Under various environmental conditions, it has become the principle of health preservation to dynamically maintain the harmonious balance of human functions. Life lies in exercise, and the goal of exercise is to achieve dynamic balance. Simply put, it is the dynamic balance of yin and yang in human body. Yin and Yang in TCM refers to the combination of the concepts of Yin and Yang in natural science and philosophy to explore the physiological function and pathological changes of human body and the experience of preventing and treating diseases. Huangdi Neijing, a classic work of traditional Chinese medicine, explains medical principles with yin and yang. Take the characteristics of water and fire as the representatives of yin and yang, because the heat, rise and movement of fire have the most positive characteristics; Cold, quiet and humid water has the most turbid characteristics. Yin and Yang have no fixed substance, but only represent the properties and dynamic and static trends of two things. This concept of yin and yang has a great influence on traditional Chinese medicine, making it a subject that focuses on the study of human functional state and ignores the changes of organic matter. When the theory of Yin and Yang explains the laws of various things, it holds that the opposing party must have positive characteristics and the other party must have negative characteristics. In addition, the theory of Yin and Yang regards the mutual transformation of the opposing sides as a cycle, that is, the transformation direction of Yin is Yang, and the transformation direction of Yang is Yin, so the theory of Yin and Yang Yang Can accurately explains the dialectical relationship between the development of things and old and new things. Yin and Yang are not isolated and static, but are reconciled in the relationship of relativity, dependence, growth and decline and transformation. 1, Relativity of Yin and Yang: Yin and Yang are two attributes that explain things, and they represent two aspects of contradiction, opposition and unity. It is a summary of the opposites of interrelated things and phenomena in nature. As far as the human body is concerned, the body surface is yang and the internal organs are yin; As far as the five internal organs are concerned, the six internal organs belong to yang and the five internal organs are yin; As far as the five internal organs are concerned, the heart and lung belong to yang in the upper part, and the liver and kidney belong to yin in the lower part; As far as the kidney is concerned, the "essence" hidden in the kidney is yin, and the "fire of life gate" of the kidney belongs to yang. It can be seen that the yin and yang attributes of things are relative. 2. Yin and Yang are mutually rooted: Chinese medicine has such sayings as "Yang roots in Yin, and Yin roots in Yang", "Solitary Yin is not born, solitary Yang is not long" and "Without Yang, Yin is not born, and without Yin, Yang is not transformed". Physiologically speaking, functional activities belong to yang, while nutrition (body fluid, essence and blood, etc.). ) is yin. Various nutrients are the material basis of functional activities. With adequate nutrition, functional activities will flourish. On the other hand, the source of nutrients is absorbed through the functional activities of internal organs. This shows that the two are interdependent, survival and * * *, and there is no Yang without Yin. If there is yin without yang alone, or there is yang without yin, it is bound to be like the saying in Neijing: "The solitary yang is not born, and the solitary yin is not long", then everything is quiet and silent. 3. The rise and fall of Yin and Yang means that the two sides of Yin and Yang are always moving and changing on the basis of opposition, and the phenomenon of "Yin eliminating Yang and Yang eliminating Yin" appears constantly, which is the process of development and change of everything. Under normal circumstances, Yin and Yang are often in a relatively balanced state. If the relationship between "ebb and flow" exceeds a certain limit and the relative balance cannot be maintained, a certain aspect of yin and yang will flourish and decline, leading to the occurrence of diseases. 4. Yin-Yang transformation: refers to the same yin-yang body. Under certain conditions, when it develops to a certain stage, both sides can be transformed into opposite aspects, Yin can be transformed into Yang, and Yang Can can be transformed into Yin. This is the so-called "Yin-Yang transformation". Clinically, all kinds of common diseases change from excess to deficiency, from deficiency to excess, from exterior to interior, from inside to outside.