Generally speaking, Qi is an essential substance that is full of vigor and flows fast. TCM believes that Qi is the most fundamental substance in the construction of the human body. Qi is often call yang qi (attributes of yang) because it is mobile and warms internal organs. It is generated from various vital processes, such as inheriting (from parents through kidney), inhaling (from air through lung), and eating (from food through spleen).

Qi has many functions related to life maintenance. It can promote heart functions and blood circulations (heart qi); it can regulate the gastric functions (stomach qi); it can prevent the invasion of external pathogenic factors into the body (zheng qi). Metabolism of materials (including blood, fluids, and other essential materials) and energy also depends on the action of qi.

Qi circulates along meridians and collaterals. A healthy body requires normal circulations of qi. Health problems occur if the flow of qi is stagnated. For example, external pathogens invade the body through skin, nose or mouth. Qi can protect the body surface, control the opening and closing of the pores, thus prevent the invasion of external pathogens. If zheng qi is stagnated, the resistance of the body against the outside invasion would be weakened. The purpose qigong is to promote qi flow and maintain the normal qi circulation.

Qigong is a set of breathing and movement exercises, by which the practitioner uses the initiative to train the body and mind, provide holistic training for self-reliance, self adjustment, body building, and prophylaxis, invigorate and strengthen the constitution, resist premature aging, and prolong life. The main characteristics of Qigong are to control the flow of Qi in the human body, which integrates mental activity with body postures and respiration. Since qi plays an important role in the vital processes of the human body, the regulation of qi flow is used to preserve health and treat diseases. Qigong is different from physical exercise. Physical exercise expends energy by tensing muscles and accelerating the heartbeat and respirations. Qigong works to ease, smooth and regulate breathing to store up or accumulate energy in the body.

Qigong works by affecting several systems of the body. These systems are the nervous system (including the autonomic nervous system), endocrine system, circulatory system, and immune system.? In order to apply qigong to these body systems, numerous training techniques are used, such as meditation, conscious breathing, chanting, visualization, stances, movements and stretches, and qi allocations and movements. There are various qigong programs, ranging from simple to complex, that are tailored to specific individual needs. Qigong can be practiced while sitting still, standing upright, or lying on the back or side. The basic requirement is to stay comfortable and relaxed.