In Canada, Europe and around the world, temperatures are soaring and heat warnings are rampant. We are reminded to stay out of the sun and stay hydrated, and in extreme conditions, stay indoors.

We are also told that children are especially vulnerable to heat-related illness.

We are researchers with 20-35 years of experience finding out how children, adolescents and adults thermoregulate when active — that is, how they maintain their body temperature within a normal range despite the stresses of exercise and heat. We are also each parents to children who grew up as very active and competitive athletes, spending many hours training and competing outdoors, in all weather conditions. We write this article as scientists and as parents.

How adults and children regulate body heat

For many years the public has been told that children are at increased risk of heat illness, especially when being physically active in a hot environment. Being cautious in demanding situations or hazardous conditions is obviously warranted. But are children especially at risk?

In 1980, the late Oded Bar-Or, a pioneer of pediatric exercise physiology, published a seminal article describing the risks particularly relevant to children exercising in the heat. Subsequent studies consistently demonstrated that children sweat much less than adults. This was the case regardless of the environmental conditions, whether at rest or during exercise.

When we exercise, our working muscles produce heat which must be lost, and body temperature stay within our normal, healthy boundaries (36.5 to 38.5 C). Inability to lose this heat can result in heat illness symptoms........

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