The state of hemodynamics of trainees of vocational training during a fire training class

Arkhipov Sergei Nikolaevich Associate Professor at the Department of Firearms Training of Tyumen Institute of Professional Training of Internal Affairs Officers 625000, Russia, g. Tyumen', ul. Amurskaya, 75/2 as.master13@mail.ru Other publications by this author

Sinitsyn Evgeniy Igorevich Lecturer at the Firearms Training Department of Tyumen Professional Training Institute of the Ministry of Internal Affairs of Russia 625049, Russia, Tyumenskaya oblast', g. Tyumen', ul. Amurskaya, 75 evgeniy.sinitsyn.2019@mail.ru Other publications by this author

Introduction.

Continuously working, the human heart always responds accurately to the needs of the body, maintaining the necessary level of blood flow. The adaptation of the heart to the changing needs of the body occurs with the help of a number of regulatory mechanisms ^[2]. Some of them are localized in the heart itself, the second group consists of extra-cardiac extracardial nervous and humoral regulatory mechanisms ^{[3, 4]}. Nervous extracardial regulation is carried out by impulses coming to the heart from the central nervous system via vagus and sympathetic nerves. The nervous system carries out the most urgent actions that allow changing the functional activity of the heart quickly, with the least latency period. Stimulation of sympathetic and parasympathetic nerves usually has opposite effects on the heart ^[5]. Prolonged continuous irritation of the vagus nerves reduces the contractions of the heart until it stops completely in the diastole. The vagal reflexes also include the Aschner ocular reflex (reduction of heartbeats by 10-20 beats / min when pressing on the eyeballs). However, the idea of antagonism between sympathetic and parasympathetic influences on the heart is a simplified scheme ^[2]. In the whole organism, the relationship between them is much more complex. They are formed at different structural and functional levels - from the central nervous system to the membrane of myocardial cells. Under certain conditions, the parasympathetic system can have not only inhibitory, but also reinforcing and accelerating effects on the heart.

         The study of hemodynamic and external respiration indicators can be of great benefit not only in preserving the life and health of employees, but also to improve the quality of tasks in fire training classes when mastering vocational training programs in educational organizations of the Ministry of Internal Affairs of Russia ^[6]. In order to establish the connection of hemodynamic and respiratory indicators of students with training in an educational organization of the Ministry of Internal Affairs of Russia, a set of functional tests was developed. The method of conducting exercises and trials should be accessible and easily applicable. In this case, conditions will be created for regular examination of students to determine their functional state.

The purpose of the study: to establish the relationship between hemodynamic and respiratory indicators of trainees of vocational training in a fire training class.

To achieve this goal , the following tasks were formulated:

1. To consider the features of the activity of some functional systems of the human body.

2. Develop a set of functional diagnostics of employees and determine its main indicators during the study.

3. Systematize the results obtained by the method of mathematical statistics.

   The course of the study.

  This study was conducted in the period from 2021 to 2022 on the basis of the Tyumen Institute for Advanced Training of Employees of the Ministry of Internal Affairs of Russia. The study involved 48 trainees who received professional training in the main program: "Professional training of enlisted personnel and junior commanding officers who were first recruited to the internal affairs bodies as a "Policeman" employee." The respondents were divided into 2 subgroups of 24 people each.  Male employees were represented in the first subgroup, female employees in the second subgroup.

  A set of functional tests was developed for the study. This complex includes the following indicators: heart rate, frequency of respiratory movements, duration of an individual minute, heart rate after pressing fingers on the eyeballs (Danini-Aschner reflex), duration of breath retention during inhalation and exhalation (at rest, after exercise, after hyperventilation).

    The heart rate (HR) was determined by palpation on the radial artery in a sitting position. The number of heartbeats per 1 minute was determined several times, then the arithmetic mean heart rate per minute was calculated. The frequency of respiratory movements (BDD) was determined by the excursion of the chest. Two breathing acts (inhalation and exhalation) were taken for one breathing movement.

             The duration of an individual minute was determined as follows: the subject was told that they had started counting, and he, without seeing the clock, had to answer when, in his opinion, a minute had passed. Next, the time elapsed from the beginning to the end of the experiment is recorded in seconds.

