Sturdy legs could mean healthy brains, according to a new study of British twins.
As I frequently have written in this column, exercise may cause robust improvements in brain health and slow age-related declinesin memory and thinking. Study after study has shown correlations between physical activity, muscular health and mental acuity, even among people who are quite old.
But these studies have limitations and one of them is that some people may be luckier than others. They may have been born to have a more robust brain than someone else. Their genes and early home environment might have influenced their brain health as much as or more than their exercise habits. Their genes and early home environment also might have influenced those exercise habits, as well as how their bodies and brains responded to exercise.
In other words, genes and environment can seriously confound experimental results.
That problem makes twins so valuable for scientific purposes. (Full disclosure, I am a twin, although not an identical one.) Twins typically share the same early home environment and many of the same genes, and if they are identical, all their genes are the same.
So if one twin's body, brain and thinking abilities begin to differ substantially over the years from the other's, the cause is less likely to be solely genetic or the early environment, and more likely to be attributable to lifestyle, including exercise habits.