Responses of high altitude natives a standard cold test at sea level

Studies have been conducted to evaluate the thermoregulatory, calorigenic, and peripheral vascular responses to cold of high altitude (HA) natives on their descent to sea level. Two groups of subjects (18 each), one representing high altitude (3500 m) natives and the other lowlanders, were exposed to a standard cold test at 10 degrees C wearing only shorts for 2 h. Their heart rate (HR), blood pressure (BP), oxygen consumption (VO2), oral temperature (Tor), mean weighted skin temperature (Ts) and shivering activity were recorded initially in a thermoneutral room, and 30 min intervals during the cold exposure. Afterwards, their cold-induced vasodilatation (CIVD) response was studied and the peripheral blood flow during local cold stress was calculated. The responses were statistically compared. The highlanders maintained significantly higher Tor, Tb (mean body temperature), Ts and peripheral Ts during cold stress, and they shivered much less and showed higher CIVD response and peripheral blood flow than the other group. The rise in VO2 on cold stress was identical. The observations showed better cold tolerance for high altitude natives compared to lowlanders, even at sea level.