What?s the purpose of using water?
The beneficial effects of water are contained in its composition: H2O, mineral
salts, neutral pH and very specific physical characteristics: relative density,
viscosity, surface tension, hydrostatic pressure, which enable a body to have
its own specific buoyancy.
The relative density and the specific weight determine the buoyancy of a
body by countering two other forces: hydrostatic thrust and gravity.
Moreover, relative density (specific weight) affects the sinking speed of a
body: fat mass floats more than lean mass, and the latter sinks faster.
According to the level of submersion of a body into water, there is the
possibility to move weightlessly, allowing much easier movements than in
presence of gravity (as on land).
Picture 1 Perceived weight
Hydrostatic pressure is constant in every point under the water surface and
increases going deeper of 0,029 atm (29,38 bars) per foot (30,48 cm). This
pressure helps in case of edema.
Viscosity is the resistance/friction caused by cohesive/attractive force among
the molecules of a fluid. It is higher into water than in the air, thus working
into water, which is apparently easier, is actually quite tough. It helps with:
muscular enhancement, at a cardio-circulatory level, in stabilizing the joint.
Surface tension is the tendency of water molecules to stick to each other; it is
also called ?cohesion?. It is higher on the surface, so a weak animal with
problems on the forefeet must swim underwater.
