The role of physical activity in the correction of hemostasis system parameters under the influence of hypobaric hypoxia

BACKGROUND: The combined effects of extreme environmental factors cause disruption of the body's organs and systems, including the hemostasis system. Identification of safe and effective ways to improve the body's adaptive capacity helps to reduce or avoid the effects of stress.

AIM: To evaluate the hemostasis system's response to a single daily exposure to hypobaric hypoxia and the possibility of correcting deviations by preliminary physical activity.

MATERIALS AND METHODS: The experiment involved 60 sexually mature male rats. The first group (n=24) was the control; the animals of the second group (n=12) were subjected to 2-hour physical activity in the form of walking on a treadmill at a speed of 6–8 m/s for 30 days; the third group of rats (n=12) were subjected to a single daily hypobaric hypoxia by placing the animals in a pressure chamber with an air vacuum of 0.55 kgf/cm² for 24 hours, which corresponds to an ascent of 6,500 m above sea level; the animals of the fourth group (n=12) were subjected to 2-hour physical activity for 30 days before exposure to daily hypobaric hypoxia. Platelet aggregation activity, plasma hemostasis, and the activity of the anticoagulant and fibrinolytic systems were assessed in all groups using diagnostic test systems from Tekhnologiya-Standart (Russia). Statistical analysis was performed using the Statistica 10.0 package. The significance of differences was determined using Student's t-test and the nonparametric Mann–Whitney U-test.

RESULTS: Exposure to daily hypobaric hypoxia was accompanied by activation of platelet and plasma hemostasis, which was manifested by a decrease in platelet aggregation time (p=0.000), silicone (p=0.006) and prothrombin (p=0.008) time, while the content of antithrombin III decreased (p=0.000) and the time of fibrin lysis increased (p=0.001) compared to the control group of intact animals. Preliminary physical training followed by exposure to hypoxia was accompanied by hypocoagulation with an increase in platelet aggregation time (p=0.000), silicone (p=0.011), kaolin (p=0.000) and prothrombin (p=0.000) time, as well as an increase in the concentration of antithrombin III (p=0.000) and a decrease in the time of fibrin clot lysis (p=0.002) compared to untrained animals after exposure to hypoxia only.

CONCLUSION: A single hypoxic stress is characterized by hypercoagulation at all stages of blood coagulation, inhibition of anticoagulant and fibrinolytic activity of plasma, which are leveled by preliminary physical training.