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

Ithink the dna sequences may vary but the amino acid sequences are identical.