Exercise can’t stop the years from ticking by, but it certainly appears to protect against some of the diseases of aging. A study shows that white blood cells of endurance athletes had longer telomeres the tiny, protective units of DNA that cap the end of chromosomes like plastic shoestring tips and grow shorter as cells age.
The results may explain how exercise can protect against two big killers: heart disease and cancer. “Younger” white blood cells may be able to move efficiently out both abnormal cells that progress to cancer and the plaques implicated to heart disease. Moreover, specific cancers are uniquely affected by exercise. The reason colon cancer odds are reduced by exercise, for example is probably that it decreases the time food spends in the digestive system. Exercise cuts the amount of estrogen circulating in the system and may cause changes in the menstrual cycle that reduces exposure over month or years.
Somehow exercise seems to preserve brain function as you age, too. There’s evidence from animal studies that regular physical activity may help generate new neurons; it also may help create new blood vessels that forge connections between neurons. And it might be that even if the plaques implicated in Alzheimer’s disease appear, they don’t have the same impact as they would on a couch potato.
