Yu.G. Kalinnikova
Associate Professor, PhD E.S. Inozemtseva
Professor, Dr.Sc.Psych. E.V. Galazhinskiy
Professor, Dr.Med. L.V. Kapilevich
National Research Tomsk State University, Tomsk

Keywords: heart rate variability, spectral analysis, coherency, rhythmic load, electroencephalographic indices, EEG rhythm.

Introduction. Heart rate variability analysis is a method of assessing the state of physiological functions regulation mechanisms in the human body, in particular the overall regulatory mechanisms activity, neurohumoral regulation of the heart and the ratio of the sympathetic and parasympathetic nervous systems [6, 8].

Processing of electroneurophysiological data is gaining particular importance in modern biology and medicine [5]. Recording of the local potential of brain cells in man whose coherent electromagnetic field is characteristic of determined frequency and energy is important. The integrity of the brain as a system is ensured by the coherence of signal streams circulating therein [2]. The brain and particularly its cortex present a network of thousands of functional systems of various adaptive significance, from which it is difficult to single out structures belonging to each of these functional systems [1]. The intensity and nature of physical activity affect the laws of formation of the cerebral cortex alpha-activity patterns [7].

Coherence of the electrical signals of the brain is a quantitative indicator of involvement synchronicity of different cortical areas during their interaction. High coherence means that there is an activity in two points of electrical potentials registration that is coincident in frequency and constant in terms of phases ratio. Coherent analysis can serve as a basis to assess the interrelation of physical and cognitive activity [3, 4].

Objective of the study was to explore the effects of rhythmic loads of various intensity on the intra-hemispheric coherent communication formation process and on the heart rate control variability.

Research methods. Subject to the study were 30 young women of 17-20 years of age. The coherent communication was tested by a computerized Neuron-Spectrum Electroencephalograph System (made by NeuroSoft Research and Production Company based in Ivanovo, Russia). Electroencephalograms were recorded monopolarly in the following leads: F3, F4, С3, C4, P3, P4, O1, O2 using the 10-20% system. An EEG was recorded with the testee's eyes closed during 1 minute before the exercise and immediately after the aerobic part of the exercise with different levels of rhythmic loads: S (slow) – 115-125 beats/min, M (medium) – 125-140 beats/min and F (fast) – 140-160 beats/min for 20-25 minutes. Cardiointervalography was used to study the adaptation characteristics of the cardiovascular system of young women to the level of rhythmic loads.      

Research results and discussion. Classes with the S (slow) rhythmic load increase the maximum power of alpha and beta rhythms, which indicates an increase in the readiness level of the body for physical loads. A further load increase to M (medium) level leads to a decrease in the capacity of these rhythms indicating discernible psychological and emotional fatigue, weakening mental alertness and worsening of body fatigue. In case of F (fast) rhythmic load an increase in the maximum capacity of the delta rhythm was observed, which is seen as a reflection of the inhibitory processes intensification in the central nervous system, including those of protective nature.   

The level of alpha rhythm coherence after the rhythmic loads of S (small) and M (medium) levels decreases in the occipital regions (Table 1).

Table 1. Coherence level of alpha and theta rhythms in the frontal and occipital leads (Me (Q₁;Q₃)

Rhythmic loads of 125-140 beats/min and 140-160 beats/min also reduced the rate of theta activity coherence in all the derivations. The rhythm increase from 115-125 to 140–160 beats/min led to a decrease in delta activity coherence and dominating frequency in the frontal region. In the central and parietal regions the S (small) load reduced the level of delta activity coherence, while the F (fast) load restored it to its original level.

LF, HF and VLF indices significantly decrease after the S (slow) load (Table 2), indicating the prevalence of the central influence on the heart rhythm by reducing the activity of the autonomous regulation center. 

Table 2. Heart rate characterized using spectral analysis (Me (Q₁;Q₃)

Note. * – significant difference at р<0.05 compared with the group of young women engaged in M (medium) level aerobics;  

** – significant difference at р<0.05 compared with the group of young women engaged in aerobics in group 3;

↓– significant decrease after load.

An increase of the load intensity to the M (medium) level reduced VLF, indicating a decrease in the activity of the cardiovascular subcortical nervous center, while reduced HF characterizing the tone of the vasomotor center confirms the assumption about the increasing autonomous influence on the heart rate. The F (fast) load level increases VLF, which indicates an increased activity of the subcortical regulation center by heart rate. Changing the load rhythm from 125–140 to 140–160 beats/min led to increased LF, confirming a greater activity of the vasomotor center, baro- and chemoreceptors in this group. Judging by HF values, when the load rhythm increases to 160 beats/min, the vagus activity increases along with the ergotropic and vagoinsular influences.

