Dr.Biol., professor R.V. Tambovtseva
I.A. Nikulina
Russian State University of Physical Culture, Sport, Youth and Tourism (GTsOLIFK), Moscow

Keywords: physical working capacity, hormones, graduated exercise, carbohydrates, lipids, ATP, metabolic substrates, concentration, metabolism.

Introduction. It is known that physical working capacity is determined by a number of various factors among which of particular importance is neuroendocrine regulation of mobilization, use and replenishment of energy substrates stock, plastic processes support, homeostasis maintenance, functioning of ion pumps and adaptive synthesis of protein [1, 2, 3, 4, 6, 7]. There are three types of hormonal reactions to physical loads: 1 – fast reactions which include an increase in the catecholamine, cortisol, corticotropin and corticotropin concentrations during the first minutes after starting an exercise; 2 – reactions of moderate intensity when increased secretion of aldosterone, thyroxine, vasopressin and thyreotropin takes place; 3 – reactions with a lag-period when the levels of somatotropic hormone, glucagon and calcitonin increase, but the level of insulin revealed not sooner than 15-20 minutes after the start of exercise decreases. It should not be overlooked that the same metabolic effect can be achieved by affecting the body using various regulators, and individual differences in the response of the body to exercise of varying intensity and duration can be quite significant. In this connection it is beneficial for sport practice to study the characteristics of body adaptation that are specific of a particular sport. Detection of specific adaptive changes can contribute to the improvement of training techniques in various sports and selection of the most informative methods of biochemical control. While making changes to the organization of sport training requires studying biochemical processes that take place in a specific training and competitive activity, improvement of biochemical control methods in sport requires laboratory testing. These biochemical tests are necessary not only to ensure accurately graduated exercises, but also have a great potential in terms of studying the dynamics of biochemical parameters during and after exercising.

Objective of the research was to study the dynamics of concentration of various energy substrates and hormones in athletes of various specializations (speed skaters, track and field athletes), having high sport skill levels. 

Research method and organization. The research was conducted in the premises of the Laboratory of Sport Bio-energetics at the Department of Biochemistry and Bio-energetics of sport named after N.I. Volkov of Russian State University of Physical Culture, Sport, Youth and Tourism. The experiment involved elite athletes specializing in all-round speed skating (n=11) and long-distance track and field athletes (n=8). Step load test on a cycle ergometer was used. The load at the first stage was one watt per one kilogram of the body weight. The increase of the load at each subsequent stage was equal to the initial one. The stages were three minutes long. The duration of the test was 15 minutes. A blood draw took place at rest, at the time of «failure», at the third and tenth minutes of recovery. Urine was collected before the exercise and within 10 minutes after it. The concentrations of insulin and somatotropiс hormone, non-esterified fatty acids, glycerol and glucose were determined in venous blood. The lactic acid concentration was determined in capillary blood. The catecholamine concentration - in urine.

     Research results and discussion. The study of changes in the hormones and energy substrate concentrations in athletes of various specializations during the test performance revealed a number of features in the response reaction to the maximum load. Table 1 shows the concentration of peptide hormones and metabolic substrates in the blood as well as the urinary excretion of catecholamines and dihydroxyphenylalanine in a state of relative rest in speed skaters and track and field athletes.

Table 1. Concentration of hormones and energy substrates in the blood and urinary excretion of catecholamines in a state of rest in speed skaters and track and field athletes.

Note: (*Р<0.05; **Р<0.001)

The results showed significant differences between the speed skaters and the track and field athletes in terms of insulin, somatotropic hormone, adrenaline, noradrenaline, dihydroxyphenylalanine and dopamine levels and insignificant differences in terms of glucose, non-esterified fatty acids and glycerol.

The concentration of hormones in the blood and urine as well as energy exchange metabolites at the moment of «failure» undergoes a few changes. There is a decrease of insulin concentration at the moment of «failure» compared with the resting level of both the speed skaters and the track and field athletes. Meanwhile, the somatotropic hormone concentration significantly increases in the same athletes. The load takes place against the background of the growth of adrenaline excretion, significant in all the groups. Increased excretion of noradrenaline was recorded only in the track and field athletes.

The direction of changes in blood glucose in response to the load is opposite to the insulin dynamics: an increase in glycose concentration is noted in the speed skaters and the track and field athletes. A small increase of non-esterified fatty acids is recorded. Glycerol level changes during the exercise were insignificant. A large increase in the blood lactate concentration is noted in all the groups.

There was a sharp increase in insulin concentration in the speed skaters during the 3rd minute of the recovery period. The level of the somatotropic hormone remains high in both the speed skaters and the track and field athletes, but in the speed skaters this level is increased even more by the 10th minute of recovery. The glucose level also remains elevated compared to the state of rest in two of the groups of athletes. For most of the subjects the strong dynamics of hormonal changes during the transition from rest to exercise and after its completion is revealed. 

The specificity of adaptation of athletes of various specializations in response to the load is reflected in various interconnections between the concentration of hormones and energy substrates (Table 2).          

Table 2. Matrices of correlations between the dynamics of hormones and energy substrates of speed skaters and track and field athletes. 

Note: (^х0.1<Р>0.05; *Р<0.05; **Р<0.01)

  As the data in the table show, representatives of various sports have different correlation dependences. While there is a strong negative association between the production of the somatotropic hormone and catecholamine excretion in the speed skaters, in case of the track and field athletes this relationship is direct.

