WATER AND SKIN
The special properties of water make it a good medium for heat and cold application. The applica-tion of water for therapeutic purposes is termed hy-drotherapy.
Water is referred to as a flexible therapeutic agent because of its unique chemical and physical properties. It can be used as a liquid, solid (ice), or gas (steam). Water transports heat by convection as it easily circu-lates. Because many calories (the unit of quantity of heat; also expressed in joules) are required to increase temperature by even one degree, cold water absorbs a lot of heat energy when it is warmed by surrounding objects. Conversely, a lot of heat is liberated when wa-ter is cooled. Also, a number of heat calories are re-quired for the conversion of water to steam. This prop-erty is advantageous as sweat evaporation from the surface of the skin cools the body effectively. Another therapeutic property of water is that of the Archimedes’ principle, which states that a body wholly or partly im-mersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced. Patients with muscu-loskeletal problems are able to move with considerable ease under water. Water is frequently used as a medium for applying thermal stimuli. Table 2.1 gives an arbitrary classification of temperatures and adjec-tives used for describing temperature.
It should be noted that the results of hydrotherapy vary with age, weight, and general physical condition.
Therefore, care must be taken when treating young per-sons, elderly persons, those in a poor state of nutrition, and those suffering from chronic vascular diseases.