Kidney qi is a term in traditional Chinese medicine. According to the theory of visceral outward manifestation and channels and collaterals, the functions of the kidney are: (1) Essence is stored in the kidney. Kidney essence is the fundamental matter for human growth and reproduction. It is
anessentialof life. (2) The kidney regulates fluid in the human body and governs the discharge of waste fluids. (3) The kidney is the governing organ of bone marrow. (4) The kidney takes in qi. (5) The kidney qi goes to the ear, indicating the two are closely related.

1. Winter is the season when life in all things is concealed. Rivers are frozen and the earth cracks because of the cold.
2. People should not disturb the yang qi. They should go to bed early and get up late, just like the rise and setting of the sun.
3. Let the nund rest in peace as if you  have a secret you don't want to divulge. It is also pleasant, as if someone told you a secret.
4. Avoid cold and keep warm. Don't let your skin perspire, otherwise the stored yang qi will be disturbed.
5. This is why you must store qi to suit winter. If you transgress, you will harm your kidney qi. You will suffer from flaccid paralysis in spring and your ability to suit spring will be weakened.
Learn more about the theory of Chinese medicine, please read Physiological Functions of Kidney.