Warmth can be supplied to the body in various ways: by direct thermal conduction (e.g. fango, heat cushions, hot water bottle), by convection (e.g. hot air) or by radiation (infrared).
1. Conduction
Conduction is heat transfer through direct contact with a source of heat, such as a heat cushion, a hot water bottle, peat or a hot stone. Thermal energy is transferred here directly between molecules. We now know that the heat source transfers oscillation energy to the skin in this case. The potential disadvantage of this way of applying heat is that it can interfere with temperature regulation of the skin.
In other words: the pressure created on the area where the heat source (e.g. heat cushion) is applied can impair blood circulation in the skin. Heat cannot therefore be sufficiently removed from the skin. Beyond this, additional cooling offered by the evaporation of sweat cannot take place. Thus, ‘hot spots’ can form relatively easily, where damage to the skin occurs.
2. Convection
With convection, heat transfer takes place as transport by particles. These carry thermal energy and can move more or less freely. Consequently, convection cannot take place in solids or vacuums. It can only occur in gases or fluids. This type of heat application too can possibly interfere with temperature regulation of the skin. Especially the pressure caused by fluids can interrupt blood circulation through the skin and prevent cooling by evaporation. The convection principle is used for instance in radiators (heating), in steam baths and saunas.
3. Radiation
Infrared radiation in contrast transfers its energy without contact, as thermal energy. Thus, circulation, heat emission and skin perspiration are not impaired by direct contact with a source of heat. Infrared radiation additionally offers a number of advantages, since it is easy to contain (locally) and the dosage can be set (radiation intensity).
- Overview of the different ways of applying heat
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