Dr.Biol., Professor O.L. Nifontova¹
Dr.Biol., Professor S.I. Loginov²
Postgraduate V.Z. Kon'kov¹
Postgraduate S.V. Kolomeets¹
Postgraduate S.G. Sagadeeva^2
1Surgut State Pedagogical University, Surgut
²Surgut State University, Surgut

Keywords: cardiorespiratory system, athletes, students, Yugra North.

Introduction. It is well known that physical activity is a recognized factor in prevention of diseases and health promotion [7]. A complex of adaptive structural and functional changes develops in the body of an athlete under the influence of physical activity. The cardiorespiratory system plays a major role in this process, and optimization of its function is a prerequisite for achieving high performance. The problem of human body adaptation to physical activity in the specific climatic conditions of the Yugra North territory of the Russian Federation is of particular interest, since in addition to strenuous physical loads a whole range of negative environmental factors impacts the body of an athlete – low air temperature, lack of light, sudden changes in temperature, atmospheric pressure, etc. [9].

Objective of the study was to identify the functional features of the cardiorespiratory system of athletes with different training purposes in comparison with those not doing sports.   

Methods and structure of the study. Seventy-five first-, second- and third-year students of Surgut State Pedagogical University and Surgut State University aged 18-20 were involved in the study. There were the following groups: cyclic sport group (n=25), acyclic sport group (n=25) and reference group of non-sporting students (n=25). All the athletes had at least the 1^st category and trained regularly, at least 6 days a week for 1.5-2 hours a day. The reference group consisted of students of health groups 1 and 2, attending physical education classes in line with the university curriculum. Functional state features of the cardiorespiratory system were studied using the Spiro-Spectrum hardware-software complex (Russia) in the first half of the day, in the conditions of thermal comfort, after a 20-minute rest, in the sitting position. Heart rate (HR) was measured three times using an A&D Medical tonometer. Adaptation potential (AP), stroke volume (SV) by the formula of Isaac Starr and cardiac index (CI) were calculated. Cardiac output (CO) was calculated as the product of SV times HR. Normality of variables distribution was tested using the Shapiro-Wilk test. Assessment of observed differences was performed by the Student’s t-test using BIOSTAT statistical package and Microsoft Excel 2007 software.

Results and discussion. Analysis of the results of the study of the students’ respiratory system showed that average values of vital capacity (VC) in all the surveyed groups were normal [4]. However, this indicator was significantly higher (р=0.041) in the cyclic sport group compared with the reference group (Table 1).

Table 1. Respiratory system indicators of students with different training purposes (M±m)

Note: 1 – cyclic sport group, 2 – acyclic sport group, 3 – reference group, n/s – not significant. Explanation of abbreviations in the text.

Forced vital capacity (FVC) is one of the main indicators characterizing the respiratory system when there is a forced load and allowing to assess the airflow through the respiratory tract [3]. FVC was normal in all the surveyed groups, however, the highest values were recorded in the cyclic sport group.

In order to identify possible violations in bronchial patency we studied the Tiffeneau index since it indicates the presence of obstructive disorders [4]. It was found that the Tiffeneau index is significantly higher in the reference group compared with the athletes of the cyclic (р=0.013) and acyclic (р=0.031) sport groups. In addition, the average values of the maximum expiratory flow (MEF) were proved to be lower in athletes than in non-sporting persons. Thus, it can be assumed that the high-intensity exercises in the Far North conditions may be the reason of obstructive disorders formation. 

It is known that the respiratory system reserves of a person can be assessed by the value of the maximal pulmonary ventilation (MPV) [10]. In addition, this number gives an indication of integral changes of breathing mechanics, since it depends on the strength of the respiratory muscles, lung and chest compliance, as well as air flow resistance [4]. Our studies showed that MPV is significantly higher (р=0.041) in the cyclic sport group compared with the acyclic sport group subjects. MPV of the athletes from the cyclic sport group was normal, while the acyclic athletes and the reference group members had it slightly lower than normal. This fact may indicate a decrease in pulmonary ventilation effectiveness caused by incoordination in the respiratory muscles function and respiratory rhythms violation [8].

It is known that the cardiovascular system is involved in all aspects of life-sustaining functions of the body, ensuring due delivery of oxygen and nutrients as well as excretion of wastes. In addition, it is one of the leading factors of adaptation of the human body to the environment [9]. HR is one of the main integral characteristics of the cardiovascular system state. Our studies revealed that HR was within the physiological norm in all the studied groups [6]. However, the average HR value of the non-sporting group members was significantly higher than in the groups of students involved in cyclic (p=0.01) and acyclic (p=0.001) sports (Table 2).

AP was calculated to assess the level of functioning of the circulatory system and determine its adaptive capabilities [1]. Its average value was indicative of stressed adaptation mechanisms in all the surveyed groups. Meanwhile, it should be noted that the AP value was significantly higher in the group of non-sporting students compared with the those from the cyclic and acyclic sport groups (р=0.023 and р=0.007, respectively).

Stroke volume indicates the amount of stroke output and characterizes the heart pumping performance [2]. In our studies this value was within the normal range in all the surveyed groups, and no significant differences were found.  

Table 2. Indicators of peripheral and central circulation of students with different training purposes (М ± m)

Note: 1 – cyclic sport group, 2 – acyclic sport group, 3 – reference group, n/s – not significant. Explanation of abbreviations in the text.

Comparison of CO values revealed significant differences between the non-sporting students and the athletes from both of the groups. Thus, the average value of this indicator in the reference group exceeded the one of the cyclic sport group by 0.69 l/min and the one of the acyclic sport group – by 1.07 l/min (p=0.001). It was found that in case of similar SV values the increase of CO in the reference group was associated with higher HR values, which may indicate a worse state of the heart and hemodynamics as a whole, including the regulatory mechanisms. 

Assessment of the cardiac index value allowed to reveal that non-sporting students were characterized by the eukinetic circulation type (ECT), while in case of the cyclic and acyclic athletes the average CI values corresponded to the hypokinetic circulation type (HCT) (Table 2).

Conclusion. External respiration system of cyclic athletes functions most efficiently against the background of a general increase in its capacity limits. It was found that the high-intensity exercises in the Far North conditions may be the reason for a reduction in air permeability in medium and small bronchioles. All this increases the risks of obstructive disorders development, as evidenced by the indices values. 

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Corresponding author: logsi@list.ru

Abstract

The study presents the cardio-respiratory system (CRS) performance test data of 75 university students residing on a permanent basis in the Yugra North territory. The subjects were split up into the following 3 groups: cyclic sport group; acyclic sport group; and reference group of non-sporting students. The study data gave the grounds to find that the high-intensity physical loads in the Far North conditions tend to increase the risks of obstructive disorders as verified by the higher Tiffeneau indices in the reference group (90.4%) versus the cyclic sport group (83.5%) and the acyclic sport group (83.2%). The CRS adaptive response rates of the non-sporting students were indicative of less efficient heart performance process with the higher minute volumes of 5.4 l/min and higher heart rates of 79.3 bpm.