150 SECTION II. WHAT TO DO WITH THE INFORMATION hysical activity can bring dramatic health benefits to people of all ages and abilities, with these benefits extending over the life span... and improve the quality of life The position taken in both of these reports was shaped by four important developments that have taken place over the past half century(9). First, the biomedical community identifed and clearly described those aspects of physical fitness that are related to health. Second, the scientific knowledge base underlying the original hypothesis that regular physical activity benefits health became firmly established. Third, the epidemiology of physical activity and inactivity has been studied and described in increasing detail over the years. Fourth, it has been recognized that both moderate and intense physical activity benefit health A major challenge is how to use all of our knowledge and understanding to actually help patients become regular exercisers at a level that is both comfortable and useful to them. Sound clinical advice, provided i an appropriate way by clinicians, can help patients unleash their own motivational process to become regular exercisers There are no known clinical trials of different approaches to the"nuts and bolts"of regular leisure-time exercise Controlled research comparing the effectiveness of one particular leisure-time exercise program versus another n fostering an ongoing pattern of regular exercise would be difficult to design and very expensive to conduct On the other hand, there is research on various exercise programs used as therapeutic interventions for the treatment of specific diseases and disorders. Therapeutic exercise regimens(and there are many very useful ones)are beyond the scope of this chapter Exercise: Aerobic and nongerobic There are two types of regular exercise based on level of intensity: "aerobic"" and"nonaerobic. "Exercise is considered aerobic when it is intense enough to lead to a significant increase in muscle oxygen uptake Nonaerobic exercise is any physical activity above the normal resting state involving one or more major muscle groups that is sustained but not so intense as to cause a significant increase in muscle oxygen uptake (Anaerobic exercise is intense physical activity, necessarily of very short duration [usually measured in seconds], fueled by energy sources within the contracting muscles, without the use of inhaled oxygen, most often incurred in competitive sports. It is not a factor in regular exercise. The heart rate is a simple measure to distinguish aerobic exercise from nonaerobic exercise. The exercise is considered to be aerobic when the pulse reaches or exceeds a level of 60% of the theoretical maximum normal, age adjusted heart rate(220- the persons age;0.6(220-age. It is important to note that this commonly used formula roughly approximates the true degree of increased oxygen uptake by the muscles (10) and is more accurate