Senior author Dr. Jarett Berry of the University of Texas Southwestern Medical Center in Dallas and colleagues at The Cooper Institute examined data on 18,670 patients participating in the Cooper Center Longitudinal Study -- research that contains more than 250,000 medical records maintained over a 40-year span.
These data were linked with the patients' Medicare claims filed later in life from ages 70-85.
The study, published in the Archives of Internal Medicine, indicated when patients increased fitness levels by 20 percent in their midlife years, they decreased their chances of developing chronic diseases -- congestive heart failure, Alzheimer's disease and colon cancer -- decades later by 20 percent.
"We've determined that being fit is not just delaying the inevitable, but it is actually lowering the onset of chronic disease in the final years of life," Berry said in a statement.
This positive effect continued until the end of life, with more-fit individuals -- walking, jogging or running at least 2.5 hours per week -- living their final five years of life with fewer chronic diseases in both men and women, Berry said.