Muscle fitness in the legs is strongly associated with an improved rate of aging in the brain, according to a recent study.

Researchers at King's College of London found that simple interventions, such as increased levels of walking, targeted to improve leg power in the long term may have an impact on healthy cognitive aging.

For the study, researchers collected and analyzed data from more than 300 healthy female twins and followed them over a ten-year period from 1999, measuring various health and lifestyle predictors.

"Everyone wants to know how best to keep their brain fit as they age. Identical twins are a useful comparison, as they share many factors, such as genetics and early life, which we can't change in adulthood," Dr. Claire Steves, lead author of the study, said in a statement.

Thinking, learning and memory were measured at both the beginning and end of the study and it was found that leg power was a better predictor of cognitive change than any other lifestyle factors tested. Generally, the twin who had more leg power at the start of the study sustained their cognition better and had fewer brain changes associated with ageing measured after ten years.

"It's compelling to see such differences in cognition and brain structure in identical twins, who had different leg power ten years before. It suggests that simple lifestyle changes to boost our physical activity may help to keep us both mentally and physically healthy," Steves said.

The study is thought to be the first that shows a specific link between power (i.e. force and speed) in the lower limbs and cognitive change in a normal, healthy population.

The findings are detailed in the journal Gerontology.