Dr.Biol., Associate Professor S.V. Pogodina¹
PhD, Associate Professor V.S. Yuferev¹
Dr.Med., Professor G.D. Aleksanyants^2
1V.I. Vernadsky Crimean Federal University, Simferopol, the Republic of Crimea
²Kuban State University of Physical Education, Sports and Tourism, Krasnodar

Keywords: skilled female athletes, age range, hormonal status, ovulation/ menstrual functionality, oral contraceptives, control and adaptation processes.

Introduction. Over the recent years, a trend has emerged in modern sports towards an increase in both the duration of the stage of preservation of sports achievements and the number of professional athletes demonstrating high sports results within a wide age range - from adolescent age to mature period II. A similar trend is observed in women's sports [5]. In turn, most mature female athletes face a serious problem of the need to administer oral contraceptives, which also affects their hormonal functions [3, 4].

Objective of the study was to analyze the adaptation functions of 16-45 year-old professional female athletes versus their hormonal statuses.

Methods and structure of the study. Subject to the study were highly-skilled female athletes aged 16-45 years (Candidate Masters of Sport, Masters of Sport, Masters of Sport of International Class, engaged in long distance running, swimming and cycling), who did not use any antifertility agents (n=48) but took oral contraceptives (n=7). We conducted 4 empirical studies, during which the female athletes’ indicators were determined in different periods of their menstrual cycle (MC). The 1st-3rd days were taken for the menstrual period, the 8th-9th days - for the postmenstrual one, the 13th-16th days - for the ovulatory cycle, the 20th-22nd days - for the post-ovulatory phase, the 26th-27th days - for the premenstrual phase from the beginning of MC [1]. In the first and second series of studies we evaluated: bioenergetic abilities and nonspecific adaptation functions by analyzing the lacto- and leukograms using the biochemical and haematological methods; hormonal functions using the enzyme-linked immunosorbent assay (ELISA) to determine the hormone levels - estradiol, follicule-stimulating hormone (FSH), luteinizing hormone (LH), cortisol. Ovulation was detected using the immunoassay OVUPLAN LUX.

In the third series of the studies we analyzed the autonomic regulation and hemodynamic functions. We used a rheographic method and analyzed heart rate variability (HRV) and central hemodynamics. In the fourth series of studies we evaluated ventilatory functions using spyropneumotaxometry and gasometry. A step test with graduated loading on a bicycle ergometer was applied, during which, based on the load power (W) and intensity (HR) values, the following work modes were simulated: aerobic (W1 – 50W, HR - 130-140 bpm); aerobic-anaerobic (W2 – 100-120, HR - 150-160 bpm); anaerobic-aerobic (W3 – 150-220, HR - 170-185 bpm). The female swimmers were subject to "long-distance swimming" as a specific stress test, where the threshold work modes were simulated by means of increasing the swimming distances and swimming intensity.

Results and discussion. The study of the hormonal status of the 16-45 year-old female athletes not taking antifertility agents found the differences in their gonadotropic and gonadal profiles within the ranges of 16-36 and 37-45 years of age. In the age range of 16–36 years, the in vitro OVUPLAN LUX test gave a positive result in 100% of cases, which made it possible to single out the age group of female athletes with OMC. The estrogen level in the OMC group was within the normal limits typical for the reproductive age - estradiol (Me [min; max]) with a pronounced ovulatory peak in the period from the 13th to the 16th day - 103.8 [90.00; 183.3] pg/ml. Within the range of 37-45 years of age, a negative result in the in vitro test was registered in 72% of cases, which revealed the age group of female athletes with the predominant AMC. In the AMC group, the FSH level in the menstrual period (2nd-3rd days), indicating possible ovulation, exceeded the threshold values ​​- 25.4±1.42 mIU/ml, the LH level in the inter-menstrual period (from the 8th to the 27th day) - above the norm typical ​​for the reproductive age (above 70 mIU/ml). The estradiol level was within the normal limits without an ovulatory peak (93.4 [83.0; 97.5] pg/m, p=0.00338). In the female athletes taking oral contraceptives (OC group), the estradiol level in the gonadal profile was extremely low (it decreased up to 3-6 pg/ml) in the period ​​from the 8th to the 16th day from the beginning of MC.

The analysis of bio-energy resources of the female athletes under swimming loads in the anaerobic-aerobic work mode revealed intensive production of lactic acid (La) in the OMC group. The AMC group female athletes, when transiting to the W₃ anaerobic-aerobic swimming mode, did not demonstrate any differences in the La level (Me [min; max]) (W₃ mode La=8 [0,,,; 10] mMol/l; p=0.054061). Consequently, in the AMC group, as opposed to the OMC one, the threshold load decreased to intensify production of La.

Blood, and in particular the system of non-specific protection, is highly sensitive to the humoral factors that are activated in specific environmental conditions. In the OMC and AMC groups, the formation of non-specific adaptability is determined mainly at the level of smooth activation. The female athletes with OMC were found to have some sagging of the activation of non-specific adaptation processes in the period from the 8th to the 16th day - to the level of training reactions. Given that the intensity of production of La in the anaerobic-aerobic mode in the OMC group is higher, it can be said that the cost of adaptation to loads in these female athletes is relatively low, especially in the period from the 8th to the 16th day.

