In Chinese medicine, "Where there is pain, there is no free flow; where there is free flow, there is no pain." So, the major cause of pain in Chinese medicine is stagnation – stagnation of qi and blood.
What is qi? It is commonly translated as energy in English, like Qi Gong as energy work. Energy is only one aspect of qi, however. I don’t think there is one English word that can describe the whole aspect of qi. According to Merriam-Webster’s Chinese-English dictionary, qi can be translated into gas, air, breath, mood, smell, manner, and anger, depending on with which character it is combined.
I once heard someone explain qi as oxygen. I think it is a good word to explain qi when talking about qi and blood in medical term. So, we use acupuncture needles and herbs to move oxygen and blood because “where there is free flow, there is no pain.”
Licensed acupuncturist, herbalist, and a mom of two wonderful boys who taught me a lot about unconditional love