This is the third of a series related to physical fitness entitled: Think of Exercise as a Pill that Promotes Long Life and a Whole Lot More.
In parts 1 and 2, we learned that regular exercise delays death for many people and enhances quality of life in many wonderful ways. But surely for the very old and for individuals in very poor health, there can’t be much point in exercising, right? Doesn’t “the perfect life” imply gently fading away in a rocking chair?
Well, the Centers for Disease Control and Prevention (CDC) in Atlanta, along with other research institutions including the University of Minnesota, studied exercise in a large group of older women in the 1990s, asking them how far and how vigorously they walked each day and how often they danced or gardened, did aerobics or swam. The average age of these women was 77 years at the beginning of the study. The researchers found that those women who were sedentary at the start of the study but began exercising regularly during the 10-year observation period reduced their risk of death from all causes by 48 percent. In their data analysis, the researchers classified these women into groups according to overall health, ranging from good health to poor health, and found that basically this 48 percent reduction in mortality rate held true for every one of these health groups. This piece of evidence and many others like it have shown that regular exercise not only prevents chronic diseases like heart disease and diabetes, it also benefits people who already have these diseases, even people in poor health.
These same researchers went on to find that recent physical activity was a more important predictor of longevity than past physical activity. Sedentary women who became active over the course of the study had mortality rates similar to those who had exercised all along, and women who stopped exercising during the study had mortality rates similar to women who had been sedentary all along. This means that, in this trial, ongoing exercise was important for longevity.
Many studies published over the last 10 years have shown the benefits of exercise for both men and women in their 70s and 80s. An observational study from Pennsylvania and Tennessee in 2006 recruited men and women ages 70-79 and looked at all kinds of physical activity, not just dedicated exercise activity. This study found that any physical activity, if sustained for some period of time, helped lower mortality rates. It didn’t need to be dedicated exercise; any physical activity helped. These researchers estimated from their findings that 1 ¼ hours of physical activity per day doing things like vacuuming, mopping floors, washing windows, caring for children, and walking 2.5 miles per hour would reduce mortality rates by 30 percent. And this reduction in mortality was just as apparent for people who had heart disease, vascular disease, lung disease, and diabetes, and also for people who were current or former smokers. As you might expect, these researchers showed that increased activity produced increased benefits.
The medical benefits of regular exercise appear to start accruing after about 1 year. Even individuals who have been previously sedentary but who initiate exercise as late as age 85 demonstrate a significant survival benefit in three years in comparison to individuals who are sedentary. 
 Gregg E, Cauley J, Stone K, et al. Relationship of Changes in Physical Activity and Mortality Among Older Women. JAMA 2003: 289:2379.
 Manini T, Everhart J, Patel K, et al. Daily Activity Energy Expenditure and Mortality Among Older Adults. JAMA 2006; 296:171.
 Morey M. Physical Activity and Exercise in Older Adults. UpToDate, Wolters Kluwer Health. October 20, 2014.