Central Research Institute of the RTK, the popularizer of cosmonautics Alexander Khokhlov, who took part in the experiment "The effectiveness of low-frequency EMS in the prevention of muscle detraining, which develops in the conditions of ground simulation of space flight conditions", which in March - April of this year was held at the Institute of Biomedical Problems of the Russian Academy of Sciences (SSC RF - IBMP RAS).

“This morning I learned that the investigator who was in front of me was ill, I was urgently summoned to the IBMP, and I entered the experiment a day earlier. I go to the immersion bath on Thursday (the first in the second tab). Today there were experiments: "Pose", "Field test", "Vision", "Breathing", "H-reflex", "Algometria" and "Vulcan-I". On the "Vision" they put weights on my eyes (for four minutes), having previously instilled anesthetic. This is how the astronauts used to measure their eye pressure, and then they switched to air."

“My participation in the experiment has entered a new phase. At about 9:30 am, I immersed myself in a dry immersion bath for five days.

The water, with a comfortable temperature, is covered with a film that wraps around my body from all sides. Only the head and sometimes the hands look out. The body is protected from the film by a sheet, which changes every day. From clothes: socks, underpants and a T-shirt.

The first day is going unusual. New sensations that will intensify towards the night. Our life in the baths of dry immersion is supported round the clock by teams of three people on duty: a doctor, a laboratory assistant and a technician.

You don't have to get bored here, experiment is replaced by experiment, everyday moments also take time. In the evening, the first three-hour electrical myostimulation began. Its presence is the main difference of this experiment in a dry immersion bath from the previous ones. Low-frequency EMS can help to overcome the harmful effects of weightlessness on astronauts, as well as elderly people with limited mobility on Earth. The stimulation is reminiscent of rhythmic punctuations on the thighs and shins."

There are several ways to study the effect of weightlessness on the human body. For example, this can be done in an airplane falling along a parabolic trajectory. But the duration of the zero gravity phase in this case is so short that there is no need to talk about long-term effects.

To achieve stronger effects, you can simply lie on the bed with the head end lowered. Bed rest will lead to muscle atrophy, and the blood constantly rushing to the head will bring the state of the subject's cardiovascular system closer to that of an astronaut. True, you will have to lie for a long time - at least a few weeks, and preferably a few months.

The most unusual and at the same time the closest model to the effects of weightlessness is the "dry" immersion (from the English immersion - "immersion"), in which a person is immersed in water for several days or weeks.

Research on the model of "dry" immersion / Oleg Voloshin

The invention of the model was helped by the following observation - a long stay in water acts on the human body in a manner similar to weightlessness. The first immersion dives were "wet" - the subjects were in a pool of fresh water for several days.

On the one hand, scientists' guesses about the similarity of the observed changes were confirmed, but on the other hand, due to constant contact with water, people literally began to peel off their skin. The volunteer testers were not helped by protective ointments, and the sides of the pool turned black from the sebum that had been planted on them and oxidized. Also, the subjects, so that they would not drown, were forbidden to sleep in the pool, and the doctors on duty were forced to wake them up.

“The first night in the immersion bath was challenging. Dozing off at about 00:00, I soon woke up with strange sensations that the water was squeezing me through the film, my back began to ache, then my stomach tightened (began to swell). And as a result, I slept only two hours in the morning, and at six I was already looking at the ceiling.

In the morning until 10:00, I had experiments on an empty stomach. For example, SPLANCH, in which ultrasound showed that I have a lot of air in my stomach and intestines. It took a day in the bath. I have no appetite. I only plan to drink for dinner.

Since the adaptation period is still underway, it is difficult to write and read, so I mostly listen to music with headphones. You don't have to get bored, there is enough attention from the duty team and researchers.

And more about the good. One of the experiments is called Ryazhenka, and in the evening we drink a mug of a tasty and healthy product."

It became clear that carrying out an experiment under such conditions is impossible and the model needs significant improvement. The most elegant version of its improvement was proposed by the employees of the Institute of Medical and Biological Problems, E. B. Shulzhenko and I. F. Vil-Williams in the early 70s. The pool was covered with a waterproof fabric of a large area so that the subject was completely immersed in the water column, but at the same time did not come into contact with the sides and bottom of the bowl. Only the subject's head and arms remain on the surface.

