PhD A.I. Golovachev¹
Dr.Biol. T.F. Abramova¹
PhD E.A. Gorbunova¹
PhD S.V. Shirokova^1
1Laboratory assistant researcher E.A. Sigov¹
PhD N.B. Novikova
¹Federal Science Center of Physical Culture and Sport, Moscow
²Saint-Petersburg Federal State Budgetary Institution “Research Institute of Physical Education”, Saint-Petersburg

Corresponding author: malta94@mail.ru

Abstract

Objective of the study was to identify the peculiarities of functional adaptation of elite racing skiers at the venue for the final stage of training for the main start of the season in different phases of acute acclimatization.

Methods and structure of the study. Sampled for the study were 8 male racing skiers aged 24-36 years, having the sports qualifications from Masters of Sport to Honored Masters of Sport. The subjects were tested during the 21-day training in the middle altitude conditions (1820 m, Khmelevskiye mountain lakes, Krasnodar Krai), at the final stage of training for the 2021 World Championship in Oberstdorf (Germany) and the 2021 Russian Cup Final in Syktyvkar (Russia).

The athletes were asked to perform 8-min non-maximum muscle work on the Monark cycle ergometer (Sweden) at the resistance load set in accordance with the following protocol: starting stage – 720 kgm/min (120 W), surplus load – 240 kgm/min (40 W), duration of each stage - 2 minutes, pedaling rate – 80 rpm.

The following parameters were measured during the ergometric test: exhaled air parameters, using the automatic gas analyzer Metalyzer-II (Cortex, Germany) – before and during the test, and during the recovery period (first 3 minutes) – to measure the oxygen (% O₂) and carbon dioxide (% CO₂) levels;  pedaling rate;  lactate concentration – before and after the test, and 3 minutes into recovery, heart rate – using the Polar sports testers, with further data processing in ProTrener (Finland).

The readings of the 1st, 3rd, 5th, 7th, 9th, and 11th days of the acclimatization period (AcP) that covered the entire acute acclimatization phase were used as the basis for the identification of the peculiarities of strengthening of the functional status of the main energy supply systems (oxidative and lactic acid energy systems) at the venue for the final stage of training for the main start of the season.

Results and conclusions. The study enabled to identify the peculiarities of the adaptation processes and determine the most significant individual markers of formation of the oxidative energy system, lactic acid energy system, and cardiovascular system in terms of the middle altitude training (Khmelevskiye mountain lakes, 1820 m). The following parameters turned out to be the most significant: maximal oxygen consumption, lactate concentration, heart rate, balanced ratio of MBC to O₂UC and mechanical efficiency coefficients, together with the oxygen pulse value, which reflect the maturity of the regulatory mechanisms. A peculiar feature of the adaptation processes is the established heterochrony and mutual compensation of the studied systems in the acute acclimatization phase. In terms of the selected methodical direction of the training process design (trainings at the altitude of 1820 m, Khmelevskiye mountain lakes), the time-frame to reach the stable level of the functional status is 7 to 11 days.

Keywords: adaptation to middle altitude conditions, functional status, energy systems (oxidative, lactic acid), acute acclimatization phase, elite racing skiers, final training stage.

Background. The current level of development of cross-country skiing is determined by continuous improvement of racing skiers’ functional capabilities [2, 3, 5]. Trainings in the middle altitude conditions [1, 4, 6] are among the factors that may contribute to the improvement of the athletes’ functional status and, as a result, enhancement of their physical fitness level. However, positions related to the strengthening of the athletes’ functional status at different stages of acute acclimatization, with simultaneous exposure to harsh environmental conditions, primarily, oxygen deficit, as well as to the training loads performed at the altitude of 1820 m (Khmelevskiye mountain lakes) chosen as the venue for the final stage of preparation for the 2022 Winter Olympics (officially known as the XXIV Olympic Winter Games), Beijing, China, remain underinvestigated and require a systematic study aimed to scientifically substantiate the athletic training process design.

Objective of the study was to identify the peculiarities of functional adaptation of elite racing skiers at the venue for the final stage of training for the main start of the season in different phases of acute acclimatization.

Methods and structure of the study. Sampled for the study were 8 male racing skiers aged 24-36 years, having the sports qualifications from Masters of Sport to Honored Masters of Sport. The subjects were tested during the 21-day training in the middle altitude conditions (1820 m, Khmelevskiye mountain lakes, Krasnodar Krai), at the final stage of training for the 2021 World Championship in Oberstdorf (Germany) and the 2021 Russian Cup Final in Syktyvkar (Russia).

The athletes were asked to perform 8-min non-maximum muscle work on the Monark cycle ergometer (Sweden) at the resistance load set in accordance with the following protocol: starting stage – 720 kgm/min (120 W), surplus load – 240 kgm/min (40 W), duration of each stage - 2 minutes, pedaling rate – 80 rpm.

