Armed with newer, cheaper, and better biotechnologies, researchers can measure ever more of the detailed effects of good health practices such as regular exercise, calorie restriction, and the like. It is possible now to examine the workings of metabolism in any specific part of the body in very great detail, all the way down to the molecular machinery in our cells, see how it changes with age, and see how those changes differ with different lifestyle choices. Or at least this can be done in mice - in humans, more statistical work is required to use today's technology to pull apart the differences between young and old, exercising and sedentary. The option to wait around for sizable portions of a human life span isn't there, after all; science moves faster than that.
Here is an open access paper that measures a little more of the effects of exercise, and along the way provides yet another compelling argument to be someone who exercises rather than someone who sits around growing ever more unfit with each passing year:
Healthy brain aging and cognitive function are promoted by exercise. The benefits of exercise are attributed to several mechanisms, many which highlight its neuroprotective role via actions that enhance neurogenesis, neuronal morphology and/or neurotrophin release. However, the brain is also composed of glial and vascular elements, and comparatively less is known regarding the effects of exercise on these components in the aging brain. Here, we show that aerobic exercise at mid-age [also] counters several well-established glial markers of brain aging. Similarly, we show that age-related changes in neurovascular morphology and function were reduced with exercise.
Thus, our results show that exercise can potentially mitigate progressive age-related changes in several key non-neuronal elements of the brain. Further, we show that these brain processes are still highly responsive to exercise in the midlife age range, consistent with studies showing that cognitive function can benefit from exercise even if initiated at later ages.
It's never to late to start on exercise. In the future, there will be rejuvenation biotechnologies capable of restoring the old to youthful health and vigor by repairing the low-level biological damage that causes aging. This will happen, I assure you - and it will be one of the least of the amazing new things to arrive in the years ahead. But human rejuvenation will almost certainly arrive later that either you or I desire, and until such time as it does become widely available the best things you can do for your own personal future of health and longevity are pretty primitive - lifestyle choices and supporting research and development.
All told, the better you do with the cards you have now, the more likely you are to live to benefit from the future of longevity-enhancing medicine. So do better.