Hydrotherapy: Therapeutic Use of Water

Buoyancy and Density

• If the density of a body is decreased (e.g., by adding air-filled objects), it will float higher in water.
• Buoyancy is an upward thrust experienced by a body in the opposite direction to the force of gravity.

Archimedes Principle

• When a body is entirely or partially immersed in a fluid at rest, it experiences an upward thrust equal to the weight of the fluid displaced.
• Clinical application of buoyancy: weight relief depending on the proportion of the body below water level.
• Examples of weight relief: immersion to waist level (50% of body weight), shoulder level (90% of body weight).

Hydrostatic Pressure

• Hydrostatic pressure is the pressure exerted on an immersed body by the surrounding water.
• According to Pascal's law, a fluid exerts equal pressure on all surfaces of a body at rest.
• Hydrostatic pressure increases with depth and density of the liquid.
• Motion is performed more easily near the surface of the water than at greater depths.

Cohesion and Viscosity

• Cohesion is the tendency of molecules to attract each other.
• Viscosity is the internal friction that occurs between molecules of water.
• Water resistance is directly proportional to the speed of the movement.
• The viscosity of water makes it a useful strengthening medium.

Turbulence

• Turbulence is an irregular movement of water molecules.
• Examples of creating turbulence: underwater douche, or turbines.
• Moving water transfers heat by conduction and convection, having a relaxing effect.

Specific Heat

• Specific heat is the capacity of a substance to store heat.
• Water can store four times more heat than air and twice as much as paraffin wax.
• Amount of heat required to raise unit mass of a material by 1°C.

Hydrotherapy

• Hydrotherapy is a therapeutic modality that uses water in any form (gas, liquid, or solid) or temperature (hot and cold) for treatment of physical or psychological dysfunction.
• History of hydrotherapy: Carlos Andreson (1943), Hippocrates (460-375BC), Romans ( baths for hygiene), 19th-20th century (therapeutic with pleasure).

Chemical Properties of Water

• Pure water is a polar molecule consisting of 2 molecules of Hydrogen and 1 molecule of Oxygen.
• Water possesses high dissolving power, helpful in cases of additive material to water for therapeutic causes.
• Water can be pure or mixed with other substances (e.g., salt, iodine, sulfur, mud, and gas).

Physical and Mechanical Properties of Water

• Specific gravity is the ratio of the density of a substance to the density of water.
• Water has a specific gravity of 1.0 at 4°C, and the human body has a specific gravity of 0.974.
• Density = mass/volume.
• If an object's specific gravity is less than or equal to that of water (1.0), it will float in water. If the specific gravity is greater than that of water, it will sink at a rate based on the difference between the specific gravity of the object and of water.