Peripheral circulation indicators in veteran trail runners.

[Purpose] Competitive sport places strict demands on the cardiovascular systems of veteran trail runners. Our research objective was to evaluate the dynamics of microcirculation parameters of veteran runners in hypoxic and mid-altitude conditions. [Subjects and Methods] Seven male runners from Russia and Italy between the ages of 50 and 60 years were examined whilst competing at mid-altitude (1,500-2,000 m above sea level). The same runners were examined in a simulated mid-altitude hypoxic environment, which was a hypoxic chamber with 16% oxygen concentration, for 720 minutes. Under both conditions, peripheral circulation was studied using a laser Doppler flowmeter attached to the distal phalange of the second finger of the subject's right hand. All subjects had a microcirculation parameter assessed, which was the standard deviation of the erythrocytes flow vibration in peripheral circulation, under both conditions. In order to assess the intensity of vasomotor reactions of the microcirculatory vessels, the coefficient of variation was used. [Results] In the hypoxic environment, a decrease in the microcirculation parameter was noted in the short-term (360 minutes), with a subsequent compensatory increase in the long-term (720 minutes). However, the coefficient of variation showed a reverse trend with an increase in the vasomotor activity of microvessels from 12.4% to 18.2% at the stage of maximum training load within one month in the mid-altitude in the hypoxic environment, with a consequent reduction in preparation for the start. [Conclusion] In the hypoxic environment, the subjects demonstrated a two-stage change in the dynamics of the microcirculation parameter: an initial fall and a subsequent increase reaching the initial values. Similar changes were found when subjects were competing at mid-altitude. Our results show that the assessment of the peripheral circulation in a simulated mid-altitude hypoxic environment can be used to determine the readiness of veteran sportsmen for long-term trail running in mid-altitude conditions.