Yoga exercises have a very positive effect on all the systems of the body. What are the mechanisms through which these changes occur? Below we shall discuss some possible answers.
1. They massage the various important organs of the body. Depending of the movements and positions we can massage internally the liver, pancreas, intestines, the thyroids and various other organs. This pressure that is exerted creates a dual process. Some create greater blood flow to the organs, others drain the blood from the organs. In this way, we can clean out the organs of toxic substances with exercises which drain the organ and then ensure its good supply of blood again with exercises which flood that organ with blood. This is extremely important because all the healing substances of the body such as hormones, antibodies, oxygen and nutrients are found in the blood. Also the blood removes the various waste substances which accumulate and cause sluggish or defective functioning. Thus the insurance of good blood flow to an organ is a great asset in healing it or restoring its proper functioning. This is true independent as to whether the organ is under functioning or over functioning.
This massaging effect also stimulates the excretions from each organ which sometimes are sluggish. It also, in general, stimulates the functioning of all aspects of that organ.
2. Organs and various parts of the body are not only flooded with blood or drained of blood through movements but also by postures which bring the blood to certain areas and away from others. For example, it would be difficult to massage the pituitary gland which is found in the center of the brain. But we can flood it with blood through head low postures. Various postures bring blood to certain parts of the body which are difficult to affect in any other way.
3. Deep breathing in the postures and in between postures increases the circulation of blood and lymph through the veins and lymph glands which depend on muscular movement and breathing for aiding their circulation. This is an important aid for purifying the toxins that build up in the body and eventually cause illness.
4. The muscular relaxation which takes place through the stretching and relaxing in each posture allows the cells of the muscles to let go of lactic acid build up, and the nerves are in this way rejuvenated. This is combination with the deep breathing and inner concentration creates a general relaxation of all the nervous system which then brings relaxation and harmonious functioning to all of the other systems of the body.
5. Basically stimulating and harmonizing the endocrine glands, a general harmony is created which regulates the harmonious functioning of all the other systems and organs. Thus through the nervous system and endocrine system these exercises bring harmony to the pituitary and the hypothalamus which in turn regulate the rest of the body through the functioning of the adrenals and the rest of the endocrine glands and the harmonious functioning of the sympathetic and parasympathetic nervous systems. The various breathing exercises and deep relaxation have an extremely beneficial affect on this mechanism.
6. The in general more relaxed body and mind of the individual then are more stress resistant, and react in a more positive way to negative stimuli. In this way, a relaxed individual of this type accumulates much less stress and tension and thus less organic disturbance under the same conditions as the individual who is not relaxed physically or mentally.
7. The posture of the individual is gradually changed as a result of the exercises and he moves more naturally aiding rather than restricting the free functioning of the various organs of the body. His breathing becomes freer, slower and deeper and he thus takes in more oxygen with each breath. This means more energy and clarity and greater removal of toxins with each relaxation. His body thus remains cleaner and more charged with vital energy.
8. The organs of digestion are stimulated and tonified each day through these exercises and thus digest more easily and completely. In this way, he absorbs more nutrients from his food, and all the systems of the body mutually benefit from this extra supply of nutrients with diminished energy spent on digesting. Often this process of bringing his body into a healthy state will also create within him a desire for healthier more natural and fresh foods which are more easily digestible, contain less toxins and offer more vitamins, minerals and energy.
9. Perhaps the most important of all factors is the fact that the head is supplied daily with plentiful quantities of blood through head low exercises which stimulate all the brain centers. Here in the brain is where health and harmony are created or not. Most people have a serious deficiency in the blood follow to the brain. They then have a wide variety of problems that develop due to the resulting disturbance in the endocrine and nervous systems which have their control realize that their problems are actually psychosomatic, and the condition of these centers in the brain, play an important part in our psychic and somatic states. This is the price we are paying (along with lower back problems) for standing up on two legs rather than walking on all fours like our predecessors. We will have to make sure to compensate for this with daily practice of postures that bring extra blood to the head. The most simple and safe posture is the half shoulder stand in which we simply lie down near a wall and place our feet up and just lie there and relax.
There are probably more other mechanisms at play, but the major ones are these, increased blood flow and increased oxygenation of all organs but specifically the centers of the nervous system and the endocrine system.