The data obtained during the performance of the step load test to failure by athletes of various specializations – speed skaters and track and field athletes – allowed a conclusion that, in addition to general mechanisms of human body adaptation to physical load, these athletes also have some specific features of metabolic processes related to differences of parameters of loads during training and competitions and specifics of their body types. The differences in the course of metabolic processes of athletes of various specializations were manifested both in the state of rest and in response to exercise. At rest these differences included lower blood insulin and higher level of urinary excretion of adrenaline in the track and field athletes versus the speed skaters. Long-distance track and field athletes have less fat compared to representatives of other sports. This may be the explanation of the lower blood insulin level, as it is known that secretion of insulin directly correlates with the total mass of fatty tissue. Both the track and field athletes and the speed skaters demonstrated a moderate increase  in the non-esterified fatty acids concentration in the blood in response to the load, which indicates a balance of mobilization and utilization of lipids. In addition, in case of both the track and field athletes and the speed skaters the glucose mobilization rate exceeds the rate of its use, which manifested itself in the increase of its level after the load.

The study of changes in carbohydrate and lipid metabolism and their regulation characteristics in athletes of various specializations revealed differences in the reaction of the sympathetic-adrenal system, peptide hormones and the metabolic processes they regulate to the physical loads to failure. For example, in the speed skaters the activation of the sympathetic-adrenal system was mainly due to its adrenal part, and in the track and field athletes - due to the sympathetic part. In addition, a negative correlation was detected in the speed skaters and track and field athletes between the glucose and insulin concentration in the blood, which corresponds to the data found in literature regarding the relationship between blood insulin and glucose production by the liver during exercise [1, 3, 4, 5, 6, 7].

A correlation analysis of the changes in the hormone and substrate concentration regardless of the sport does not reveal significant correlations in either changes of the concentration of various hormones or the changes of the hormone and metabolite concentration. This serves as additional evidence of significance of the differences in hormonal and metabolic responses to the load in athletes of various specializations with similar qualifications and at the same stage of the annual training cycle. 

The obtained data made it possible to specify the fluctuation limits of the physiological norm values and changes in response to the graduated exercise for the concentration of energy substrates and hormones in the blood, without which it is impossible to assess test results while performing biochemical monitoring in sport.

     Conclusions

•       Differences in the course of metabolic processes in athletes of various specializations are manifested both while at rest and in response to physical load.

•       Track and field athletes have less insulin in their blood and larger urinary excretion of adrenaline while at rest compared to speed skaters. 

•       Track and field athletes have relatively less fat compared to speed skaters.

•       Speed skaters and track and field athletes have high physical working capacity while performing the test load that is associated with high efficiency in the use of energy substrates and oxygen.

•       A moderate increase in the non-esterified fatty acids concentration in the blood in response to the load is noted in the track and field athletes and the speed skaters indicating a balance of mobilization and utilization of lipids.

•       Glucose mobilization rate exceeds the rate of its use in both the track and field athletes and speed skaters, which manifests itself in the increase of its level after the load.

•       There is a strong negative association between the production of the somatotropic hormone and catecholamine excretion in the speed skaters, while in case of the track and field athletes this relationship is direct.

•       The activation of the sympathetic-adrenal system in the speed skaters takes place mainly due to its adrenal part, and in the track and field athletes - due to the sympathetic part.

References

1. Volkov N.I. Biokhimiya myshechnoy deyatel'nosti: uchebnik (Biochemistry of muscle activity: textbook) / N.I. Volkov, E.N. Nessen, A.A.Osipenko, S.N. Korsun. – Kiev: Olimpiyskaya literatura, 2013. – 503 p.
2. Volkov N.I. Trenirovka sil'neyshikh kon'kobezhtsev mira (Training of strongest skaters of the world) / N.I. Volkov, B.A. Stenin. – Moscow: Fizkul'tura i sport, 1970. – 194 p.
3. Kremer U. Dzh. Endokrinnaya sistema, sport i dvigatel'naya aktivnost' (Endocrine system, sport and motor activity) / U. Dzh. Kremer, A.D. Rogol. – Kiev: Olimpiyskaya literatura, 2005. – 599 p.
4. Severin E.S. Biokhimiya: uchebnik (Biochemistry: textbook) / E.S. Severin. – Moscow: GEOTAR-Media, 2014. – 759 p.
5. Tambovtseva R.V. Izmenenie gormonal'noy regulyatsii obmennykh protsessov u kon'kobezhtsev na raznykh etapakh trenirovochnogo tsikla (Changes in hormonal regulation of metabolism in skaters at different phases of training cycle) / R.V. Tambovtseva, I.A. Nikulina // Teoriya i praktika fizicheskoy kultury. – 2015. – № 5. – P. 52–54.

Corresponding author: ritta7@mail.ru

Abstract

Objective of this study was to investigate the dynamics of concentration of various energy substrates and hormones in elite athletes from different disciplines (skaters, athletes) during the step test "to failure" on a cycle ergometer.

The concentration of insulin and somatropin, non-esterified fatty acids, glycerin and glucose in the venous blood and lactic acid concentration in the capillary blood were measured at relative rest at the time of "failure" to work, in the 3rd and 10th minutes of recovery. The urine was tested for catecholamines and their precursors. The physical working capacity of skaters and athletes was high during the test load which is due to more economical energy substrate and oxygen consumption. Representatives of different sports have different correlations between the hormone and metabolite concentrations, indicating different hormonal and metabolic response to load in athletes from different disciplines, having a similar skill level and being in the same phase of the annual training cycle.