In Professor Dowell's Head mode, under the close supervision of a physician and researchers, the volunteer lives throughout the experiment. An exception is the time of evening hygiene procedures - scientists are not honored with dirty tricks. Before going to bed, the subject is taken out of the immersion bath, immersed in a washing trolley and taken to the shower. "Take a break" from a hard day's work is allowed no more than 15 minutes. Since then, the model of "dry" immersion has been applied practically unchanged.

Research on the model of "dry" immersion / Oleg Voloshin

It's good in space, it's better on Earth

To a person far from space biology, it may seem that over the more than 55-year history of manned astronautics, man in space has been studied up and down. But this is only partly true.

Yes, the main regularities that occur with an astronaut in flight are known - in zero gravity, the heart and blood vessels work differently, the volume of fluid in the body decreases, muscle weakness and movement illusions appear. But no scientist will tell you that all open changes are detailed and do not require further study.

Despite the fact that hundreds of people have been in space, the most extensive biological surveys rarely include more than 15-20 astronauts. Even such a small, from the point of view of statistical analysis, a group requires several years of preparatory work, often the creation of new equipment (suitable for the strict requirements of the International Space Station) and training of astronauts in all the intricacies of biological surveys.

Far from the bustle of the earth, research is proceeding decorously and measuredly - as a rule, from three to five cosmonauts can participate in one experiment in a year, and from the moment of the inception of a hypothesis to its fruits, thus, a dozen or a half years can pass.

Many studies are often carried out in parallel, both in space and in "dry" immersion, which makes it possible to compare the observed changes. For example, it has been shown that seven days of space flight and seven days of immersion cause similar changes in the cardiovascular system associated with changes in the fluid balance in the body.

“That night I slept for seven hours, it’s better, the body is adapting to unusual conditions. It turned out that the testers are divided into those who suffer more from the back, and those who have a stomach. I have a belly. But there are those who receive a whole host of surprises. Therefore, one of the favorite jokes of researchers is to suggest that the tester, who has come out of the bathroom, lie down there again and rest.

If the experiment itself is carried out by two dozen scientists, then everyday life is associated with the duty teams. The team on duty feeds the testers three times a day, monitors the cyclogram of the day, takes blood and saliva for analysis, brings a duck for minor needs, and helps scientists in conducting tests.

The most interesting thing happens in the evening. All day, the testers, like jellyfish, sway in the bathrooms, but sometimes they are taken out. Some tests require access to the body. Every minute outside the bath is recorded.

And in the evening for 15 minutes, hygiene procedures are carried out in conditions of gravity. The team includes a lift. The tester rolls onto the couch and is brought to the scales and the height meter. He gets up with the help of a doctor and measures the indicators. Then the tester is placed in a toilet with an ordinary toilet bowl in order to go in a big way, then he lies down on the washing couch and takes a shower while lying down. At this point, the team wipes the film and changes the sheet in the bath. Further into the shower room, at the command of the tester, covered with a towel, a couch with clean underpants and socks is brought in. He rolls alone and dresses lying down. He is taken to the bath, unloaded, put on a T-shirt with sensors of the "Sleep" experiment and immersed in the bath. Everything in 15 minutes maximum. The real "Formula-1".

Almost identical changes in space flight and in immersion occur with the muscles: their tone decreases and their strength decreases. In both cases, this is due to the lack of support. As it turned out, support is necessary for the normal functioning of the musculoskeletal system - bones, in the absence of shock loads that occur on the Earth when walking and running, lose calcium and become fragile. In zero gravity, fragile bones are not dangerous, but when returning to Earth and when overloaded, this can lead to injury.

In the absence of supporting stimuli, not only bones but also muscles suffer. As soon as the astronaut passes into a state of weightlessness, his muscles begin to lose their tone, which leads to functional changes within a few weeks. When exposed to "dry" immersion, the same thing happens - from day to day the muscles lose their tone and strength, and when removed from the immersion, the subjects feel like fish thrown ashore.

Unidirectional changes allow scientists to conduct more detailed studies on Earth, thereby freeing up astronauts' time for other tasks.

