(I) When we exercise, our body naturally produces heat. (II) Exercising in extreme temperatures therefore provides an added stress on our body to cool down. (III) In fact, our body cools down by redirecting the flow of blood to the skin, so the evaporation of sweat can dissipate heat from the blood. (IV) Unfortunately, individuals who take part in outdoor activities such as tennis, golf, or running are at greater risk of physical injury. (V) However, when the climate is humid, sweat cannot evaporate from the skin, and the body struggles to cool down.