Postgraduate P.N. Samikulin¹
Dr.Biol., Associate Professor A.V. Gryaznykh¹
PhD, Associate Professor R.V. Kuchin^2
1Kurgan State University, Kurgan
²Yugra State University, Khanty-Mansiysk

 

Keywords: cortisol, testosterone, anabolic index, overtraining, endocrine regulation, rehabilitation, athletes.

 

Introduction. Mobilization of the energy reserves of the body of athletes during training sessions and competitions is a necessary component of their adaptation to stresses [1].

However, increased amount and intensity of training and/or insufficient rehabilitation period, often combined with other educational and non-physical stressors, contribute to the development of fatigue and overtraining syndrome, which are characterized by lower physical working capacity, autonomic system dysfunctions, increased fatigue and subjective stress symptoms [14].

The etiology of overtraining may differ in different people, which indicates the need to study a wide variety of parameters as diagnostic criteria. Currently, a single diagnostic test to identify the overtraining syndrome is lacking. The available methods of assessment of the functional state of the body are based on the muscle damage indicators, estimation of glycogen stores, respiratory and cardiac efficiency, functioning of the neuroendocrine and immune systems, and psychological state of athletes. Alongside the determination of concentration of substrates (e.g., lactate, urea) and enzymes (e.g., creatine kinase), they are currently looking for the ways to determine the level of hormones in the blood [12].

Endogenous hormones play an important role in physiological reactions and adaptation to physical loads and influence the post-exercise recovery phase by modulating the anabolic and catabolic processes [14]. The formation of such effects is greatly affected by the steroid hormones, cortisol and testosterone, which are involved in adaptation to stressors [8, 13].

Increasing cortisol level is the response of the body to physical, physiological and psychological stresses [3]. It is essential to provide energy, maintain fluid homeostasis, increase cardiac output and blood pressure, develop an adequate excessive inflammation of the immune response. Otherwise, the response to severe stress can be swift and fatal [10]. At the same time, with overtraining of athletes, which is accompanied by a steady increase in the level of corticosteroids, an imbalance of the neuroendocrine system develops, which can lead to damage of muscle fibers, a decrease in the muscle glycogen reserve, worsening of aerobic performance, decreased immune defenses, worsening of psychological status, which inevitably leads to poor sports performance [2].

Sex hormones, despite their specific mission in the reproductive processes, are biologically extremely important in providing proliferation and anabolism [5]. Testosterone has anabolic effects on the muscle tissue, promotes maturation of the bone tissue, takes part in the regulation of the synthesis of lipoproteins, endorphins, insulin [3].

These hormones are competitive agonists at the level of muscle cell receptors [14]. Since their functions are diametrically opposed, the testosterone/cortisol ratio is used as an indicator of the anabolic/catabolic balance. It decreases when exposed to intense and continuous physical loads, as well as during training or recurring competitions, which may cause inhibition of the regeneration processes. The testosterone/cortisol ratio (anabolic index) can be used as an indicator of the actual physiological load during exercise, as well as a marker of an overtraining syndrome [11].

Objective of the study was to rate the hormonal transformations and their correlations in junior male athletes with different levels and specifics of everyday physical activity versus their rates under muscular loads and in post-training rehabilitation periods.

Methods and structure of the study. Subject to the study were 17-23 year-old athletes (n=52) classified into 3 groups by the initial fitness and load rates. The first group consisted of athletes developing their speed-strength abilities – combat athletes (n=18). The second group was made of those developing endurance - skiers, biathletes and athletes (n=18). The third group, the reference one, involved relatively healthy males, whose level of everyday physical activity depended on the volume of physical activity in terms of university (n=16). The first and second groups included elite athletes only.

Critical muscle tension at different stages of the study was secured by the 30-minute and 60-minute cycle ergometer practices rated by 2W/ of body mass, with the cycling intensity of 60 revolutions per min. Hormone concentrations in the blood serum were measured at rest by ELISA test using the "Vector Best" kits (Russia), as well as in restitution conditions under submaximal muscular load (immediately after exercise, after 1-hour recovery). All studies were performed in the morning hours on an empty stomach. Two days before the study, the athletes were exempted from training sessions.

All subjects gave their informed consent for participation in the study. The statistical data processing was made using the Student t-criterion, with the difference rated significant at p<0.05. 

Results and discussion. The calculation of the anabolic index (AI) was carried out according to the formula: AI(%) = (Testosterone/Cortisol)*100. The reference values ​​of the index are 5-8%. It is generally accepted that this range reflects the balance between the processes of anabolism and catabolism. The AI values ​​ranging between 3-5% testify to insufficient recovery and development of fatigue [3, 9]. Those less than 3% indicate serious endocrine disorders and development of the overtraining syndrome [1, 9]. These limits are not strict and may somewhat vary based on the individual characteristics.

