Cardio..some love it, most hate it. Cardiovascular exercise certainly has its benefits; increased heart rate, better blood circulation, and a release of endorphins. While cardio has its many positive benefits, in the pursuit of gaining muscle, it should be used correctly. Cardio done in excess amounts can certainly burn muscle because of the amount of calories you burn. Your body has the potential to begin feeding on your muscle as an energy source. Scary right? Lifting heavy weights is a proven and more efficient way to burn fat, as muscle metabolizes (processing by eliminating) fat. Cardio is certainly a feel good exercise and has its place in anyone's fitness journey, just make sure you're working smarter not harder: read this as lift HEAVY ASS weights!