Associate Professor, PhD O.L. Petrozak¹
Associate Professor, PhD I.R. Stovba¹
Associate Professor, PhD N.V. Stolyarova¹
Associate Professor, PhD E.Y. Savinykh^1
1South Ural State University (National Research University), Chelyabinsk

Keywords: adaptation, central and peripheral hemodynamics, heart rate variability, psychological support, self-regulation.

Introduction. Over the years, the cardiovascular system pathology has been ranking rather high in the Russian Federation. At the same time, there has been a steady trend towards rejuvenation of this disease. The results of study of physiological support for university students show that learning activities, especially during exams, are accompanied by a pronounced tension of the cardiovascular, respiratory and other systems. During exams, students are found to have increased systolic and diastolic blood pressure, increased heart rate and respiratory rate, raised body temperature, increased energy consumption [2, 4, 5]. As a result of prolonged exposure to stress factors, bodily adaptive capacity is depleted and diseased states develop [1, 6, 7]. The number of students forming a risk group and thus requiring preventive care is constantly growing, especially when their anxiety level is rather high [3, 6, 8].

In this view, the students were involved in the aerobics classes conducted with the inclusion of psychological support. These classes were focused on both active physical activity and mastery of body-oriented practices and basic techniques enabling to effectively regulate own psycho-emotional state, optimally adapt to the ever-increasing higher education requirements.

Many research works have been published recently on the peculiarities of central hemodynamics and heart rate variability [9]. However, in sports physiology this subject matter retains its relevance, thus providing a differentiated approach to the training process, also in the light of the prevailing type of autonomic regulation contributing to the improvement of students' functional readiness for learning activities [1, 5, 7] .

Objective of the study was to identify the peculiarities of the central and peripheral hemodynamics and mechanisms of regulation of the circulatory system in female students during aerobics classes conducted with the inclusion of psychological support.

Methods and structure of the study. Subject to the study run prior to the first semester (October 2017) at the Physical Education and Health Sub-department of South Ural State University were the Experimental Group composed of the beginner female students (n=23) trained in aerobics groups with special psychological support; and Reference Group (n=20) trained in classical aerobics groups.

The aerobics classes involved exercises of body-oriented psychogymnastics, as well as muscle and respiratory relaxation techniques, contributing to the formation of self-regulation skills. The aerobics classes were held at the beginning of the 1st semester (September-October) twice a week. Each class lasted 1.5 hours. Psychogymnastics and relaxation techniques were introduced at the end of the lesson and lasted 10-15 minutes.

The hemodynamic indicators were analyzed using the method of impedance rheography on the basis of the certified technology "Kentavr" and others (Chelyabinsk) (R.M. Bayevsky et al. 2003).

Results and discussion. The baseline study of the students’ cardiovascular system functionality was carried out in both Experimental Group and Reference Group (Table 1).

In the initial position, the heart rate and stroke volume values did not have any statistically significant intergroup differences, and were within the age-sex norm. The mean group cardiac index in both groups corresponded to the hypokinetic circulation type and was distributed as follows: in the majority of the examined girls SI was less than 2.75 l/min/m² - hypokinetic circulation type - about 55%; 35–40% - eukinetic circulation type and less often - hyperkinetic circulation type (6.6–10%).

Table 1. Central hemodynamics indices in female students of EG (1) and RG (2), M±m

Note. ***the differences between the results obtained in the prone and standing positions are significant at p<0.001.

At the moment of transition to the standing position - active orthostatic test - heart rate increased by 20–30%, which compensated for the magnitude of stroke volume decreased – the changes in both indicators were significantly significant (p<0.001); MBV remained at the same level.

A number of the examined female students were found to have more significant changes in the studied parameters (increase in heart rate by more than 30%), which was deemed as to manifestations of the maladaptive response: in 9 subjects of the 1st group (30%) and 8 subjects of the 2nd one (26.6%). An individual analysis of the spectral characteristics of heart rate revealed initially high values ​​of the relative oscillation rate in the low (LF) and very low frequency (VLF) ranges of the spectrum and an increase in the share of low frequency waves during the orthostatic test above 50%, which, along with a significant increase in blood pressure, was deemed as a manifestation of a hypersympathicotonic reaction (excessive vegetative support).

We conducted a spectral analysis of heart rate in the girls (Table 2).

