Thermoregulation of Tuvan pastoralists and Western Europeans during cold exposure

Objectives: This study compared the metabolic and vascular responses, to whole-body and finger cold exposure, of a traditional population lifelong exposed to extreme cold winters with Western Europeans. Methods: Thirteen cold acclimatized Tuvan pastoralist adults (45 ± 9 years; 24.1 ± 3.2 kg/m ²) and 13 matched Western European controls (43 ± 15 years; 22.6 ± 1.4 kg/m ²) completed a whole-body cold (10°C) air exposure test and a cold-induced vasodilation (CIVD) test, which involved the immersion of the middle finger into ice-water for 30 min. Results: During the whole-body cold exposure, the durations until the onset of shivering for three monitored skeletal muscles were similar for both groups. Cold exposure increased the Tuvans' energy expenditure by (mean ± SD) 0.9 ± 0.7 kJ min ⁻¹ and the Europeans' by 1.3 ± 1.54 kJ min ⁻¹; these changes were not significantly different. The forearm-fingertip skin temperature gradient of the Tuvans was lower, indicating less vasoconstriction, than the Europeans during the cold exposure (0 ± 4.5°C vs. 8.8 ± 2.7°C). A CIVD response occurred in 92% of the Tuvans and 36% of the Europeans. In line, finger temperature during the CIVD test was higher in the Tuvans than the Europeans (13.4 ± 3.4°C vs. 3.9 ± 2.3°C). Conclusion: Cold-induced thermogenesis and the onset of shivering were similar in both populations. However, vasoconstriction at the extremities was reduced in the Tuvans compared to the Europeans. The enhanced blood flow to the extremities could be beneficial for living in an extreme cold environment by improving dexterity, comfort, and reducing the risk of cold-injuries.