Hydrotherapy Lecture 1 PDF

Introduction Definition Hydrotherapy is the use of water to revitalize, maintain, and restore health. The word hydrotherapy is derived from a Greek word hydro means "water" and therapeia means "healing". Water therapy uses either hot or cold water, with the water pressure and flow varying...

Introduction Definition Hydrotherapy is the use of water to revitalize, maintain, and restore health. The word hydrotherapy is derived from a Greek word hydro means "water" and therapeia means "healing". Water therapy uses either hot or cold water, with the water pressure and flow varying among treatments. The intention is to ease both physical and mental symptoms. History of Hydrotherapy Hydrotherapy dates back as far as ancient Egyptian, Greek, and Roman times when Egyptian royalty bathed in oils and Romans Baths were frequently visited by the citizens of that era, there is also historical evidence of such therapy been used in far-eastern regions such as China and Japan – where hot springs were frequently used for people to bathe in. In these times hydrotherapy was used simply as a tool of relaxation, it wasn’t until the 19th century when Hydrotherapy started to resemble the therapy that it has become in today’s society. Sebastian Kneipp (1821-1897) re-wrote the history of hydrotherapy when he discovered a systematic and controlled application of hydrotherapy and was able to develop a revolutionary rehabilitation method to assist medical treatment. At that point in time, this style of therapy was only being administered by doctors. Hydrotherapy was first officially used as a medical tool by Vincent Priessnitz in 1829.  Properties of water Chemical properties Solvent Water is a universal solvent and can dissolve many chemical compounds while not reacting with them. Therefore, water running over the body, or over an open wound will remove some contaminants or necrotic material by dissolving them. Although adding a surfactant, such as a detergent will allow water to dissolve material that is hydrophobic, surfactants generally are not used to clean wounds because they can also damage healthy exposed cells. Other additives such as water-soluble antimicrobials or salt to make a saline may also be dissolved in water used for wound cleansing. Physical properties Specific Gravity Specific gravity is also called relative density. It refers to the density of an object relative to the density of water. It is, then, a ratio of an object’s weight to the weight of an equal volume of water. The specific gravity of water is 1. If an object has a specific gravity greater than 1, it will sink in water since its relative weight per volume is more than that of water. If an object has a specific gravity of less than 1, it will float in water. If the object’s specific gravity is 1, it will float just below the water’s surface. Specific gravity for the human body varies from one person to another and from one body segment to another. The person’s specific gravity depends on the body’s composition of lean and fat mass and the distribution of body fat. The specific gravity of fat is 0.8, bone is 1.5 to 2.0, and lean muscle is 1.0. The average range of specific gravity for the human body is 0.95 to 0.97. Since the specific gravity of the average human body is less than 1, people will usually float. Women usually have more body fat than men, so women float better than men. A lean, muscular person may have a specific gravity of 1.10; an obese person may have a specific gravity of 0.93. These wide variations in individual specific gravities lead to a wide range of abilities to float. Patients who are more muscular and have less fat mass may have a difficult time floating, so they may need flotation devices during aquatic exercises. The relative density of human is related to: Age: Child: 0.86 Adult: 0.97 Later in life: 0.86 Body parts: arms float easier than legs. Sex: women float better than men. Medical status: weaken patient or which have disabilities float easier. Buoyancy Archimedes’ principle of buoyancy states that a body partially or fully immersed in a fluid will experience an upward thrust of that fluid that is equal to the weight of the fluid the body displaces. Buoyancy can be used as assistance or resistance in Hydrotherapy (Figure 1). Center of Buoyancy The center of buoyancy is the center of gravity of the displaced fluid and the point at which the buoyant force acts on the body. In water, two opposing forces act on the body. Buoyancy is the upward force, and gravity is the downward force. Each has a center point of balance. When a floating body is in equilibrium, the center of buoyancy and the center of gravity are in vertical alignment with each other (Figure 2). In this position, the body is balanced. If the center of buoyancy and the center of gravity are not in vertical alignment with each other, the body is out of equilibrium and will tend to roll or turn. For example, if you place a kickboard between your knees, the center of buoyancy will cause your lower extremities to move upward to float. Figure 1. Buoyancy in aquatic exercises Figure 2. When the center of buoyancy and the center of gravity are not in vertical alignment, a person must actively work to keep from rolling in the water. (a) The body is in equilibrium; the centers of gravity and buoyancy are aligned vertically. (b) The body is not in equilibrium; the centers of gravity and buoyancy are not aligned vertically. Hydrodynamics Hydrodynamics is the branch of physics that explores the motion of solid objects in fluids and the forces imparted on those objects by the fluid. The fluid’s resistance to movement, the size and shape of the object moving, and the speed of the object all govern movement through water. Some of the factors that affect a body’s movement through fluid are interrelated and are important for the clinician to