Tell us what you know about the biological rhythms of living organisms. Biological rhythms of body functions

Chapter 1 Biological rhythms The search for truth should start small. The answer cannot be found on just one page. Try to slowly read the entire book from cover to cover. The grains of truth are scattered everywhere. Somewhere there are more of them, and somewhere less. Only after fully studying

The science that studies rhythm in biology arose at the end of the 18th century. Its founder is considered to be the German doctor Christopher William Gufeland. With his input, for a long period of time, organisms were considered dependent exclusively on external cyclical processes, primarily on the rotation of the Earth around the Sun and its own axis. Today, chronobiology is popular. According to the dominant theory, the causes of biorhythms lie both outside and inside a particular organism. Moreover, changes repeated over time are characteristic not only of individual individuals. They permeate all levels of biological systems - from the cell to the biosphere.

Rhythmicity in biology: definition

Thus, the property under consideration is one of the fundamental characteristics of living matter. Rhythm in biology can be defined as fluctuations in the intensity of processes and physiological reactions. It represents periodic changes in the state of the environment of a living system, arising under the influence of external and internal factors. They are also called synchronizers.

Biorhythms that do not depend on external (acting on the system from outside) factors are endogenous. Exogenous ones, accordingly, do not respond to the influence of internal (acting within the system) synchronizers.

Causes

As already noted, in the first stages of the formation of a new science, rhythm in biology was considered to be determined only by external factors. This theory was replaced by the hypothesis of internal determination. In it, external factors played a minor role. However, researchers quickly came to understand the high value of both types of synchronizers. Today it is believed that biological things are endogenous in nature, subject to changes under the influence of the external environment. This idea is at the center of the multioscillatory model of regulation of such processes.

The essence of the theory

According to this concept, endogenous genetically programmed oscillatory processes are influenced by external synchronizers. A huge number of internal rhythmic vibrations of a multicellular organism are arranged in a certain hierarchical order. Its maintenance is based on neurohumoral mechanisms. They coordinate the phase relationships of different rhythms: unidirectional processes proceed synchronously, while incompatible ones work in antiphase.

It is difficult to imagine all this activity without some kind of oscillator (coordinator). In the theory under consideration, three interconnected regulatory systems are distinguished: the pineal gland, the pituitary gland and the adrenal glands. The pineal gland is considered the most ancient.

Presumably, in organisms at low stages of evolutionary development, the pineal gland plays a major role. The melatonin it secretes is produced in the dark and breaks down in the light. In fact, it tells all cells the time of day. As the organization becomes more complex, the pineal gland begins to play a second role, yielding primacy to the suprachiasmatic nuclei of the hypothalamus. The question of the relationship in the regulation of biorhythms of both structures has not been fully resolved. In any case, according to the theory, they have a “helper” - the adrenal glands.

Kinds

All biorhythms are divided into two main categories:

physiological are fluctuations in the functioning of individual systems of the body;

ecological, or adaptive, are necessary to adapt to constantly changing environmental conditions.

Also common is the classification proposed by chronobiologist F. Halberg. He took their duration as the basis for dividing biological rhythms:

high frequency fluctuations - from a few seconds to half an hour;

average frequency fluctuations - from half an hour to six days;

low frequency fluctuations - from six days to a year.

Processes of the first type are breathing, heartbeat, electrical activity of the brain and other similar rhythms in biology. Examples of average frequency fluctuations are changes during the day in metabolic processes, sleep and wakefulness patterns. The third includes seasonal, annual and lunar rhythms.

Synchronizers external to a person are divided into social and physical. The first are the daily routine and various norms adopted at work, in everyday life or in society as a whole. Physical synchronizers are represented by the change of day and night, the intensity of electromagnetic fields, fluctuations in temperature, humidity, and so on.

Desynchronization

The ideal state of the body occurs when a person’s internal biorhythms work in accordance with external conditions. Unfortunately, this is not always the case. A condition when there is a mismatch between internal rhythms and external synchronizers is called desynchronosis. It also comes in two versions.

Internal desynchronosis is a mismatch of processes directly in the body. A common example is disruption of sleep-wake rhythms. External desynchronosis is a mismatch between internal biological rhythms and environmental conditions. Such violations occur, for example, when flying from one time zone to another.

Desynchronosis manifests itself in the form of changes in physiological indicators such as blood pressure. It is often accompanied by increased irritability, lack of appetite, and fatigue. According to chronobiologists, as mentioned above, any disease is the result of a mismatch of certain oscillatory processes.

