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A cartoon of a woman exercising under the hot sun.

Avoid exercising during the heat of the day when the sun is at its highest from 11 a.m. to 1 p.m.

Exercising in summer heat

By Pauline Oo

From eNews, July 22, 2004

Sweating is our body's way of cooling itself down. And in hot weather, especially with high humidity and when you're exercising, you can lose a great deal of body fluid from sweating and not drinking enough water. If you don't replenish what you lose, you could be asking for a heat-related illness. There are various degrees of this illness, with heat exhaustion being the most common and heat stroke being rare, but life threatening, explains U athletic trainer Moira Novak. Heat exhaustion typically occurs when body fluids are lost through heavy sweating and your sweat does not evaporate as it normally does to cool you. This can lead to decrease blood flow to the vital organs and shock. Heat stroke (also known as sunstroke), on the other hand, occurs when your body's temperature-control system, or sweat mechanism, stops working. Body temperature can rise rapidly, causing brain damage and death within minutes if the body is not properly cooled. According to Novak, the general symptoms of a heat-related illness include profuse sweating, paleness, muscle cramps, weakness and dizziness, nausea, and headache. Some people are more susceptible to it, such as the elderly, those with fair complexion, those with a history of heat-related illnesses or high blood pressure, and those who are overweight or in poor physical condition. Novak recommends the following to prevent heat-related illness: