Mature African-American woman exercising on waterfrontSmall but mighty, the hippocampus is an area of your brain that’s tasked with a range of functions related to memory formation and emotion regulation. Unfortunately, as we age, this powerhouse tends to stutter, due to things like shrinkage, inflammation, and problems with cellular signaling.

Previous studies have found that there are lifestyle behaviors that can make a difference—most notably caloric restriction and exercise.

But how much activity do you need to keep the region firing up the way it should? New research suggests the answer is not as much as you might think. In fact, even one exercise session can make a difference.

In a study published in the Journal of the International Neuropsychological Society, researchers focused on semantic memory—which is the ability to recall words, concepts, and numbers—and exercise’s effects on hippocampus activation.

They recruited 26 participants aged 55 to 85, and had them undergo either rest or 30-minute stationary cycling on two separate days. Immediately afterward, they had MRI scans while being asked to recall famous and non-famous names.

The postexercise session resulted in much bigger gains in terms of memory, compared to when the participants simply rested for a half hour. Not only was there greater activation in the hippocampus, but other parts of the brain also lit up as well.

“From previous studies, we know that regular exercise can increase the overall volume of the hippocampus, and our study shows that even one session of exercise can have a significant effect,” said lead author J. Carson Smith, Ph.D., associate professor of kinesiology at the University of Maryland School of Public Health.

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In terms of mechanism, that’s less clear, Smith added. There are a number of possibilities as to why exercise makes the brain so fired up. He suggested that it could have to do with an increase in neurotransmitters like norepinephrine and dopamine, which increase the “signal-to-noise ratio,” meaning that it can activate neural networks more efficiently.

The increased recall ability for the study participants persisted for about an hour after each exercise session, he said. But even if the effects tended to fade a little after that point, regular exercise may benefit the neural networks and hippocampus in a way similar to “training” your brain in the same way that you’d build muscles over time, he said.

“We don’t have long-term follow up that can confirm that, but based on this study and other research, it’s very possible that over time, the brain adapts to exercise in the same way that the body does,” he said. “It becomes stronger.”