Much of what is described in traditional medical systems as the "balance" of forces, such as yin and yang in the Chinese system, can be associated with the dualistic components of the nervous system. In the central nervous system yin is rest and yang is action. Balance is the state between rest and action called dynamic equilibrium. This is the state that training in Tai ji and Qigong seeks to refine. In the autonomic nervous system yin may be associated with the parasympathetic and yang may be associated with the sympathetic. The balance of yin and yang is associated with homeostasis.

Because the western world view has generally had a difficult time understanding and accepting the concepts of Qi (chi), prana or vital force from the Asian systems, there has been a strong trend toward explaining the effects of yoga, qigong, acupuncture, etc through the mechanisms of the nervous system.(25,54,55) While while these practices do have a definite effect upon neurological function, with consequent effects on body systems, the neurological mechanism may actually be an intermediary for a more refined and less quantifiable system of subtle energies. However, a great deal of research has been done that reveals the neurological mechanisms that may be activated in Qigong and Yoga and it is appropriate to explore them here.

There are a number of mechanisms associated with the brain, nervous system and other related systems that Qigong and Yoga/Pranayama practice enhance including:

1. Initiation of the "relaxation response" (RR), para-sympathetic aspect of the autonomic nervous system or resting aspect of the basic rest activity cycle (BRAC).
2. Shift of the neurotransmitter profile.
3. Dilation of blood capallaries initiating increased microcirculation in the periphery, brain and organs.
4. Supports the brain/neurological aspects of immune function.
5. Balance right/left brain hemisphere dominance.
6. Induction of alpha, and sometimes theta wave forms in EEG.
7. Affecting neuroreflex mechanisms through the stimulation of acupuncture response points.
8. Generating an affect on the function of the hypothalamus, pituitary, pineal, third ventricle complex within the brain.

1. Initiation of the relaxation response
When the predominance of autonomic nervous system activity is sympathetic the human system is working, expending energy and breaking down tissue. This is associated with the action phase of metabolism, and referred to as catabolic. This is associated, in it's extreme, with the "fight or flight response" with increased heart rate, breath rate and blood pressure. It is also called the stress state and has been associated with adrenal exhaustion and collapse (56).

This state, when overactive and not balanced to homeostasis by ample parasympathetic activity, contributes to the production of positively charged hydrogen ions. As mentioned in an earlier section on free radicals these hydrogen ions bind with oxygen. This can cause a net oxygen deficit and a general acid ph in the internal environment. Biological stress is conducive to the proliferation of a number of diseases or syndromes including hypertension, pain, depression, immune deficiency and inflammation.(57)

The opposite aspect of autonomic activity, parasympathetic, is a phase of rest and tissue regeneration. It is associated with the conservative phase of metabolism, anabolic. In its extreme this state is associated with the "relaxation response" (RR)(57), characterized by decreased heart and breath rate and a lowering of blood pressure. This is also associated with the resting phase of the basic resting activity cycle (BRAC).(58) Conscious deactivation of the sympathetic function with the activation of certain parasympathetic features of autonomic activity can neutralize the negative effects of "fight or flight" overactivity. The primary steps to initiate this state are deep, slow breathing coupled with the intention to relax.(57) These are the identical initiating steps for the practice of Qigong and Yoga. The literature alludes liberally to traditional Asian health maintenance practices as the historic source of techniques for generating the relaxation response(RR) and the typical biofeedback response(3).

With the addition of gentle movement and stretching extra oxygen is demanded from the blood, which may help to reduce the presence of hydrogen ions and initiate a swing toward a more anabolic level of activity. This may help to produce a less acid internal environment and a net greater availability of free oxygen with increased energy productivity and tissue regeneration.

Controlled, deep, slow breathing accompanied with the intention to relax initiates the RR and the resting phase of the BRAC, which are para-sympathetic/anabolic/alkaline responses, generally recognized as healing and regenerative. Increased oxygen to hydrogen ion ratio is also recognized as conducive to healing and regeneration.