         With the help of the Danini-Aschner technique, the nature of the reflex effect on the activity of the heart was studied. The heart rate for 1 minute was determined by the pulse while sitting. Then the subject pressed his fingers on the eyeballs with his eyelids closed for 15 seconds. After the start of exposure, the pulse was counted every 10 seconds, ten times. The received data were entered into a table. The sample was evaluated according to the following system:

1. A decrease in the pulse rate by 4-12 beats / min is a normal reaction.

2. A reduction of more than 12 beats /min is a sharply enhanced reaction.

3. There is no reduction – an aretive reaction.

4. The increase in frequency is a perverse reaction.

         The next part of the developed complex consisted of functional breath-holding tests. At the first stage, respiratory retention was carried out in a sitting position, at the second stage, respiratory retention was performed after physical exertion (15 squats), and at the last stage, respiratory retention was performed after hyperventilation of the lungs. The method of conducting respiratory tests: the subject takes a maximum breath and holds his breath. According to the stopwatch, the time of the onset of involuntary exhalation is marked, then rest for 10 seconds. Then the maximum exhalation is made and the breath is held. The time of the onset of involuntary inhalation is determined. After resting, the subject does 15 squats and holds his breath again on the inhale and exhale. After resting, the subject hyperventilates the lungs (breathes deeply and intensely until a slight dizziness appears) and again holds his breath on inhalation and exhalation. The complex of functional tests is completed.

            The results of the study.

The heart rate of the subjects was low (Table 1). Usually, the heart rate in the group of women is slightly lower compared to men. In our work, the heart rate of male and female employees differ little, the minimum value of the indicator was in the female group at the second stage of the survey. In both groups, there was a decrease in the number of heartbeats in the second stage of the examination (in men up to 67.8 ± 1.9 beats/min; in women up to 66.4 ± 2.5 beats/min). In accordance with the heart rate at the second stage of the examination, the frequency of respiratory movements decreased (in men up to 15.9 ± 0.6 movements; in women up to 13.8 ± 0.8 movements per minute). The highest rate was in men in the first stage of the examination - 16.4 ± 0.6 chest excursions per minute.

Table 1. Heart rate and respiratory movements

The perception of time by male employees (Fig. 1) was very close to real, both in the first stage of the survey (62.5 seconds) and in the second stage (63.3 seconds). In the female group, on the contrary, this indicator deviated from the real one (60 seconds) in the first case down (52.8 seconds), in the second case up (70.4 seconds). The reason for this may be the maladaptation of women caused by a sharp change in the usual lifestyle associated with the beginning of vocational training in an educational organization of the Ministry of Internal Affairs of Russia.

The ocular test is used to determine the state of excitability of the parasympathetic centers of heart rate regulation. Normally, pressure on the eyeballs causes a slowing of the heart rate. The increase in rhythm is interpreted as a perversion of the reflex, which proceeds according to the sympathetic type. Since the number of heartbeats was determined every 10 seconds. for 100 seconds, then subsequently multiplied each value by 6 and obtained a heart rate for every 10 seconds.

Fig. 1. Duration of an individual minute

The obtained results were put on a graph in the form of a distribution curve.

The heart rate in the group of men when pressing fingers on the eyeballs at the first stage of the examination changed little, so the heart rate distribution curve every 10 seconds. It is more stable compared to women (Fig. 2). The arithmetic mean value of the pulse recorded for 100 seconds was calculated. as follows: the number of heartbeats for every 10 seconds. multiplied by 6, we got the heart rate in min. Next, the resulting values were added and divided by 10, since the determination was made every 10 seconds. for 100 seconds (Table 2).

On average, in the group of men, the reflex effect on the activity of the heart led at the first stage to a decrease in the pulse rate by 5.4 beats /min, which corresponds to the normal excitability of the parasympathetic centers of heart rate regulation. The lowest heart rate values were observed in the last 30 seconds, when, it would seem, there should be a recovery of the values of the indicator to the value characteristic of the resting state.

Fig. 2 Reflex effect on the activity of the heart when pressing fingers on the eyeballs with closed eyelids at the first stage

The girls had a different reaction during the ocular test at the first stage. The maximum deceleration of the pulse (up to 58.0 beats/min) was noted in a time interval of 10 seconds. up to 20 seconds from the beginning of finger pressure. Thus, in this period of time, the heart rate decreased by 10.5 beats /min, which corresponds to the normal excitability of the parasympathetic centers of heart rate regulation. Partial recovery of the pulse in the girls (up to 64.4 beats / min) occurred in the time interval between 80 sec. and 90 sec. from the beginning of finger squeezing.