Another important factor in space flight is a reduction in physical activity. Despite the fact that every day the cosmonauts do a large amount of work, rather actively move around the station and do physical exercises, the load on the body remains significantly less than that of the earth. Everything they interact with has no weight, not even themselves. Consequently, very little muscle effort is required to achieve a motor target.

Under immersion conditions, the tester is forbidden to generate unnecessary muscle efforts, and this is strictly monitored by the researchers. In return, the subject receives a command of 3-4 people who fulfill, like genies, his needs and desires.

“I experience influences on my body that are similar to weightlessness in space flight. As well as there, my back aches (fortunately, not much), a little stuffy nose and problems with gas in the stomach and intestines.

Every day I undergo a three-hour electromyostimulation of the legs, which should make it easier for me to return to Earth in two nights. I will return to my usual upright position on Tuesday morning. I felt much better than on the second day of immersion, the body gets used to it. But my appetite has not returned yet, I eat with an effort of will.

For breakfast we have yoghurts, various cereals to choose from, dried fruits. Lunch: soup (broth with egg, mushroom, meatballs, etc.), main course, drink, dry bread, salad. For dinner, the main course and salad.

We eat in a position with a pillow under our back in order to swallow normally. But still not very convenient. Only on the first day, before the acute adaptation, I ate everything, now - less than half of the prescribed diet.

Drinks: tea, water, jelly and juice. Coffee is not allowed under the conditions of the experiment."

It is important to understand that despite advances in technology, not all research can be done in space. In the “dry” immersion model, there are significantly fewer such restrictions. For example, magnetic resonance imaging (a tomograph in orbit - sounds fantastic!) And transcranial magnetic stimulation in zero gravity have never been performed, but thanks to the data obtained in immersion, scientists have an idea of what to expect in space.

There are also such studies, the setting of which is not only technically difficult, but also involves risks for the astronaut. For example, we can recall a biopsy - the removal of a small piece of biological tissue. This examination requires sterile operating room conditions and the hands of an experienced surgeon, but even if all conditions are met, there is a small likelihood of complications. For an astronaut in orbit, this is an unjustified risk. Nevertheless, such studies are carried out in immersion and reveal the secrets of an unusually complex skeletal muscle.

Taller

In order to tell exactly what results can be obtained thanks to the "dry" immersion model, let us dwell in more detail on a series of experiments devoted to the study of back pain and the increase in the height of astronauts during the transition to weightlessness.

Back pain occurs in astronauts in the first days of flights, as well as in testers under conditions of "dry" immersion. In the course of previous studies, it was possible to show that under conditions of weightlessness, due to changes in the transport of nutrients, the intervertebral discs increase, and fluid accumulates inside their structures. In addition, pain could arise due to the impact on the sensitive roots of the spinal cord as a result of an increase in the length of the spine.

The reason for these disorders, as shown by studies carried out at the State Research Center of the Russian Federation - IBMP RAS over a number of years, may be a decrease in the tone of the back extensor muscles. The assumption about the presence of muscles involved in maintaining the posture was put forward by V. S. Gurfinkel back in 1965.

Changes in the tone in the leg extensor muscles were logically recorded in previous model studies. Therefore, there was reason to believe that under conditions of weightlessness, the tone of the back muscles, which are involved in maintaining posture on Earth (they are called "posture"), also decreases, where the gravitational load forces them to remain in good shape.

To test this hypothesis, a series of model experiments was carried out with "dry" immersion of various durations - from six hours to five days. At the same time, the tone of the muscles of the back was investigated with the determination of indicators of their transverse stiffness; in parallel with the means of resonance vibrography, myotonometry, magnetic resonance imaging, changes in the spine were studied. In addition, scientists measured a person's height and assessed the nature of the resulting pain syndrome.

“I have started the last, fifth day of dry immersion at IBMP RAS. The state of health is good. I have almost adapted to the conditional weightlessness. Tomorrow morning, a notch and a lot of tests. Today there are enough of them too.

During the immersion, the testers participate in various experiments. This is the study of the pain threshold ("Algometry"), and changes in vision in immersion, and the ability to control the load by squeezing the palm ("Dynamometer") and pressing the foot ("Pedal").