Circadian biological rhythms

Understanding the logic of fluctuations in physiological processes allows you to optimally organize activities. In this sense, the importance of biological rhythms lasting about a day is especially great. They are used both to determine the effectiveness and for medical diagnosis, treatment, and even choice of dosage of drugs.

In the human body, a day is a period of fluctuation of a huge number of processes. Some of them change significantly, others - minimally. It is important that the indicators of both do not go beyond the norm, that is, they do not become health threatening.

Temperature fluctuations

Thermoregulation is the key to the constancy of the internal environment, and therefore the proper functioning of the body for all mammals, including humans. The temperature changes throughout the day, and the range of fluctuations is very small. The minimum indicators are typical for the period from one o'clock in the morning to five in the morning, the maximum is recorded around six o'clock in the evening. The amplitude of the oscillations is most often less than one degree.

Cardiovascular and endocrine systems

The work of the main “motor” of the human body is also subject to fluctuations. There are two time points at which the activity of the cardiovascular system decreases: one in the afternoon and nine in the evening.

All hematopoietic organs have their own rhythms. The peak activity of the bone marrow occurs in the early morning, and that of the spleen at eight o'clock in the evening.

The secretion of hormones is also inconsistent throughout the day. The concentration of adrenaline in the blood increases in the early morning and reaches its peak at nine o'clock. This feature explains the vigor and activity that most often characterize people in the first half of the day.

Midwives know an interesting statistic: labor in most cases begins around midnight. This is also due to the peculiarities of work. By this time, the posterior lobe of the pituitary gland is activated, producing the corresponding hormones.

In the morning - meat, in the evening - milk

For adherents of proper nutrition, facts related to the digestive system will be interesting. The first half of the day is the time when peristalsis of the gastrointestinal tract increases and bile production increases. The liver actively consumes glycogen in the morning and releases water. From these patterns, chronobiologists derive simple rules: it is better to eat heavy and fatty foods in the first half of the day, and in the afternoon and evening, dairy products and vegetables are ideal.

Performance

It's no secret that a person's biorhythms affect his activity during the day. Variations in different people have their own characteristics, but general patterns can also be identified. The three “bird” chronotypes that connect biological rhythms and performance are probably known to everyone. These are “lark”, “owl” and “dove”. The first two are extreme options. “Larks” are full of strength and energy in the morning, they get up easily and go to bed early.

"Owls", like their prototype, are nocturnal. The active period for them begins at about six in the evening. Getting up early can be very difficult for them to endure. "Pigeons" are able to work both during the day and in the evening. In chronobiology they are called arrhythmics.

Knowing his type, a person can more effectively manage his own activities. However, there is an opinion that any “owl” can become a “lark” with desire and persistence, and the division into three types is due, rather, to habits than to inherent characteristics.

Constant change

The biorhythms of humans and other organisms are not rigid, permanently fixed characteristics. In the process of onto- and phylogenesis, that is, individual development and evolution, they change with certain patterns. What is responsible for such shifts is still not completely clear. There are two main versions on this matter. According to one of them, changes are governed by a mechanism inherent at the cellular level - it can be called

Another hypothesis assigns the main role in this process to geophysical factors that have yet to be studied. Adherents of this theory explain the differences in the biorhythms of individuals by their position on the evolutionary ladder. The higher the level of organization, the more intense the metabolism. In this case, the nature of the indicators does not change, but the amplitude of the fluctuation increases. They consider rhythm itself in biology and its synchronization with geophysical processes as the result of the work of natural selection, leading to the transformation of external (for example, the change of day and night) into internal (the period of activity and sleep) rhythm fluctuations.

Effect of age

Chronobiologists were able to establish that in the process of ontogenesis, depending on the stage the organism passes through, circadian rhythms change. Each development corresponds to its own vibrations of internal systems. Moreover, the change in biological rhythms is subject to a certain pattern, described by the Russian specialist G.D. Gubin. It is convenient to consider it using the example of mammals. In them, such changes are associated primarily with the amplitudes of circadian rhythms. From the first stages of individual development, they increase and reach a maximum in young and mature age. Then the amplitudes begin to decrease.

These are not the only changes in rhythms associated with age. The sequence of acrophases (acrophase is the point in time when the maximum value of a parameter is observed) and the values ​​of the age norm range (chronodesm) also change. If we take into account all these changes, it becomes obvious that it is in adulthood that biorhythms are perfectly coordinated and the human body is able to withstand various external influences, maintaining its health. Over time, the situation changes. As a result of the mismatch between different rhythms, the health reserve gradually runs out.

Chronobiologists propose using such patterns to predict diseases. Based on knowledge about the peculiarities of fluctuations in a person’s circadian rhythms throughout life, it is theoretically possible to construct a certain graph reflecting the health reserve, its maximums and minimums over time. Such testing is a thing of the future, according to most scientists. However, there are theories that make it possible to construct something similar to such a graph now.

Three rhythms

Let’s lift the veil of secrecy a little and tell you how to determine your biorhythms. The calculations in them are made on the basis of the theory of the psychologist Hermann Svoboda, the doctor Wilhelm Fiss and the engineer Alfred Teltscher, created by them at the turn of the 19th and 20th centuries. The essence of the concept is that there are three rhythms: physical, emotional and intellectual. They arise at the moment of birth and throughout life do not change their frequency:

physical - 23 days;

emotional - 28 days;

intellectual - 33 days.

If you plot their changes over time, it will take the form of a sinusoid. For all three parameters, the part of the wave above the Ox axis corresponds to a rise in indicators; below it there is a zone of decline in physical, emotional and mental capabilities. Biorhythms, which can be calculated using a similar graph, at the point of intersection with the axis signal the beginning of a period of uncertainty, when the body’s resistance to environmental influences greatly decreases.

Definition of indicators

You can calculate biological rhythms based on this theory yourself. To do this, you need to calculate how long you have already lived: multiply your age by the number of days in a year (don’t forget that there are 366 in a leap year). The resulting figure must be divided by the frequency of the biorhythm whose graph you are plotting (23, 28 or 33). You will get some integer and remainder. Multiply the whole part again by the duration of a particular biorhythm? f subtract the resulting value from the number of days lived. The remainder will be the number of days in the period currently.

If the obtained value does not exceed one-fourth of the cycle duration, this is the rise time. Depending on the biorhythm, it implies vigor and physical activity, good mood and emotional stability, creative inspiration and intellectual uplift. A value equal to half the duration of the period symbolizes a time of uncertainty. Being in the last third of the duration of any biorhythm means being in the zone of decline in activity. At this time, a person tends to get tired faster, and the risk of illness increases when it comes to the physical cycle. Emotionally, there is a decrease in mood up to depression, a deterioration in the ability to restrain strong internal impulses. At the level of intelligence, the period of decline is characterized by difficulty in making decisions and some inhibition of thought.

Relation to theory

In the scientific world, the concept of three biorhythms in this format is usually criticized. There is no sufficient basis to suggest that anything in the human body can be so immutable. This is evidenced by all the discovered patterns that govern rhythm in biology and the characteristics of internal processes characteristic of different levels of living systems. Therefore, the described calculation method and the entire theory are most often proposed to be considered as an interesting option for spending time, but not a serious concept on the basis of which you should plan your activities.

The biological rhythm of sleep and wakefulness, therefore, is not the only one existing in the body. All systems that make up our body are subject to vibrations, and not only at the level of such large formations as the heart or lungs. Rhythmic processes are inherent in cells, and therefore are characteristic of living matter as a whole. The science that studies such fluctuations is still quite young, but it is already striving to explain many patterns that exist in human life and throughout nature. The evidence already accumulated suggests that the potential of chronobiology is indeed very high. Perhaps, in the near future, doctors will also begin to follow its principles, prescribing doses of drugs in accordance with the characteristics of the phase of a particular biological rhythm.

Biological rhythms

All living things on our planet bear the imprint of the rhythmic pattern of events characteristic of our Earth. Humans also live in a complex system of biorhythms, from short ones - at the molecular level - with a period of several seconds, to global ones, associated with annual changes in solar activity. Biological rhythm is one of the most important tools for studying the time factor in the activity of living systems and their temporal organization.

Biological rhythms or biorhythms are more or less regular changes in the nature and intensity of biological processes. The ability to make such changes in life activity is inherited and is found in almost all living organisms. They can be observed in individual cells, tissues and organs, in whole organisms and in populations. [

Let us highlight the following important achievements of chronobiology:

1. Biological rhythms have been found at all levels of organization of living nature - from single-celled organisms to the biosphere. This indicates that biorhythmics is one of the most general properties of living systems.

