Koryagina Yu.V., Ter-Akopov G.N., Roguleva L.G., Abutalimova S.M., Nopin S.V. Transcranial stimulation in current recovery of triathletes during training at middle altitude

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Publication date: 15.06.2024
DOI: 10.24412/2782-6570-2024_03_02_6      
UDC 615.83; 796

TRANSCRANIAL STIMULATION IN CURRENT RECOVERY OF TRIATHLETES DURING TRAINING AT MIDDLE ALTITUDE

Yu.V. Koryagina, G.N. Ter-Akopov, L.G. Roguleva, S.M. Abutalimova, S.V. Nopin

FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, Russia

Abstract. Previously, scientists proved the effectiveness of transcranial electrical stimulation in normal oxygen conditions. Under the influence of transcranial electrical stimulation, values of central hemodynamic indices normalize, and recovery after physical activity is accelerated. Aim of the study: to investigate the effects of transcranial electrical stimulation on the recovery of triathletes during training at middle altitude. The study involved 12 athletes. It took place in Kislovodsk, on the Maloe Sedlo mountain in middle altitude conditions (1240 m). We have found that the transcranial electrical stimulation course consisting of eight 30-minute sessions increases the speed of sensorimotor actions, improves mental capacity, optimizes the sympathetic and parasympathetic balance, reduces amplitude of the beta, delta and theta rhythms. Changes in the indices of temporal and spectral analysis of heart rate variability, variation pulsometry in male and female triathletes show positive effect of transcranial electrical stimulation on heart rate autonomic regulation mechanisms, which was more pronounced in women. The course also contributed to the improvement of psychophysiological indices, i.e. reduced time and stability of a simple sensorimotor response.

Keywords: transcranial electrical stimulation, physiotherapy, triathletes, middle altitude, recovery, functional status.

Introduction. Nowadays, in the field of sports medicine, doctors, coaches and athletes show interest in methods that allow to promptly neutralize the consequences of psychoemotional and physical stress associated with sports, restore the psychofunctional status of the body, primarily the regulatory systems (nervous, humoral and hormonal systems) [1-3].

Transcranial electrical stimulation (TES) was invented as a method of exposure in the Pavlov Institute of Physiology. Numerous biological and clinical studies made it possible to identify the necessary stimulation parameters (rectangular pulses with a frequency of 77 Hz and duration of 3.75±0.25 ms combined with a galvanic component exceeding in its value by 2-5 times the average pulse current) in order to achieve antinociceptive, sedative and tranquilizing effects [4]. Previously, beneficial effects of TES used to recover and improve the functional status of athletes under normal oxygen conditions have been reported [5-9], but the application of TES in athlete training at middle altitude has not been sufficiently studied.

Aim of the study: to determine the effectiveness of transcranial stimulation for the recovery of triathletes during training at middle altitude.

Methods and organization. The study involved 12 triathletes: 6 female athletes (qualification: 1 First-Class Athlete, 2 Candidates for Master of Sports, 3 Master of Sports), age – 17.7±0.9 years, and 6 male athletes (qualification: 1 Candidate for Master of Sports, 4 Masters of Sports, 1 Master of Sports, International Class), age – 21.7±2.3 years. The study was conducted in the Center of Biomedical Technologies of FSBI “Yug Sport” (Kislovodsk, Maloe Sedlo mountain, 1240 m) in conditions of training camps.

To conduct TES, we used the Transair-05 pulse electrical stimulators (registration certificate No FSR 2010/07062, TES Center LLC, Saint Petersburg, Russia). TES was performed with pulsed bipolar current at a frequency of 77.5 Hz according to the fronto-occipital technique, gradually increasing the current until a pronounced painless vibration occurred under the electrode. The first electrode was placed above the eyebrows on the forehead, the second (consisting of two parts) – on the hairless skin behind the ears (on the mastoid bones of the skull). Such fixation allowed the current to flow through both the brain and the external tissues of the head.

The study consisted of 7 TES sessions. The first one lasted 20 minutes, the following ones – 30 minutes. The current was adjusted from 1.5 to 5 mA according to the subjective feeling. 

The effect of the TES course was assessed by electroencephalography (EEG) and heart rate variability indices, psychophysiological indices, full blood count and chemistry panel. EEG was recorded at rest with the EEG Neuron Spectrum complex (Neurosoft, Russia) (monopolar from 16 standard points according to the “10-20” system). HRV was studied with the Poly-Spectrum complex (Neurosoft, Russia) according to the standard procedure.

To study the effect of the TES course on the psychophysiological indices, we performed a psychophysiological test with the Vienna Test System (Schuhfried company, Austria) according to the RT (reaction time test) and ZBA (time and movement anticipation) methods.

The study of the complete blood count and chemistry panel indices was conducted+ before and after the course. The following were identified: transaminase (ALT-d), tranaminase (AST-d), cholesterol (CHO-d), alkaline phosphatase (ALP-d), total bilirubin (TB-D), creatinine (CRE-d), erythrocytes, hemoglobin, leukocytes, platelets.

