Localized temperatures and water vapour pressures within clothing during alternate exercise/rest in the cold.

The purpose of this study was to determine the variation of localized skin temperatures, clothing surface temperatures and water vapour pressures within a clothing system when worn during alternating work/rest cycles in a cold environment. A two-layer prototype clothing system comprising underwear and a uniform was studied on eight subjects (Ta = Tr = 5 degrees C; Tdp = -3.5 degrees C; va = 0.32 m s-1; Itot = 0.24 m2 K W-1). The 2 h experiment comprised a twice-repeated bout of 40 min cycle exercise (W = 56 W m-2; M = 313 W m-2) followed by 20 min of rest (M = 62 W m-2). Esophageal, skin, clothing, and ambient temperatures, as well as dew-point temperatures near the skin, in the clothing and in the environment were monitored. In addition, evaporation of sweat and sweat accumulated in the clothing were determined. The temperatures and water vapour pressures in all clothing layers varied significantly with the human thermoregulatory responses (skin temperature, sweating) to alternating work/rest cycles. Different courses of localized corresponding temperatures and water vapour pressures indicated that various forms of heat transport and heat exchange in the skin-clothing-environment system are of significance in different body areas.