2. Biological rhythms are recognized as the most important mechanism for regulating body functions, ensuring homeostasis, dynamic balance and adaptation processes in biological systems.

3. It has been established that biological rhythms, on the one hand, have an endogenous nature and genetic regulation, on the other, their implementation is closely related to the modifying factor of the external environment, the so-called time sensors. This connection at the basis of the unity of the organism with the environment largely determines environmental patterns.

4. Provisions on the temporary organization of living systems, including humans, are formulated as one of the basic principles of biological organization. The development of these provisions is very important for the analysis of pathological states of living systems.

5. Biological rhythms of the sensitivity of organisms to the action of factors of a chemical (among them drugs) and physical nature have been discovered. This became the basis for the development of chronopharmacology, i.e. methods of using drugs, taking into account the dependence of their action on the phases of the biological rhythms of the functioning of the body and on the state of its temporary organization, which changes with the development of the disease.

6. The patterns of biological rhythms are taken into account in the prevention, diagnosis and treatment of diseases.

Biorhythms are divided into physiological and environmental. Physiological rhythms, as a rule, have periods from fractions of a second to several minutes. These are, for example, rhythms of blood pressure, heartbeat and blood pressure. There is evidence of the influence, for example, of the Earth’s magnetic field on the period and amplitude of the human encephalogram.

Ecological rhythms coincide in duration with any natural rhythm of the environment. These include daily, seasonal (annual), tidal and lunar rhythms. Thanks to environmental rhythms, the body orients itself in time and prepares in advance for the expected conditions of existence. Thus, some flowers open shortly before dawn, as if knowing that the sun will soon rise. Many animals hibernate or migrate even before the cold weather sets in. Thus, environmental rhythms serve the body as a biological clock.

Rhythm is a universal property of living systems. The processes of growth and development of the body are rhythmic in nature. Various indicators of the structures of biological objects can be subject to rhythmic changes: orientation of molecules, tertiary molecular structure, type of crystallization, growth form, ion concentration, etc. The dependence of the daily periodicity inherent in plants on the phase of their development has been established. In the bark of young apple tree shoots, a daily rhythm in the content of the biologically active substance phloridzin was revealed, the characteristics of which changed according to the phases of flowering, intensive growth of shoots, etc. One of the most interesting manifestations of the biological measurement of time is the daily frequency of opening and closing of flowers and plants. Each plant “falls asleep” and “wakes up” at strictly defined times of the day. Early in the morning (at 4 o'clock) chicory and rose hips open their flowers, at 5 o'clock - poppy, at 6 o'clock - dandelion, field carnation, at 7 o'clock - bellflower, garden potatoes, at 8 o'clock - marigolds and bindweed, at 9-10 o'clock - marigolds, coltsfoot. There are also flowers that open their corollas at night. At 20 o'clock the flowers of fragrant tobacco open, and at 21 o'clock - adonis and night violet. Flowers also close at a strictly defined time: at noon - field sow thistle, at 13-14 o'clock - potatoes, at 14-15 o'clock - dandelion, at 15-16 o'clock - poppy, at 16-17 o'clock - marigolds, at 17 -18 o'clock coltsfoot, at 18-19 o'clock - buttercup, at 19-20 o'clock - rosehip. The opening and closing of flowers also depends on many conditions, for example, on the geographical location of the area or the time of sunrise and sunset.

There are rhythmic changes in the body's sensitivity to damaging environmental factors. In experiments on animals, it was found that sensitivity to chemical and radiation injuries varies very noticeably during the day: at the same dose, the mortality of mice, depending on the time of day, varied from 0 to 10%

The most important external factor influencing the rhythms of the body is photoperiodicity. In higher animals, it is assumed that there are two ways of photoperiodic regulation of biological rhythms: through the organs of vision and then through the rhythm of the motor activity of the body and through extrasensory perception of light. There are several concepts of endogenous regulation of biological rhythms: genetic regulation, regulation involving cell membranes. Most scientists are inclined to think about polygenic control of rhythms. It is known that not only the nucleus, but also the cytoplasm of the cell takes part in the regulation of biological rhythms.