Since the testosterone level at rest was at the upper normal level in the overwhelming majority of the subjects, the low AI, characteristic of the state of fatigue and overtraining syndrome, was due to the high cortisol level. It was also noted that the intensity and direction of changes in AI during rehabilitation after muscular load mostly depended on the changing level of cortisol rather than testosterone, since the changes in the glucocorticoid concentration were found to be more significant. We identified two types of adaptation reactions of the endocrine system to submaximal loads, not influenced by the level of physical fitness of the subjects (see Table 1).

The first type of reaction is typical for the subjects with the normal background level of cortisol (N = 190-690 nmol/L) and AI within the reference values ​​of 5-8% (the representatives of the experimental and reference groups in the 60-minute load period). The representatives of these groups demonstrated an increase in the cortisol level and a decrease in AI after physical exercise. Such a reaction to physical activity is adequate, since an increase in the blood cortisol is due to the "switch" of metabolism to the catabolic processes due to an increase in energy expenditure [8].

The second identified type of reaction to physical stress is an increase in AI, associated with a decrease in the cortisol concentration versus the background values. This type of response was observed in the groups of subjects with the background values of glucocorticoid being above the physiological norm, and AI level below 5% (all groups at the 30-minute load stage and representatives of the speed-strength group at the 60-minute load stage). The decrease of the cortisol level in terms of physical stress can be indicative of the endocrine disorders against the background of developing fatigue and overtraining syndrome [4, 6]. Apparently, in terms of the high background values of this hormone, a process of protective inhibition of the hypothalamus-pituitary-adrenal axis activity starts, which prevents excessive physical loading, as well as damage to the bodily organs and tissues. The reduction of the cortisol level after exercise should probably be deemed a positive reaction, since a continuous and steady increase in the hormone blood level upon competition of exercise prevents recovery of the body [7].

 

Table 1. Average blood cortisol (N = 190-690 nmol/L) and testosterone (N = 12-35.4 nmol/L) in the subjects, anabolic index (N = 5-8%)

30` muscular load
Group	Indicator	Background indices	Muscular load	60` recovery
Speed-strength qualities (n=10)	Cortisol	894.9±54.2	890.9±73.3	640.7±54.8*^
	Testosterone	31.9±1.2	36.3±1.8	30.2±1.3^
	AI	3.6±0.3	4.1±0.2	4.8±0.3*
Endurance level (n=10)	Cortisol	870.3±60.8	744.4±61.0	601.2±53.8*
	Testosterone	30.9±1.4	33.7±2.2	29.5±2.1
	AI	3.7±0.3	4.6±0.4*	5.2±0.6*
Reference (n=8)	Cortisol	844.0±89.0	776.6±63.1	585.9±77.8*
	Testosterone	32.0±1.4	34.4±1.4	29.0±1.3^
	AI	4.0±0.4	4.8±0.4	5.7±0.4*
60` muscular load
Group	Indicators	Background values	Muscular load	60` recovery
Speed-strength qualities (n=8)	Cortisol	1068.0±118.2	581.3±45.9*	616.7±71.2*
	Testosterone	31.3±2.7	30.6±1.3	22.5±1.0*^
	AI	2.9±0.2	5.4±0.2*	4.3±0.1*^
Endurance level (n=8)	Cortisol	536.1±31.7	784.4±69.0*	1080.5±58.1*^
	Testosterone	32.3±1.0	37.4±1.4*	44.7±0.5*^
	AI	6.2±0.5	4.6±0.1*	4.2±0.2*
Reference (n=8)	Cortisol	543.0±6.9	813.1±139.1	866.5±113.0*
	Testosterone	31.5±3.4	35.1±1.8	31.4±1.3
	AI	5.8±0.6	4.5±0.4	3.5±0.2*

* – р<0.05 versus background; ^ – р<0.05 versus muscular load.

 

The criteria selected for determining the balance between the anabolic and catabolic processes in the body can be the blood cortisol ​and anabolic index, which values should be within the physiological norm. In our situation, the reaction to muscular load is expressed in a temporary increase in the cortisol level and, accordingly, a decrease in AI, which is due to the activation of stress-realizing systems (hypothalamus-pituitary-adrenal and adrenergic), causing a significant and long-term release of the corresponding hormones, including glucocorticoids having a pressor and catabolic effects [8, 11].

Conclusion. The background values of the anabolic index were found to fall with developing fatigue and overtraining syndrome, which is due to the elevated cortisol level. A reverse normal reaction is observed under muscular loads, consisting in the inhibition of the hypothalamus-pituitary-adrenal axis and an increase in AI.

Therefore, determination of AI and the indices of its dynamics after the cycle ergometer test can be used as effective criteria for diagnosing the development of pre-nosological and pathological conditions.

 

The study was financed by the Foundation for Assistance to Small Innovative Enterprises in Science and Technology as part of the “UMNIK” program.

