Long Term Physical Activity Has an Anti Aging Effect at the Cellular Level

According to research reported in Circulation: Journal of the American Heart Association concluded harder exercise prevents aging of the cardiovascular system. i found this article from sciencedaily.com

Researchers measured the length of telomeres -- the DNA that bookends the
chromosomes and protects the ends from damage -- in blood samples from two
groups of professional athletes and two groups who were healthy nonsmokers, but
not regular exercisers.
Essentially, the longer telomere of athletes is an efficient telomere. The
body's cells are constantly growing and dividing and eventually dying off, a
process controlled by the chromosomes within each cell. These chromosomal "end
caps" -- which have been likened to the tips of shoelaces, preventing them from
fraying -- become shorter with each cell division, and when they're gone, the
cell dies. Short telomeres limit the number of cell divisions, Laufs said. In
addition, the animal studies of Laufs and colleagues show that the regulation of
telomere stabilizing proteins by exercise exerts important cellular functions
beyond the regulation of telomere length itself by protecting from cellular
deterioration and programmed cell death.

This article is about a clinical study who picked two different kind of groups. One group are professional athletes and the other group are untrained athletes who were healthy nonsmokers, but who did not exercise regularly. The professional athlets had a better resting heart rate, lower blood pressure and body mass index, and a more favorable cholesterol profile.
I think it is really interesting that if you have a long-term exercise training that activates telomerase and reduces telomere shortening in human leukocytes, so its reducing the impact of age-related disease.