Glossary

Jiao Qi (Leg Qi), or Zu Qi (Foot Qi) is a disorder characterised by numbness, pain, limpness and either swelling or atrophy of the leg or foot due pathogenic accumulation. It may come in Damp, Dry, Hot, Cold, Excess or Deficient, Internal or External and Fulminating (Chong Xin, Rushing to the Heart) forms.

• Damp forms involve swelling which is most common, whereas the Dry form usually involves wasting.
• Excess forms may be caused by External invasions of climatic factors or from Excessive dietary indulgence. Deficient forms are usually due to dietary deficiencies which may give rise to Foot Qi directly, or by making us vulnerable to External invasion.
• The Fulminating form may be a consequence of any of the others left untreated allowing it to rise and invade the Heart causing palpitations, shortness of breath, chest pain, nausea or disturbance of the Shen.

Hilary Smith (2017) has shown that it probably arose as a popular term for foot pain and has meant many things over time as various classical doctors attempted to categorise it including:

• A disease caused by miasmic vapours that affected refugees from the north who moved south treated mainly with moxa in Ge Hong's Emergency Formulas to Keep Up Your Sleeve, 3rd century.
• A disorder of excess caused primarily by "plumpness" and treated with draining therapies and the avoidance of meat. Left untreated it could rise and attack the heart, described by Sun Simiao, 7th century, and perhaps equating to cardiovascular diseases.
• A painful foot disorder caused by excessive consumption of rich food, advanced by Li Gao, 13th century, and probably equivalent to gout.
• Nerve degeneration with swelling of the extremities that eventually leads to cardiac failure caused by thiamine (Vitamin B₁) deficiency, advanced by 20th century nutritionists as the definitive explanation for Leg Qi.
• A colloquial term for foot fungal infection, equivalent to Athlete's Foot, in modern Chinese language.

She warns against assuming "foot qi" is any one of these disorders and may refer to any of these, or even none of them and should be interpreted according to its specific signs and symptoms, or the formulas prescribed at each time since, for example, the advice to avoid meat and rich foods advised by Sun Simiao and Li Gao would actually be detrimental to a sufferer of beriberi, while good advice to someone suffering from gout or cardiovascular disease. For more information see: Smith, H.A. (2017). Forgotten Disease: Illnesses Transformed in Chinese Medicine. Stanford University Press.