The normal temperature of the body is approximately 37°C. The heat carried by the blood is determined by the temperature of the surrounding tissue. In order to ensure that one portion of the body is not significantly hotter than another portion, heat transfer must be distributed evenly through the bodily tissues.

The principles of heat transfer in engineering systems can be applied to the human body in order to determine how the body transfers heat. When a person engages in elevated levels of physical activity, the body requires additional fuel which increases the metabolic rate and the rate of heat transfer. The body must then use additional methods to remove the additional heat produced in order to keep the internal temperature at a healthy level.

Heat transfer by convection is driven by the movement of fluids over the surface of the body. This convective fluid can be either a liquid or a gas. For heat transfer from the outer surface of the body, the convection mechanism is dependent on the surface area of the body, the velocity of the air, and the temperature gradient between the surface of the skin and the ambient air.