Hot Bath, Cold Bath
When we get sick with cold or other illnesses, we usually get a fever. This is a natural body reaction against the illnesses.
With elevated body temperature, your immune systems work at a heightened level so that your body can fight against any viruses or bacteria more effectively. The elevated body temperature also increase the speed and efficiency of the blood circulation, thereby increasing the supply of blood to the "battle zones" in the body and also speeds the removal of the wastes. In other words, the body's healing power is enhanced.
The higher body temperature also facilitates recovery from fatigue or stress. That is why wounded wild animals have been seen bathing in hot springs in the mountains. They have a natural wisdom to speed up healing by soaking themselves in hot water.
In order to take advantage of a hot bath, you must stay in hot water for at least 15 minutes or longer. This is because the heat of the water takes that much time to "penetrate" deep into your body. You should also know that the temperature of the hot water should be only a little higher than your body temperature and should not be too hot. If the water is too hot, it will be damaging to the body rather than helpful. "Moderation" is the key for everything.
First, fill the bath tab and soak your whole body in it, keeping the water comfortably warm enough but not too hot. Keep adding hot water to maintain the steady water temperature.
You may add three to four table spoonfuls of Epsom Salt or Sodium Bicarbonate in the water. Soaking in the hot water with these salts helps keep your body warmer for a longer period of time after you get out of the tub.
For many painful ailments, we commonly use a "hot pack" or "heat pad" to relieve pain because the heat improves circulation and healing processes. However, the benefit of the heat is only temporary and lasts only for as long as the heat is applied. Once the heat pad is taken off, the aching part chills off and starts hurting again.
I learned that a doctor in Japan developed a technique called "Cryotherapy" for arthritic pains. It consists of chilling the aching joints, or even placing a patient in a very cold room, for 10 - 15 minutes or longer. When the chills removed (or coming out of the cold room), the body goes into a rebound phase. The chilled joints have much improved circulation for very long time due to a "rebound" phenomenon. This is much better than applying a heat pad because the benefit lasts much much longer.
Instead of staying in a very cold room, you may just soak in a very cold bath tub for as long as you can tolerate. Some people jump into cold sea in a very cold winter. Obviously, these people are not just showing off their guts but know how to take advantage of their body's natural wisdom.
Hot & Cold Bath
When I used to attend "Sesshins" (a week-long intensive Zen training sessions) in a Zen temple in Japan, I saw many Zen monks take hot bath and cold bath alternatively. In the bathroom, there are two tubs, one with hot water and another with cold water. They dip in the hot one for awhile and then slowly dip in the cold one for as long as they can. Then, they repeat this cycle four to six times.
One of them told me that, this alternating hot-and-cold bath is far more effective in building a stronger body. It seems to increase immune resistance, improve circulation, enhance tolerance against very hot or very cold weather, and loosens muscle tensions.
This is fascinating because this 'hot and cold" process is used to create strong, durable, and beautiful Japanese swords. A sword maker first heats a block of iron in very high temperature oven. Then, he will "strike while the iron is hot." Next, he will put the semi-shaped iron block into cold water to chill it. He repeats this hot and cold process until the iron block is perfectly shaped and strengthened as a steel sword.
The "stress" of this alternating "hot and cold" processes seems to enhance our physical as well as mental durability and strength.
However, this is not for everyone. You should consult with your physician first and use this "stress" technique cautiously.