Dr.Biol., Professor R.V. Tambovtseva¹
PhD, Associate Professor Y.L. Voitenko¹
PhD, Associate Professor A.I. Laptev¹
E.V. Pletneva^1
1Russian State University of Physical Education, Sports, Youth and Tourism (SCOLIPE), Moscow

Corresponding author: ritta7@mail.ru

Abstract

Objective of the study was to determine the level of tolerance of the physiological systems of athletes working in the anaerobic mode to normobaric hypoxic exposure.

Methods and structure of the study. The study was carried out at the premises of the Research Institute of Sports and Sports Medicine (Russian State University of Physical Education, Sport, Youth and Tourism). Sampled for the study were the active highly-skilled swimmers (Group 1 - n=10, Group 2 - n=10). The individual glycolitic anaerobic power and capacity were tested in Wingate test on a Monark Ergomedic 894E Peak Bike vertical cycle ergometer (Sweden): three times of 90'' with the rest intervals of 180". The following indicators were recorded: relative working capacity (W/kg), maximum working capacity per unit of time (W/kg), average working capacity (W/kg), fatigue coefficient (c.u.), relative maximum oxygen (O₂) consumption (ml/min/kg), absolute oxygen consumption (l/min), carbon dioxide (CO₂) content in the exhaled air (l/min), lung ventilation (l/min), ventilatory equivalent for O₂, heart rate (HR), HLa. The following gas exchange indicators were recorded: lung ventilation, O₂ and CO₂ contents in the exhaled air; O₂ consumption, and other related comprehensive diagnostic parameters. HR was measured on the cycle ergometer using Polar T34 pulsometer (Finland). HR and blood oxygenation during the hypoxic tests were recorded in three stages: at rest – before the hypoxic exposure, for 1 min; during the 30-min exposure to the 9% O₂ gas mixture; after the hypoxic exposure (recovery period) – under normal breathing conditions, for 3 min.

Results and conclusions. The findings showed an ambiguous reaction of the body of athletes to the single and multiple hypoxic exposure when working in the anaerobic mode. The multiple hypoxic exposure in the anaerobic mode decreases many physiological indicators, especially working capacity. The efficiency of hypoxic exposure is largely determined by the rate of recovery of the functional systems of the body and individual hypoxic tolerance rate. The use of hypoxia with the low content of O₂ in the inhaled air adversely affects many functions of athletes’ body.

Keywords: athletes, working capacity, hypoxia, anaerobic load. 

Background. Until recently, various hypoxic exposure techniques have been extensively used in sports to improve athletes’ physical working capacity, speed up the short-term recovery processes, maintain their high training level over a long period of time, increase the body functionality and adaptation reserves [1-4]. All athletes face hypoxic issues, though exercise-induced hypoxia is most expressed in athletes engaged in cyclic sport disciplines (middle, long, and extra-long distances) [4-6]. Therefore, the main direction in the training of athletes of various specializations is hypoxic training aimed to determine the metabolic pathway, enhance the enzymatic activity in terms of aerobic and anaerobic resynthesis of ATP, as well as improve the systems responsible for oxygen supply to the working muscles.

Objective of the study was to determine the level of tolerance of the physiological systems of athletes working in the anaerobic mode to normobaric hypoxic exposure.

Methods and structure of the study. The study was carried out at the premises of the Research Institute of Sports and Sports Medicine (Russian State University of Physical Education, Sport, Youth and Tourism). Sampled for the study were the active highly-skilled swimmers (Group 1 - n=10, Group 2 - n=10). The individual glycolitic anaerobic power and capacity were tested by Wingate test on a Monark Ergomedic 894E Peak Bike vertical cycle ergometer (Sweden): three times of 90'' with the rest intervals of 180". The following indicators were recorded: relative working capacity (W/kg), maximum working capacity per unit of time (W/kg), average working capacity (W/kg), fatigue coefficient (c.u.), relative maximum oxygen (O₂) consumption (ml/min/kg), absolute oxygen consumption (l/min), carbon dioxide (CO₂) content in the exhaled air (l/min), lung ventilation (l/min), ventilatory equivalent for O₂, heart rate (HR), HLa. The spirometric studies were conducted using the Cortex METALYZER 3B-R2 gas analyzer (Germany). The following gas exchange indicators were recorded: lung ventilation, O₂ and CO₂ contents in the exhaled air; O₂ consumption, and other related comprehensive diagnostic parameters. HR was measured on the cycle ergometer using Polar T34 pulsometer (Finland). The pulse oximetry method implied the use of the following devices (pulse oximeters): stationary - NONIN8600 (USA); carpal - MD300W (China). The pulse oximetry method enabled to continuously record arterial oxygen saturation (blood saturation - SO₂) and HR. HR and blood oxygenation during the hypoxic tests were recorded in three stages: at rest – before the hypoxic exposure, for 1 min; during the 30-min exposure to the 9% O₂ gas mixture; after the hypoxic exposure (recovery period) – under normal breathing conditions, for 3 min.

