Being 'aerobic' means with air or oxygen, or, as it applies to your workouts, when you exercise at an intensity that allows the cardiovascular system to supply the muscles with sufficient oxygen. This means exercising continuously (such as walking, running or cycling) and elevating your heart rate
between 70 to 80 percent of your maximum heart rate
This type of activity can usually be sustained for longer periods of time and helps build endurance and burn calories. If you get your heart rate too high, you end up in your anaerobic zone, which is a more advanced level of training and can only be sustained for a short period of time. During aerobic exercise, you should be able to carry on a conversation.