It must be good to insist on a cold bath. Cold water bath is a method of exercising by using natural factors. Cold water bath can improve the body's adaptability to cold stimuli. When the human body is stimulated by cold water, the skin blood vessels contract sharply, resulting in a large amount of blood flowing to the deep tissues and organs of the human body. Then, the skin blood vessels expand again, and a large amount of blood flows to the body surface again. In this way, all the blood vessels in the whole body participate in relaxation and contraction. This movement of relaxing and contracting blood vessels can increase the elasticity of blood vessels, which is beneficial to the prevention and treatment of arteriosclerosis, hypertension and coronary heart disease. During cold water bath exercise, due to the redistribution of blood and the enhancement of hematopoietic function of bone marrow, red blood cells and hemoglobin in blood can increase, thus making people rosy and energetic. At the same time, this kind of exercise can make people's skin elasticity increase and wrinkles disappear, which has obvious cosmetic effect. Cold water bath can also enhance lung function by deepening breathing, increasing diaphragm activity and increasing lung ventilation. By promoting gastrointestinal peristalsis, digestive function can be effectively improved; By increasing the release of heat and reducing the accumulation of subcutaneous fat, you can lose weight. Cold water bath is suitable for the prevention and treatment of cardiovascular diseases, chronic bronchitis and emphysema, early hypertension, gastroptosis, constipation, hyperlipidemia and other diseases, as well as for weight loss, beauty, immunity improvement, fitness and anti-aging exercise. Main points of exercise ① The optimum water temperature for cold water bath is 20℃. ② The methods of cold water bath, from weak to strong, are wiping, washing, showering and swimming. (3) Generally, brush from cold water, use a stronger method after adaptation, and stick to autumn or winter. ④ The starting time of exercise should be short, just 2-3 minutes, and then gradually extended to 10- 15 minutes, which is generally considered to be no more than 15 minutes. ⑤ If the water temperature is lower than 20℃, the time should be shortened accordingly. The lower the water temperature, the shorter the time should be. Precautions ① The cold water bath should be gradual, persistent, and insist on exercise to achieve the desired effect. ② It is not advisable to take a cold bath immediately after strenuous activity. ③ It is not advisable to take a cold bath immediately after a meal. (4) warm-up activities should be done when taking a cold bath or swimming, which should be carried out after the body is hot. ⑤ People with weak constitution, serious organic diseases, fever, drinking and female menstrual period are not suitable for cold water bath. ⑥ During cold water bath exercise, you should pay attention to the changes of self-feeling and weight. If you have discomfort, weight loss, insomnia, loss of appetite, etc., you should suspend cold water bath.