Endothelial function in athletes in the process of adaptation to training loads of different orientations

Abstract

Studies on endothelial dysfunction and its relationship with adaptive disorders in highly skilled athletes are few in number and mainly carried out in cyclic kinds of sports due to larger volumes and higher intensities of training loads associated with endurance performance gain. Stress and sex hormones and growth hormone play an important role in the regulation of endothelial function, but factors, which can stimulate negative vascular changes, remain a matter of debate. It is also unclear, whether changes in the vascular system depend on the type, mode or intensity of physical activity. The aim of the work was to perform a comparative assessment of endothelial function and to study the role of some hormones in its regulation in highly qualified athletes in the process of adaptation to various training loads. Material and methods. After signing a written informed consent, the study involved 104 athletes (80 men and 24 women) qualifying from the First-Class athletes to Masters of Sports of International Class (MSIC): 63 – athletes, who mainly trained endurance performance (triathletes, swimmers, long-distance runners, rowers), 31 – strength performance (weightlifters, powerlifters, kettlebell lifters), 10 – speed performance (sprinters). The mean age of the examined athletes was 21.75 ± 3.32 years. Among them, there were Masters of Sports of International Class (MSIC) – 2 athletes, Masters of Sports (MS) – 25, Candidates Master of Sports (CMS) – 48, First-Class athletes – 29. Plasma levels of endothelin-1, 6-keto-PG, erythropoietin, growth hormone, testosterone, free testosterone were determined by enzyme-linked immunoassay on a Seac ELISA-Reader Sirio S (Seac Radim Company, Italy). Results. There was no statistically significant difference in endothelin-1 levels between the endurance and strength athletes, but the strength-trained athletes showed a tendency towards endothelin-1 level predominance (0.77 ± 0.04 fmol/ml vs. 0.72 ± 0.06 fmol/ml; P = 0.176) and 2 times (P = 0.017) higher levels of 6-keto-PG. The endothelin-1 and 6-keto-PG levels did not differ significantly between the endurance and speed athletes. The strength-trained athletes exhibited 5.2 % (P = 0.016) higher endothelin-1 levels than speed-trained athletes. However, these athletes did not differ statistically in the 6-keto-PG (292.30 ± 70.38 pg/ml against 106.92 ± 74.44 pg/ml; P = 0.834) level. A positive correlation was found between the levels of erythropoietin and 6-keto-PG in the endurance-trained (r = 0.57; P = 0.00001) and strength-trained (r = 0.46; P = 0.013) athletes. Analysis of testosterone and free testosterone levels did not reveal statistically significant differences between endurance-, strength- or speed-trained athletes. At the same time, there was a trend towards higher levels of testosterone and free testosterone in the strength-trained athletes as compared to those in the endurance- or speed-trained athletes. The strength athletes showed a positive correlation (r = 0.46; P = 0.013) between the levels of free testosterone and endothelin-1. The highest level of somatotropic hormone was in the speed-trained athletes (11.74 ± 3.13 mIU/l), 2 times less - in the endurance-trained athletes (5.69 ± 1.19 mIU/l), and the lowest one – in the strength-trained athletes (2.66 ± 1.32 mIU/l). A positive correlation between the growth hormone and erythropoietin levels (r = 0.29; P = 0.038) was revealed in the endurance athletes. Conclusions. The endurance and speed athletes did not differ in the levels of endothelin-1, 6-keto-PG, erythropoietin, and testosterone. The strength-trained athletes showed signs of endothelial dysfunction: higher endothelin-1 levels with significantly reduced growth hormone and a tendency of increase in the serum testosterone level, as well as a compensatory increase in 6-keto-PG to maintain the balance between vasoconstrictors and vasodilators.