PhD A.V. Dobrin
Yelets State Ivan Bunin University, Yelets

Keywords: heart rate, heart rate variability, autonomic nervous system, emotions, adaptation to physical loads, primary schoolchildren.

Introduction. Numerous studies in the field of regulation of primary schoolchildren’s motor regime show that adaptation to physical loads is an important factor in prevention of cardiovascular diseases [1, 3, 4, 6, 10]. In turn, it has been established that physical exercises are among the factors minimizing the impact of negative emotions on the cardiac function [6, 7]. It is known that emotional state is associated with the activity of the autonomic nervous system [5, 14]. Negative emotions like anxiety, fear, uncertainty, lead to a decrease in the level of mobilization of the body’s energy resources, while positive emotions cause their increase [7, 12, 13]. This suggests that, among other tasks, the measures taken to preserve and protect children’s health are to be focused on the organization of physical education classes at primary school, during which physical exercises are to be combined with a certain emotional state of the children, contributing to better mobilization of the body’s energy resources and, as a result, successful adaptation to motor activity.

It is known that heart rate variability indices are among the indicators of adaptation to physical loads, and one of the psychophysiological methods that adequately reflect individual’s emotional responses is registration of the HRV indices, which demonstrates the collaborative effect of the sympathetic and parasympathetic nervous system in the process of adaptation to a particular situation [1, 9].

Therefore, the analysis of the HRV indices under emotional stress may reveal the state of the body's regulatory systems and, as a consequence, make it possible to predict the specifics of primary schoolchildren’s adaptation to physical loads.

The HRV results during physical activity demonstrate that, with the predominance of one or another type of heart rate regulation, equal loading during the primary school physical education classes causes various adaptive reactions in the schoolchildren [6]. At the same time, available literature lacks the information on the peculiarities of heart rate control in primary schoolchildren under emotional stress. That is why the objective of our study was to analyze the peculiarities of primary schoolchildren’s heart rate regulation when they recall positive and negative emotions. It is assumed that detection of the heart rate control peculiarities indifferent emotional situations will make it possible to predict the degree of influence of these emotions on their heart rate regulation and thus improve their adaptation to physical loads.

Objective of the study was to analyze the heart rate variability (HRV) in the primary schoolchildren under emotional stress.

Methods and structure of the study. The study involved 7-8 year-old primary schoolchildren (n=150). The sample of the experimental study was represented by 86 boys (mean age – 7.27±0.45 years) and 64 girls (mean age – 7.19±0.39 years). The HRV data were obtained using the modern Omega-M computerized test system in the following test modes: background condition test; motivation-related condition test; and punishment-related condition test, with 300 R-R intervals recorded in every test [3]. We registered such HRV parameters as: average duration of R-R intervals, standard deviation of R-R intervals from their arithmetic mean (RMSSD), mode of R-R intervals (Mo), amplitude mode of RR intervals (AMo), variation range of R-R intervals (dX), HRV triangular index, HF-wave power in the spectrum of HRV (HF - High Frequency), LF-wave power in the spectrum of HRV (LF - Low Frequency), LF/HF ratio, total spectrum power (total) .

Results and discussion. The results of the HRV study were presented in Table 1 below. There were statistically significant differences in the standard deviation of the R-R intervals at rest and when recalling punishment. The standard deviation of the R-R intervals is an indicator reflecting the functioning of the parasympathetic regulation unit, and the higher its value, the more active the parasympathetic regulation unit [2]. We found the standard deviation of the R-R intervals to be lower when recalling punishment than at rest and when recalling encouragement. Consequently, recalling negative emotions promoted an increase in the activity of the sympathetic nervous system in the 7-8 year-olds.

Table 1.Heart rate variability indices in the 7-8 year-olds (mean value and standard deviation)

Note: * – differences in the resting and encouragement/punishment-related psychophysiological parameters in the children, significance level p≤0.05 (Mann-Whitney U-test); ** – p≤0.01 (Mann-Whitney U-test).

We also detected the statistically significant differences in such heart rate variability indices as HF and LF/HF at rest and when recalling a highly emotional situation.

The HF-wave power in the state of rest and when recalling positive emotions was proved to be higher than that when recalling negative emotions, and since this index reflects the functioning of the parasympathetic nervous system, its increase is associated with the activation of the parasympathetic division of the nervous system.

The LF/HF parameter reflects the ratio of the sympathetic and parasympathetic effects of the ANS on the heart rhythm. At the same time, this indicator increases significantly with an increase in the tone of the sympathetic division. We found that, as opposed to the state of rest, the values of this parameter increase when recalling encouragement, and the highest values are registered when recalling punishment.

These data are consistent with the previously obtained data, according to which, it is the sympathetic nervous system that is activated in the 7-8 year-old children when recalling punishment, while the parasympathetic one is activated when recalling encouragement [3].

Heart rate control is known to have a hierarchical structure. Decreasing HRV is not specific for the way physical load is formed [8, 10, 11]. Our findings are consistent with the data obtained earlier, namely, that heart rate regulation in the 7-8 year-olds is characterized by an increase in the total neurohumoral effects and autonomous control contour activity, represented by the high- and low-frequency waves, the same is true for the central contour, which is estimated based on the analysis of the ultra-slow waves. By the age of 8, we observed a gradual decrease in the power of the high-frequency (HF) waves and an increase in the power of the low-frequency (LF) ones, which indicated the decreased activity of the parasympathetic influences on the cardiac rhythm and increased role of the central regulatory influences on the cardiac activity. In addition, we detected a shift in the autonomic balance towards increasing sympathetic influences on the heart rate, which corresponds to the data on the significance of the sympathetic division in the heart rate regulation in the 8-year-olds [4].

Conclusions. The research findings prove the necessity of planning primary schoolchildren’s physical loads with due regard to the functional state of their body’s regulatory systems. The amount and intensity of load, as well as types of exercises, are to be individually adjusted depending on the individual typological features of the regulatory systems, while physical loads are to be supported by positive emotions, as negative emotions were found to increase the activity of the central control contour, which facilitates the processes of disregulation due to growing fatigue in children

The study was performed with financial support from the Russian Research Foundation (Project № 18-013-00323 “The formation of sensorimotor integration and inhibitory control in ontogeny in children with different lateral preferences” )

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Corresponding author:doktor-alexander@mail.ru

Abstract

Many studies show the need for high priority to be given to the health-centered primary physical education process models designed to secure due emotional backgrounds to improve the energy mobilization and adaptation to physical activity. Objective of the study was to analyze the heart rate variability (HRV) to estimate 7-8 year-olds’ (n=150) physical education process efficiency versus the process emotionality indices, with the modern Omega-M computerized HRV test system applied for the tests. The HRV data were obtained in the following test modes: background condition test; encouragement-related condition test; and punishment-related condition test, with 300 R-R intervals recorded in every test. The study data showed that the highly emotional situations are associated with the activation of the sympathetic nervous system in the HR control domain. Positive emotions were found to increase the influence of the parasympathetic nervous system on the HR to facilitate adaptation of the primary schoolchildren to physical loads. The study data largely agree with other study reports in the finding that the primary schoolchildren’s HR control is secured by summated neurohumoral effects and activity of the autonomous control contour.