Dr.Biol., Professor N.I. Shlyk¹
PhD, Associate Professor A.E. Alabuzhev¹
Master Yu.S. Nikolaev^1
1Udmurt State University, Izhevsk

Keywords: middle altitude training, middle- and long-distance runners, HRV, health disorders, overtraining.

Introduction. Running (sport) places high demands on the body of athletes, particularly on their cardiovascular system. A properly designed training process, customized to the peculiarities of the recovery process and subjective state of athletes, contributes to the optimal level of adaptation of their autonomic nervous system regulation mechanisms. Among the causes of overtraining and overtension of the regulatory systems are: overloading, irrespective of the individual peculiarities of the regulatory systems; acute chronic infections and their recurrence; influence of environmental conditions. Athletes’ complaints of sleep disturbance, fatigue, nasal congestion, sore throat, etc. often stay out of sight of their trainers, which results in the deterioration of the body's immunobiological reactions. That is why the incidence of the upper respiratory tract diseases among athletes is constantly increasing [1]. Any workload performed against this background leads to degradation of the adaptive-regulatory capabilities of the body. The vegetative dysfunction is the most common disorder found in sports. The importance of autonomic regulation in homeostasis in the cardiovascular system during the training process in different environmental conditions has been proved [2-4]. Until now, the question not yet settled is whether middle altitude trainings contribute to the improvement of sports results. Most experts believe that middle altitude trainings are ineffective as applied to elite athletes [2-4]

Objective of the study was to evaluate individual tolerance of middle- and long-distance runners to two types of training loads through the dynamic studies of HRV at rest and during orthostatic test conducted with due regard to health deteriorations and middle altitude conditions.

Methods and structure of the study. Subject to the study were 16 elite (CMS, MS) long-distance runners examined during the middle altitude training camp (Kislovodsk, 2017), which lasted 22 days. The HRV express analysis was conducted daily prior to the training session (in the morning hours), based on the prevailing type of autonomic regulation and autonomic reactivity: in the lying position (5 min) and in the standing position (6 min) using the “Varicard 2.51” device and “Iskim-6” software. The HRV analysis conducted at rest and during orthostatic test, based on the prevailing type of autonomic regulation, was described in a number of research works [2, 3]. When analyzing the HRV rates, we considered the state of health and nature of training loads performed by the athlete on the previous day.

Results and discussion. The HRV express analysis results presented in Fig. 1 indicated that, during the training camp, 4 middle-distance runners demonstrated different adaptive-regulatory capabilities of their body under various training loads in each micro-cycle.

Fig. 1. HRV rates in middle-distance runners within 4 micro-cycles of middle altitude training camps (Kislovodsk, 2017)

The HRV rates in the 1st athlete Ch. were characterized by the considerable variations in the resting MxDMn, SI, HF, LF indices and paradoxical reactions during orthostatic test (from the I to the IV micro-cycle), which indicates instability of the autonomic balance and autonomic reactivity. It is known that among the main displays of pronounced fatigue and overtraining are poor sleep, fatigue and a heart rhythm disorder [1]. Of 22 days of the training camp, in 15 cases the athlete complained of poor sleep, especially in the III and IV micro-cycles.

Thus, for instance, following another complaint of poor sleep, the presented cardiointervalograms, HRV scattergrams and ECGs at rest and during orthostatic test (Fig. 2) showed that, after a 1-day rest, the athlete had a low-variable heart rhythm in the morning prior to the training session, there was a spread of points on the scattergram graph and extrasystoles on his ECG at rest and during orthostatic test. These HRV analysis results indicate that the performance of the daily training loads were accompanied by the high tension of the cardio-regulatory systems and sinus node malfunction.

Fig. 2. HRV rates, cardiointervalograms, scattergrams and ECGs in middle-distance runner Ch. (MS) prior to training during third micro-cycle of Kislovodsk training camp

According to Fig. 2, the 2nd athlete K. demonstrated high HRV MxDMn, HF, LF values and low SI ones at rest in all micro-cycles, which resulted from the pronounced predominance of the autonomous regulation circuit activity. During orthostatic test, throughout the entire training camp, there was a hyperreaction, when MxDMn, HF, LF rates sharply decreased and those of SI increased significantly, especially in the IV micro-cycle. The athlete complained of constant nasal congestion, sore throat in the morning, and at the end of the training camp - of a systematic lack of sleep, which indicated increasing fatigue, especially in the IV micro-cycle. The HRV analysis testified to the inclusion of suprasegmental structures of autonomic regulation and a decrease in the adaptive reserves and immune processes against the background of ever-changing environmental conditions, nasopharyngeal diseases, excessive training loads for him at that moment.

The results of the analysis of HRV in the 3rd athlete Kh., presented in Fig. 1, revealed an increase in the MxDMn, LF rates and a decrease in the SI ones from the I to the IV micro-cycle. Since the second day of training, the athlete had been constantly complaining of poor sleep, and in the IV micro-cycle of the training camp - of nasal congestion and sore throat. What is meant here is increasing health deviations. At the same time, the orthostatic test showed an increased hyperreaction from MxDMn, SI, LF. In the IV micro-cycle, there was an increase of imbalance between the regulatory systems at rest, while the respiratory waves (HF) decreased and vasomotor waves (LF) increased with increasing MxDMn. This suggests that in this micro-cycle it was difficult for the athlete to perform loads.

