Comparison of thermal responses between young children (1- to 3-year-old) and mothers during cold exposure.

To investigate thermal responses of children during cold exposure, children and their mothers were exposed to identical environmental conditions in climatic chambers. Subjects comprised 14 mothers (age, 29-40 years) and 15 children (age, 15 months-3 years; 9 boys, 6 girls). Each mother and child wore a t-shirt and short pants over underwear. Subjects were initially seated in a chamber at 25 degrees C for 60 min, then moved to a chamber at 15 degrees C where they were seated for 30 min. During the recovery period, they were returned to the 25 degrees C chamber and kept there for an additional 30 min. During exposure to 15 degrees C, declines in skin temperature (T (s)) of the hand and foot were significantly greater in children than in mothers. Rectal temperatures (T (re)) of children increased during cold exposure, whereas T (re) of mothers decreased. This variation in T (re) in children might be linked to homodynamic alterations accompanied by greater decreases in T (s) of the extremities due to a greater degree of vasoconstriction in distal regions during cold exposure. Increases in T (re) during cold exposure for children correlated with body surface area to mass (Ab/mass), mass and decreases in T (s) of the abdomen, thigh and leg. During the rewarming period, children exhibited a greater increase in T (s) of the arm, hand and foot than mothers, and this was attributed to greater relaxation of vasoconstriction in distal regions of children during exposure to the thermoneutral environment. T (re) in children and mothers decreased during the rewarming period. A gender difference was found only with regard to T (re) and heart rate (HR) responses in children during cold exposure, and neither physical characteristics nor any T (s) differed between genders. Furthermore, no significant differences were observed in resting HR of mothers and girls, whereas boys showed significantly lower heart rates at 15 degrees C than at 25 degrees C.