Brisk walking might delay cognitive decline in older adults by helping the brain re-grow certain regions associated with memory and planning.

The study, conducted by researchers at the University of Pittsburgh, was based on data on 120 people aged between 60 and 80 years. They found that people, who engaged in moderate but regular exercise, had slower cognitive decline than others, according to the Independent.

According to researchers moderate exercise helps re-grow parts of brain that shrink with age.

"The results suggest that brain and cognitive function of the older adults remain plastic and highly malleable. There is not this inevitable decline that we used to think there was. We can improve brain function by relatively modest amounts of physical activity," Kirk Erickson of the University of Pittsburgh in Pennsylvania told The Independent.

Participants in the study were divided into two groups; one group was asked to walk for 35 to 45 minutes for three days a week while the other group took part in stretching exercises. Brain scans of participants showed that both groups benefited from the exercise regimen, but people who walked had growth in some parts of the brain.

Researchers found that brisk walking was associated with an increase of two to three percent in the size of prefrontal cortex and hippocampus- regions of brain associated with planning and memory.

"It may sound like a modest amount but that's actually like reversing the age clock by about one to two years," said Erickson, according to the Guardian.

The study was presented at the annual meeting of the American Association for the Advancement of Science.

People should get at least 2 hours and 30 minutes (150 minutes) of moderate physical activity a week along with muscle strengthening exercises for two or more days a week, according to Centers for Disease Control and Prevention (CDC). Previous research has shown that brisk walking can extend life.