It's a scientifically proven fact that physical exercise of any type makes you smarter. Take two identical twins and have one of them work out while the other lays around, and the exercising one of the pair will show cognitive improvements the couch potato doesn't.

But let's say this research-backed truth has spurred you to commit to being more active, what type of exercise specifically should you take up? A new study makes the case that, if it's brain benefits you're after, you should seriously considering running.

Running is a lot more mentally challenging than it looks.

To the outsider putting one foot in front of the other over and over again for miles on end doesn't sound particularly mentally taxing, but according to a new brain scan study out of the University of Arizona highlighted in both the New York Times and on the Science of Us blog, running requires a lot more brain power than you might first imagine.

For the research, a team of scientists used an MRI machine to scan the brains of both 11 committed runners and 11 guys who claimed not to have exercised at all in the past year. They noticed significant differences between the runners and the non-athletes.

"It turned out that the runners' brains displayed a number of different connections than did the brains of the sedentary young men, and those connections involved areas of the brain needed for higher-level thought," reports the Times' Gretchen Reynolds.

The scientists also "noted more connectivity in the runners than in the inactive men between parts of the brain that aid in working memory, multitasking, attention, decision-making, and the processing of visual and other sensory information." And less in a section that's associated with mind wandering and lack of focus.

What does all that add up to? Despite appearances, running seems to demand as much of your brain as it does of your legs and heart.

"To me, this suggests that running may not be such a simple activity after all," Gene E. Alexander, a co-leader of the study, commented. "It requires complex navigational skills... plus an ability to plan, monitor and respond to the environment, juggle memories of past runs and current conditions, and also continue with all of the sequential motor activities of running, which are, themselves, very complicated."

Managing all that means running is a work-out for your brain too, and one that just might make you smarter in ways that could benefit you off the track or jogging path.

A few caveats

This is a tiny study, so it could never prove any link between intelligence and running conclusively,. More research is also needed to see if other endurance athletes like cyclists show the same brain benefits. Other types of exercise might even be more beneficial (other studies, for instance, have shown that weight lifting can slow cognitive decline in older adults.)

But the findings at least suggest that, if one of your primary objectives when it comes to exercise is to help your brain perform at its peak, you could probably do a lot worse than running. Plus, existing research confirms runners' self-reports that running really does clear the mind, opening up space for breakthrough ideas.