1. Electrolyte imbalance is an exaggeration, and the coach has a point. However, it is limited to drinking a lot of water, and ordinary people tend to drink too much water because of lack of water after exercise. If you drink too much water at one time because of thirst, it will reduce the salt content in blood and the osmotic pressure of cells, leading to imbalance of sodium metabolism and muscle spasm. Due to the insufficient blood supply to the gastrointestinal tract during strenuous exercise, the function is not good, and the absorption capacity of water is weak, and too much water penetrates into cells and intercellular space. Brain tissue is fixed in a hard skull. The swelling of brain cells will cause the increase of brain pressure, which will lead to the symptoms of "water poisoning" such as headache, vomiting, lethargy, blurred vision and slow heart rhythm. 2. For obese people, drinking water quickly at one time will quickly dilute blood and increase the burden on the heart. After exercise, this situation will be more serious. Therefore, it is necessary to replenish water several times after exercise to give the body a buffer time for electrolyte balance. The coach said he couldn't drink water for an hour and a half, so he took a simple and rude approach. In addition, if you are overloaded with aerobic exercise to lose weight, drinking water is the most taboo in the whole process. Drinking water before exercise is easy to cause stomach pain, and drinking water during exercise is easy to vomit. Drinking water immediately after exercise, especially cold water, is very harmful to the stomach. Drinking water before and after exercise is subject to dry mouth and throat.