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Thermoregulation at rest and during exercise in prepubertal boys
P Delamarche1, J Bittel, J R Lacour
1Laboratoire STAPS, Physiologie et Biomécanique de l'Exercise Musculaire UER EPS, Rennes, France.
Summary
Children exhibit distinct thermal regulation compared to adults during heat exposure and exercise. Their bodies dissipate heat differently, with greater sweating at rest and lower evaporative heat loss during exercise, influenced by body surface area.
Area of Science:
- Pediatric thermoregulation
- Exercise physiology
- Environmental heat stress
Background:
- Understanding thermal balance in children is crucial for predicting responses to environmental heat.
- Previous research has primarily focused on adult thermoregulation, with limited data on pediatric responses.
Purpose of the Study:
- To investigate and compare the thermal balance and thermoregulatory responses of prepubescent boys to passive heat exposure and exercise.
- To examine the relationship between maximal oxygen uptake (VO2max) and thermoregulatory responses in children.
Main Methods:
- 11 healthy boys (10-12 years) underwent two randomized trials in a climatic chamber: 90-min passive heat exposure (45°C) at rest and 60-min cycling exercise (60% VO2max) at 20°C.
- Measurements included rectal temperature, mean skin temperature, and sweat rate to assess heat exchange and dissipation.
Main Results:
- During passive heat exposure, children showed increased rectal and mean skin temperatures, higher heat transfer coefficients, and greater sweat heat dissipation than adults.
- During exercise, children's rectal temperature increase was similar to adults, but their evaporative heat loss was lower, suggesting greater radiative/convective heat loss due to larger body surface area.
- Thermoregulatory responses in children were not correlated with their VO2max.
Conclusions:
- Children possess unique thermoregulatory strategies, differing from adults, particularly in heat dissipation mechanisms during rest and exercise.
- Body surface area plays a significant role in heat exchange during exercise in children.
- Maximal oxygen uptake (VO2max) is not a determinant of thermoregulatory responses in this age group.