Table 2. Heart rate

         Change in heart rate for 100 seconds. at the second stage of the examination, there were a number of distinctive features (Table 2, Fig. 3). The distribution of heart rate in young men had an atypical picture, since the maximum slowing of the pulse occurred in the last 50 seconds, instead of the expected recovery of heart rate.

Fig. 3. Reflex effect on the activity of the heart when pressing fingers on the eyeballs with closed eyelids at the second stage

If we take the average value for 100 seconds, but in terms of 1 minute (Table. 2), then we see that the pulse slowed down by 5.8 beats/min and amounted to 62.6 beats/min. This effect indicates the normal excitability of the parasympathetic centers of heart rate regulation.

       In women at the second stage, the heartbeat distribution curve has more significant deviations compared to men (Fig. 3). The maximum slowing of the heart rate (up to 57.3 beats/min) was noted in the time interval of 60-70 seconds. after ocular exposure. The decrease in heart rate compared to the indicator recorded at rest is 9.6 beats / min and indicates the normal excitability of the parasympathetic centers of heart rate regulation.

     In general, both women and men had normal excitability of the parasympathetic heart rate regulation centers during the ocular test during two examinations. Arousal in this department leads to a slowing of the heart rate in the range from 4 to 12 beats /min.  Sexual dimorphism was revealed in the reflex effect of finger squeezing of the eyeballs. In women, the heart rate at ten-second readings for 100 seconds. after the beginning of squeezing, it has a higher spread in both the first and second examinations.

             The duration of breath retention in men on inspiration was more than twice as long as the delay on exhalation (Table 3). At the first stage, men maximally held their breath after inhalation for 72.80 ± 2.4 seconds, after exhalation for 31.15 ± 1.2 seconds. At the second stage of the survey, this indicator was 76.83 ± 2.5 seconds and 32.54 ± 1.3 seconds, respectively, slightly exceeding the previous result. In the group of women on exhalation, the duration of breath retention differed little from men and amounted to 33.20 ± 1.7 seconds at the first stage, 31.23 ± 1.7 seconds at the second stage. When inhaling, the women held their breath for less than a long time: 53.60 ± 2.4 seconds. at the first stage and 56.34 ± 2.4 sec. at the second stage.

Table 3. Duration of respiratory retention at rest

The duration of breath retention decreased sharply after performing a standard load (15 squats). The physical development of the listeners varies, respectively, and the reaction to physical exercises changes. In one case, the duration of breath retention decreases sharply, due to reduced adaptability to physical exercises, in the other case, the duration of breath retention does not change significantly. The latter is especially relevant for professional athletes whose cardiovascular and respiratory systems have long been adapted to intense physical exertion.

After 15 squats, the men held their breath while inhaling for half of the result (Table. 4), achieved at rest (34.83 ± 1.4 sec. on the first and 35.91 ± 1.4 sec. at the second stage). In women, the duration of the inhalation delay after physical exertion was slightly lower compared to men (33.54 ± 1.7 sec. on the first and 31.26 ± 1.9 sec. at the second stage). However, compared to the result achieved at rest, the duration of breath retention decreased by 20-25 seconds. When exhaling after physical exertion, women held their breath a little longer than men. This phenomenon can be explained by the fact that men were holding their breath with great enthusiasm, trying to hold out without breathing as long as possible. There was a "sporting interest". Therefore, they exhaled after a delay when severe hypercapnia occurred. Breath retention on exhalation was already performed at a higher concentration of carbon dioxide in the body and, accordingly, the duration of breath retention on exhalation decreased. 

Table 4. Duration of breath retention after physical exertion

After intensive lung purging, the time of breath retention increased sharply, exceeding not only the previous value, but also the indicator obtained at rest (Table 5). Men held their breath the longest at the first stage of the examination (83.16 ± 2.7 seconds).

Table 5. Duration of respiratory retention after hyperventilation of the lungs

At the second stage, the duration of delay after hyperventilation was also high (78.31 ±2.6 sec.). Women managed to hold their breath after hyperventilation of the lungs for a slightly shorter time (68.43 ± 3.0 sec. at the first stage of the survey). At the second stage, the duration of the delay after lung purging did not even reach a minute (57.36 ± 2.8 seconds).

A similar result may be due to the fact that the strength of the contractions of the muscles involved in the act of breathing in women is lower than in men. Therefore, women do not manage to purge the lungs so intensively and reduce the hypercapnia of the body.

Thus, based on the performed functional diagnostics, hemodynamic parameters and external respiration during fire training classes in the studied category, the data obtained can be used to develop and implement individually differentiated technologies for self-regulation of employees.