Older adults can improve their brain function by exercising more, a new study has found.

US researchers set out to determine the ideal amount of exercise required to experience benefits in the brain. They followed healthy adults aged 65 and older for a six-month period. None of the participants had any cognitive problems.

They were split into one of four groups. The first group were not involved in any monitored exercise. The second group was expected to undertake moderate exercise for 75 minutes per week, which is less than the weekly recommendation.

The third group undertook the recommended 150 minutes of moderate exercise per week, while the last group undertook 225 minutes per week.

The study found that all of those who exercised experienced some benefit. However, those who exercised more, experienced more benefits. This was especially true in the area of visual-spatial processing, which is the ability to perceive where objects are and how far apart they are from each other.

Other areas which benefitted from exercise included the ability to focus and the ability to pay attention.

"Basically, the more exercise you did, the more benefit to the brain you saw. Any aerobic exercise was good, and more is better," commented the lead researcher, Prof Jeffrey Burns, of the University of Kansas Medical Center.

The findings also suggested that the intensity of the exercise mattered more than the duration.

"For improved brain function, the results suggest that it's not enough just to exercise more. You have to do it in a way that bumps up your overall fitness level," the researchers said.

Details of these findings are published in the journal, PLOS ONE.