In both groups, the highest oscillation rate was determined in the low-frequency range, with an individual analysis of the low-frequency oscillations prevailed in 19 subjects of the 1st group (63.3%) and in 21 subjects of the 2nd group (70%); the highest absolute power of very low frequency waves was found, respectively, in 36.7% and 30% of the examined individuals.

Table 2. Spectrum power indices of the heart rate of the female students of Experimental and Reference Group, M±m

At the moment of transition to the standing position the total spectrum power (TSP) decreased in both groups by 21.5–22.5% (p<0.05), which was associated with a decrease in the power of very low frequency waves (p<0.05), and significant - ULF (p<0.001) and high frequency waves (p<0.001) while maintaining the activity of the sympathetic division of the autonomic nervous system (the power of low frequency waves did not change).

Of great interest is the dynamics of relative oscillation rate within various ranges during the orthostatic test (see Figure 1).

In the prone position, heart rate was determined by the activity of the sympathetic division (the share of low frequency waves was 35–37% of TSP) and supersegmental structures of the autonomic nervous system (the share of very low frequency waves was 30–30.5% of TSP).

The transition to the standing position led to the activation of the sympathetic division and baroreflex mechanisms of regulation of the chronotropic function of the heart (the share of low frequency waves reached 48–49%); changes in the share of ULF and very low frequency waves was insignificant (within 10%), while the activity of the parasympathetic division decreased almost twofold - from 21% to 11–11.5%.

Percentage distribution of the total spectrum power of the heart rhythm in the female students of Experimental Group (1st group) and Reference Group (2nd group) over the frequency bands in the prone and standing positions

The ratio between the activity levels of the sympathetic and parasympathetic divisions of the autonomic nervous system (vagosympathetic balance index) at rest equaled 1.66–1.72 c.u., indicating a slight sympathicotonia; the centralization index (VLF+LF/HF) was equal to 3.0–3.3.

The mean group blood pressure values ​​in the initial position ranged within the physiological norm. At the moment of transition to the standing position, there was a tendency towards an increase in systolic blood pressure and a more pronounced increase in diastolic one (within 10%, p<0.01), which is a physiological response to the active orthostatic test.

A more significant increase in systolic blood pressure was detected in 9 female students (30%) of the 1st group and in 8 female students (26.6%) of the 2nd one, which testified to the hypersympathicotonic nature of orthostatic reaction.

The rheo-wave oscillation amplitude in the toe vessels decreased during the functional test (p<0.001), reflecting the way the peripheral vessels responded - narrowed to prevent orthostatic collapse. It decreased twice; in the trained subjects there was a less pronounced reaction.

Conclusions. According to the findings, the vegetative status of the examined female students of Experimental and Reference Group was described as eutonia. In both groups, the highest oscillation rate was determined within the range of low frequency waves, while the greatest absolute power of very low frequency waves was found, respectively, in 36.7% of the Experimental Group girls and 30.0% of Reference Group ones, thus reflecting tension of the adaptation processes.

The study results were included in the database of the primary functionality cardiovascular system test data and spectral characteristics of slow-wave heart rate variability of female students, on the basis of which the psychophysiological state and functional state of cardiovascular system in female students involved in aerobics with psychological support are monitored nowadays. Based on the data obtained, the development of corrective psychophysical self-regulation model and test in benefits in an annual training cycle is carried out.

References

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8. Nikulina, A., Kozlov, V., Shukanov, A. Changes in heart rate variability as a reflection of implemented physiological mechanisms of adaptation. HUMAN. SPORT. MEDICINE. 2017. no. 17(4). pp.14-20.

Corresponding author: 24022403@mail.ru

Abstract

The study analyses the cardiovascular system and blood circulation control mechanisms in female aerobics groups supported by psychological service; and offers a psychological self-regulation model to improve the functions. Subject to the study run prior to the first semester (October 2017) at the Physical Education and Health Sub-department of South Ural State University were the Experimental Group composed of the beginner female students (n=23) trained in aerobics groups with special psychological support; and Reference Group (n=20) trained in classical aerobics groups. The pre-experimental cardiovascular system and blood circulation control mechanisms functionality tests found high stress indices, vegetative Kerdo indices, sympathicotonic primary vegetative tonus and excessive autonomic regulation in 30% of the sample. The primary functionality test data were used to develop the corrective psychophysical self-regulation model and test in benefits in an annual training cycle.