A cold bath is to scrub the whole body with cold water below 20℃. When middle-aged people start to exercise in cold water bath, it is best to exercise with water 35℃ lower than their body temperature in summer, and gradually reduce the water temperature to below 20℃ as the body adapts. Those who are in good health can also take part in winter swimming.
Hot and cold water bath first washes the whole body with hot water, then with cold water, and then rubs the whole body skin red with a towel and produces a sense of heat. The method of hot and cold water bath can stimulate the whole body's blood vessels, make them relax and contract, enhance the elasticity of blood vessels, improve the cold resistance of human body, and promote lung function and adaptability.