The central place among rhythmic processes is occupied by the circadian rhythm, which is of greatest importance for the body. The concept of circadian (circadian) rhythm was introduced in 1959 by Halberg. The circadian rhythm is a modification of the circadian rhythm with a period of 24 hours, occurs under constant conditions and belongs to freely flowing rhythms. These are rhythms with a period not imposed by external conditions. They are innate, endogenous, i.e. determined by the properties of the organism itself. The period of circadian rhythms lasts 23-28 hours in plants, 23-25 ​​hours in animals. Since organisms are usually found in an environment with cyclical changes in its conditions, the rhythms of organisms are prolonged by these changes and become daily.

Circadian rhythms are found in all representatives of the animal kingdom and at all levels of organization - from cellular pressure to interpersonal relationships. Numerous experiments on animals have established the presence of circadian rhythms of motor activity, body and skin temperature, pulse and respiration rates, blood pressure and diuresis. The contents of various substances in tissues and organs, for example, glucose, sodium and potassium in the blood, plasma and serum in the blood, growth hormones, etc., were subject to daily fluctuations. Essentially, all endocrine and hematological indicators, nervous and muscular indicators fluctuate in a circadian rhythm. , cardiovascular, respiratory and digestive systems. In this rhythm, the content and activity of dozens of substances in various tissues and organs of the body, in blood, urine, sweat, saliva, the intensity of metabolic processes, energy and plastic supply of cells, tissues and organs. The body's sensitivity to various environmental factors and tolerance to functional loads are subject to the same circadian rhythm. In total, about 500 functions and processes with circadian rhythms have been identified in humans to date.

The body's biorhythms - daily, monthly, annual - have remained virtually unchanged since primitive times and cannot keep up with the rhythms of modern life. Each person has clearly visible peaks and valleys of the most important life systems throughout the day. The most important biorhythms can be recorded in chronograms. The main indicators in them are body temperature, pulse, breathing rate at rest and other indicators that can only be determined with the help of specialists. Knowledge of a normal individual chronogram allows you to identify the dangers of the disease, organize your activities in accordance with the capabilities of the body, and avoid disruptions in its work.

The most strenuous work should be done during those hours when the body's most important systems function with maximum intensity. If a person is a “pigeon,” then peak performance occurs at three o’clock in the afternoon. If you are a “lark”, then the time of greatest activity of the body falls at noon. "Owls" are recommended to perform the most intense work at 5-6 pm.

Much has been said about the influence of the 11-year cycle of solar activity on the Earth's biosphere. But not everyone knows about the close relationship that exists between the phase of the solar cycle and the anthropometric data of young people. Kyiv researchers conducted a statistical analysis of the body weight and height of young men who came to conscription stations. It turns out that acceleration is very susceptible to the solar cycle: the upward trend is modulated by waves synchronous with the period of “reversal of polarity” of the solar magnetic field (which is a double 11-year cycle, i.e. 22 years). By the way, longer periods have been identified in the activity of the Sun, spanning several centuries.

The study of other multi-day (about a month, annual, etc.) rhythms, the time sensor for which are such periodic changes in nature as the change of seasons, lunar cycles, etc., is also of great practical importance.

In recent years, the theory of “three rhythms” has gained wide popularity, which is based on the theory that these multi-day rhythms are completely independent of both external factors and age-related changes in the body itself. The triggering mechanism for these exceptional rhythms is only the moment of birth (according to other versions, the moment of conception) of a person. A person was born, and rhythms arose with a period of 23, 28 and 33 days, determining the level of his physical, emotional and intellectual activity. The graphic representation of these rhythms is a sine wave. One-day periods in which phase switching occurs ("zero" points on the graph) and which are supposedly distinguished by a decrease in the corresponding level of activity are called critical days. If two or three sinusoids cross the same “zero” point at the same time, then such “double” or “triple” critical days are especially dangerous.

Multiple studies conducted to test this hypothesis have not, however, confirmed the existence of these super-unique biorhythms. Super unique because similar rhythms have not been identified in animals; no known biorhythms fit into an ideal sinusoid; periods of biorhythms are not constant and depend on both external conditions and age-related changes; No phenomena have been discovered in nature that would be synchronizers for all people and at the same time be “personally” dependent on the birthday of each person.

