Effects of thermal stress during rest and exercise in the paediatric population

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Deutscher übersetzter Titel:Auswirkungen von temperaturbedingtem Stress in Ruhe und unter koerperlicher Belastung auf Kinder
Autor:Falk, B.
Erschienen in:Sports medicine
Veröffentlicht:25 (1998), 4, S. 221-240, Lit.
Format: Literatur (SPOLIT)
Publikationstyp: Zeitschriftenartikel
Medienart: Gedruckte Ressource Elektronische Ressource (online)
Sprache:Englisch
ISSN:0112-1642, 1179-2035
DOI:10.2165/00007256-199825040-00002
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Erfassungsnummer:PU199805301934
Quelle:BISp

Abstract

Thermoregulation during exposure to hot or cold environments differs between children and adults. Many physical and physiological changes occur during growth and maturation that can affect thermoregulation during rest as well as during exercise. Thus, physical as well as physiological differences between children and adults may explain the different response to thermal stress. The main physical difference between children and adults affecting thermoregulation is the much higher surface-area-to-mass ratio of children. In a warm environment this allows them to rely more on dry heat loss and less on evaporative cooling. However, in extreme conditions, hot or cold, the greater surface-area-to-mass ratio results in a higher rate of heat absorption or heat loss, respectively. The lower body fat in girls compared with women provides lower insulation and presents a disadvantage in a cold environment. The smaller blood volume in children compared with adults, even relative to body size, may limit the potential for heat transfer during heat exposure and may compromise exercise performance in the heat. The main physiological difference between children and adults is in the sweating mechanism, affecting their thermoregulation in the heat, but not in the cold. The lower sweating rate characteristic of children is due to a lower sweating rate per gland and not to a lower number of sweat glands. In fact, children are characterised by a higher density of heat-activated sweat glands. The lower sweating rate per gland may be explained by the smaller sweat gland size, a lower sensitivity of the sweating mechanism to thermal stimuli and, possibly, a lower sweat gland metabolic capacity. Neither children nor adults sufficiently replace fluid loss during exercise in the heat. Nevertheless, recent studies suggest that in children, when the available beverage is flavoured and enriched with NaCl and carbohydrates, dehydration can be prevented. The hypohydration, which frequently accompanies exercise in the heat, and the resultant added cardiovascular strain, may be more detrimental in children than in adults, because children rely more on dry heat loss, and therefore on elevated skin blood flow, to dissipate body heat. Based on a few studies, it appears that acclimation to heat is similar in children and adults. The main difference is the slower rate of heat acclimation in children. No studies are available on cold acclimatisation or acclimation in children or adolescents. Verf.-Referat (gekuerzt)