LECTURE 2:- THE PHYSIOLOGICAL, THERAPEUTIC AND PSYCHOLOGICAL EFFECTS OF ACTIVITY IN WATER The uniqueness of water lies mainly in its buoyancy, which relieves stress on weight bearing joints and permits movements to take place with reduced gravitational forces, thus non- weight- bearing activities can be commenced before they are possible on land. The physiological effects of ex. Combined with those brought about by the warmth of water are one of the advantages of activity in this medium.

The therapeutic effects of ex. In water relate to:- 1- The relief of pain muscle spasm. 2- The maintenance or increase in range of motion of joints. 3- The strengthening of weak muscles and an increase in their tolerance to ex. 4- The re- education of paralyzed muscles. 5- The improvement of the circulation. 6- The encouragement of functional activities. 7- The maintenance and improvement of balance, co- ordination and posture. 8- The improvement of gait pattern.

In addition, water provides the potential for ex. In water in three dimensions which cannot be achieved on land. There is the possibility of considerable perceptual stimulation:- A - Visually. B – Aurally. C – Via the skin propriocepors. D - By heat.

Basic Physical Principles Applied To Water Therapy:- 1- TEMPERATURE: - Is a measure of the level of heat. Water has a much greater specific heat than other common material as shown in the table below so that it takes a great deal of heat energy to increase the temperature of water and conversely hot water stores much heat per unit mass.

Specific Heat( kg /1c) 4.185Water 3.77SkinSkin 3.75Muscle 3.64 Whole blood 3.56 Whole human body

2- BUOYANCY:- This is the force acting in the opposite direction to the force of gravity and is experienced as an up thrust "According to Archimedes principles; when a body is wholly or partially immersed in a fluid, it experiences an up thrust which is equal to the weight of the fluid displaced.

3- HYDROSTATIC PRESSURE:- This property of water provides even pressure on all surfaces of an immersed limb or body at any one given depth pressure increases with depth and with the density of the fluid.

SPECIFIC PHYSIOLOGICAL EFFECTS OF WATER:- 1- Effect on cardiac output:-The changes in cardiac output and stroke volume when normal subjects were immersed to neck level in water at a neutral temperature, a shift of blood from the legs to the thorax in turn, produced an increase in the cardiac output of some 30% and an increased stroke volume of 35 %, this was presumed to be due to an improved diastolic filling, plus an almost unchanged heart rate.

2-Effect on blood pressure:- The effects of water therapy on the blood pressure are increase in the diastolic pressure as a result of both pre- and post treatment showers. Also there is drop of the mean blood pressure after entering the pool therapy.

3- Renal response to immersion:- As the hydrostatic pressure gradient to which the patient is subjected when standing immersed to neck level in the hydrotherapy pool, results in striking changes in the distribution of the body fluids. On average, 700ml of BLd moves from the limbs to the thorax, and this stimulates the volume receptors which in turn bring about a profound diuresis, so from a practical point of view, this gives a scientific back ground to the practice of requiring patients to empty their bladders before attending for hydrotherapy.