Conclusion. The study showed that the low-frequency rhythmic loads are associated with the intra-hemispheric short coherent communications being desynchronized, whilst the higher-frequency movements were found to help synchronize the cerebral electric activity. These changes were found to affect the heart rate control system – at the S (slow) level load the central influence on the heart rate prevails, growth of the load intensity to the M (medium) level increases the autonomous influence, the F (fast) level enhances the activity of the subcortical heart rate regulation center.

We assume that the specific effects of different physical activity on the cortical processes are basically due to bioelectrical activity patterns with variable coherence rates being formed in the cortex, the patterns being able to modulate the centralization level of the vegetative system control mechanisms.

References

1. Balanev D.Yu., Kapilevich L.V., Shil'ko V.G. Perspektivy primeneniya metodov monitoringa dvigatelnoy aktivnosti cheloveka v sporte [Perspectives of Application of Motor Activity Monitoring Techniques in Sport]. Teoriya i praktika fiz. kultury, 2015, no. 1, pp. 58-60.
2. Kabachkova A.V., Lalaeva G.S., Zakharova A.N., Kapilevich L.V. Vliyanie urovnya dvigatel'noy aktivnosti na prostranstvennoe raspredelenie alfa-ritma elektroentsefalogrammy [EEG alpha rhythm spatial distribution depending on level of motor activity]. Teoriya i praktika fiz. kultury, 2016, no.2, pp. 83-85.
3. Kalinnikova Yu.G., Inozemtseva E.S., Kapilevich L.V. Vliyanie ritmo-tempovoy struktury na psikhofiziologicheskie kharakteristiki pri zanyatiyakh aerobikoy [The Effect of Different Rhythm and Tempo of Aerobics Classes on Psychophysiological and Electroneuromyographic Characteristics]. Teoriya i praktika fiz. kultury, 2014, no.9, pp. 98-101.
4. Kalinnikova Yu.G., Inozemtseva E.S., Galazhinskiy E.V., Balanev D.Y., Kapilevich L.V.  Kogerentny analiz EEG pri fizicheskikh nagruzkakh i zvukovom soprovozhdenii razlichnoy ritmo-tempovoy struktury [Analysis of EEG coherence effects of physical loads and rhythmic auditory stimulation]. Teoriya i praktika fiz. kultury, 2015, no.11, pp. 36-38.
5. Kalinnikova Yu.G., Inozemtseva E.S., Galazhinskiy E.V., Balanev D.Y., Kapilevich L.V.  Vliyanie fizicheskikh nagruzok i muzykal'nogo soprovozhdeniya razlichnoy ritmo-tempovoy strukturoy na bioelektricheskuyu aktivnost' golovnogo mozga [Effect of exercise and sound accompaniment with different rhythm and tempo on brain bioelectrical activity]. Teoriya i praktika fiz. kultury, 2015, no. 7, pp. 5-7.
6. Koshel'skaya E.V., Kapilevich L.V., Bazhenov V.N. Fiziologicheskie i biomekhanicheskie kharakteristiki tekhniki udarno-tselevykh deystviy futbolistov [Physiological and biomechanical characteristics of targeted kicking technique of football players]. Bulletin of Experimental Biology and Medicine, 2012, vol. 153, no.2, pp. 235-237.
7. Lalaeva G.S., Zakharova A.N., Kabachkova A.V. Vliyanie urovnya dvigatel'noy aktivnosti na prostranstvennoe raspredelenie teta-ritma elektroentsefalogrammy [Effect of level of motor activity on spatial distribution of EEG theta rhythm]. Novosibirsk State Pedagogical University Bulletin, 2016, no.1 (29), pp. 141-148.
8. Potovskaya E.S., Kabachkova A.V., Shil'ko V.G. Primenenie analiza variabel'nosti serdechnogo ritma dlya otsenki funktsional'nogo sostoyaniya organizma studentok [Analysis of heart rate variability to assess functional state of female students: application features]. Tomsk State University Bulletin, 2011, no.346, pp. 140-143.

Corresponding author: kapil@yandex.ru

Abstract

Objective of the study was to explore the effects of rhythmic loads on the intra-hemispheric coherent communication formation process and on the heart rate control variability. Subject to the study were 30 young women of 17-20 years of age. The coherent communication was tested by a computerized Neuron-Spectrum Electroencephalograph System (made by NeuroSoft Research and Production Company based in Ivanovo, Russia).

The study showed that the low-frequency rhythmic loads are associated with the intra-hemispheric short coherent communications being desynchronized, whilst the higher-frequency movements were found to help synchronize the cerebral electric activity. These changes were found to affect the heart rate control system, with the growing movement frequency being of strengthening effect on the autonomous control mechanism. We assume that the specific effects of different physical activity on the cortical processes are basically due to bioelectrical activity patterns with variable coherence rates being formed in the cortex, the patterns being able to modulate the centralization level of the autonomic system control mechanisms.