Why should a pool used for competitive swimming be kept cooler?
If you are vigorously training, your body generates an increased amount of heat energy. In air, this heat is dissipated by sweating. The evaporation of the sweat is the cooling mechanism to help control the body temperature at 98.6 F. In water, your body generates the same amount of heat, but there is no evaporation to provide cooling. Cooling is provided by conduction/convection of heat from your warm body to the cool water. This is roughly proportional to the temperature difference between your body and the water. The warmer the water the less heat is dissipated.
