The second pulse of Ren Du is in accordance with Chapter 60 of The Yellow Emperor's Internal Classic Su Wengu's Confucius Theory, which states that Ren Mai starts from the middle pole, goes up to the hairline, goes up to Guanyuan in the abdomen, reaches the throat and goes up to the face. "The du meridian starts from the center of the hypogastric bone, and the woman enters the auditory foramen, and its foramen is also the end of the drowning foramen." The two meridians of Ren and Du originate from the cells of human body (less abdomen), from the Qugu point on the body surface of human abdomen, and from the front of the body surface along the center up to the pith-containing point under the lip. This meridian is Renmai.
The Du Meridian runs backward from Qugu point along the back of human body, reaches the top of the head and then goes forward between the eyes, reaching the gingival point of the oral cavity. Ren meridian governs blood and Du meridian governs qi, which is the main meridian of human body. If Ren Du's two veins are connected, then the eight veins are connected; Eight veins connected with hundreds of veins can further enhance physical fitness, strengthen tendons and bones, and promote circulation.
Ren-Du pulse is very important in TCM pulse diagnosis and Taoist health guidance. At the same time, because there are exaggerated descriptions in martial arts novels, for example, people with high martial arts can get through their second pulse of Ren Du, and once the second pulse of Ren Du is connected, their martial arts will advance by leaps and bounds, so it has become the most familiar name of one pulse.
Ren meridian and Du meridian originally belonged to odd meridian and eight meridians. Because they have definite acupoints, doctors call them fourteen meridians together with the twelve meridians. Ren pulse governs blood, which is the sea of yin pulse; Du meridian governs qi, and qi is the sea of yang pulse. In other words, Ren meridian and Du meridian respectively play a leading role in the six yin and six yang of twelve meridians. When the twelve meridians is full of qi and blood, it will overflow into Ren Du and Er Mai. On the contrary, if the Ren Du pulse has vitality, it will also circulate on the the twelve meridians, so it is said that "Ren Du pulse can be connected."