Sun et al1 found an association between midlife physical activity and exceptional health among older women. It reminded me of some other articles that I have read recently that may be relevant to it.
The epigenetic drift theory of aging holds that epimutations that develop over the course of a lifetime, resulting in the deterioration of the epigenome, contribute to the degenerative diseases of aging.2,3 For example, epigenetic drift leading to hypomethylation of repeat elements and the hypermethylation of the promoters of tumor-suppressor genes is believed to play a role in cancer. Epigenetic mechanisms have also been proposed as a factor in Alzheimer disease, type 2 diabetes mellitus, atherosclerosis, and osteoarthritis.3
Ross CM. A Possible Epigenetic Explanation for the Relationship Between Physical Activity and Exceptional Health Among Older Women. Arch Intern Med. 2010;170(12):1081-1083. doi:10.1001/archinternmed.2010.192