Abstract:Background and Objectives: The cardiovascular system of young athletes is subject to functional changes associated with an increase in both vasodilator capacity of blood vessels and an increase in vasoconstriction. Diagnostics of functional changes in the vascular system of athletes can be carried out by the sphygmographic method when measuring the reflection index, which characterizes the change in the tone of the smooth muscle wall of the vessel during an occlusive test. Materials and Methods: Two groups of 16-year-old patients were selected for the examination: a group of 10 athletes engaged in kayaking and Canoeing, and a control group including 10 non-athletic control subjects without identified cardiovascular pathologies. Registration of reflection indices was performed by sphygmography in the brachial artery area before and after the occlusion test. Results: Compared with a group of non-athletic subjects, the reflection indices measured in athletes with high sportive results after removal of the shoulder cuff occlusion have higher values than before the occlusion. The change in the reflection index is characterized by non-monotonic dynamics, consisting of an initial increase, and then a decrease to a value close to the original one. Conclusion: The more pronounced dynamics of vascular tone and reflection index after removal of occlusion can be explained both by an increase in the thickness of the glycocalyx layer, due to regular physical training, and by an increased blood flow rate in athletes before and after occlusion compared to the group of untrained subjects.