Since Dr. Shindo Yoshiharu's book, "Lower-body Bathing That Works for All Diseases," became a best seller in Japan, lower-body bathing has become a trend in many homes. Meanwhile, a public medical broadcast program by KBS (Korean Broadcasting System), "Secret of the Four Phases of Life: Birth, Aging, Sickness, and Death," introduced positive effects of the lower-body bathing on human health. Since then, lower-body bathing has become very popular among the public in South Korea. Nowadays, you can find people sitting around in a circle enjoying lower-body bathing in many Korean bathhouses. Many foreign tourists are fascinated about two bathing traditions in Korea: first, bathers can ask a "Ttaemiri" professional scrubber to scrub down their whole body in a bathhouse. Second, most Koreans enjoy lower-body bathing as much as taking a full bath.
When a human's upper body gets too hot because it is full of qi (energy) and the lower body cools down, the unbalance of temperature may cause sickness. Lower-body bathing warms up your body and helps balance the body's temperature which improves your health. The 18th century Dutch physician, Hermann Boerhaave, said "Keep your head cool, your feet warm, and you'll make the best doctor poor." There is a similar saying in oriental medicine theory, "Head cool, feet warm, no illness." All these quotes from history reinforce the idea that lower-body bathing has positive effects.
Oriental medicine theory considers the human heart as Yang (sunny side) and the Kidney as Yin (shady side). They believe when your Yang energy goes down and Yin energy goes up, it balances your body temperature and improves your health. In contrast, when your body temperature is below 35℃ and your lower body temperature is significantly lower than your upper body temperature, it disturbs the blood circulation and makes it easy for you to get sick. Taking a full bath raises the temperature of your upper and lower body simultaneously which retains the imbalance of your body temperature. Moreover, if you take a full bath for more than 10 minutes raising your body temperature over 42℃, it may damage cells in your body. However, taking a lower-body bath only heats up your lower body while your upper body cools down via sweating. This helps your body temperature to be well-balanced while staying in a bathtub for longer than 20~30 minutes.