New research supports the idea that light to moderate physical activity, such as walking and
swimming, could reduce the severity of strokes.
A study of nearly 1,000 individuals who had had a stroke found that those who had been doing 4
hours per week of light or 2–3 hours each week of moderate activity had less severe strokes than
those who had not been exercising.
The researchers defined light activity as walking at normal pace and moderate activity as brisk
walking, swimming, and running.
"While exercise benefits health in many ways," says study author Katharina S. Sunnerhagen, of
the University of Gothenburg in Sweden, "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."
She and her colleagues emphasize, however, that due to the nature of their study, their findings
do not prove that physical activity actually reduces stroke severity — only that there is a
significant link to it.
Commenting on the study, Nicole Spartano and Julie Bernhardt, both of Boston University
School of Medicine in Massachusetts, say that while the underlying mechanisms are not fully
understood, exercise likely helps maintain the brain's complex system of blood vessels.
A recent report on the study and an editorial article by Spartano and Bernhardt both feature in the
Stroke is a major cause of significant disability in adults. In the United States, where
approximately 795,000 people have a stroke every year, it is the fifth main cause of death.
There are two main kinds of stroke: ischemic, which occurs when a blood clot or constriction in
an artery stops blood flow in part of the brain; and hemorrhagic, which happens when a blood
vessel ruptures, causing a bleed in the brain.
Both types of stroke stop oxygen and nutrients from reaching brain cells, which eventually —
starved of this sustenance — will die.
The amount of disability that can follow a stroke depends on its location and the number of cells
killed. It can, for example, result in difficulty walking, talking, and thinking.
The study data came from 925 people — aged 73 years, on average — in Sweden who had had a
stroke. Sunnerhagen and colleagues identified them from stroke registries that gave information
about the severity of the stroke.
Symptoms such as facial, arm, and eye movement, as well as language ability and consciousness
level, determined the level of severity. Based on this, 80 percent of the cohort were classed as
having had a "mild" stroke.
The individuals had also answered questions following their stroke about the extent to which
they engaged in leisure time physical activity in the period before the stroke. Where necessary,
the team confirmed the answers by checking with relatives.
Walking for at least 4 hours each week was classed as light activity, while more intensive
exercise, such as swimming, running, and brisk walking for 2–3 hours per week, was classed as
In this context, 52 percent of study participants were inactive in the period leading up to their
Studies that rely on self-reported physical activity levels often cite this as a possible weakness or
limitation of the research. In this case, the researchers are especially cautious about their findings
because stroke can affect memory and the questions were put to the individuals after they'd had a
The analysis revealed that those whose physical activity levels were light to moderate in the
period leading up to their stroke had double the chance of having a mild stroke compared with
those who were inactive.
Of the 59 people whose physical activity levels in the period before their stroke were moderate,
53 (89 percent) had a mild stroke. Of the 384 people whose physical activity level was light, 330
(85 percent) had a mild stroke. Of the 481 who were inactive, 354 (73 percent) had a mild stroke.
When the researchers considered the effect of younger age on stroke severity, however, they saw
that physical activity accounted for only 6.8 percent of the differences between the active and
The team suggests that further research should now be done to clarify the extent to which
exercise might reduce stroke severity.
Sunnerhagen also advises that "physical inactivity should be monitored as a possible risk factor
for severe stroke."
Spartano notes that animal studies have revealed that physical activity helps safeguard the brain's
complex network of blood vessels by boosting the ability for several arteries to supply the same
regions of the brain.