Heart Rate and Body Temperature Responses during and after Exposure to Cold

Abstract

In summer, 15 male students wearing only shorts were exposed to 15°C for 90 minutes in supine posture (exposure period), and then they were covered with blankets for 60 minutes (recovery period). Heart rate, blood pressure, heat production, rectal temperature and skin temperatures at 9 sites were recorded on subjects before, during and after exposure to a cold environment.Heart rate decreased significantly under the cold exposure, and in the recovery period, it decreased further significantly. In the recovery period, subjects with the lowest mean skin temperature tended to decrease their heart rate most. Skin temperature at finger was maintained at a higher level due to active vasomotor tone than that at toe during cold exposure, and increase rate of temperature at finger (7.9°C/hr) was larger than that at toe (1. 6°C/hr) in the recovery period. Rectal temperature fell by 0. 38°C by the end of the exposure. For 60 minutes in the recovery period, while the skin temperatures rose quickly, rectal temperature fell steeply to 0.34°C below the end of exposure value. In the recovery period, subjects with the lowest forehead skin temperature tended to fall their rectal temperature most, there was no significant relationships between fall in rectal temperature and change in skin temperatures of other sites.