PhD, Associate Professor S.V. Pogodina¹
Dr.Med., Professor G.D. Aleksanyants^2
1V.I. Vernadsky Crimean Federal University, Simferopol, Republic of Crimea, Russia
²Kuban State University of Physical Education, Sport and Tourism, Krasnodar

Keywords: highly-skilled athletes, gender specifics, adaptation processes, 16-46 year-old, age-specific changes, threshold physical loads.

Introduction. The current focus is on the significantly increasing duration of the stage of preservation of sports achievements, during which the athletes’ body undergoes various age-specific changes in the adaptation processes that determine the physiological characteristics of the athletes’ functionality [1].

The have not been conducted any fundamental studies of the age-specific changes in the adaptation processes in highly-skilled athletes within a wide age range.

Objective of the study was to determine the patterns of age-specific changes in the adaptation processes in highly-skilled 16-46 year-old male and female athletes.

Methods and structure of the study. Subject to the study were highly-skilled athletes engaged in long-distance swimming, cycling, track and field athletics ("endurance" group) and kettlebell lifting ("strength" group). The male athletes were distributed into 3 age groups: juvenile age (17-18 years old, n=123), mature period I (22-26 years old, n=82) and mature period II (40-46 years old, n=156). The highly-skilled 16-46 year-old female athletes of the "endurance" group (n=50) were examined at different periods of menstrual cycle (MC). Series of tests were performed under the study to rate the adaptation processes - hormonal, metabolic, nonspecific, autonomic nervous, hemodynamic and respiratory, with application of the latest technologies for assessing the adaptation functions: anthropometrical and functional measurements to study the athletes’ physical fitness level; enzyme-linked immunosorbent assay (ELISA) to evaluate the hormonal functions; biochemical and haematological methods to study the lacto- and leukograms; rheographic method and heart rate variability (HRV) analysis to assess the autonomic and hemodynamic reactions; spiropneumotachometric method and exhaled gas analysis to evaluate the athletes’ ventilatory reactions. The evaluations were made during the step test on a cycle-ergometer, performed in the following work modes (W): aerobic W1 - 50 W, HR - 130-140 bpm; aerobic-anaerobic W2 - 100-120 W, HR - 150-160 bpm; anaerobic-aerobic W3 - 150-220 W, HR - 170-185 bpm. The swimmers were subject to "long-distance swimming" as a specific stress test, and the "kettlebell lifters" were to perform "a jerk", where the threshold work modes were simulated by means of increasing the swimming distances and swimming intensity and by changing the weight of the kettlebell.

Results and discussion. Age-specific changes in the body of the female athletes were associated with the reorganization of the ovarian menstrual function. ELISA helped to determine the levels of gonadotropic hormones in the female age group of 37-45 years (luteinizing hormone in the inter-menstrual period (70.9±4.49 mIU/ml) and follicle-stimulating hormone in the menstrual period (25.4±1.42 mIU/ml), which exceeded the reproductive age limits [3]. The detected reproductive hormone imbalance in this age period indicates the age-specific involutory processes, low probability of preservation of the ovarian menstrual cycle (OMC), its reorganization into anovulatory one [5]. The shifts of the morphofunctional parameters of physical fitness of the 37-46 year-old male and female athletes were expressed in the significant decrease in the integrated bio-energy rates and in body weight gain, limited (in males) and excessive (in females) thoracic mobility.

The analysis of bio-energy resources under specific loads in the anaerobic-aerobic work mode revealed intensive production of lactic acid (La) in the 16-26 year-old male and female athletes. At the same time, the bulk of anaerobic energy supply was detected in the age group of 22-26 years (La level (Me [min; max]) in both the "endurance" group - 9 [6, 20] and "strength" group - 20 [6, 24] mMol/l, p=0.000655) [2]. In the 37-46 year-old athletes intensive production of lactic acid was registered in a relatively low-intensity threshold mode – aerobic-anaerobic.

