(Reuters Health) - People who regularly engage in light to moderate physical activity - like walking four hours a week or swimming two hours weekly - might have less severe strokes than individuals who aren’t as active, a Swedish study suggests.

Researchers examined data on 925 patients who were treated for strokes at Sahlgrenska University Hospital in Gothenburg, Sweden, between 2014 and 2016. Overall, four in five of these patients had a mild stroke.

Slightly more than half of the patients were inactive before their stroke. Compared to this inactive group, people who got at least some exercise before the stroke were twice as likely to have a mild stroke, researchers report in Neurology.

“We knew from earlier research that physical activity could reduce stroke incidence,” said lead study author Malin Reinholdsson of the University of Gothenburg.

“However, whether or not pre-stroke physical activity could also influence stroke severity was not clear,” Reinholdsson said by email.

Patients in the study were 73 years old on average and most of them had what’s known as an ischemic stroke, the most common kind, which occurs when a clot blocks an artery carrying blood to the brain. About 6 percent of patients had hemorrhagic strokes, a less common type that is caused by a ruptured blood vessel in the brain.

To assess pre-stroke activity levels, researchers surveyed participants about the duration and intensity of any exercise they got before they were hospitalized.

Researchers defined “light” activity as walking at a leisurely pace for at least four hours a week, and classified exercise as “moderate” intensity when people did things like swimming, running or walking briskly for two to three hours weekly.

Among 481 people who were inactive, 354, or 74 percent had a mild stroke.

For those who managed light physical activity, 330, or 86 percent had a mild stroke.

And among the 59 participants who got moderate intensity exercise, 53, or 90 percent, had a mild stroke.

Age also mattered, with higher odds of a mild stroke for younger people in the study.

The study wasn’t designed to prove whether or how the amount or intensity of exercise might influence stroke severity. Another limitation is that researchers relied on stroke survivors to accurately recall their previous exercise habits, and memory is often compromised after a stroke.

Even so, the results add to evidence suggesting that an active lifestyle can both lower the risk of stroke and reduce the chances that a stroke will be severe, said Nicole Spartano, coauthor of an accompanying editorial and a researcher at Boston University School of Medicine.

“Regular exercise helps the brain to maintain healthy arteries that have more complex networks,” Spartano said by email. “So when a blockage (stroke) happens in one area, there may be another route to provide oxygen to the affected area.”

Being physically active can also help prevent risk factors for stroke like obesity, diabetes, and high blood pressure, Spartano noted.

“This study is exciting because it suggests that you might not have to do a lot of intense exercise to see an effect,” Spartano said.

SOURCE: bit.ly/2zyXd9S and bit.ly/2IG3jIs Neurology, online September 19, 2018.