Summary
Highlights
Conduction occurs through direct molecular contact and the displacement of free electrons, especially in metals. It is more efficient in solids due to closer molecular proximity compared to liquids and gases.
Convection primarily uses fluids for heat transfer. When a liquid is heated, warmer, less dense layers rise, and cooler layers descend, creating convection currents. This can be forced, like heating water in a kettle, or natural, such as air currents between areas of different temperatures.
Radiation transfers heat via electromagnetic waves, with infrared radiation being the most significant for heat production. When infrared rays impact a surface like the skin, this radiant energy transforms into thermal energy.
Evaporation, particularly of sweat, requires a minimum temperature of 30°C to cool the body. The body naturally regulates heat this way. Expiration also removes heat, as inhaled air warms inside the body and carries heat away upon exhalation.
Conduction in thermotherapy involves agents like hot compresses, electric pads, hot water bottles, hot sand, paraffin, peloids, and parafango. These are applied directly to the skin to transfer heat through thermal differences.
Convection therapy includes hot showers and baths, saunas (which use hot steam), and fluid therapy (using hot water or gases). These methods generate heat transfer through the movement of heated fluids.
Other agents include shortwave, microwaves, and ultrasound. All these thermotherapeutic agents generally provide analgesic (pain-reducing), anti-inflammatory (edema and inflammation reduction), antispasmodic (muscle relaxation), revulsive (causing abrupt changes in affected areas), and cauterizing (promoting healing) actions.