Main mechanism in thermoregulation-heat loss during intense physical activity is

Thermoregulation is defined as the control of body temperature and its maintenance within narrow limits in spite of factors tending to change it.There are four avenues of heat loss: convection, conduction, radiation, and evaporation. If the skin temperature is greater than that of the surroundings, the body can lose heat by radiation and conduction. But, if the temperature of the surroundings is greater than that of the skin, the body actually gains heat by radiation and conduction. In such conditions, the only means by which the body can rid itself of heat is by evaporation. So, when the surrounding temperature is higher than the skin temperature, anything that prevents adequate evaporation will cause the internal body temperature to rise. During intense physical activity (e.g. spos), evaporation becomes the main avenue of heat loss. Humidity affects thermoregulation by limiting sweat evaporation and thus heat loss.Ref: Ganong&;s review of medical physiology;24th edition; page no-316