Physiological responses and thermal sensation during extremely cold exposure (−20 °C)

Abstract

Extremely cold events have occurred frequently around the world in the past few years, and people will inevitably be exposed to extremely cold environments during certain activities in modern society. Cold stress seriously threatens human health and safety. The purpose of this study was to study the physiological responses and thermal sensation of humans exposed to extreme cold. Twelve healthy males were exposed to a cold (−20 °C) environment in a climate chamber for 30 min after a preconditioning phase. This cold exposure was followed by 40 min of recovery at 24 °C. Thermal sensation and physiological parameters, including core temperature, local skin temperature, blood pressure, and heart rate, were recorded throughout the entire process. The results show that the ear is the most sensitive to ambient temperature changes. Blood pressure increased 17.6% within a minute of cold exposure. The average heart rate continued to drop in each period. Establishing a transition space can relieve the pressure stimulus of a large temperature difference. There are functional correlations between the local skin temperature and thermal perception, and the ear exhibits the best correlation. The asymmetry of thermal sensation in extremely cold environments is eliminated when the temperature difference exceeds a certain threshold between 40 °C and 44 °C. The results of this study are of great significance for extreme cold protection.