Special studies of fluctuations in the functional state of people have shown that they are in no way related to the date of birth. Similar studies of athletes conducted in our country, in the USA and other countries did not confirm the connection between the level of performance and sports results with the rhythms proposed in the hypothesis. It is shown that there is no connection between various industrial accidents, accidents and other road accidents with the critical days of the people who are responsible for these events. Methods of statistical processing of data that allegedly indicated the presence of three rhythms were also tested, and the fallacy of these methods was established. Thus, the “three biorhythms” hypothesis is not confirmed. However, its appearance and development have a positive significance, as they attracted attention to an urgent problem - the study of multi-day biorhythms, reflecting the influence of cosmic factors (Sun, Moon, other planets) on living organisms and playing an important role in human life and activity.

Biological rhythms— periodically repeating changes in the nature and intensity of biological processes and phenomena in living organisms. The biological rhythms of physiological functions are so precise that they are often called the “biological clock.”

There is reason to believe that the timekeeping mechanism is contained in every molecule of the human body, including DNA molecules that store genetic information. The cellular biological clock is called “small”, in contrast to the “large” one, which is believed to be located in the brain and synchronizes all physiological processes in the body.

Classification of biorhythms.

Rhythms, set by the internal “clock” or pacemakers, are called endogenous, Unlike exogenous, which are regulated by external factors. Most biological rhythms are mixed, that is, partly endogenous and partly exogenous.

In many cases, the main external factor regulating rhythmic activity is photoperiod, i.e., the length of daylight. This is the only factor that can be a reliable indicator of time and is used to set the "clock".

The exact nature of the clock is unknown, but there is no doubt that there is a physiological mechanism at work that may involve both neural and endocrine components.

Most rhythms are formed during the process of individual development (ontogenesis). Thus, daily fluctuations in the activity of various functions in a child are observed before birth; they can be recorded already in the second half of pregnancy.

• Biological rhythms are realized in close interaction with the environment and reflect the peculiarities of the organism’s adaptation to the cyclically changing factors of this environment. The rotation of the Earth around the Sun (with a period of about a year), the rotation of the Earth around its axis (with a period of about 24 hours), the rotation of the Moon around the Earth (with a period of about 28 days) lead to fluctuations in illumination, temperature, humidity, electromagnetic field strength, etc. etc., serve as a kind of indicators, or sensors, of time for the “biological clock”.
• Biological rhythms have large differences in frequency or period. There is a group of so-called high-frequency biological rhythms, the oscillation periods of which range from a fraction of a second to half an hour. Examples include fluctuations in the bioelectrical activity of the brain, heart, muscles, and other organs and tissues. By recording them using special equipment, they obtain valuable information about the physiological mechanisms of the activity of these organs, which is also used for diagnosing diseases (electroencephalography, electromyography, electrocardiography, etc.). The rhythm of breathing can also be included in this group.
• Biological rhythms with a period of 20-28 hours are called circadian (circadian, or circadian), for example, periodic fluctuations throughout the day in body temperature, pulse rate, blood pressure, human performance, etc.
• There is also a group of low frequency biological rhythms; these are peri-weekly, peri-monthly, seasonal, peri-annual, perennial rhythms.

The basis for identifying each of them is clearly recorded fluctuations of any functional indicator.

For example: The peri-weekly biological rhythm corresponds to the level of excretion of some physiologically active substances in the urine, the peri-monthly rhythm corresponds to the menstrual cycle in women, seasonal biological rhythms correspond to changes in sleep duration, muscle strength, morbidity, etc.

The most studied is the circadian biological rhythm, one of the most important in the human body, acting as a conductor of numerous internal rhythms.

Circadian rhythms are highly sensitive to the action of various negative factors, and disruption of the coordinated functioning of the system that generates these rhythms is one of the first symptoms of a disease in the body. Circadian fluctuations have been established for more than 300 physiological functions of the human body. All these processes are coordinated in time.

Many circadian processes reach maximum values ​​during the day every 16-20 hours and minimum values ​​at night or in the early morning hours.

For example: At night, a person's body temperature is lowest. By morning it increases and reaches a maximum in the afternoon.

The main reason for per diem fluctuations physiological functions in the human body there are periodic changes in the excitability of the nervous system, depressing or stimulating metabolism. As a result of changes in metabolism, changes in various physiological functions occur (Fig. 1).

For example: The respiratory rate is higher during the day than at night. At night, the function of the digestive apparatus is reduced.

Rice. 1. Circadian biological rhythms in the human body

For example: It has been established that the daily dynamics of body temperature has a wave-like character. At about 6 p.m., the temperature reaches its maximum, and by midnight it decreases: its minimum value is between 1 a.m. and 5 a.m. The change in body temperature during the day does not depend on whether a person is sleeping or engaged in intensive work. Body temperature determines speed of biological reactions During the day, metabolism is most intense.