 

References

1. Afanasyeva I.A., Taymazov V.A. Zabolevaemost sportsmenov na raznyih etapakh trenirovochnogo tsikla i ee svyaz s biokhimicheskimi i gormonalnymi markerami peretrenirovannosti [Athlete's morbidity at different stages of training cycle and its relation to biochemical and hormonal overtraining markers]. Uchenye zapiski un-ta im. P.F. Lesgafta, 2011, no. 11 (81), pp. 12-18.

2. Afanasyeva I.A. Zavisimost fagotsitarnoy aktivnosti leykotsitov ot urovnya kortizola u sportsmenov pri intensivnykh fizicheskikh nagruzkakh [Dependence of leukocyte phagocytic activity of cortisol in athletes during exercise]. Uchenye zapiski un-ta im. P.F. Lesgafta, 2011, no. 8 (78), pp. 19-23.

3. Vinnichuk Yu.D., Gunina L.M. Prediktory i markery funktsionalnogo sostoyaniya sportsmenov pri trenirovkah v srednegore [Predictors and markers of athlete's functional state in middle altitude training]. Zdorovye dlya vsekh, 2014, no. 2, pp. 3-9.

4. Viru A.A. Funktsii kory nadpochechnikov pri myishechnoy deyatelnosti [Functions of Adrenal Cortex at Muscular Activity]. Moscow: Meditsina publ., 1977, 176 p.

5. Gryaznykh A.V. Indeks testosteron/kortizol kak endokrinny marker protsessov vosstanovleniya vistseralnykh sistem posle myshechnogo napryazheniya [Testosterone/cortisol ratio as endocrine marker of restoration processes of visceral systems after muscle work]. Chelovek. Sport. Meditsina, 2011, no. 20 (237), pp. 107-111.

6. Isaev A.P., Erlikh V.V. Polifunktsionalnaya mobilnost i variabelnost organizma sportsmenov olimpiyskogo rezerva v sisteme mnogoletney podgotovki [Multifunctional mobility and variability of the body of Olympic team athletes in long-term training system]. Chelyabinsk: SUSU publ., 2010, 503 p.

7. Namozova S.Sh., Baranova T.I. Dinamika kortizola v krovi basketbolistok na raznykh etapakh podgotovki [Blood cortisol dynamics in basketball players at different training stages]. Zdorovye – osnova chelovecheskogo potentsiala: problemy i puti ikh resheniya, 2012, no. 1, vol. 7, pp. 262-269.

8. Pogodina S.V., Kozlova S.N., Liskonog L.V. et al. Izmeneniya soderzhaniya kortizola v organizme muzhchin razlichnogo vozrasta i urovnya trenirovannosti pri vypolnenii fizicheskoy raboty [Changes in cortisol level in men of different age and fitness levels during exercise]. Uchenye zapiski Tavricheskogo natsionalnogo un-ta im. V.I. Vernadskogo. Ser. Biologiya, khimiya, 2014, vol. 27 (66), pp. 132-141.

9. Taymazov V.A., Afanasyeva I.A. Sindrom peretrenirovannosti u sportsmenov: endogennaya intoksikatsiya i faktory vrozhdennogo immuniteta [Overtraining syndrome in athletes: endogenous intoxication and factors of innate immunity]. Sb. nauch. trudov Universiteta im. P.F. Lesgafta, 2011, vol. 12, no. 82, pp. 24–30.

10. Boonen E., Stefan R., Bornstein, Greet Van den Berghe New insights into the controversy of adrenal function during critical illness. The Lancet. Diabetes and Endocrinology, vol. 3, no. 10, 2015, pp. 805-815.

11. Brownlee K.K., Kaye K., Brownlee, Alex W. Moore, Anthony C. Hackney Relationship Between Circulating Cortisol and Testosterone: Influence of Physical Exercise. Journal of Sports Science and Medicine, 2005, no. 04, pp. 76-83.

12. Fry R.W., Morton A.R., Keast D. Overtraining in athletes. Sports Medicine, 1991, Jul, 12(1), pp. 32-65.

13. Hackney A.C. Cortisol, stress and adaptation during exercise training. Education Physical Training Sport, 2008, no. 3(70), pp. 34-41.

14. Urhausen A., Gabriel H., Kindermann W. Blood Hormones as Markers of Training Stress and Overtraining. Sports Medicine. October 1995, vol. 20, no. 4, pp. 251-276.

 

Corresponding author: psamikulin@mail.ru

 

Abstract

Objective of the study was to rate the hormonal transformations and their correlations in junior athletes versus their physical activity and muscular loads in the rehabilitation periods. Testosterone and cortisol levels were tested versus the background values straight after and one hour after the exercise in the recovery process, with the anabolic indices being calculated. Strenuous physical loads were secured by 30/60min cycle ergometer practices rated by 2W/ kg of body mass, with the cadence of 60 revolutions per min. Subject to the study were 17-23 year-old athletes (n=52) grouped by the initial fitness and exercise rates. The study found a correlation of the metabolic index with the muscular load with background cortisol levels. Normally the index was found to fall after the cycle ergometer test and grow in case of fatigue and/or overtraining.