The analysis of the glucocorticoid responses in the body of the female athletes revealed the hyperergic cortisol responses in all threshold load modes.  The hyperergic responses were typical of the subjects with OMC in the premenstrual phase, as well as of the females with AMC during menstruation, where the estrogen level was reduced. In the OC group in the period from the 8th to the 16th day, with extremely low levels of estradiol, the cortisol level increased - above 1750 nmol/l. Lower doses of the antifertility agents led to a decrease in the cortisol level up to the standard. In other words, the kinetics of glucocorticoid reactions in the groups of female athletes correlated with the level of estrogen saturation. The study of the range of glucocorticoid reactions revealed its pronounced reduction in the AMC group as opposed to the OMC one (IQR cortisol, nmol/l OMC min - 150, max - 500; AMC min - 25, max - 140). The peculiarity of the response range (variability) in the female athletes with different hormonal statuses is important because it determines its stability, which is higher in the AMC group.

The analysis of the HRV parameters in the initial state of female athletes revealed significantly higher values ​​of the spectral parameters in the OMC group, as well as relatively low values ​​of the tension index of the regulatory systems (TI) relative to the AMC group. We observed autonomic reactions to physical loads associated with an increase in the spectral power ​​of high-frequency (HF) waves and a decrease in the power ​​of very low frequency (VLF) waves in the heart rhythm in the female athletes with OMC within the period from the 8th to the 16th day, and in the female athletes with AMC - within the period from the 20th to the 22nd day. Such correlations between these spectral HRV components are most favorable for the cardiovascular system (CVS). During the mentioned periods of OMC and AMC, we determined: enhancement of the cardiohemodynamic functions, increased stroke volume and contraction power of the left ventricle. Within the period from the 8th to the 16th day, the OC group was found to have a decrease in the statistical indicators of HRV and an increase in TI, which ranged within 230-280 c.u. The revealed facts testify to different chronobiological dynamics of the level of CVS functioning in the OMC, AMC and OC groups.

When analyzing the structure of the respiratory response in the female athletes with OMC, we detected an ovulatory phase shift towards an increase of the respiratory system (RS) reactivity, expressed in the increase of oxygen consumption (VO₂) under the anaerobic-aerobic threshold load conditions to its highest value - 3140.08±14.79 ml·min^-1 (p<0.01). In the female athletes with AMC, the RS reactivity increased in the period from the 20th to the 22nd day (the highest VO₂ value - 3398.37±17.10 ml·min^-1  p<0.01). During these periods, under high-intensity threshold load conditions, the LF-wave power increased in terms of the HRV parameters, which indicated an increase in the sympathetic influences. The detected correlation between the reactions of the ventilatory and neural adaptation links was confirmed by the significant correlation relationships between VO₂ and LF (OMC day 13-16 - r=0.92; AMC day 20-22 - r=0.58). We also found a correlation between an increase of the parasympathetic influences and a decrease in the elimination of CO2 from the body. Such periods in the female athletes with OMC fell on the 8th-9th day (correlation between VCO₂ and HF r=-0.66), and in the female athletes with AMC - on the 20th-22nd day (correlation between VCO₂ and HF r =-0.87). The respiratory pattern in the AMC group in the period from the 20th to the 22nd day was characterized by a decrease in the threshold of the ventilatory reaction, which was obviously not only due to the increased integral regulatory activity, but also due to the prerequisites for increasing the CO₂ level in the body [2].

In the OC group we observed an uneconomic increase in VO₂ within the period from the 8th to the 16th day from the beginning of MC under relatively low aerobic-anaerobic threshold load conditions (VO₂ - 3638.32±31.87 ml·min^-1 p<0.001). Under the high-intensity anaerobic-aerobic threshold load conditions, VO₂  was found to decrease to 3276.32±24.02 ml·min^-1 (p<0.01) due to reduced pulmonary ventilation, apparently, caused by the respiratory muscle fatigue. In this group, we revealed a significant correlation between VO₂ and LF within the periods from the 8th to the 9th day and from the 13th to the 16th day (r=0.67; r=0.88, respectively). Therefore, the female athletes with different hormonal statuses were characterized by different MC periods, where the nervous-control effects on the structure of the ventilatory reactions were enhanced.

Conclusion. The training programs for 16-45 year-old female athletes should be designed to preserve their ovulation/ menstrual functionality, especially when they are on oral contraceptives, and with due regard to the chronobiological variations of the nervous-control effects of OMC and AMC on the cardiovascular and respiratory system adaptabilities.

References

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Corresponding author: sveta_pogodina@mail.ru

Abstract

The study analyzes the adaptation problems of 16-45 year-old professional female athletes versus their hormonal statuses. Research methods applied were as follows: immunological, biochemical, hematology tests, rheography, spyropneumotaxometry, gasometry and standard/ special load tests to rate the bodily system functionality and adaptability. In the competitive swimming group, the ovulation/ menstrual functionality was analyzed versus the bio-energy resource including the lactic acid generation in the anaerobic-aerobic and aerobic-anaerobic training regimen for the 16-36 and 37-45 year-old subgroups, respectively. The study data showed some age-specific differences in the non-specific adaptation processes – dominated by a smooth activation in the 37-45 year-olds versus some sagging of the activation threshold in the 16-36 year-olds in the first half (8-16 days) of the ovulation/ menstrual cycle. The 37-45 year-old non-ovulating/ menstrual subgroup, the 16-36 year-old ovulating/ menstrual subgroup and oral contraceptives applying subgroup were tested with some chronobiological variations of the hormonal and nervous-control effects on the cardiovascular and respiratory system adaptabilities. The ovulating/ menstrual and non-ovulating/ menstrual subgroups were tested with the highest hemodynamic and respiratory functionality rates in days 8-16 and 20-22 of the cycles, respectively. The oral contraceptives applying subgroup was tested with a notable stress of the key adaptation functions in days 8-16 of the menstrual cycle associated with the minimal estrogen levels.