Kerokan (rubbing or coining) is scraping the back ribs with the edge of a coin or spoon to bring up long red welts. Kerokan looks primitive and cruel to Westerners and nobody know exactly since when kerokan be used as a therapy, but they believe that kerokan therapy exist since kingdoms time. Most, if not all, Indonesians know about the treatment of kerokan, including they who never had experienced it, and they swear it’s an effective cure for masuk angin or equivalent in English as “catching a cold”.
(Kerokan by Setiyo)
Pain diversion. Perhaps that is the simple way to explain kerokan.
The feeling of pain was triggered because the damaged cells release prostaglandins, and this substance stimulates the pain nerve receptors. Inharmonious contraction can occur in the muscles of the peripheral vasculature. During kerokan, blood vessels can be broken and made skin seems so reddish. Stimuli from kerokan can ‘divert’ attention that causes muscular discoordination being in tune again. But according to some doctors, to overcome the pain caused by muscular discoordination is enough by drinking antiprostaglandins, paracetamol, or aspirin.
Update: Apparently kerokan is not only popular in Indonesia. It’s known as “cai giodi” in Vietnam, “gah kyol” in Cambodia, or “gua sua” in China.