Athletic Training Practice Exam

What percentage of heat produced by the body during exercise is lost through evaporation?

1. Convection

2. Conduction

3. Evaporation

4. Radiation

The correct answer is: Evaporation

The body produces heat as a byproduct of metabolic processes, particularly during exercise. Of the various mechanisms by which the body loses heat, evaporation is the most significant during physical activity. When we exercise, our body temperature rises, and to maintain homeostasis, we sweat. As sweat evaporates from the skin surface, it requires energy in the form of heat, which is drawn from the body. This process effectively cools the body down. Evaporation accounts for about 80% of the heat loss during intense physical activity, particularly in warm and humid environments where other mechanisms, such as convection, conduction, and radiation, become less effective. Understanding this helps athletes and trainers appreciate the importance of hydration and the role sweat plays in thermoregulation during exercise.