2. Neurotransmitter profile
Much of the new science of psychoneuroimmunology is founded upon findings in the area of neuro-hormones, neuropeptides or neuro-transmitters. It has already been mentioned that neurotransmitter receptor sites have been found on lymphocytes. A particular profile of neurotransmitters is present in a person who is experiencing pain, anxiety or depression. (59) In contrast joy, comfort or celebration produce unique neurotransmitter profiles as well. (60)

In hypertension, pain and inflamation, which which have been associated with the hyperactivity of the sympathetic aspect of the autonomic nervous system, a number of specific neurotransmitters are present in the blood. In patients suffering from pain increased norepinephrine, reduced cholinesterase and depressed beta endorphine were found to be typical.(59)

When methods are employed that regulate the sympathetic function through the hypothalamus a neurotransmitter profile characterized by decreased norepinephrine, elevated cholinesterase and elevated beta endorphine emerge.(59) The neurotransmitter profile present in the parasympathetic and usually more anabolic (alkaline) environment is recognized as able to reduce pain and depression(59), reduce cravings for addictive substances(61) and promote healing. Chinese research has quantified neurotransmitter activity specific to Qigong exercise. It was found that the Qigong effect is associated with specific shifts in the monoamine neurotransmitter content of the blood.(62) 5HT and 5HE generally tend to be decreased by Qigong practice. Noradrenaline and dopamine tend to increase. The aspects of Qigong and Yoga that quiet the mind and relax the body induce a neurotransmitter profile that is conducive to healing.

3. Increased microcirculation
A classic body response in Qigong and Yoga is the elevation of skin temperature. In the fight or flight state, hyper-sympathetic, the arterioles in the skin, muscles and certain organs constrict. During the systematic deactivation of sympathetic function, typical in Qigong and Yoga/Pranayama, vasodilation occurs with the accompanying warmth of the surface of the skin. This is one of the primary goals in biofeedback training and was found as a typical response when the skin temperature of meditators was evaluated in research.(3)

A number of studies from China explore the microcirculatory mechanism very thoroughly and conclude that this mechanism is a major reason for the continued successful application of such an ancient health maintenance method. (63,64,65,66,67,68)

In traditional chinese medicine it is said "the blood is the sister of the Qi". (28,29) Because Qi and blood are in a direct relationship the inhibition of the circulation of one tends to inhibit the circulation of the other. In addition, the theory suggests that when the blood is optimally circulating in a part of the body that the Qi or vitality is circulating there as well. If the Qi is a bio-electrical, electromagnetic or subtle energy aspect of the human being, the presence of increased blood circulation and its accompanying heat may also signify the presence of increased electromagnetic or other subtle energy potential. This may be a key to explain how Qigong practitioners and mental healers are able to support the healing process in a person from a distance through "Qi emission" or "external conductance of the Qi".

4. Brain/neurological aspects of immune function
In the classic tradition of Western science it has been thought that the immune system was an autonomus self regulating system, operating on its own. A tremendous amount of reseaearch has demonstrated that this view was incorrect. Mental emotional states have been found to effect resistance to disease and infection.(60)Immune organs including the thymus gland, spleen, lymph nodes and bone marrow have been found to be invested with nerve endings.(60) Lymphocytes and macrophages have been shown to have receptors for neurochemicals, including catacholamines, prostagandins, serotonin and endorphin.(60) There is a definate relationship between brain and nervous system function and immune capability.

In the practice of Qigong and Yoga, as has been discussed, the hypothalamus regulates the autonomic nervous system function toward a lessening of the sympathetic activity, which is associated with the stress response.(3,57) A number of studies have demonstrated that the hypothalamus has an influence over immune function.(60) Meditation, progressive relaxation, deep breathing and slow relaxed movement all tend to move the practitioner out of the sympathetic state and induce the relaxation response. Research on the effect of relaxation and visualization sheds some light on the effect that the Qigong and Yoga states may have on immune function. Groups of elders who recieved relaxation training had significant increases in the activity of "natural killer cells" while control groups did not. Chinese research has corroberated the positive effect of Qigong practice on the status of the immune system. (65,69,70,71,72)