Why we get muscle cram after playing football for long time?

Hey there! So usually, muscle cramps occur to parts of your body that you haven't used in a long time. Once those muscles get used to the exercise they tend to not hurt or ache anymore. 

As for long period of time. I don't think there is a connection. It depends on how much you stretch that muscle during that hour. But to answer, the cramps only last for a few games- but then your body gets used to using that muscle a lot. 

Does it make sense? 

This is due to accumulation of lactic acid in the muscles and presence of oxygen debt