The water bath is followed by a cold bath. This is called hot and cold water bath. It is a good fitness method. Hot and cold water bath can promote metabolism, enhance the functions of nervous system and cardiovascular system, and improve the adaptability of human body to rapid changes in external environment and resistance to diseases.

When a person takes a hot bath, blood vessels in the skin relax, blood flow accelerates, blood volume in the skin increases, sweat gland secretion increases, exercise muscles relax, heat production in the body decreases, heartbeat frequency increases, and metabolism accelerates. When people switch from hot water above 40 degrees Celsius to cold water below 20 degrees Celsius, their muscles will tighten and they will have difficulty breathing. But after a while, the whole body will feel warm and relaxed. A series of reactions occur under the stimulation of cold water, which is beneficial to improve cardiac output and enhance cardiac function. Cold water stimulation and vasoconstriction can improve the elasticity of blood vessels and help prevent hypertension and arteriosclerosis.