The word Cryotherapy stems from the green words "Cryo" or cold and "therapy" or cure. Modern Whole Body Cryotherapy (WBC) began in Japan in 1978 by Dr. Yamaguchi. He used short duration freezing treatments of the skins surface to treat pain in his rheumatoid arthritis patients. He discovered that rapidly decreasing the temperature of the outer layer of skin lead to an immediate of release of endorphins.
These endorphins significantly reduced the patients's sensitivity to pain. Up on further study, he and his associates concluded that this rapid shirt term freezing of the skins surface to lower than 32 degrees F is more beneficial to eh the while body than the gradual cooling of an ice bath where the lowest possible temperature is 41 degrees F; and since the cooling process affects no more than 5% of the body (i.e. the parts that safely endure the variations of temperature), the treatment is comfortably endured.