A single sweaty workout may boost some people’s memory

SAN FRANCISCO — For some older people, the brain boosts from exercise can be almost immediate. Improvements in their thinking abilities after a single 20-minute bout of pedaling a stationary bike mirrored those produced by three months of regular exercise, according to a preliminary study presented March 24 at the annual meeting of the Cognitive Neuroscience Society. 

In addition to being good news for people who struggle with lofty workout goals, the results suggest that the short-term benefits may predict who will benefit from long-term exercise. 

The similarity between a single bout of exercise and months of training “suggests we don’t have to wait three months to see an improvement,” cognitive neuroscientist Michelle Voss of the University of Iowa in Iowa City said. “We can get a day-by-day boost.”

Voss and her colleagues enlisted 34 people with an average age of 67 to undergo brain scans, memory tests and exercise. In the first part of the study, she and her colleagues were looking for effects of a single 20-minute stint on a stationary bike, designed to be rigorous enough to make people sweat. Participants were huffing and puffing, but could still talk during the workout. 

Before and after exercising, participants underwent functional MRI brain scans and took memory tests that involved remembering previously seen faces. The team did similar brain tests on a different day, after participants spent 20 minutes on a bike that pedaled for them.

On average, after 20 minutes of intense exercise, people were better at remembering the faces, especially when the task was hard, than after sitting on the self-pedaling bike. And certain connections between brain areas got stronger, too, the fMRI scans showed. 

Participants then were divided into two groups — one that spent the next three months exercising three times a week for 50 minutes, and one that spent just four minutes exercising three times a week. When studied as a group, people’s results after this longer-term exercise were similar to their results after the 20-minute bout of exercise, with an overall improvement on the face task for people with the longer workouts compared with those who exercised for 12 minutes a week.

But within that average, people’s responses varied. To Voss’ surprise, the people who improved a lot after 20 minutes had similar memory improvements, and similar brain changes, after the three months. And those who didn’t improve after the 20 minutes were less likely to have improved after three months. 

“If it’s not working for some people, that’s good to know,” Voss says. “But you can go one step further and ask, ‘Are the reasons it’s not working modifiable? And can we learn that quickly? Can we fail fast?’”

Teasing apart the individual variation among exercise effects is “really exciting,” says cognitive neuroscientist Wendy Suzuki of New York University in New York City. She cautions that the study is preliminary. Still, she says, “this is exactly the right question to ask.” 

Suzuki thinks of exercise as medicine. “The key word is ‘personalized’ medicine,” she says.
“Can it be designed for you at your age and fitness level and gender and genetic background?” The answer, she says, is theoretically yes, though scientists have much more work to do to understand how exercise affects people differently.