Dr.Med., Professor Y.Y. Byalovsky¹
Dr.Med., Professor M.M. Lapkin¹
Dr.Med., Associate Professor A.L. Pokhachevsky³
Dr.Med., Professor V.V. Davydov¹
Dr.Med. S.V. Bulatetskiy²
Dr.Med., Associate Professor R.M. Voronin^3
1Ryazan State Medical University n.a. academician I.P. Pavlov, Ryazan
²Ryazan branch of Kikot Moscow University of the Russian MIA, Ryazan
³Academy of Law and Administration of the Federal Penitentiary Service of Russia, Ryazan

Keywords: inspiratory, resistance load, lipid metabolism.

Introduction. Physical load tolerance largely depends on hypoxia tolerance. In addition, hypoxic adaptation efficiency is what determines sports training effectiveness. Marked biochemical shifts resulting from tissue hypoxia are due to a decrease or an increase of physical working capacity affected by duration, intensity and frequency of hypoxic exposure. This equally applies to physical working capacity and recovery potential of the human body. Positive cross-effects of adaptation to hypoxia form the basis of prevention of ischemic heart diseases and reperfusion disorders in experimental and clinical medicine [8].

Classical studies by F.Z. Meyerson were further developed in modern approaches to ischemic and hypoxic preconditioning. The essence of these approaches was in the alternation of short periods (5-15 min) of ischemia with reperfusion and hypoxia and normal oxygenation. At the same time, one-time (up to 3-5 times) implementation (alternation of hypoxia and normal oxygenation) is defined as preconditioning, and systematic one (daily, within 3 or more days) - as interval hypoxic training [3, 4-7, 10-15].

Nevertheless, the wide use of natural factors, environmental simulation, the use of physical loads in terms of reduced oxygen partial pressure (midlands-highlands, pressure chambers, hypoxic tents, etc.), the study of objective physical load tolerance criteria do not give a clear picture of the optimal conditions and criteria of effectiveness of these methods [5, 9]. Variability of adaptive reactions of the human body depending on the duration and conditions of hypoxic exposure is still an open question.

Objective of the study was to detect differences in the hypoxic effects depending on the hypoxic load duration.

Methods and structure of the study. Subject to the study were 57 apparently healthy individuals of both sexes aged 18 to 28 years. Hypoxic exposures - non-threshold inspiration resistance respiratory loads (RL) - were controlled by means of the respiration simulator "BVD-01". The resistance load (RL) amount was regulated based on the maximum oral cavity pressure (100% Pmax) registered during the first loaded inhalation when performing the Muller test. The sample was split up into the following three groups of 19 people each: Group 1 subject to hypoxic loads rated at 20% of the maximum and applied 3 times per 3 min; Group 2 trained by uninterrupted 10-min hypoxic loads; and Reference Group 3. The hypoxic training micro-cycle lasted 10 days.

The lipid metabolic rates were evaluated before and after RL by the blood levels of malondialdehyde (MDA), free fatty acids (FFA), hydroperoxides (HP); activity of antioxidant systems (AOS) - by the integral indicator of total antioxidant activity (AOA) and catalase activity (CAT) in the blood plasma.

The serotonin (Ser), adrenaline (Ad) and noradrenaline (N-Ad) blood levels were measured using the fluorimetrical analysis. The blood samples were taken from the cubital vein twice - before the resistance respiratory load and immediately after it.

The data were processed using the standard package Statistica.

Results and discussion. In order to ferret out the influence of RL on the metabolic processes, we started the analysis with testing the findings for normality of distribution (test of normality - the values of kurtosis and asymmetry do not exceed 2; in case of abnormal distribution, the rows were discarded). Due to this circumstance the dispersion factor analysis was applied, where a controlled factor is the time of hypoxic exposure; the activity parameters are the indicators of metabolic processes. The factor response markers were conventionally divided into two components: oxidative damage: HP, MDA, FFA, Ad, N-Ad and antioxidant protection: AOA, Cat, Ser. The oxidative damage components were statistically significantly affected (p<0.05) by such an organized factor as "duration of continuous hypoxic load". At the same time, this influence decreased as the duration increased: the minimum response rate was registered during the 10-min exposure, the maximum - during the 3-min one. The antioxidant protection indicators were also significantly affected by hypoxic load (p<0.05), and they were especially pronounced in the catalase rates registered during the 3-min exposure.

Table. Lipid metabolic activity and concentration of biogenic amines in terms of hypoxic training (median level)

Therefore, all factor response markers were significantly affected by the duration of hypoxic load, which indicates certain patterns of adaptation and necessitates more detailed parameterization of these mechanisms.

The 3-minute series of RL significantly decreased lipid metabolism: the MDA concentration (p<0.01), FFA (p<0.001), and HP (p<0.001) decreased. The 10-min exposure resulted in the mobilization of HP and FFA, not actually affecting the concentration of MDA (Table 1).

The adrenaline and noradrenaline levels increased in direct proportion to the time of continuous RL, reaching the maximum at the 10th minute of exposure (p<0.05). The nature of changes in the serotonin concentration also depends on the time of RL: at the 3^rd minute of exposure it increased, making up to 130% of the baseline (p<0.01), at the 10th minute – remained almost unchanged - 103% (p>0.05).

The effect of the 3-min RL was accompanied by the activation of antioxidant protection by means of increasing AOA and Cat rates (p<0.01). A reverse dynamics was observed in both substrates during the 10-min exposure.

Therefore, the majority of the parameters under study changed reciprocally in terms of different time parameters. The 3-min exposure slowed down the oxidative damage and activation of antioxidant protection, the 10-min exposure, on the contrary, led to an increase in lipid metabolism and decrease in oxidative protection. According to the present study, the stability of the antioxidant and lipoprotective effects was registered in nearly all subjects, irrespective of their sex and age.

Conclusion. The 3-min exposure of RL significantly slowed down the processes of oxidative damage to membranes and enhanced antioxidant protection. The reverse dynamics was detected during the 10-min RL exposure. The antioxidant and lipoprotective effects of short inspiratory resistance loads are observed in all subjects, irrespective of their age and sex, which indicates significant differences in the adaptation responses depending on the duration of hypoxic exposure.

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Corresponding author: sport_med@list.ru

Abstract

Individual physical working capacity and rehabilitation process efficiencies are determined by the hypoxic adaptation efficiency. Objective of the study was to rate the bodily oxygen debt process versus the hypoxic loads applied. Subject to the study were 57 healthy individuals of both sexes aged 22 to 42 years. The inspiration resistance respiratory loads (RL) were controlled by respiration simulator ‘BVD-01’. The sample was split up into the following three groups of 19 people each: Group 1 subject to hypoxic loads rated at 20% of the maximum and applied 3 times per 3min; Group 2 trained by uninterrupted 10-min hypoxic loads; and Reference Group 3. The hypoxic training micro-cycle was 10 days long. The lipid metabolism and catecholamine blood levels were tested on a daily basis prior to and after each training session. The study data were indicative of the 3-min RL being beneficial as it was found to effectively slow down the membrane oxidation and damaging process and improve the anti-oxidation protection mechanisms; whilst the 10-min RL yielded an opposite result. The membrane protecting effects of the short inspiration hypoxic loads tested in every subject irrespective of age and gender showed the adaptive responses being highly dependent on the hypoxic training process design and management.