T.V. Tat'yanina, associate professor, Ph.D.
O.I. Chudaeva, postgraduate
Mordovian State Pedagogical Institute named after M.E. Evsev'ev, associate professor, Ph.D., Saransk

Key words: cardio-respiratory system, teenagers, sports and fitness activities, physical load, body adaptation.

Relevance. Youth sport is one of the most effective factors of conscious harmonization and individualization of human development. Sport most effectively stimulates positive functional and morphological changes in the developing body of an individual and is good for the formation of motor skills. Regular sports classes promote mental development of a person, especially adolescents, who are distinguished by the rapidly forming consciousness, the desire to cultivate their valuable personality traits (volitional, moral and physical). In sport they are displayed, stimulating the social and personal growth of a person. Adolescence is a sensitive period for the active drive for attainment of a particular social position associated mainly with self-actualization, consolidation in the adult world and a desire to maximize own potentials [1; 4].

The issue of adaptation during physical activity is relevant in modern sport with its extreme training loads and emotional stress. The adaptation of young athletes to the increasing physical load implies the acceleration in the recovery of physiological parameters of the body after strenuous training and a direct improvement in physical performance [3]. It is impossible especially for young athletes to achieve high results without doing any harm to health without the optimally balanced control over the functional training of an adolescent’s body. Therefore, it becomes very urgent to study the peculiarities of the process of adaptation of an adolescent’s body to strenuous muscular activity.

The purpose of the study was to investigate the features of cardiorespiratory adaptation of adolescents to perform physical loads during sports and fitness activities.

Materials and methods. Cardiorespiratory system is a crucial one as it determines the activity of the whole organism under conditions of both relative physiological rest and strenuous muscular activity. That's why for the sake of the study of the nature of functional adaptation of a young organism to physical activity, we studied the nature of the influence of muscle work on the indicators of oxygen transport system. The research on the adaptation of the adolescents’ cardiorespiratory system to exercises during sports and fitness activities, involving adolescent athletes, was conducted at the Regional Applied Research Center of Physical Culture and Healthy Lifestyle which is a structural subdivision of Mordovia base center for pedagogical education of Mordovian State Pedagogical Institute. The total sample was 120 adolescents divided into one experimental and two control groups.

Results and discussion. In order to study the nature of the functional adaptation of the organism 20 students aged 14-16 were examined (the mean age 15,45±0,22, height 167,5±3,01, weight 56,35±2,17) including 10 adolescents not involved in sports and whose motor activity was reduced to exercises during school physical education lessons (control group) and 10 teenagers having been practicing athletics (running) for 3 years (the experimental group). The groups did not differ in the age, height or weight (Table 1).

Table 1. The average parameters of the subjects

The nature of the functional adaptation of the organism (based on the indicators of the cardiorespiratory system) to exercises at rest and immediately after muscle work was studied by measuring heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure and respiratory rate in both groups. Other parameters calculated were pulse pressure (PP), average dynamic pressure (ADP), systolic output (SO), cardiac output (CO) and the period of recovery of heart rate. In addition, the following indicators were determined in both groups at rest: breathing capacity (BC), inspiratory (IRV) and expiratory reserve volume (ERV), pulmonary minute volume (PMV) and vital capacity (VC). The 800 m distance run was used as a test exercise (subjects had to run as fast as possible).

The results showed that the basic average statistical parameters of the cardiorespiratory system in a state of relative physiological rest are within the physiological range (Table 2). Unlike the control group, the subjects of the experimental group are characterized by a significant HR fall, a decrease in SBP and DBP, as well as increase in resting VC, that indicates the economized functioning of the oxygen transport system of the adolescents engaged in athletics during the long-term adaptation to physical activity [3]. There have not been detected any significant differences in BC, IRV, ERV and PMV among the subjects of both groups.

The implementation of intense muscular activity led to a significant increase of the functional indicators of cardiorespiratory system such as HR, SBP, PP, SO, CO, RR in control and experimental groups. In addition, the exercise also caused a significant increase in ADP among the representatives of the experimental group, while among the representatives of the control group this indicator was statistically insignificant. The findings suggest that the reaction to muscular work is within a physiological range for the subjects of both groups.

However, despite the unidirectional change in the indicators of oxygen transport system of trained (athletes) and untrained adolescents, the degree of manifestation of these indicators was different in various groups. Particularly, it was found that a single intense muscle activity leads to a significantly greater increase in HR, SBP, DBP, RR and less pronounced increase in SO among the adolescents who are not trained for physical load (control group) compared to teenagers with considerable experience in athletics (the experimental group). It was also found that the time of heart rate recovery after muscle work in the control group is somewhat greater than that in the experimental group although the difference is not significant.

Table 2. Some functional indicators of the cardiorespiratory system

Note: Р_c-e - the significance of differences between the control and experimental groups; P - the significance of differences between the indicators at rest and during muscular activity

Conclusions. The detected differences are consistent with those of previous studies and suggest that regular sports classes are accompanied by the regular economization of body functions of adolescents, particularly the function of the oxygen transport system, and accelerated processes of recovery and reduction of the physiological cost of loads during long-term adaptation.

References

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2. Dubrovsky, V.I. Sports medicine / V.I. Dubrovsky. – Moscow: Vlados, 2002. – 480 P. (In Russian)
3. Zakhar'eva, N.N. Individually-typological features of adaptation of young athletes to physical loads in speed-strength forms of athletics / N.N. Zakhar'eva // Teoriya i praktika fizicheskoy kultury. – 2010. – № 2. – P. 25–28. (In Russian)
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