CHANGES IN HEART RATE AND PERIPHERAL SATURATION IN YOUNG ORIENTEERING ATHLETES WHEN PASSING SPORT DISTANCES OF DIFFERENT DIFFICULTY
Authors: Biryukova E. A. , Yarmolyuk N. S. , Abdurashitova L. E. , Tkach E. S. , Yukalo E. V. , Abdulganieva E. F. 
Published: October 2021

Nowadays, youth sport, on a par with professional sport, imposes stringent requirements for physical and emotional preparation of athletes [1]. Orienteering is no exception, where in the system of preparation of young athletes an important task is to control the formation of adequate adaptive reactions to intensive muscular activity [2]. Running orienteering is characterized by performing maximum and even excessive physical loads during different time intervals, which is associated with significant mobilization of energy systems of young athletes’ organism – cardiovascular, respiratory, humoral and metabolic, etc. [2, 3]. Due to the fact that for ethical reasons invasive methods (blood lactate control) of functional diagnostics, as well as some stress tests (load testing «to failure») are often not applicable to school-age children, including orienteering athletes, the search for simple noninvasive, applicable in the field methods of functional state control during and after passing sports distances of different complexity in order to monitor adequacy of training process and prognosis is actual.
We think that assessment of blood oxygen saturation degree (SpO2 %), which, according to literature data, reflects real efficiency of cardiorespiratory system operation, is one of such methods along with heart rate (HR) recording [4–9]. SpO2 % determination by direct oximetry has been introduced into clinical practice for quite a long time. However, recently it has become possible to monitor blood oxygen saturation out of clinical control due to the development of portable pulse oximeters for indirect transdermal determination of SpO2 %. However, to date in the scientific literature there are virtually no studies of functional changes in the degree of blood saturation, as well as HR, in young orienteering athletes.
Therefore, the aim of our study was to assess the changes in heart rate and peripheral saturation in young orienteering athletes when passing sport distances of different difficulty.
After athletic distance the HR values in young athletes increased on average by
130–170 % (boys) and 140–150 % (girls) relative to the values recorded at rest in these subjects. The maximum increase in heart rate was recorded in both groups of test athletes after cross sprint distances – by 177.4 % (p<0.05) and 147.05 % (p<0.05)) cross-long – by 251.6 % (p<0.05) and 141.2 % (p<0.05) for boys and girls respectively, indicating the greatest changes in functional state, particularly tension of energy supply mechanisms during these distances.
After cross-sprint and cross-long distances the reliable decrease of peripheral blood saturation ≈ on 1,8 % (p<0,05) at boys and ≈ on 2,6 % (p<0,05) at girls has been registered in young orienteering athletes. The data obtained by us testify to the fact that the passage of distances cross-sprint and cross-long caused the greatest change in blood saturation and tension of mechanisms of their energy supply in young orienteering athletes associated with the development of hypoxic states, caused by lactate acidosis.
Significant differences in the dynamics of changes in the studied parameters between the groups of boys and girls 13–14 were recorded only for the saturation index: on the distances cross-sprint and cross-long SpO2 values for both distances for girls were ≈1.03 % (p<0,05) lower than for boys. This indicates that young men have an advantage in adapting to physical loads associated with cross-country sport distances compared to girls of the same age.