Regular exercise of the cardiovascular system has been proven to reduce, heart disease, lower blood pressure, help weight loss and reduce the risk of many diseases. In addition it helps speed up the body’s metabolism. To exercise the cardiovascular system it is necessary to use large muscle groups. Aerobics uses dance movements and rhythmical stepping, directly targeting the large muscle groups of the body, which in turn work the heart and respiratory system. All fitness classes begin with warm up and stretching before beginning the more intensive exercises. Classes likewise end with a cool down and developmental stretching.