Statistical data processing was done using Microsoft Excel 2013 and Statistics 13.0 software packages. During the analysis, we identified the arithmetic mean (M). The representative error (m) served as a sign of changes in the studied indices. The non-parametric Wilcoxon’s test was applied for an analysis of the studied indices. P=0.05 was used as the critical level of significance for testing the differences between the two samples.

Results and discussion. The study showed the following. Mean and maximum amplitude of the alpha rhythm in male triathletes did not change significantly under the influence of TES. Analysis of mean amplitude of high-frequency beta rhythm revealed a statistically significant trend for its reduction in the right occipital lead (before – 10.0±2.5 mV, after – 3.8±0.4 mV, p<0.04). Maximum amplitude of the high-frequency beta rhythm did not alter significantly.

Mean amplitude of the low-frequency beta rhythm also decreased under the influence of the course, a substantial reduction was registered in the right occipital lead (before – 15.3±6.2 mV, after – 4.2±0.2 mV, p<0.04). Maximum amplitude of the low-frequency beta rhythm did not change significantly.

Mean amplitude of the delta rhythm tended to decrease without statistically significant differences. Maximum amplitude of the delta rhythm did not alter.

Mean amplitude of the theta rhythm revealed a trend for its reduction after the course, with significant alterations in the left occipital, central occipital and right occipital leads (table 1). There were no significant changes in maximum amplitude of the theta rhythm in male triathletes.

Table 1

Mean amplitude of the theta rhythm in male triathletes before and after the course, M±m, mV

EEG leads	Before	After	P<
FP1-A1	12.8±1.9	9.8±2.0	-
FPZ-A1	18.7±6.8	9.2±1.9	-
FP2-A2	12.2±2.9	9.2±1.8	-
F4-A2	15.2±6.8	7.2±0.8	-
FZ-A2	10.0±1.7	8.0±1.2	-
F3-A1	15.5±5.9	9.6±1.3	-
C3-A1	15.3±5.8	7.8±1.4	-
CZ-A1	14.8±5.9	8.4±1.2	-

C4-A2	13.7±5.6	6.6±1.0	-
P4-A2	12.0±5.7	7.2±2.5	-
PZ-A2	8.7±1.5	8.0±3.0	-
P3-A1	13.2±5.1	8.0±3.0	-
O1-A1	12.2±4.8	8.2±3.7	0.04
OZ-A1	12.3±4.5	7.4±2.5	0.04
O2-A2	16.3±5.6	6.0±1.8	0.04

Note: EEG – electroencephalogram;  FP1-A1 – left pre-frontal lead; FPZ-A1 –  central pre-frontal lead; FP2-A2 – right pre-frontal lead; F4-A2 – right frontal lead; FZ-A2 – central frontal lead; F3-A1 – left frontal lead; C3-A1 – left central lead; CZ-A1 – central lead; C4-A2 – right central lead; P4-A2 – right parietal lead; PZ-A2 – central parietal lead; P3-A1 – left parietal lead; O1-A1 – left occipital lead; OZ-A1 – central occipital lead; O2-A2  – right occipital lead

Mean amplitude of the alpha rhythm of female athletes revealed a tendency to increase without statistically significant differences. There were no statistically significant differences in maximum amplitude of the alpha rhythm, mean and maximum amplitude of the high-frequency, low-frequency beta rhythms, delta and theta rhythms in female triathletes.

Therefore, the 7-session TES course did not influence amplitude of the alpha rhythm. After the course, male triathletes showed a reduction in mean amplitude of fast (high-frequency and low-frequency beta) activity and average amplitude of theta rhythm. In female athletes, the TES course had no effect on amplitude of the EEG rhythms.

Study of the HRV temporal analysis for male athletes before and after the course revealed a statistically significant reduction in HR and increase in RRNN and pNN50 (table 2), reflecting increased activity of the parasympathetic division and, consequently, higher cardiac function economization.

Table 2

Indices of heart rate variability temporal analysis of male triathletes before and after the course, M±m

Indices	Before	After	P<
HR, beats/min	69.9±3.1	66±3.8	0.04
R-R min, ms	644.5±80.2	528.6±124.9	-
R-R max, ms	1231.3±211.8	1094.2±46.7	-
RRNN, ms	872.5±40.8	923.8±53.6	0.04
SDNN, ms	59.3±10.9	67.6±12.0	-
RMSSD, ms	57.3±16.7	56.2±13.9	-
pNN50, %	17.0±6.3	23.458±8.4	0.04
CV, %	6.9±1.3	7.33±1.2	-

Note:  p – level of significance of differences according to the Wilcoxon’s test; HR – heart rate; R-R min – minimum R-R interval duration; R-R max – maximum R-R interval duration; RRNN – average value of all R-R intervals in the sample; SDNN – mean square deviation; RMSSD – root mean square of successive differences; pNN50 – proportion of R-R intervals that differ by more than 50 ms; CV – coefficient of variation

The HRV spectral analysis of male triathletes did not show statistically significant differences after the course. According to the variation-pulsometric indices, a number of cardiac cycles and an index of regulation process adequacy substantially decreased (table 3). These changes reflect an increased activity of the autonomic regulation curve, a reduced centralization in terms of heart rhythm regulation, and increased adaptation reserves.