Sleep and awakening are closely related to the circadian rhythm. A decrease in body temperature serves as a kind of internal signal for rest to sleep. Throughout the day it changes with an amplitude of up to 1.3°C.

For example: By measuring body temperature under the tongue (with a regular medical thermometer) every 2-3 hours for several days, you can quite accurately determine the most appropriate moment for going to bed, and use temperature peaks to determine periods of maximum performance.

Grows during the day heart rate(heart rate), higher arterial pressure(BP), more often breathing. Day after day, by the time of awakening, as if anticipating the increasing need of the body, the content of adrenaline in the blood increases - a substance that increases heart rate, increases blood pressure, and activates the work of the whole organism; By this time, biological stimulants accumulate in the blood. A decrease in the concentration of these substances in the evening is an indispensable condition for restful sleep. It is not without reason that sleep disturbances are always accompanied by excitement and anxiety: in these conditions, the concentration of adrenaline and other biologically active substances in the blood increases, and the body is in a state of “combat readiness” for a long time. Subject to biological rhythms, each physiological indicator can significantly change its level during the day.

Life routine, acclimatization.

Biological rhythms are the basis for the rational regulation of a person’s life schedule, since high performance and good health can only be achieved if the rhythm of life corresponds to the rhythm of physiological functions inherent to the body. In this regard, it is necessary to wisely organize the regime of work (training) and rest, as well as food intake. Deviation from the correct diet can lead to significant weight gain, which in turn, disrupting the body’s vital rhythms, causes changes in metabolism.

For example: If you eat food with a total calorie content of 2000 kcal only in the morning, weight decreases; if the same food is taken in the evening, it increases. In order to maintain the body weight achieved by the age of 20-25, food should be taken 3-4 times a day in strict accordance with individual daily energy expenditure and at those hours when a noticeable feeling of hunger appears.

However, these general patterns sometimes hide the diversity of individual characteristics of biological rhythms. Not all people experience the same type of fluctuations in performance. Some, the so-called “larks,” work energetically in the first half of the day; others, “owls,” in the evening. People classified as “early people” feel drowsy in the evening, go to bed early, but when they wake up early, they feel alert and productive (Fig. 2).

Easier to tolerate acclimatization a person, if he takes (3-5 times a day) hot meals and adaptogens, vitamin complexes, and gradually increases physical activity as he adapts to them (Fig. 3).

Rice. 2. Work capacity rhythm curves during the day

Rice. 3. Daily rhythms of life processes under constant external living conditions (according to Graf)

If these conditions are not met, so-called desynchronosis (a kind of pathological condition) may occur.

The phenomenon of desynchronosis is also observed in athletes, especially those training in hot and humid climates or mid-altitude conditions. Therefore, an athlete flying to international competitions must be well prepared. Today there is a whole system of measures aimed at maintaining familiar biorhythms.

For the human biological clock, the correct movement is important not only in the daily rhythm, but also in the so-called low-frequency rhythms, for example, in the periweekly rhythm.

It has now been established that the weekly rhythm is artificially developed: no convincing data have been found on the existence of innate seven-day rhythms in humans. Obviously, this is an evolutionarily fixed habit. The seven-day week became the basis of rhythm and rest in ancient Babylon. Over thousands of years, a weekly social rhythm has developed: people are more productive in the middle of the week than at the beginning or end of it.

The human biological clock reflects not only daily natural rhythms, but also those that have a longer duration, such as seasonal ones. They manifest themselves in an increase in metabolism in the spring and a decrease in it in the fall and winter, an increase in the percentage of hemoglobin in the blood and a change in the excitability of the respiratory center in spring and summer.

The state of the body in summer and winter to some extent corresponds to its state during the day and night. Thus, in winter, compared to summer, the blood sugar level decreased (a similar phenomenon occurs at night), and the amount of ATP and cholesterol increased.

Biorhythms and performance.

Rhythms of performance, like the rhythms of physiological processes, are endogenous in nature.

Performance may depend on many factors acting individually or jointly. These factors include: level of motivation, food intake, environmental factors, physical fitness, health status, age and other factors. Apparently, the dynamics of performance are also affected by fatigue (in elite athletes, chronic fatigue), although it is not entirely clear in what way. Fatigue that occurs when performing exercises (training loads) is difficult to overcome even for a sufficiently motivated athlete.

