eli5: how does cardio exercise increase your stamina to do more cardio?

Question

It makes sense that legs get stronger and build muscle, making cardio easier. But how does cardio make it easier to breathe and run longer distances before becoming fatigued and winded?

In: 0

Answer 1

Your heart is a muscle too. With exercise it gets stronger (pumps more blood per beat).

There are other body changes with cardio too, but largely it works like any other exercise.