The 4th male athlete Zh. was characterized by the low exercise tolerance in terms of the middle altitude trainings, which was true for all the micro-cycles. From the first days of his stay in the mountains, he complained of poor sleep, nasal congestion, and at the end of the training camp - on sore throat. The HRV express analysis results (Fig. 1) indicated a descent of the HF waves, especially during the III and IV microcycles when at rest, and paradoxical reactions to orthostatic test from MxDMn, SI and LF.

Therefore, the Kislovodsk November training camp, characterized by the transition from the cold climate on the plain to the warmer one in the middle altitudes, led to acute exacerbation of chronic nasopharyngeal infections (nasal congestion, sore throat) and sleep disturbance, which, in turn, resulted in weakening of the body defenses and, consequently, deterioration of the adaptive-regulatory mechanisms. After the latitude trainings, the athletes did not demonstrate any prominent results during the competitions.

The analysis of the state of the long-distance female runners’ regulatory systems revealed that, since the 1st day of their stay in the mountains, they had been involved in the twice-per-day running trainings, though their individual peculiarities of adaptation during acute acclimatization were not taken into account. Therefore, they began to complain of a poor subjective state (lack of sleep, nasal congestion, sore throat) and low exercise tolerance as early as during the 1st week of the training camp.

According to the HRV analysis, these health deviations in the female athletes' significantly affected their vegetative balance towards a sharp increase in the predominance of autonomous or central contour of autonomic regulation at rest and the appearance of para-doxal reactions to orthostasis. Thus, for instance, Fig. 3 illustrates the HRV rates in the female long-distance runner (MS), who, since the first week of the training camp, had been complaining of poor sleep and sore throat, and still kept on training against this background. These changes in the autonomic regulation testify to the female athletes’ inability to perform two workouts per day, and hence, to the dangers of such training camps.

Fig. 3. Cardiointervalograms, scattergrams and ECGs of female athlete U. (MS) during training camp in Kislovodsk

On the 12th day of the training camp, she was found to have a strongly pronounced paradoxical reaction to orthostatic test from HR indices and HRV rates SI, TP, HF. At the same time, no variability was detected in the cardiointervalograms, while the scattergrams at rest and during orthostatic test were characterized by a pronounced local cluster of points and changes in the ECGs. All these deviations in the HRV rates and ECG patterns (Fig. 3) indicate a pronounced tension of the autonomic regulation. However, the trainer suspended the female athlete from the training process on the 12th day of the training camp only. After 5 days of rest, she continued her training, for which she was not ready yet.

As a rule, athletes arrive to the middle altitude training camps without prior medical examinations. As a result, some get involved in the training process being already affected by serious cardiovascular system disorders (Fig. 4). In this view, the HRV analysis is irreplaceable.

Fig. 4. Cardiointervalograms, scattergrams and ECGs of female athlete D.

Figure 4 gives the cardiointervalogram, HRV scattergram and ECG data obtained in the overtrained female athlete with a sinus dysfunction. This example once again proves that, along with the HRV rate, it is important to visually monitor the athletes’ cardiointervalograms, scattergrams and ECGs at rest and during orthostatic test in order to avoid mistakes in interpreting the state of their cardio-regulatory systems. It should be emphasized that, after the camp, none of the female athletes demonstrated high results during the competitions.

Conclusion. During adaptation to physical loads in middle-altitude conditions, the body of runners undergoes a number of physiological changes, particularly, in the cardio-regulatory systems. However, there still exists a pattern of changes that are significantly over the normal limits, which can be deemed a manifestation of a pre-pathology or overexertion of the heart.

References

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Corresponding author: medbio@uni.udm.ru

Abstract

The article analyzes the cardiac activity regulation and variations based on the middle-/ long-distance runners’ heart rate variability (HRV) data in the middle altitude training process, with a special emphasis on their exposure to fatigue and overtraining due to the training process mismanagement, inadequate customization to the individual capacities and/or untimely health rating tests and examinations. It was found by the study that the daily HRV tests of runners in the middle altitude trainings give the means to find, on a timely basis, the individual limits of the bodily resources and regulatory mechanisms that shall in no case be surpassed otherwise the trainees may be exposed to risks of regulatory deficiencies, overtraining and cardiac function disorders. It was also found that most of the athletes arrive to the middle altitude training camps without prior medical examinations. The HRV data and analyses showed that the challenging altitude acclimatization in the first training week with two training sessions per day is often detrimental to adaptability, resource mobilization, autonomic balancing and autonomic response mechanisms with the associating health disorders and, hence, excessive fatigue and overtraining by the end of the altitude training cycle. The issues related to the cardiac function regulation mechanism in the twice-per-day running trainings and the relevant health disorders are still largely underexplored and need to be duly addressed by the sport science.