There’s no shortage of research saying that exercise is good for our brains. And those who do exercise can’t deny that it provides a sense of clarity and sharpness that’s hard to find elsewhere. But most of us are fundamentally lazy and can’t help but wonder: What is the absolute bare minimum you can do and still reap the huge amounts of cognitive benefits that come from working out? As researchers publishing in Proceedings of the National Academy of Sciences write, the answer is very little.
The regimen proposed in the study is encouragingly doable: Ten minutes of moderate exercise at an intensity the authors liken to tai chi or yoga. It probably won’t even make you sweat, but study authors Michael Yassa, Ph.D., a neurobiologist at the University of California Irvine, and Hideaki Soya, part of the Faculty of Health and Sport Sciences at the University of Tsukuba, found that even a short, moderate workout can grease the gears of an important brain circuit involved in memory.
“One missing question is what is the right prescription, what is the right formula for exercise?” Yassa tells Inverse. His recent findings, coupled with an earlier study, suggest that mild exercise actually may be more beneficial to memory than intense exercise. “In an earlier study, we found that when we compared the mild and the moderate, for the mild we found a bigger benefit,” he adds.
His previous findings led him to conduct this current study on 36 volunteers. In his experiments, volunteers did 10 minutes of mild exercise (defined as a workout that gets you to 30 percent of your peak VO2) on a cycle ergometer and then completed a memory task while Yassa performed brain scans on 16 of them. People in the control group didn’t exercise but also completed the memory task and had their brains scanned.
As expected, mild exercise was correlated with improved performance on the memory task compared to the control group. But even more interestingly, the amount of improvement on the task was linked to the extent of physical changes in the brain, as measured by the scans.
The scans revealed “increased connectivity” in one specific circuit of neurons in the hippocampus, an area of the brain that plays a role in memory. Normally, neurons in a subunit of this memory circuit called the dentate gyrus make connections with a neighboring subunit called CA3. When individuals performed mild exercise, Yassa noticed that this circuit seemed to be more active than usual, sending more signals from the dentate gyrus to the CA3 region via this neuron highway. Improved performance on the memory task, the team writes, was correlated with an increase in connectivity shown in the brain scans.
Yassa’s previous work showed that, over longer periods of time, exercise can actually help create new neurons in this area of the brain, leading to higher connectivity. In the new study, he and his team show that 10 minutes of exercise isn’t enough time to make a whole new batch of neurons, but it does still have effects on the brain’s memory circuit. Mild exercise seems to pave the road between the dentate gyrus and CA3, somehow enabling more communication between them.
But Yassa still isn’t sure what causes this.
“We suspect that his has a lot more to do with synaptic wiring than neurogenesis,” says Yassa, referring to the process of new neurons being born. An early hypothesis explaining the results is that mild exercise may increase levels of certain neurotransmitters, the chemical messengers that neurons use to talk to one another, which in turn increases neuron communication.
“This is striking evidence in terms of exercise intensity,” adds Soya. Perhaps the coolest part of this study is that these researchers actually practice what they preach. Researchers at Soya’s lab are now encouraged to take 10-minute walks throughout the day. When they get back to the lab, their hippocampi ready to fire, they’re likely to keep coming up with new, publishable results.
