Regular, low-intensity exercise reduces severity of stroke
People who walk just 35 minutes a day may have less severe strokes
People who participate in light to moderate physical activity, such as walking at least four hours a week or swimming two to three hours a week, may have less severe strokes than people who are physically inactive, according to a study published in the September 19, 2018, online issue of Neurology®, the medical journal of the American Academy of Neurology.
“Stroke is a major cause of serious disability, so finding ways to prevent stroke or reduce the disability caused by stroke are important,” said study author Katharina S. Sunnerhagen, MD, PhD, of the University of Gothenburg in Sweden. “While exercise benefits health in many ways, our research suggests that even simply getting in a small amount of physical activity each week may have a big impact later by possibly reducing the severity of a stroke.”
For the study, researchers looked at two Swedish stroke registries and identified 925 people with an average age of 73 who had a stroke. The registries included data on stroke severity based on symptoms such as eye, arm and facial movements, level of consciousness and language skills. Of study participants, 80 percent had a mild stroke.
To determine physical activity, participants were asked after the stroke how much they moved or exercised during leisure time before the stroke. Questions about duration and intensity of exercise were used to determine the average amount of physical activity. Relatives were asked to confirm exercise levels when needed.
Light physical activity was defined as walking at least four hours a week. Moderate physical activity was defined as more intense exercise such as swimming, brisk walking, or running two to three hours a week. Of study participants, 52 percent said they were physically inactive before having their stroke.
It is important to note that participants reporting on their own physical activity after having a stroke is a limitation of the study. It is possible that memory may be affected by a stroke, and more so in people with more severe stroke.
Researchers found that people who engaged in light to moderate physical activity before their stroke were twice as likely to have a mild stroke rather than a moderate or severe stroke when compared to people who were physically inactive. Of 481 people who were physically inactive, 354 had mild stroke, or 73 percent. Of 384 who engaged in light physical activity, 330 had mild stroke, or 85 percent. Of 59 people who engaged in moderate physical activity, 53 had mild stroke, or 89 percent. Researchers found that light and moderate physical activity were equally beneficial.
“There is a growing body of evidence that physical activity may have a protective effect on the brain and our research adds to that evidence,” said Sunnerhagen. “Further research is needed to better understand just how physical activity influences the severity of a stroke. Finally, physical inactivity should be monitored as a possible risk factor for severe stroke.”
Sunnerhagen noted that the difference in physical activity did not account for a large amount of the difference in stroke severity. When combined with younger age, greater physical activity accounted for only 6.8 percent of the difference between the two groups.
Sunnerhagen also stated that the study does not prove that physical activity reduces stroke severity; it only shows an association.
Stroke significantly impacts the ability of individuals to function independently. Research suggests that individuals who are physically active before suffering a stroke tend to have better outcomes.
In an editorial in this week’s Neurology, Nicole Spartano, PhD, research assistant professor of medicine at Boston University School of Medicine (BUSM), agrees that a recent study (Reinholdsson et. al.), which proposes that individuals who reported being physically active (defined as either two hours of moderate intensity or four hours of light activity per week) before their stroke had milder symptoms. She attributes this protection to maintenance of a complex network of blood vessels within the brain. “Animal studies have shown that exercise promotes redundancies in the cerebrovascular system, in which multiple arteries feed the same brain regions. While the mechanism for an active lifestyle’s effect on stroke severity is not fully understood, current literature seems to suggest that these individuals may be protected.”
Spartano acknowledges that while these studies are promising, more work remains to be done. “Further research will need to investigate the specific doses of physical activity (frequency, duration, and intensity) and contexts that can provide the most benefit for cerebrovascular health.” She also notes larger studies that gather data about baseline level of physical activity before their stroke may help to remove some bias from the data. “A study design that assesses lifestyle factors retrospectively through self-report is prone to recall bias, potentially influenced by disease status/severity.”
Ultimately, Spartano is optimistic that further study in this area can make a major difference in lowering the impact of stroke on patients’ function and independence. “Reducing the size and severity of stroke has great potential to benefit individual and public health.”