It is hormonal mechanisms that play a key role in the maintenance of adaptation processes of energy supply. The age-specific features of the athletes’ hormonal reactions manifested themselves in the kinetics and magnitude of the range of reactions. When working in the anaerobic-aerobic mode, the male athletes were found to have a tendency to the enhancement of their glucocorticoid responses. In the period of 40-46 years of age, the threshold load was reduced to the aerobic-anaerobic work mode in order to increase cortisol production. In terms of specific work, the "kettlebell lifters" were found to have a previously excessive increase in cortisol production - over 930 nmol/l (p<0.01). The specificity of glucocorticoid reactions in the female athletes was associated with their weakening in the inter-menstrual period. Their amplification was recorded in the menstrual and premenstrual periods, when estrogen saturation was reduced. Given that the range of adaptation reactions forms the basis of the body’s adaptive capabilities, we studied the range of glucocorticoid responses based on the interquartile range (IQR) of the cortisol level. A relatively narrow range of glucocorticoid response in the 40-46 year-old athletes (IQR up to 200 nmol/l) indicated its high stability. In turn, high stability of excessive glucocorticoid response in the 40-46 year-old "kettlebell lifters" suggested the need to reduce the specific workload. In the age groups of female athletes with OMC, a relatively wide range of glucocorticoid response (IQR up to 500 nmol/l) was detected, which indicated its high variability. Also, in the female athletes with OMC, when working in the aerobic-anaerobic mode, the range of glucocorticoid response was most sensitive to cyclic changes in the endocrine profile.

It was found that autonomous regulation, and the autonomous regulatory link in particular, contributes to the development of age-specific variations of the highly-skilled athletes’ functionality [6]. Autonomous regulation of heart rate and hemodynamic functions was the most efficient in the age group of 17-18 and especially 22-26 years. In terms of the anaerobic-aerobic work mode, the 40-46 year-old "kettlebell lifters" demonstrated a significant decrease in the parasympathetic influences, which led to an increase in the regulatory system stress index by more than 230 c.u. (p<0.01), improved chronotropic effects (HR increase above 147%, p<0.05), a significant increase in the stroke volume (SV) to 36%, (p<0.05) with a decrease in the external myocardial contractile activity (left ventricular stroke work) from 87% at 22-26 years of age to 21% at 40-46 years of age, (p<0.01), an increase in the systolic blood pressure up to 178.8±3.70 mmHg, (p<0.01). In the athletes who train aerobic endurance during exercise, the parasympathetic tone decreases insignificantly, weakening of the cardiovascular system response to physical load was observed.

Highly-skilled athletes from different age groups are characterized by the chrono-biological peculiarities of the regulatory effects of the autonomic nervous system on the heart rate and hemodynamic functions [4]. In terms of the anaerobic-aerobic work mode, the most favourable algorithm of regulation of the cardiovascular system (CVS) functions in the female athletes with OMC falls within the period from the 8^th to the16th day, and in the female athletes with AMC - within the period from the 20^th to the 22nd day. These periods, along with the increase in the power of LF waves that reflect the level of sympathetic activity, are characterized by an increase in the power of HF waves, which indicates an increase in the parasympathetic tone, as well as a decrease in the supra-segmental activity (a decrease in the power of VLF waves) in the heart rate regulation. Also, in these periods of OMC and AMC, we registered an increase of the hemodynamic functions, an increase in the stroke volume and left ventricular stroke work indices. The revealed fact indicates to different periods with a high level of the CVS functionality in the highly-skilled 16-26 year-old female athletes with OMC and 37-45 year-old female athletes with AMC.

When assessing the age-specific features of the respiratory system (RS) adaption reactions in the male athletes, we detected comparatively high reactivity and conjugation of the ventilatory and gas exchange functions, effective respiratory patterns at all stages of stress testing within the range of 17-26 years of age. In the period of 40-46 years of age, high efficiency of the respiratory patterns is maintained under relatively low threshold load conditions. In the anaerobic-aerobic work mode we found a decrease in the effectiveness of the respiratory reactions that was more pronounced in the "kettlebell lifters". Thus, in the anaerobic-aerobic work mode the ventilator system efficiency decreases in the latter – there is observed an increase in the ventilatory equivalent for carbon dioxide (VECO2) to 47.32±1.92 l/min, (p<0.01), excessive CO2 and increase in the respiratory coefficient (VCO2 /VO2) to 1.02±0.02 c.u., (р<0.05), decrease in the oxygen cost of breathing (VО2/f), bringing down the oxygen delivery to the lungs to 52.30±2.12 ml/min/cycle, (p<0.001).