Table 3

Variation-pulsometric indices of male triathletes before and after the course, M±m, mV

Indices	Before	After	P<
Number of cardiac cycles	347.0±15.3	327.8±18.8	0.04
Мо, s	0.9±0.0	0.9±0.1	-
АМо, %	45.1±5.2	37.0±3.5	-
Ме, s	0.9±0.0	0.9±0.1	-
VR, s	0.6±0.3	0.6±0.1	-
ABI, c.u.	171.4±57.2	94.7±34.3	-
RPAI, c.u.	52.5±6.6	41.1±5.4	0.04
ARI, c.u.	4.0±0.9	2.6±0.7	-
SI, c.u.	98.7±33.1	52.3±19.3	-

Note: p – level of significance of differences according to the Wilcoxon’s test; Мо – mode; АМо – mode amplitude; Ме – median of cardiac interval duration; VR – range of variation; ABI – autonomic balance index; RPAI – regulation process adequacy index; ARI – autonomic rhythm index; SI – stress index. Cardiointervalography recording lasted for 300 s.

Comparison of indices in the HRV temporal analysis among female triathletes before and after TES showed no statistically significant differences. In terms of the HRV spectral analysis, total spectrum power of the low-frequency component (%LF) of variability increased substantially from the total power of oscillations (before – 25.2±3.3 mV, after – 29.3±2.7 mV, p<0.05). No statistically significant changes were found in terms of variation pulsometry for female athletes.

Therefore, the HRV data obtained before and after the course prove the positive effect of TES, consisting in increased activity of the autonomic regulation curve and cardiac function economization, a reduced centralization in heart rhythm regulation, increased adaptation and mobilizaion reserves of an athlete’s body.

The psychophysiological analysis before and after the course demonstrated a substantial reduction of motor response in the test with one critical stimulus (S1 form) both for male (before – 122.4±14.1 ms, after – 110.8±11.5 ms, p<0.04), and female athletes (before – 153.7±20.9 ms, after – 133.2±21.7 ms, p<0.05). No other statistically significant changes were found.

Comparison of the full blood count data before and after the TES course showed statistically significant hemoglobin increase both in men (before – 157.0±2.7 g/l, after – 168.2±3,9 g/l, p<0.05), and in women (before –133.4±3.2 g/l, after – 137.0±3.1 g/l, p<0.04). Since the change occurred during the training camps at an altitude of 1240 m, it may be associated with adaptation to middle altitude conditions.

Comparison of the chemistry panel data before and after the course revealed a statistically significant increase in tranaminase in men (before – 30.1±4.4 unit/l, after – 48.7±8.1 unit/l, p<0.04), as well as an increase in tranaminase and alkaline phosphatase in women (table 4). We do not associate these changes with the TES effect, since the reason for their occurrence is the intense strength training activity during the period studied (training camps).

Table 4

The chemical panel data of female triathletes before and after the course

Indices	Before	After	Р<
Transaminase, unit/l	5.2±2.0	16.2±1.1	-
Tranaminase, unit/l	4.5±1.7	26.9±2.5	0.04
Cholesterol, mmol/l	4.5±0.2	4.4±0.1	-
Alkaline phosphatase, unit/l	103.0±38.9	213.3±46.5	0.03
Total bilirubin, µmol/l	1.9±0.7	6.7±1.1	-
Testosterone, nmol/l	4.1±0.9	3.9±0.5	-

Note: p – level of significance of differences according to the Wilcoxon’s test

Conclusion. Therefore, triathletes had a decrease in mean and maximum amplitude of fast- and slow-wave activity, reflecting a restorative effect of TES. Changes in indices of HRV temporal and spectral analysis, variation pulsometry in male and female athletes demonstrated a positive effect of TES on heart rate autonomic regulation mechanisms, which was more pronounced in women. The TES course contributed to an improvement of psychophysiological indices, i.e. a reduced motor response time. The effects, including an increase in hemoglobin and an increase in tranaminase and alkaline phosphatase, are more likely the result of adaptation to the conditions of middle altitude and training activity, and therefore they are not a direct consequence of TES.

Conflict of interest. The authors declare no conflict of interest.

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INFORMATION ABOUT THE AUTHORS:
Yulia V. Koryagina – Doctor of Biological Sciences, Professor, Head of the Center of Biomedical Technologies, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Gukas N. Ter-Akopov – General Director, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki.
Lyudmila G. Roguleva – Candidate of Medical Sciences, Head of the Sports Medicine Department of the Yunost” Medical Center, Branch of the FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki.
Sabina M. Abutalimova – Candidate of Medical Sciences, Senior Researcher of the Center of Biomedical Technologies, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Sergej V. Nopin – Candidate of Technical Sciences, Leading Researcher of the Center of Biomedical Technologies, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..

For citation: Koryagina Yu.V., Ter-Akopov G.N., Roguleva L.G., Abutalimova S.M., Nopin S.V. Transcranial stimulation in current recovery of triathletes during training at middle altitude. Russian Journal of Sports Science: Medicine, Physiology, Training, 2024, vol. 3, no. 2. DOI: 10.24412/2782-6570-2024_03_02_6