Why are middle school students so physically poor?

I am also a middle school student. Let's talk about my point of view.

First of all, I think it has a lot to do with education. Because today's schools only pay attention to grades, few schools care about students' physique, saying that they care only about words. At present, students simply don't have much time to exercise. Apart from physical education class and morning exercises, I have no time at all. Even if the class is over, the teacher will delay the class for a while. When they arrived at the playground, the bell rang. Even holidays, all kinds of make-up classes, all kinds of homework. Also, some students often do it in the early morning because they have too much homework. How can this be healthy?

Because of the poor air quality here, primary and secondary schools are closed, but the best high school here is not closed.