Cardiovascular exercise builds the heart and lungs, boosting oxygen transportation and consumption. The work itself requires energy and therefore, burns calories.
Heart rate is a measure of how hard your heart is working and thus helps people determine the intensity of a particular workout. When you work your body harder, your heart beats faster and your body turns to different fuel sources when working at various levels of intensity. It makes sense that people seeking to lose weight would want to maximize fat loss, so often times they strive for a heart-rate level that falls within the “fat burning” zone.
The fat burning zone refers to a heart rate working range in which a greater percentage of calories burned comes from fat stores. This benefit occurs in the lower end of the cardio zone–about 55 to 70 percent of one’s maximum heart rate. To improve cardiovascular fitness, you need to strengthen your heart and its ability to deliver oxygen to working muscles. The American College of Exercise (ACE)recommends that a sedentary person who is new to exercise work between 55 and 65 percent of their maximum heart rate to improve cardiovascular fitness. More conditioned exercisers will see an improvement in cardio fitness working at 65 to 80 percent of their maximum heart rate.
Industry experts debate as to whether high intensity or low intensity cardio is best for fat burning. Proponents of high intensity cardio argue that it burns more total calories. They agree that even though you burn a higher percentage of fat with low intensity cardio, you will still ultimately burn more TOTAL fat with high intensity cardio because the total calories burned is so much higher. On the contrary, proponents of low intensity cardio argue that you burn a higher percentage of fat with low intensity cardio. They believe that the higher the intensity, the less fat is burned due to the body not being able to pull fuel from fat fast enough and ultimately relies on muscle as fuel.
The truth is, both are beneficial. Variety, also known as cross-training, is an excellent way to keep your body in good fitness shape and to keep your body “guessing”. Cross-training will ultimately lead to a healthy heart and lungs and improved overall physical conditioning.