Hemodynamic responses in Tian Shan indigenous populations during shift work under high-altitude conditions

Objective: To study the adaptive hemodynamic responses of miners from different high-altitude regions of the Tien Shan during long-term work in an ultra-high-altitude mine. Materials and Methods: The study involved 87 healthy male miners aged 20 to 33. They were divided into four groups based on their initial region of residence (low altitude 760 meters or mid-altitude 1800 meters) and length of service at the Kumtor gold mine (3600-4200 meters). Results: Analysis of baseline hemodynamic parameters at rest revealed statistically significant differences between the groups in heart rate (HR) and stroke volume (SV) (F(3,83)=8.94, p<0.001) and SV (F(3,83)=4.12, p<0.01). HR in group 3 (natives of mid-mountain areas with long-term experience) was significantly lower than in groups 1 and 4 (p<0.01), and SV in group 3 was significantly higher than in group 4 (p<0.05). Total peripheral vascular resistance (TPVR) in Group 4 was significantly higher than in Group 3 (p<0.05). In low-altitude residents, both new arrivals (Group 4) and those with 3 years of experience (Group 1), the predominant strategy was characterized by tachycardia (both at rest and under exertion), a significant increase in TVR, and a cardiac output dependent primarily on heart rate rather than stroke volume. On the contrary, among those native to the midlands, especially those with long work experience (group 3), a more economical profile was observed: lower HR, higher SV. Conclusion: The duration of stay in high-altitude conditions is a critically important factor determining the nature of the body's hemodynamic adaptation to ultra-high-altitude hypoxia during physical exertion.