What actually happens with your body if you increase cardio?

Question

For example you could be super in shape from a muscular perspective but have really bad cardio and vice versa.

How is cardio different from physical shape and what exactly happens in your body that makes you have more cardio?

In: 368

Answer 1

Think of cardio as lifting weights for your heart. If you want to build up your biceps, you do curls, if you want to build up your legs, you do squats and leg presses, if you want to build up your heart and make it stronger, you do aerobic exercises (e.g. running, bicycling, swimming, etc.)