The science of Tai Chi regimen holds that Qi is the foundation of life, manifesting itself in yin- yang. Traditional Chinese medicine employs yin-yang to explain pathologic changes and diseases of the human body and accordingly provides diagnosis and treatment.

In brief, in regimen concepts in ancient China, there were two fundamental elements within the body, “Yangqi” and “Yinjing (essence)”, and health was guaranteed by balance between yin and yang. To be specific, the organizational structure of the body can also be summarized by yin and yang: the back is yang, and the abdomen is yin; the five internal organs (heart, liver, lungs, spleen and kidney) are yin, and the six hollow organs (gallbladder, stomach, large intestine, small intestine, urinary bladder, and San Jiao are yang (San Jiao, literally “triple burners” , is a special term in traditional Chinese medicine, which doesn’t refers to a single internal organ, but to a function. There are three “burning spaces”, Shang Jiao or upper burner, Zhong Jiao or middle burner, and Xia Jiao or lower burner. Traditional Chinese medicine divides the trunk into three parts: Shang Jiao, which is above the diaphragm, including heart and lungs; Zhong Jiao, which is between the diaphragm and the umbilicus, including spleen and stomach; and Xia Jiao, which is below the umbilicus, including liver, kidney, large intestine, small intestine and urinary bladder. The function of San Jiao is in fact the combined functions of the five internal organs and six hollow organs.). Yangqi and Yinjing of the human body constrain and promote each other, whichever dominates gives rise to illness. To be healthy, one must have balanced yin and yang, harmony between inside and outside, sufficient Qi and blood, and healthy internal organs.