In general, it is more appropriate to swim for about 40 minutes. The specific reasons are as follows: 1, swimming for about 40 minutes can not only achieve the purpose of losing weight and fitness, but also won't make people too tired to have side effects. Because the energy consumed during exercise is mainly sugar and fat in the body. In the first 20 minutes or so, exercise mainly consumes sugar in the body, so it is impossible to lose weight if you only exercise for this period of time; After 20 minutes, the sugar is consumed and the fat is consumed. So if you want to lose weight, you must swim for more than 30 minutes. 2. Because there are many disinfectants in the water in the indoor swimming pool, it is easy to cause harm to eyes and throat, so try to control the time when swimming in the indoor swimming pool, and don't swim for too long, so as not to cause harm to the body. 3. Because the human body emits a lot of heat when swimming, and the heat dissipation speed of the human body in water is much faster than that in air.