The role of fast running in prevention of negative effects of prolonged exposure to weightlessness

The prospects of deep space exploration necessitate modification of the principles and methods underlying the system designed to prevent negative impact of weightlessness on the human body. This work aimed to determine how fast running, as part of locomotor training during a space flight (SF), helps maintain physical ability of a person. The study involved 10 cosmonauts; their physical performance was assessed at all stages of the SF with the help of the Individual Strategies Test (IST). The parameters registered when the participants were doing the IST included heart rate (HR), gas exchange, capillary blood lactate concentration. The cosmonauts were divided into two groups based on the differences in the mean distance covered while fast running on a treadmill (single session). Group A (n = 4) run 949 m/day on average, group B (n = 6) — 2669 m/day. After SF, HR in group A increased at speeds from 5 to 8 km/h (p < 0.05), pulmonary ventilation indicators grew at speeds from 8 to 15 km/h (p < 0.05), and the capillary blood lactate concentration measured during the post-test recovery period increased by 37% (p = 0.03). Moreover, after SF, the pulse sum recorded under load and during recovery was 14% (p = 0.02) and 15% (p = 0.03) in group A, respectively, while in group B we registered no differences. Thus, our hypothesis that fast running triggers sensory reactions simulatingEarth conditions for the body, which consequently activates physiological mechanisms counteracting the negative effects of weightlessness, has been confirmed in a space experiment.