Welcome to the fourth and final module. This module will focus on the role of exercise in health and disease. The concept that exercise is medicine, involves its role in both the prevention and treatment of various conditions and diseases. Strong scientific evidence has emerged in the recent years to fortify this claim. In this module, I will discuss the role of exercise in the prevention and treatment of obesity, heart disease, diabetes, cancer and the implications for aging and the brain. Today's video will set the stage for these topics, by exploring the contributions of exercise in the reduction of all cause mortality. Before I tout the benefits of exercise, let's look at the other end of the spectrum. That, of a sedentary lifestyle. It is becoming increasingly more evident that leading a sedentary lifestyle is a common risk factor in many serious diseases, including a host of cardiovascular diseases, cancer, obesity and Type 2 diabetes. In fact, being physically inactive is one of the major risk factors for all of these conditions. A number of recent studies have clearly demonstrated the negative health effects from prolonged city. Here are just a few of the attention getting headlines reporting the results from these studies. In particular I draw your attention to the Mayo Clinic news release indicating that more hours spent sitting in front of the TV resulted in a 61% greater risk of dying, compared to individuals who watched less than 1 hour per day. Similar consequences are found for prolonged sitting in front of your computer or laptop, whether at work or at home. Shown here are some of the alarming statistics as it relates to what is now referred to as the sitting disease. On average, American's sit approximately 11 hours per day. In the United States alone over 300,000 annually as the result of inactivity and poor dietary choices. In fact, 20% of all deaths of people 35 years and older are attributed to a lack of physical activity. I cannot emphasize enough that physical activity or lack thereof is a major risk factor in all cause mortality. But, it is a modifiable risk factor. Shown here are some of the key organs and tissues adversely affected by a sedentary lifestyle. This includes impaired blood vessel function, an increase in adipose tissue and obesity, cardiopulmonary decline, increased risk for heart disease and diabetes and atherosclerosis. Of all the major risk factors associated with all-cause mortality physical activity or low fitness continually ranks in the top two. Smoking, hypertension, high cholesterol, and obesity are the other major risk factors. In this and subsequent slides today, I will be discussing the risk factors and health consequences of the diseases and conditions that I will be examining throughout module 4. Let's begin with obesity. While there are several variables that contribute to one's risk for obesity such as genetic and cultural factors, maintaining a positive energy balance as shown here is the primary culprit. In order to lose weight a negative energy balance must be maintained, either by reducing one’s caloric intake, increasing one’s daily energy expenditure through exercise or, ideally, from a combination of both. The need to prevent and treat obesity stems from its role in the development of many life threatening diseases and disorders indicated here. At the top of the list for established risk factors for coronary heart disease or CHD is physical inactivity. It is becoming increasingly clear that physical inactivity puts an individual at a greater risk for many other forms of cardiovascular diseases as well, including hypertension and stroke. When looking at the modifiable risk factors for developing Type 2 diabetes you'll find physical inactivity at the top of the list along with obesity or high body fat. As we'll see in the video on diabetes, there is no better prevention or treatment for Type 2 diabetes than participation in regular exercise. You may be surprised to learn that regular exercise can lower your risk for several of the more common forms of cancer including colon, breast and prostate cancers. Just as important in cancer patients undergoing chemotherapy, exercise has been shown to reduce the fatigue as well as the depression and anxiety associated with such treatments. With individuals 65 years and older being the fastest growing segment of the population, healthy aging is of paramount importance. Shown here are just two of the many variables affected by the aging process. In sedentary populations, there is a significant reduction in both skeletal muscle mass, known as sarcopenia, and bone mineral density, known as osteoporosis. Loss of muscle strength coupled with frail bones contributes to increase in falls and fractures, common among the elderly. Further limitations in mobility reduce one's independence and overall quality of life. Participation in regular exercise will strengthen endurance, offset these negative effects of sedentary aging. You may be also surprised to learn of the beneficial effects that exercise has on the brain. The mind body connection is clearly at work during exercise. Not only is the activity in the brain stimulated during exercise, but blood flow and vascular function is enhanced. This can explain why regular exercise helps to maintain cognitive function, reduce dementia and even reduce the severity of depression. I've just covered the tip of the iceberg regarding the role of exercise as medicine. Here is a more comprehensive list of the health benefits of regular exercise. And if that's not enough incentive to get out and remain active, here's even more good news. The exercise intensity required to reap these health benefits does not have to be as high as is needed for improvements in fitness or VO2 max. Moderate exercise can significantly lower the risk factors for all cause mortality. Shown here is one example where walking nine or more miles each week reduced the mortality by 21% compared to individuals walking three miles or less. A study examining aerobic fitness in over 13,000 men and women is shown here. These investigators accounted for other risk factors such as smoking, hypertension, diabetes, high cholesterol, and family history in making their conclusions. As expected, the least fit group had the highest mortality rates. However, please notice that in going from the least-fit group to the second least-fit group, there was over a 50% reduction in mortality rates. Thus, even a moderate increase in the amount of physical activity can have pronounced health benefits. Finally I show you these studies to strongly emphasize that it's never too late to reap the health benefits from regular exercise. Notice that if you were unfit when you were young and remain sedentary throughout adulthood, you would have the highest risk of death. The opposite is true if you are fit when you were young and remain active throughout adulthood, thus having the lowest risk of death. However, if you are sedentary when young but started a regular exercise program later in life, your risk of death can drop as much as 50%. The take home message from these studies is that it's never too late. In summary, exercise is indeed medicine in both the preventative and rehabilitate sense. A sedentary lifestyle and prolonged have multiple negative health consequences. Regular exercise can reduce risk factors associated with many life threatening diseases. Moderate exercise is sufficient to reap these health benefits and it is never too late to start.