I hope so and here is some evidence suggesting long term endurance exercise may mitigate the aging process which is part seems to be due to one's "chromosomes shortening". I had written earlier about claims that vitamin D has a similar effect.
This is not the first such article making this type association. This article by La Rocca et al in Circulation demonstrated longer leukocyte telomere length (LTL) in older endurance exercisers and correlated LTL with aerobic capacity and an index of endothelial dilatation.
An interesting study published in the Archive of Internal Medicine which in part involved study of twins showed that the inactive twin had shorter telomeres that the more active sibling. A companion editorial offered the appropriate caveats which might serve to mitigate any undue exuberance forthcoming from overly smug ,older long time runners:
A great deal of research has been done on telomere length in the past few years, and exactly what it is telling us is still being argued. Cross-sectional studies show that telomeres in humans are shorter at older ages and telomere length is shorter in peripheral white blood cells in a variety of chronic diseases. However, although shorter telomere length has been associated with cell senescence, its direct effect on organ function is not well documented, and telomere length in postmitotic cells has not been related to life span in the experimental animal in which it has been extensively studied, Caenorhabditis elegans.
Yeah, I know you shouldn't get carried away by surrogate makers. Further, this study of older Chinese found no such relationship.
So, I continue to run as long as I can even if the effect on telomeres really means little or nothing because after each run I seem reassured that I am not really that old yet (the marked reduction in running speed notwithstanding) as irrational as that belief is.