To make sure you can refresh your memory quickly, you may want to go for a little jog after you learn something.
Healthy volunteers who exercised four hours after pattern learning had better recall 48 hours later than those who did not exercise at all or exercised immediately after learning. The delayed exercise may stimulate the release of molecules that boost the brain’s normal ability to consolidate and store memories for long-term storage, researchers report in the journal Current Biology. If the finding holds up in further studies, it may indicate that a little exercise after blocking can help your noggin swell.
For the study, researchers had 72 healthy volunteers spend 40 minutes learning the location of 90 objects on a screen, such as a cartoon beach ball in the middle right. The researchers immediately tested how well each participant learned the locations of the objects and then divided the participants into three groups. One group immediately began a 35-minute interval workout on a stationary bike (at an intensity of up to 80 percent of their maximum heart rate). The second group entered a quiet room and watched nature documentaries until it was time for their four-hour deferred workout. And a third group acted as a control group, just watching nature documentaries and hanging out — but not working out — at the gym.
To make sure the time of day didn’t affect the participants’ memory results, the researchers also divided each group so that some volunteers started the entire experiment at 9 a.m. and others at noon.
Two days later, the researchers retested all of the participants’ memories. They found that the control group and direct exercise group did about the same on the memory test. However, those in the delayed exercise group had better scores overall. The researchers made sure to take individual participants’ scores on the first memory test into account so that people with just really good or really bad memories didn’t throw the results out.
To support the finding, the researchers then looked at functional magnetic resonance images of the participants’ brains — which show brain activity based on blood flow. The images revealed that when participants in the delayed exercise group took the memory test again, they had stronger patterns of activity in their brain’s hippocampus — a part involved in memory — compared to the other groups.
While the study doesn’t explain why delayed exercise boosts memory, the authors speculate it could be caused by exercise-induced molecules in the blood. Sweating is known to release brain-altering molecules such as dopamine, norepinephrine, and a protein called BDNF that promotes brain cell growth and development. Such molecules, say the authors, are critical to solidifying and storing memories for long-term recovery. So a stream of these molecules may have no useful effect when memories are fresh, but could make a big difference later on when the brain wraps memories for safe storage.
Scientists will have to do more research to confirm that suspicion. Also, the authors point out that while a four-hour delay improved memory in this study, the experiment did not test different delay times — two hours, six hours, etc. — to see which one would be optimal for increasing memory. The researchers also aren’t sure if the muscular recall will last more than a few days.
But if you’re cramming for an upcoming test or big presentation in the meantime, a delayed workout can help train your brain.
Current Biology2016. DOI: 10.1016/j.cub.2016.04.071 (About DOIs).