This from BBC Health:

Older women who have strong legs are likely to fare better when it comes to ageing of the brain, a decade-long study of more than 300 twins suggests.

The King’s College London team says leg power is a useful marker of whether someone is getting enough exercise to help keep their mind in good shape.

Exercise releases chemicals in the body that may boost elderly brains, say the scientists, in the journal Gerontology.

Leg muscle strength is a good marker of brain health, say researchers who have studied pairs of twin sisters.

Full BBC Health article: Fit legs equals fit brain, study suggests – BBC News