understand when he or she makes decisions about the aquatic exercises to include in a patient’s rehabilitation program. Viscosity is an internal friction “result from Cohesion” occurring between molecules of liquid resulting in resistance to flow and motion of the body. The resistance increases in proportion to the relative speed of the motion, surface area and decrease with higher temperature of water. Drag Drag is the water’s resistance to a body that is moving through it. The three types of drag are form drag, wave drag, and frictional drag. Form Drag Form drag is the resistance that an object encounters in a fluid. The amount of form drag is determined by the object’s size and shape. A larger object has more drag than a smaller object. A broad object has more drag than a streamlined object. Form drag is directly related to turbulence. The greater the form drag, the greater the turbulence. Form drag can be used in an aquatic therapy program as a means of altering resistance to exercises. A change in the position of the body or body segment can increase or decrease form drag. For example, moving the arm horizontally in the water with the palm down causes less form drag than with the hand in a vertical position. Shortening or lengthening the body’s extremity decreases or increases the form drag, respectively, since a longer lever arm pushes more water than a shorter one. Adding equipment such as hand paddles increases the surface area of the hand, and adding long paddles increases the lever-arm length; both provide additional form drag to increase the resistance of an exercise. Wave Drag is the water’s resistance because of turbulence caused primarily by the speed of the object in the water. The greater the speed of the object, the greater the wave drag. Wave drag is reduced if movement remains underwater because less wake is produced. The amount of water wake is an indication of wave drag. Swimming pools often have a splash gutter around the periphery to reduce wave drag for swimmers. Exercises performed in calm water produce less resistance than those performed in turbulent water. The person can create wave drag during an exercise by changing positions often and rapidly. Increasing the speed of an exercise also increases the wave drag, thereby increasing the exercise’s resistance. For example, walking in water provides the body with 5 to 6 times the resistance that walking in air does. Running in water, however, increases the resistance to more than 40 times that of air. Frictional Drag is the result of water’s surface tension. This is not a factor in rehabilitation, but it becomes an important element for competitive swimmers. Frictional drag can add crucial milliseconds to a race time; swimmers reduce frictional drag by shaving body hair before competition. Recently, custom-made bodysuits constructed from unique new fibers have reduced frictional drag. Turbulence Turbulence is an irregular movement of water molecules. It may be created by an underwater douche, or turbines. Hydrostatic Pressure Pascal’s law states that pressure from a fluid is exerted equally on all surfaces of an immersed object at any given depth (Figure 3). The more deeply the object is immersed, the greater the pressure it encounters. Atmospheric pressure at the surface is 14. psi (pounds per square inch). For every foot of submersion, water pressure increases by 0.43 psi. Hydrostatic pressure can positively affect edema both by reducing post injury edema and by allowing exercise without the risk of increasing it. Figure 3. Pascal’s law Clinical Tips Several major physical properties of water, including specific gravity, buoyancy, center of buoyancy, and hydrodynamics, affect the way people exercise in water. These properties contribute to an optimal environment for exercise when body segments are very weak, or weight bearing is restricted. Several aquatic exercises can be initiated early in a rehabilitation program, and others may continue well past the time when the patient has achieved enough strength and weight-bearing ability to perform land-based exercises. Weight Bearing in Water Since buoyancy and gravity are opposing forces acting on a body in water, the more deeply the body submerges in water, the less weight is borne by the lower extremities (Figure 3). Because a male’s center of gravity is higher than a female’s, the specific percentage of body weight borne at different depths varies slightly from female to male. For example, with the body immersed to the xiphoid process, females bear 28% of their weight, whereas males bear 35% of their weight. Note that individual percentages will vary depending on body structure and weight distribution. In most cases, the percentage differences between men and women are not enough to require a distinction between the sexes when it comes to determining the most appropriate water depth for exercises. Figure 4 may be used as a general rule for males and females. Figure 4. Weight bearing in water at different depths Clinical implications of hydrostatic pressure Weak patients will find horizontal movements are easier to perform just below the surface of water. Standing in water can assist patients with lower limb edema or effusion encourage fluids in higher pressure areas to flow proximal. Thermodynamics Specific Heat Specific heat of water is the amount of energy required to raise temperature of 1 gm of water 1⸰ C. The specific heat capacity of water is equal to 1. The specific heat capacity of air is 0.001. So, it is apparent that water holds heat well, approximately 1000 times more than an equivalent volume of air. Thermal Conductivity Thermal conductivity is accomplished by conduction, convection and radiation. Air and paraffin are insulators. While water is a conductor, no other medium conducts heat as efficiently as water does. In fact, water conduct heat 25 times faster than air does.