In the structure of the respiratory reaction in the 16-26 year-old female athletes there is a phase of ovulatory shift towards the greatest increase in the RS reactivity, which leads to an increase in the oxygen cost of breathing to 99.76±1.64 ml/min/cycle (p<0.05), decrease in the efficiency of the oxygen regime. A decrease of the RS reactivity falls within the period from the 8th to the 9th day and is associated with an increase in the parasympathetic tone (r ranging between VCO2 and HF-0.66), a decrease in the elimination of CO2 from the body, a drop in the energy cost of breathing to the VO2/f =80.13±1.14 ml/min/cycle (p<0.05). In the 37-45 year-old athletes, an increase in the RS reactivity falls within the period from the 20^th to the 22^nd day, when the conditions for hyperkinetics of the ventilatory function are formed - the respiratory rate increases (36.82±2.69 cycles∙min^-1, p<0.05), ventilatory equivalents for oxygen (31.95±0.87 l∙min^-1, p<0.05) and carbon dioxide (29.92±1.08 l∙min^-1, p<0.05), that is, the respiratory apparatus functionality decreases [7]. It should be noted that in the period of 20-22 days, we detected low elimination of CO2 from the body (VCO2=2102.16±10.37 ml∙min^-1, p<0.01). However, in this case, the RS reactivity was high. If we consider that in the period of OMC with reduced elimination of CO2 the RS reactivity is not high in the 16-26 year-old athletes, it becomes obvious that the ventilatory reaction threshold decreases in the 37-45 year-old athletes.

The studies revealed the specific features of adaptation of highly-skilled 17-46 year-old male athletes, which find expression in the principle of differentiated adjustments in a row of the basic adjoint adaptive functions (their amplification and (or) weakening) during high-intensity work. Systematization of chrono-biological changes in the structure of autonomic, hemodynamic and ventilatory reactions made it possible to identify the periods of OMC and AMC in highly-skilled 16-45 year-old female athletes, when they reach a relatively high level of functionality of the oxygen transport systems.

Conclusions. The detected age-specific changes in the adaptation processes occurring between 16 to 46 years old can be used to develop the functional models of highly-skilled athletes of different gender and age groups. Implementation of the findings during the biomedical monitoring of the stages of long-term training will make it possible to predict how fit highly-skilled athletes of different gender and age groups are to perform threshold physical loads.

References

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Corresponding author: sveta_pogodina@mail.ru

Abstract

Series of tests were performed under the study to rate the adaptation processes in the key body systems of highly-skilled 16-46 year-old athletes (male and female) with application of immunological, biochemical, haematological, rheographic, spirographic and anthropometric methods; exhaled gas analysis; and workload tests to profile the age-specific variations of the athletes’ functionality, anthropometrical measurements and physicality to explain the natural reduction of the integrated bio-energy rates in the period of 37-46 years of age. The study data and analyses made it possible to find the age-specific changes in the bio-energy resources under specific loads, including: intensive production of lactic acid in the anaerobic-aerobic work modes in the 16-18 year-old and particularly 22-26-year-old athletes; and intensive production of lactic acid in the anaerobic-aerobic work modes in the 37-46 year-old athletes. The study found the following age-specific tensions in the adaptation process: unspecific responses at the relatively high activation level in the male age groups of 17-26 and 40-46 years; fall in the activation level in the male age group of 22-26 years; and the unspecific responses at the relatively high activation level in the female age group of 40-45 years. The study found the age-specific fast adaptation responses of the core body systems in the male group under high-intensity loads, including: growth in the hormonal-metabolic responses in the 17-18 year-old males; general growth of the adaptation responses of the core body systems in the 22-26 year-old males; and weakening of the ventilatory and metabolic responses in the 40-46 year-old males. Furthermore, the study found some chrono-biological regularities in the adaptation processes in the 16-45 year-old females including the high probability of detriment to the ovulatory and menstrual cycles at the age of 37-45 years; weakening of the hormonal responses in the inter-menstrual periods; and specific variations in the autonomic influences in the 37-45 year-old females with the anovulatory cycle and in the 16-26 year-old females with the ovulatory and menstrual cycles versus the hemodynamic and ventilator functions.