Response to rest and exercise in the cold: effects of age and aerobic fitness

The aim of this study was to determine whether age-related differences in the response to cold exposure are due to aging per se or are caused by a reduced maximal oxygen uptake (VO2max) often observed with aging. Three groups of men, 8 young adults (YA), 8 well-trained seniors (TS), and 11 untrained seniors (US), were tested on a cycle ergometer in thermoneutral (22 degrees C) and cold (5 degrees C) conditions during rest and then during exercise (approximately 50 W). In the thermoneutral conditions, 10 min of rest were followed by 10 min of exercise. After 60 min of rest, subjects entered the cold where 30 min of rest were followed by 30 min exercise. The subjects of the three groups had similar body surface area and subcutaneous fat thickness. It was found that rectal temperature (Tre) decreased during rest in the cold and continued to decrease at a higher rate during exercise in TS and US but not in YA. The mean skin temperature was similar in all the groups, except for the thigh temperature, which was lower in YA than in TS and US. Oxygen uptake (VO2) increased during cold, significantly more so at rest than during exercise. YA displayed the highest VO2 during the first 10 min of rest in the cold, whereas TS displayed the highest VO2 during exercise in the cold. Neither aging nor VO2max appeared to affect thermal comfort or cold sensation.(ABSTRACT TRUNCATED AT 250 WORDS)

Changing physiological relationships in men under acute cold stress

Thirty-four men were exposed to 8 °C for 2 h. Their reactions were studied to indicate how physiological relationships change during exposure to cold. Measurements of various body temperatures, MST, MBT, body heat content (BHC), [Formula: see text], heat production, and heart rate (HR) were made before the onset of and periodically during cold exposure. Various skin temperatures fell to different levels while rectal temperature rose slightly, then fell 0.3 °C by the end of the exposure. BHC declined by 6%, [Formula: see text] nearly doubled, [Formula: see text] and heat production increased by 66 and 75% respectively, and HR changed little during cold exposure. Relationships which changed most significantly during cold exposure were those between MST and rectal temperature, certain skin temperatures and rectal temperature, [Formula: see text] (also heat production) and BHC, [Formula: see text] and rectal temperature, and finally, those between every body temperature and the age of the subjects. Relationships which also changed were those between finger and toe temperature as well as those between [Formula: see text] (also heat production) and each of the following: [Formula: see text], rectal temperature, thigh temperature, HR, and age. These results indicated that (1) temperature in the upper extremities was actively maintained at a higher level than temperature in the lower extremities, (2) increased metabolism became a progressively more effective adaptation than redistribution of blood volume, (3) subjects with the lowest BHC tended to increase their metabolism the most, (4) [Formula: see text] was inversely related to core temperature after the latter fell below normal, (5) HR was unrelated to the increase in [Formula: see text], (6) the usual inverse relationship between age and metabolism was not found in the cold, and finally, (7) older subjects generally tended to maintain higher body temperatures than younger subjects.

A new weighting system for mean surface temperature of the human body

On the basis of an analysis of the skin temperature data on three resting human subjects from 112 experiments, a simple weighting system for computing the mean skin temperature from observations on four areas of the body, namely, chest, arms, thighs, and legs, has been proposed. The proposed system of weighting yields mean skin temperature values identical with the elaborate Hardy-Dubois weighting formula. The value of the medial thigh temperature as an index of the mean skin temperature has also been investigated and discussed. skin temperature measurement Submitted on May 20, 1963