The following parameters were measured during the ergometric test: exhaled air parameters, using the automatic gas analyzer Metalyzer-II (Cortex, Germany) – before and during the test, and during the recovery period (first 3 minutes) – to measure the oxygen (% O₂) and carbon dioxide (% CO₂) contents;  pedaling rate;  lactate concentration – before and after the test, and 3 minutes into recovery, heart rate – using the Polar sports testers, with further data processing in ProTrener (Finland).

The readings of the 1st, 3rd, 5th, 7th, 9th, and 11th days of the acclimatization period (AcP) that covered the entire acute acclimatization phase were used as the basis for the identification of the peculiarities of strengthening of the functional status of the main energy supply systems (oxidative and lactic acid energy systems) at the venue for the final stage of training for the main start of the season.

Results and discussion. The following data were obtained: dynamics of changes in the rate of response to loading on the part of the oxidative energy system and its forming components (MBC, O₂UC), lactic acid energy system, and cardiovascular system (CVS); mechanical efficiency coefficient at the maximal heart rate, oxygen consumption (O₂C) and lactate concentration (LC) (absolute values are presented in the table), together with the estimated percentage at each stage of acclimatization (from 3 to 11 AcP). These data were compared to the data obtained on the first day of stay at the altitude (1 AcP, prior to the acute acclimatization phase) taken as a basal level of physical fitness.

It was found that the relative mechanical power (W₁₄₄₀), after its decrease at the beginning of the acute acclimatization phase (3AС; -0.5%), started to increase from the 5th day of AcP (middle of the acute acclimatization phase), reaching its peak level on the 7th day of AcP (19.29±1.07 kgm/min/kg; +0.6%). The achievement of this work power level was due to the highest intensity of the oxidative energy system functioning: MOCabs^7AC₍₁₄₄₀₎=3.415±0.316 l/min (+6.7%) and MOCrel^7AC₍₁₄₄₀₎= 45.68±4.03 ml/kg (+7.7%).

We assume that the highest MOC rate on the 7th day of AcP was due to the compensatory role of the oxidative energy system, high anaerobic glycolysis rate from the 3rd to 7th day of AcP (from the beginning to the middle of the acute phase), which, in turn, itself (lactic acid energy system) acted as a mechanism of compensation for oxygen deficiency when performing muscle work from the 3rd to 5th day, reaching its peak level on 5AC (La^5АC₍₁₄₄₀₎= 3.70±0.44 mM/l; +22.7%).

This AcP is also notable for the fact that the oxygen consumption level (MOCabs₍₁₄₄₀₎) was formed against the background of the predominance of the external respiration (MBC^7AC₍₁₄₄₀₎=98.4±10.8 l/min; +17.0%) over the oxygen uptake by the muscles (O₂UC^7AC_{(1440 )}= 6.0±0.53%; -9.2%), and only starting from the 9th day of acclimatization, there was a steady downward trend in the lung ventilation and increased oxygen utilization, with a minimum deviation from the basal level – 4.1% – on the 11th day of acclimatization (La^11AC₍₁₄₄₀₎ = 3.01±0.36 mM/l).

The adaptation processes were the most pronounced in terms of the dynamics of changes in the cardiovascular system functioning. After the increase in HR^3AC₍₁₄₄₀₎ = 139.5±10.7; +0.2%, there was a steady downward trend in the pulse cost of work (HR^5-11AC₍₁₄₄₀₎ = -1.2% to -2.5%) and, as a result, the mechanical efficiency improved (ME^5-11AC₍₁₄₄₀₎ = +1.2 to 2.6%), with an increased level on the 11th day of acclimatization.

It should be emphasized that it is during this AcP – from the 5th to the 7th day of acclimatization – that the oxygen pulse rate started to increase steadily (OP^5-7AC₍₁₄₄₀₎ = 7.3-7.1%), thus indicating that the regulatory mechanisms of functioning of the oxidative system started to complete their formation, with the cardiovascular system playing the leading role.

The final stage of formation of the main energy systems (oxidative, lactic acid) and the cardiovascular system was most evident in the steady approach of the mechanical efficiency coefficient to the basal level of oxygen consumption and glycolytic activity on the 9th and 11th day of acclimatization: MEC^9-11AC_MOC = 440.9-441.0 kgm/l and MEC^9-11AC_La = 452.4-479.1 kgm/mM.

Conclusions. The study revealed the peculiarities of the adaptation processes and determine the most significant individual markers of formation of the oxidative energy system, lactic acid energy system, and cardiovascular system in terms of the middle altitude training (Khmelevskiye mountain lakes, 1820 m). The following parameters turned out to be the most significant: maximal oxygen consumption, lactate concentration, heart rate, balanced ratio of MBC to O₂UC and mechanical efficiency coefficients, together with the oxygen pulse value, which reflect the maturity of the regulatory mechanisms. A peculiar feature of the adaptation processes is the established heterochrony and mutual compensation of the studied systems in the acute acclimatization phase. In terms of the selected methodical direction of the training process design (trainings at the altitude of 1820 m, Khmelevskiye mountain lakes), the time-frame to reach the stable level of the functional status is 7 to 11 days.

Table. Dynamics of changes in studied indicators at different stages of acute acclimatization

References

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