Better brain connectivity could be yet another benefit of running, because researchers have found that a good run can affect the brain in much the same way as playing a musical instrument.

MRI scans have revealed improved functional connectivity in the brains of runners who took part in the new study, showing different regions of the brain were more closely connected than usual, and more in sync with each other.

The team from the University of Arizona says the findings could help us understand how repetitive tasks, such as running or practicing the piano, alter brain functionality, as give us new insight into how best to fight cognitive decline later in life.

"One of the things that drove this collaboration was that there has been a recent proliferation of studies, over the last 15 years, that have shown that physical activity and exercise can have a beneficial impact on the brain, but most of that work has been in older adults," says one of the team, anthropologist David Raichlen.

"This question of what's occurring in the brain at younger ages hasn't really been explored in much depth, and it's important."

The researchers compared brain scans from 11 male cross country runners with scans from 11 males who hadn't taken part in organised athletic activity for more than a year.

The groups were roughly the same age (18 to 25 years old) had similar BMI, and were from the same educational background.

In resting state scans - where participants don't perform explicit mental tasks during the MRI - the team found that the functional connectivity of the runners was greater than the non-runners in areas such as the frontal cortex, where the brain handles planning, decision-making, and multitasking.

Previous research has established similar links between functional connectivity and tasks that require fine motor control, such as learning a musical instrument.

Based on these similarities, the researchers suggest that running could engage the brain in the same way, even if running seems like a relatively 'automatic' task that doesn't require much thought.

"These activities that people consider repetitive actually involve many complex cognitive functions - like planning and decision-making - that may have effects on the brain," explains Raichlen.

While scientists still don't fully understand the impact of improved functional connectivity on the way we think, we do know that damage to the brain (say, from a stroke) reduces this connectivity, and makes regions of the brain more isolated.

A drop in functional connectivity has also been noted in older people - particularly those with condition such as Alzheimer's - and the team suggests that regular exercise could be one way to minimise this risk.

However, they acknowledge that their study only involved a very small sample of runners and non-runners, and say research with larger and more diverse groups of people is needed to further investigate that link.

The results don't necessarily suggest that athletic types are cleverer than the rest of us, although previous research has found links between regular exercise and improved performance at certain types of mental tasks.

"The areas of the brain where we saw more connectivity in runners are also the areas that are impacted as we age," says Raichlen, "so it really raises the question of whether being active as a young adult could be potentially beneficial and perhaps afford some resilience against the effects of ageing and disease."

So if you were thinking of taking up running as a New Year's resolution, now you've got another reason to stick at it.

The findings have been published in Frontiers in Human Neuroscience.