Foreword
Water is the fundamental constituent of all living beings, and is present in the human body in quantities equal to about 60-70% of body weight, varying according to gender and age. Water, either in a free state or linked to other molecules, absolves several biological functions, such as: It participates in the digestion, facilitating the chime fluidification and passage through the gastrointestinal system, so that nutrients in a solution can penetrate the intestinal wall and be channelled to the blood and lymph. It is the vehicle for metabolic reactions. Blood, which contains about 92% of water, ferries the catabolism residues from the cells to the excretory organs: kidneys, lungs and skin.
It makes it possible for substances to go from the cells to the intercellular spaces and vessels, and vice versa.
It helps regulate body temperature through perspiratio insensibilis (insensible perspiration), perspiration and the elimination of aqueous vapour through the lungs.

Organic water can be classified in two major sections: intracellular water, constituting about 50% of body weight, and extracellular water, corresponding to about 70% of body weight, 5% of which is blood water and 15% interstitial water.

In medicine, the term �retention� means the organism�s difficulty in eliminating a solid, liquid or gaseous substance that is normally slated for elimination. �Water retention�, therefore, describes the tendency to retain liquids within the body. Rarely is this a predisposition issue. Quite often, this issue is related to an incorrect life style, with a lack of sufficient and appropriate physical exercise and diet imbalances; by correcting these problems, the situation can improve considerably. The efficiency of the venous system has an important role in water retention and in lower limb fluid stasis, because, if the veins lose their tone because of reduced wall elasticity, the �swallow�s nest valves� (the name recalls their shape, and they favour the blood�s return to the heart) are no longer fully functional. Part of the blood pools in the veins, encouraging fluid seepage from inside the veins into the interstitial spaces thanks to capillary porosity. This creates venous stasis, often localised in the lower limbs and especially in the ankles, with, consequently, a feeling of heaviness, oedema, heavy legs, muscle cramps, skin discolouration (alteration of the skin�s pigmentation) and sometimes pain.
Moreover, in the areas characterised by the presence of hormone-dependent fat accumulations, such as the thighs and glutei, water retention causes a subcutaneous adipose tissue pathology called oedematous fibrosclerotic panniculopathy or dermo-hypodermosis in its first stage, but which is generally known as cellulitis. This condition, if not treated consistently, can worsen with clear aesthetic damage, such as �orange peel skin�, or �mattress skin� when it is in a particularly advanced stage; besides being unaesthetical, cellulitis can cause sensitivity to touch and pressure. In a previous study performed by our group, it was demonstrated that a single mud treatment session induces a considerable loss of fluids, with a significant weight loss and pressure variation. These alterations show a rebalancing of body water in the various districts, especially the skin.

Purpose of the Study
Given the above, and given that localised water retention is a common problem, especially among the female population, our hypothesis is that thermal treatment might induce alteration in water retention, with a rebalancing of body water distribution and of the hydro-electrolyte balance. The aim, therefore, is to study the effects of thermal treatments on the hydro-electrolyte balance of the body and analyse its effects in terms of localised water retention.

Sample Study Protocol:
12 adult subjects, females, healthy, of average age. Informed consent.
Measurements:
In the morning, before treatment, on an empty stomach and an empty bladder:
A) Detailed patient history
B) Clinical and anthropometric assessments: medical examination, body weight measurement with precision weighing balance, height, arterial blood pressure, skin folds measure in 12 places, circumference of the upper and lower limbs.
C) Multifrequency segmental BIA to determine TBW (total body water), ECW and ICW (extra and intra-cellular body water) in the various body districts, D) analysis of total blood cholesterol, HDL, triglycerides.

Measurements
(except for the blood chemistry parameters) shall be repeated that same day, at the end of the thermal treatment, prior to the subject ingesting any fluids. In some cases the assessment shall be carried out also immediately before and after the mud treatment. It will be ensured that the subject�s skin is perfectly clean and dry.

The protocol shall be implemented always at the same time in each subject:
on the 1� day of treatment
on the 6� day of treatment (with blood sample)