Studies confirm what runners already know:
Older runners are healthier than non-runners.
Here are two examples that prove our point:  

Stanford University School of Medicine conducted a twenty-one year long study of women and men age 50 and older who ran regularly. They reported  that these runners lived much longer and had significantly better survival and less disability than volunteers in the study who did not run. Here’s what they said:  

“Our findings support recommendations to encourage moderate to vigorous physical activity at all ages”, and that such activities “may not only improve length and quality of life but also hopefully lead to reduced health care expenditures”. 1

In another study, this one at Yale University School of Medicine, Marathon runners 50 and older, and female athletes in particular, showed greater improvement in running times than younger runners. From 1983 through 1999 the top fifty women  marathon runners in the 50-59 age category improved their average race time by 2.08 minutes per year, which was substantially greater than men runners of the same age, whose running time improved on average about eight seconds per year. The older male runners, in turn, increased their running time at a much greater rate than younger male runners. The younger runners, male and female ages 20 to 30, did not significantly improve their running times during the period studied. The most significant trends in improved running times noted in the top 50 women finishers were in ages 50-59 and 60-69.

"Our data reflect the potential for improvement of the general health status of our aging population," Jokl said. "It is not surprising that the number of participating master athletes continues to rise. There is a general trend towards increasing numbers of our aging population who are in good health and physically able to participate in these types of strenuous competitions." 2