People Who Exercise May Have Bigger Brains

Here’s good motivation to get up and move more, even in the dead of winter: a new study published in the journal Neurology found that people who weren’t as physically active in midlife had smaller brains than their peers 20 years later.

In the new study, the researchers looked at 1,583 men and women who didn’t have dementia or heart disease. They worked out on a treadmill to assess their fitness levels. Then, 20 years later, the people in the study did another treadmill fitness test and had brain scans.

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The brain scans revealed that people with a lower exercise capacity — defined as the amount of time people could exercise on the treadmill before their heart rate hit a certain threshold — in midlife were more likely to have smaller brains years later, compared with people who had high fitness levels in middle age. They also found that people whose blood pressure and heart rate went up more during exercise were more likely to have smaller brains down the line. Higher-than-average blood pressure and heart-rate spikes could indicate a lack of physical fitness.

People in the study only had brain scans at the end of the trial, which means the researchers couldn’t say whether their brains had gotten smaller over time. But past research has shown that exercise makes the brain better able to combat cognitive decline.

It’s not yet known at what point in life exercise is most critical for brain volume, the authors say. “We are not able to tell from our study whether fitness in midlife or later life matters more,” says study author Nicole Spartano, a postdoctoral fellow at the Boston University School of Medicine. “In future studies I would like to explore this distinction, to see whether one is more important than the other. But it is likely that both are important.”