How does running everyday 4 miles help endurance?

Question

I am a person who wants to know what is happening in my body so I can benifit myself. What does running a long run do to your body to make your endurance and strength better? Eg. something with the heart, lungs, oxygen, blood vessels...anything will help.

Answer 1

Your heart and lungs get stronger and more efficient.

Your lungs develop more of those little air sacs, and the sacs move more blood thu them.

Your heart gets stronger, like any muscle when it is worked.