Few kinds of therapy can boast a history as long as that of hydrotherapy. Curing with water has been used in cultures as disparate as China's and the Romans'. These days it is common for people with stress or suffering from a wide variety of chronic diseases go to spas -the word comes from the Latin term Salutem per Aqua- for health treatment through water.

Water is a natural element that has lived in permanent contact with man. But its therapeutic benefits comes from manipulating it in function of what effect is desired. Each alternative does a different thing to the body, depending on the chemical and physical substances that make up its composition, its temperature and mechanical characteristics. From all of this there emerge specific techniques such as Turkish baths or jacuzzis.

One experience that almost all of us have had� -and the simplest way to benefit from water- is to swim or simply get into water. When in water the body weighs less, so joints and muscles are more flexible. This allows people with some kind of physical paralysis to do exercises that are very helpful.

If we speak about therapies that depend on water temperature, we need to point out hot and cold baths. The former exceed the body's temperature, in other words they are above 37� C, and they can last 20 minutes while the latter are not above 18 � C and do not last more than half a minute.

You can also combine the two and take a so-called contrast bath: four minutes of hot water and one minute of cold water.

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Hot water relaxes and dilates arteries. It also helps the body expel toxins through the skin. Also, as the pores are more open they can better absorb the active agents in the different therapeutic plants used in the bath. On the other hand, cold water invigorates, stimulates peripheral circulation. It also tonifies. The difference in� temperature between the water and the body can be unpleasant but in time this effect goes away. The combined or contrast treatment causes appropriate actions and reactions to stimulate blood flow and ease inflamations.

Two well-known and common techniques are the Turkish bath and the sauna. Both take place in hot rooms, the first with a very high level of humidity which does not allow the body's perspiration to evaporate. In a sauna the heat is dry. Therefore you sweat less in a sauna. And by pouring water to hot rocks that cause the heat, the temperature goes up. The Turkish bath is purifying what the sauna is basically relaxing. Another variation is the Finnish bath, with high temperature and lots of humidity. It is a bronchiodilator that is good for respiratory problems.

Besides baths, which can be for the whole body or just part of it like the feet and arms, and hot rooms, hydrotherapy also uses showers. They vary in temperature and the water comes out of very small holes. The Scottish bath is based on a gradual change in water temperature -- first rising until it is hot, then reverting to cold.

Treatment based on water pressure is also therapeutic and very popular. This the principle on which jacuzzis are based: underwater streams that aim at different parts of the body and are relaxing. They also tight� muscles and stimulate circulation. This same technique of pressure-based streams of water is also used outside swimming pools.

Meanwhile talasotherapy is a therapy that uses sea water, mud and seaweed. Here the water temperature is between 35 and 37�C and its curative properties are varied: it eases everything from circulatory and rheumatoid problems to skin infections and fatigue.