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Useful news for the next time you’re cramming for an exam: Physical exercise done four hours after learning something new helps solidify newly learned memories.

Why it matters:

Exercise releases some hormones that are known to be beneficial in solidifying memories. But the optimal time for that chemical boost hasn’t yet been studied in people.


The nitty gritty:

Seventy-two people of average fitness were brought into the lab and taught 90 picture-location associations — basically, learning where certain objects had previously appeared on the screen. Then they had different fitness regimes. One-third of them did 35 minutes of cycling immediately after. One-third did the cycling four hours later, and the rest didn’t exercise at all.

Two days later, the volunteers were brought back to the lab and quizzed on the pictures while in an MRI machine. Researchers found that the group who exercised immediately after learning didn’t show any better retention than those who avoided exercise. However, exercise four hours after learning led participants to remember almost 10 percent more material. The study was published Thursday in Current Biology.

But keep in mind:

The research only looked at those two time points, so it is possible that four hours isn’t the most ideal time point for exercise after learning. “We still don’t know what the ideal time is,” said Rosanna Olsen, a scientist studying memory at the Rotman Research Institute in Toronto, who wasn’t involved in the study. “Maybe it’s after only two hours of delay. Maybe they missed the sweet spot.”


“And it could be the case that exercise will not work for everybody,” said Olsen.

You’ll want to know:

Researchers suggest that the effect may be the result of catecholamines, including dopamine and norepinephrine. Previous research has shown that exercise can boost these hormones, and animal studies suggest that catecholamines can help improve memory consolidation.

The bottom line:

Aerobic exercise after learning something new may help you retain it if you wait awhile between putting down the books and picking up the weights.