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).