Results and discussion. Given in Tables 1, 2, 3 are the athletes’ HR and levels of oxygen saturation (SO₂) under the single and multiple hypoxic exposure.

Table 1. Dynamics of changes in SO₂ and HR of athletes under single hypoxic exposure, before anaerobic load ( , n=10)

Table 2. Dynamics of changes in SO₂ and HR of athletes under multiple hypoxic exposure, before and after anaerobic load ( , n=10)

It is shown that under the multiple hypoxic exposure, the blood saturation rate decreased, while HR increased. There is a close correlation between these indicators, which is linear and negative. Under the single normobaric hypoxic expsure, blood oxygenation decreased slightly, as under the multiple exposure, but HR increased by 20% relative to the initial level. The low HR values under the multiple hypoxic exposure appear to be associated with the adaptation mechanisms developed under hypoxic conditions.

Table 3. Dynamics of changes in SO₂ and HR of athletes before and after hypoxic exposure, before anaerobic load on cycle ergometer ( , n=10)

There was a decrease in the level of blood oxygenation under the single and multiple hypoxic exposure, at which the rate of deviation of the average blood saturation values in the athletes of EG 2 changed slightly and corresponded to the sigmal deviations under the single hypoxic exposure in EG 1. Under the multiple hypoxic exposure, after the anaerobic load, the athletes’ HR increased significantly during the 2nd test, probably due to the fast recovery and insufficient liquidation of the oxygen debt. However, increased HR was maintained throughout the entire 30' hypoxic test.

The figure illustrates the initial blood lactate concentration rate under the multiple hypoxic exposure before the 1st and 2nd tests in the anaerobic mode. The 30-min hypoxic exposure was found to adversely affect the rate of decrease in the blood lactate concentration rate. The great sigmal deviations in the lactate concentration up to 97% after the 2nd hypoxic test were associated with a high rate of individual response to the combined effect of the hypoxic exposure and anaerobic load.

Fig. 1. Blood lactate concentration rate in athletes under multiple hypoxic exposure before anaerobic load.

In EG1, in the recovery period after the anaerobic load under the 30-min hypoxic exposure, there was an increase in W_gen., W_crit., W_{avg.in 90 sec} against the background of accumulated fatigue, which resulted in the increased anaerobic glycolysis efficiency as well as increased power and capacity.

Given in Table 4 are the data on the performance rates in EG 2 in the anaerobic mode and recovery period.

Table 4. Dynamics of changes in physiological indicators in EG2 in recovery period after anaerobic load under 30' multiple hypoxic exposure

It is shown that after the multiple hypoxic exposure, the lung ventilation rates, maximum HR, and working capacity rates decreased. In addition, the fatigue coefficient and ventilatory equivalent for O₂ statistically significantly decreased due to the onset of decompensation and inability to maintain gas homeostasis. After the single and multiple hypoxic exposure - 3x90'' at the recovery stages, the relative and absolute O₂ consumption, CO₂ content in the exhaled air, and lung ventilation rates decreased.

Conclusions. The findings showed an ambiguous reaction of the body of athletes to the single and multiple hypoxic exposure when working in the anaerobic mode. The multiple hypoxic exposure in the anaerobic mode decreases many physiological indicators, especially working capacity. The efficiency of hypoxic exposure is largely determined by the rate of recovery of the functional systems of the body and individual hypoxic tolerance rate. The use of hypoxia with the low content of inhaled O₂ adversely affects many functions of athletes’ body.

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