Aerobic Exercise - The American College of Sports Medicine (ACSM) defines aerobic exercise as "any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature." Aerobic means in the presence of oxygen. In other words, your body is burning its fuel (glucose) in the presence of oxygen. It is performed at less than 85% of your maximum heart rate. An aerobically fit individual can work longer, more vigorously and achieve a quicker recovery at the end of the aerobic session. Jogging, cycling, swimming, aerobics classes, and rowing are examples of aerobic exercise.