Thermoregulation during heat exposure of young children compared to their mothers

Abstract

The study was conducted to investigate the thermoregulation of young children compared to that of adults. A group of 19 children (ages 9 months-4.5 years), with only 3 children aged 3 years or above, and 16 adults first rested in a thermoneutral room (air temperature 25 degrees C relative humidity 50%, air velocity 0.2 m.s(-1)). They were then exposed to a hot room (air temperature 35 degrees C, relative humidity 70%, air velocity 0.3 m.s(-1)) next door for 30 min, and then returned to the thermoneutral room where they stayed for a further 30 min. The rectal temperature (Tre), skin temperatures (Tsk) at seven sites, heart rate (HR), total sweat rate (Msw,t), local sweat rate (Msw,l) and the Na+ concentration of the sweat were measured. There was no significant difference in Tre between the children and their mothers in the rest phase. However, the Tre of the children increased as soon as they entered the hot room and was significantly higher than during the control period, and than that of the mothers during heat exposure. Mean Tsk, forehead, abdomen and instep Tsk were significantly higher in the children during both the thermoneutral and heat exposure. The Msw,t was significantly higher and Na+ concentrations in the sweat on the back and upperarm were significantly lower for the children during the heat exposure. They had a greater body surface area-to-mass ratio than the mothers by 64%, which indicated that they had advantages for thermal regulation. However, the sweating and Tsk responses of the children were not enough to prevent a rise in body temperature. These results would suggest that the young children had the disadvantage of heating up easily due to their smaller body sizes and there may be maturation-related differences in thermoregulation during the heat exposure between young children and mothers.

National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses

“…These include decreased sweat gland activity, 190 higher skin temperatures, [191][192][193] decreased cardiac output (increased heart rate and lower stroke volume) due to increased peripheral circulation, 194 decreased exercise economy, 195 decreased ability to acclimatize to heat (slower and takes longer), 192 smaller body size (issues related to body surface-to-mass ratio), maturational differences, 190 and predisposing conditions (obesity, hypohydration, childhood illnesses, and other disease states). 190,192,196 • Decrease the intensity of activities that last longer than 30 minutes, 197 and have the athlete take brief rests 50 if the WBGT is between 22.8ЊC and 27.8ЊC (73ЊF and 82ЊF); cancel or modify the activity if the WBGT is greater than 27.8ЊC (82ЊF). 31,[69][70][71][72][73] Modification could involve longer and more frequent rest breaks than are usually permitted within the rules of the sport (eg, insert a rest break before halftime).…”

Effects of Heat Stress on Working Populations when Facing Climate Change

“…Children may also be present in workplaces, and babies may sometimes be strapped on the back of their mothers as they are working. An excess death rate due to heat illness has been reported among infants and children during heat waves compared with adults 50) .…”

Core and local skin temperature: 3–24 months old toddlers and comparison to adults

“…Thermoregulation in infants is different [15][16][17][18], both during exposure to hot [15,17] and cold [17] environments; during rest [16,17] and exercise [17], evolving rapidly in the first few months after birth [19]. The evolution of the thermoregulatory system includes the emergence of circadian rhythmicity for core temperature [20], skin temperature and motor activity [21].…”

“…A relatively small number of studies investigated the differences and similarities between infants and adults [15,17,21,[30][31][32][33] as discussed below but none addressed toddlers. Preterm newborn children of up to 13 days of age were observed to be already responsive to the operative temperatures within the incubators in the range of 28-32 °C, with skin temperatures dependent on the location [31,32].…”

“…Three months-old infants sleep for longer when exposed to lower ambient temperatures [30]. Adaptation and local disparity continues while the children grow up, presenting higher mean and local skin temperatures (forehead, abdomen, instep) than adults both at thermoneutral conditions and heat exposure [15] as well as exercise activities [17]. Similarly skin temperature is lower than in adults when exposed to cold due to greater vasoconstriction [17].…”