The first factor is that you don't protect yourself well after exercise. You should know that your immune system is still in the recovery stage after exercise, which is very fragile and can't accept any virus invasion at all. But some people just don't pay attention to self-protection after exercise, and like to go to some particularly cool places, such as air-conditioned rooms, when they are sweaty after exercise. Isn't this destroying your immune system in disguise?
Moreover, some people smoke and drink before the motor system has fully recovered, which is equivalent to adding a certain burden to the body and making it easy to get sick. Not only that, the body's desire for nutritional supplements is very strong after the exercise, which is why protein powder can be sold so expensive. People who don't like protein powder can buy some digestible food.
The second factor is that the intensity of exercise is not correctly grasped. Everyone has different requirements for fitness intensity. For people with poor physique, the intensity must be reduced, otherwise it will exceed the load of the body and the immunity will naturally decline. For example, a person's physical fitness is very weak, but he practices in the gym three or four times a day, so that his immune system will not have enough time to recover, and naturally it will slowly fail. You can also strengthen training when your physical fitness is good, and improve your physical fitness step by step.
Therefore, it is not that the more time you spend exercising, the better your immune system will be. Everyone, whether training in the gym or outdoors, should strictly grasp the intensity, and can't turn on the air conditioner and take a cold shower immediately after the training. I don't know what you think.