For example: Fatigue reduces performance, and repeated training (with an interval of 2-4 hours after the first) improves the athlete’s functional state.

During transcontinental flights, the circadian rhythms of various functions are rearranged at different speeds - from 2-3 days to 1 month. To normalize cyclicity before the flight, you need to shift your bedtime by 1 hour every day. If you do this within 5-7 days before departure and go to bed in a dark room, you will be able to acclimatize faster.

When arriving in a new time zone, it is necessary to smoothly enter the training process (moderate physical activity during the hours when the competition will take place). Training should not be of a “shock” nature.

It should be noted that the natural rhythm of the body’s life is determined not only by internal factors, but also by external conditions. As a result of the research, the wave nature of changes in loads during training was revealed. Previous ideas about a steady and straightforward increase in training loads turned out to be untenable. The wave-like nature of changes in loads during training is associated with the internal biological rhythms of a person.

For example: There are three categories of “waves” of training: “small”, covering from 3 to 7 days (or slightly more), “medium” - most often 4-6 weeks (weekly training processes) and “large”, lasting several months.

Normalization of biological rhythms allows intense physical activity, and training with a disturbed biological rhythm leads to various functional disorders (for example, desynchronosis), and sometimes to diseases.

Source of information: V. Smirnov, V. Dubrovsky (Physiology of physical education and sports).

BIOLOGICAL RHYTHMS (biorhythms), periodically repeating changes in the nature and intensity of biological processes characteristic of living organisms. In other words, it is “repetition of similar things in similar periods of time.” Biological rhythms are characteristic of plants, animals, and humans. They manifest themselves at all levels of the organization of life: molecular genetic, cellular, tissue, organismal, population-species, biocenotic and biosphere. They are divided into exogenous, occurring in organisms in response to cosmic, geophysical and other fluctuations occurring in the environment (for example, population fluctuations associated with the rhythms of solar activity), and endogenous, generated by the organism itself (cardiac, respiratory, etc.) . Physiological biorhythms change their parameters (frequency, strength) depending on the state of the body (age, illness, etc.). Ecological biorhythms depend on cyclical changes in the environment and are relatively stable. Moreover, they can persist if the animal finds itself in different conditions, for example. littoral invertebrates maintain the rhythm of the ebb and flow of the tide, being in an aquarium with a constant water level and stable indicators of its salinity and temperature. Among the ecological rhythms there are: annual with a period of 10 to 13 months, lunar with periods of 29.53 days and 24.8-12.4 hours (tidal), daily solar (24 hours).

The biorhythms of animals and humans are generated by a group of special pacemaker cells, or pacemakers (often called the biological clock). They are located in various organs, for example. in jellyfish - in the rhopalia (sensory organs), in crustaceans - at the base of the stalked eyes. In mammals, including humans, there are several rhythm centers, for example. in the region of the heart, diencephalon and medulla oblongata.

In humans, biorhythms, depending on the period of oscillation, are divided into high-frequency (from a second to half an hour), medium frequency (from half an hour to 28 hours), and low frequency (weeks, months, years). An example of biorhythmic fluctuations of high frequency are the rhythms of breathing, heart contractions, etc. Biorhythms of medium frequency (with an interval of 1.5 hours to 3 hours) are observed both in newborns, in whom activity is replaced by a state of rest every 90 minutes, and in adults - with With this frequency, the stages of sleep alternate, and during wakefulness, performance is replaced by relaxation. Rhythms with a period of 20–28 hours correspond to fluctuations in temperature, pulse, blood pressure, and bowel movements. The identification of low-frequency biorhythms is based on clearly recorded susceptibility fluctuations. functional indicator. For example, the weekly rhythm corresponds to the level of accumulation of certain hormones in the blood, the monthly rhythm corresponds to the menstrual cycle in women, and the seasonal rhythm corresponds to the duration of sleep.

Studying and maintaining established rhythms of human life is important for the rational organization of work and rest, which is especially important for people working different shifts, living in the Far North, and flying across several time zones. Scientists pay great attention to the so-called. calculated low-frequency rhythms - physical with a period of 23 days, emotional - with a period of 28 days and intellectual - with a period of 33 days. These rhythms are “started” at the moment of birth and then persist with amazing constancy throughout life. The first half of the period of each rhythm is characterized by an increase, the second - by a decrease in physical, emotional and intellectual activity.