Wdv. Lichtenbelt et al., Individual variation in the relation between body temperature and energy expenditure in response to elevated ambient temperature, PHYSL BEHAV, 73(1-2), 2001, pp. 235-242
The question we address here is whether a mild increase in environmental te
mperature affects body temperature and energy expenditure, focusing on the
individual variation in the relation between energy expenditure and body te
mperature. We studied eight normal weight healthy females, 48 h at an ambie
nt temperature of 22 degreesC, and 48 h at 27 degreesC. Energy expenditure
GEE) was measured in a respiration chamber. Subjects' skin temperature was
measured continuously from 8:00 a.m. until 12:00 p.m.: forehead, infraclavi
cular zone, thigh, hand, and foot. Core temperature was determined tympanic
ally. Body composition was determined by under water weighing. Exposure to
27 degreesC caused a significant increase in body temperature (both skin an
d core), a decrease in temperature gradients, and a decrease in energy expe
nditure. At 27 degreesC 24 h EE, adjusted for body composition, was signifi
cantly related to body tympanic temperature. The decrease in 24 h EE, at 27
0C ambient temperature, was significantly negatively related to the increas
e in T-tym, indicating individual responses in adaptation to elevated ambie
nt temperature. Changes in temperature gradient (comparing 27 degreesC with
22 degreesC) were negatively related to changes in EE. This shows that ind
ividuals differ in their response to an increase in environmental temperatu
re regarding the relative contribution of insulative or metabolic adjustmen
ts. (C) 2001 Elsevier Science Inc. All rights reserved.