The evidence was published last month in the journal Gerontology. Researchers at King's College London demonstrated that leg strength is tied to an improvement in brain function as we age. Culling subjects from the TwinsUK volunteer registry, scientists studied 324 healthy female twins aged 43 to 73 (average age 55) over a ten-year period. Various markers were analyzed, but the strongest predictor of late-age brain function was leg power measured at the onset of the study.