Many instruments that are now available are either on board the ISS or are used before and after the flight for experiments with astronauts.

In my free time I listen to music and read the book Beyond the Earth.

As a result, it turned out that the pain syndrome does not belong to radicular pain, but is muscular in nature, without irradiation. Staying under conditions of gravitational unloading is accompanied by a decrease in the tone (or lateral stiffness) of the extensors of the back, belonging to the group of posture muscles, and it is in the first hours and days that this process is especially pronounced.

The same changes led to an increase in the height of the astronaut under microgravity conditions. In the lumbar spine, according to MRI data, the height of the intervertebral discs increased and the lumbar lordosis smoothed out.

In the group of studies in which prophylactic means were used, such as a suit of axial load "Penguin" and a hardware complex of myostimulation, the severity and assessment of pain syndrome, as well as an increase in height were less than in the group of "pure" immersion without the use of prophylactic means.

Not just for space

The "dry" immersion model reproduces cosmic disturbances quite well, but, in addition, it also helps to fight certain diseases. For example, a course of immersion baths brings relief to people with excessively increased muscle tone, which prevents them from fully moving.

Taking an immersion bath is a good way to lower your blood pressure. The mechanism of the process is simple: the water surrounding a person squeezes blood and lymph from the peripheral vessels into the central bloodstream, which is perceived by the body as an excess of fluid and leads to its removal (in a natural way - urination increases) and a decrease in pressure. By the way, to achieve this effect, diving does not have to be "dry" - probably, many have noticed that while swimming, they start to want to use the toilet, and now you know why.

“At 9:30 in the morning, the fifth day of dry immersion ended for me. I was taken out of the bathroom. Day zero is one of the most important, it is for the sake of the data on this day that the testers lie for five days without support. On a gurney I was taken to the laboratory of gravitational physiology, where tests were immediately carried out on the experiments "Architecture", "Pose", "Field test", and then DEXA, "Dynamometer", TMS, "Tonus", "Isokinesis".

My condition is improving every minute, at first I had a headache, as if I donated 450 milliliters of donated blood, my legs were shaking a little during tests with my eyes closed. Now everything is fine and the stomach does not hurt.

Today I am spending the night at the institute because of the "Sleep" experiment. Then two more days of research, and April 11 - the last day on which the adventure with immersion will end for me. This is a very rewarding experience that will come in handy in the future.

It is interesting that the next stage of immersion is planned in the autumn at the IBMP - 21 days. But there will be a special set."

Model experiments are carried out in special medical or scientific institutions equipped with unique equipment, under the supervision of highly qualified researchers. At the moment, an experiment with the use of a five-day "dry" immersion is being carried out at the State Research Center of the Russian Federation - IBMP RAS.

It is interesting that the changes occurring with the body in immersion can simulate not only space flight, but also the state of senile sarcopenia - age-related atrophy of skeletal muscles. This immersion is the first to use low-frequency electromyostimulation of the leg muscles, aimed at preventing negative muscle changes. In the course of studies on young, but detrained volunteer test subjects, the most effective electrical stimulation protocols will be selected.

After completing the dive, the subjects will have to undergo a variety of tests that will assess how the muscle tone, their structure, as well as the vertical stance and gait of the volunteers have changed.

Publications devoted to biomedical experiments in space and their modeling are rare. In our article, only a small part of this vast topic was considered, which includes the well-being of astronauts on board the station, launches of satellites inhabited by animals,model experiments with the participation of primates and space technologies in the rehabilitation of patients.

Literature

I. B. Kozlovskaya, D. A. Maksimov, Yu. I. Voronkov, I. Sunn, V. N. Ardashev, I. G. Dorogan-Suschev, I. V. Rukavishnikov. Changes in the lumbar spine and acute back pain when exposed to a 3-day "dry" immersion // Kremlin Medicine. Clinical Bulletin. - 2015. - No. 2.

I. V. Rukavishnikov, L. E. Amirova, T. B. Kukoba, E. S. Tomilovskaya, I. B. Kozlovskaya. Influence of gravitational unloading on the muscle tone of the back // Human Physiology. - 2017. - No. 3.