Why physical exercise can enhance physical fitness and health?

As we all know, physical exercise can strengthen the body, but it also has scientific basis. When the body is strong, the body's ability to resist diseases will be strengthened, while moderate exercise will increase the body's oxygen supply ability, the fluidity and vitality of cells will increase, and brain cells will become flexible and quick-thinking because of the increase in oxygen content. Hehe, so exercise is more valuable. Let's go