Think it's OK to take a week off from working out? Think again ... if you even can. A study published last month in Frontiers in Aging Neuroscience finds the benefits of exercise on the brain can fade after just 10 days.

Previous studies have shown that exercise increases blood flow to the brain, which can create new neurons, increase volume in important places, and possibly even improve memory and thought, the New York Times reports.

But it was unclear how long that healthy increased blood flow and its benefits would last. Now we know: Less than 10 days. Researchers looked at a dozen "exceedingly fit" seniors—ages 50 to 80—who still ran 35 or more miles per week.

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After 10 days of doing nothing, the seniors had less blood flow to eight regions of their brain, including significantly less to the hippocampus, which is associated with memory, Medical News Today reports.

Medical Daily quotes the study's lead author, Dr. J. Carson Smith, who says the hippocampus is "one of the first brain regions to shrink in people with Alzheimer's disease." The seniors didn't perform any worse on cognitive tests after 10 days of loafing about, and more research is needed to see if a cessation of exercise actually impacts the functioning of the brain.

In the meantime, keep on that workout schedule. (Eleven hours of this brain game can cut dementia risk in half.)

This article originally appeared on Newser: Exercise Is Good for Your Brain, Just Don't Skip Workouts