Cutaneous Vasodilation Response to a Linear Increase in Air Temperature from 28°C to 40°C in Prepubertal Boys and Young Men

Abstract

The cutaneous vasodilation and sweating responses of prepubertal children to heat stress were examined. Seven prepubertal boys (9-11 years old) and 9 young men (20-24 years old) were seated wearing only swimming trunks while the air temperature (T(a)) was linearly increased from 28 degrees C to 40 degrees C over 50 min and then maintained at 40 degrees C for an additional 10 min. Skin temperature, cutaneous vascular conductance (CVC), and local sweating rate (m(sw)) were measured at multiple sites on the body. The boys had a significantly greater mean surface area-to-mass ratio compared with the young men. The rectal temperature did not change in either group with increasing T(a), although it was significantly higher in the boys. During the first half of the exposure period, when T(a) was less than the mean skin temperature (T(sk)), the boys had significantly higher CVC on the chest and significantly lower m(sw) on the chest and thigh as compared with the young men. During the latter half of the exposure, when heat stress was increased as T(a) exceeded mean T(sk), the boys had significantly higher mean T(sk), greater CVC on the chest and finger, greater rate of increase in the CVC on the forehead and finger, lower m(sw) on the chest and thigh, greater increase in heart rate, and higher thermal sensation. The mean body temperature at the onset of sweating was significantly greater in the boys than in the men. These results suggest that, compared with young men, prepubertal boys manifest greater physiological and perceptual strain under heat stress induced by T(a) exceeding mean T(sk), which is most probably attributable to a combination of lower evaporative heat loss, as evidenced by lower m(sw), and greater heat gain owing to a larger surface area-to-mass ratio. The maturation-related differences in heat loss responses vary according to body site.

Sweating responses to isometric hand‐grip exercise and forearm muscle metaboreflex in prepubertal children and elderly

“…; Inoue et al . ), which was generally consistent among skin sites (Shibasaki et al . a, b ; Inoue et al .…”

“… a, b ; Inoue et al . ). We demonstrated an inconsistent attenuation of the local sweating response to IH exercise on the forehead and to the muscle metaboreflex on the chest, forearm and thigh but not on forehead and palm in the present study (Figs and ).…”

“… a, b ; Inoue et al . ), whereas an ageing‐related decline of thermal sweating occurs from the lower limbs to the torso and finally to the head in elderly subjects (Inoue et al . ).…”

Speed ratio but cabin temperature positively correlated with increased heart rates among professional drivers during car races

“…We postulated that the average HR would increase with increasing cabin temperatures. Even if the thermal stress was moderate and the core temperature did not increase, hot conditions would induce greater perspiration, dehydration and peripheral vascular dilation [19]. We supposed that even moderate thermal stress would cause an increase in HR.…”

Exercise Thermoregulation in Prepubertal Children: A Brief Methodological Review

“…Despite a limited number of studies, a relatively consistent finding has been that children demonstrate greater cutaneous vasodilatation, and thus, skin blood flow relative to adults ( 21 – 24 ). For instance, during lower-limb hot-water immersion, Shibasaki et al ( 22 ) observed higher skin blood flow in children (7–11 yr) relative to young adults (21–25 yr) at the chest and back, but not the forearm or thigh region.…”