People who walk on a treadmill even years after stroke
damage can significantly improve their
health and mobility, changes that reflect actual "rewiring"
of their brains, according to research
spearheaded at Johns Hopkins.
"This is great news for stroke survivors because
results clearly demonstrate that long-term
stroke damage is not immutable and that with exercise it's
never too late for the brain and body to
recover," said Daniel Hanley, professor of neurology at the
Johns Hopkins School of Medicine.
The study's results, published in Stroke: Journal
of the American Heart Association, suggest
that patients' brains may retain the capacity to rewire
through a treadmill exercise program months
or years after conventional physical therapy has ended.
The research was conducted by scientists at Johns
Hopkins, the University of Maryland and the
Department of Veterans Affairs' Maryland VA Medical Center
at its Geriatric Research, Education
and Clinical Center, or GRECC. Researchers at the GRECC,
led by Richard F. Macko and Andrew P.
Goldberg, have developed treadmill therapy for stroke
patients over the past decade. Investigators at
the three institutions combined efforts to recruit 71
patients who had had a stroke at least six
months earlier, with an average time lapse of nearly four
years. At the study's onset, half the
subjects could walk without assistance, while the rest used
a cane, walker or wheelchair.
The subjects, separated into two random groups
regardless of disability, were tested for
mobility and aerobic capacity (also known as VO2 peak), a
measure of cardiac fitness. Thirty-two
patients, drawn equally from both groups, underwent
functional magnetic resonance imaging to assess
brain activity linked to moving their legs in a walking
motion.
One group then participated in an exercise program
that principally involved walking three times
a week on a treadmill for up to 40 minutes, assisted by a
supporting sling and tether if needed.
Physical therapists assigned to each subject increased the
intensity of the workouts over time by
increasing the treadmills' speed and incline, though the
workouts never taxed the patients beyond a
moderate level of 60 percent VO2 peak.
With the second group of patients, therapists assisted
the patients in performing stretching
exercises for the same period of time.
After six months, patients were again tested for
walking speed and VO2 peak, and the group
that had undergone fMRI was rescanned. Walking speed for
the treadmill group increased 51 percent,
compared to about 11 percent for those in the stretching
group. Ground walking speed among the
treadmill exercisers increased 19 percent, compared to
about 8 percent for the stretchers. The
treadmill exercisers also were significantly more fit at
study completion, with VO2 peak increasing by
about 18 percent; VO2 peak decreased slightly in the
stretching group.
Hoping to find evidence that improved brain activity
was responsible for the results, the
investigators analyzed the brain scans and found among all
the treadmill exercisers markedly
increased metabolic activity in brainstem areas associated
with walking; brain scans of patients in the
stretching group showed no such changes.
"This suggests that the brain is responsible for the
improvement we saw in patients' walking
ability. It seems to be recruiting other regions to take on
the job of areas damaged by stroke," said
Andreas Luft, a visiting researcher who worked with all
three institutions conducting this study. Luft
is currently a stroke attending physician and professor of
neurorehabilitation at the University of
Zurich in Switzerland.
Those patients with the most improvement in walking
showed the strongest change in brain
activity, though the researchers don't yet know whether
these brain changes were caused by more
walking, or whether participants walked better because
brain activity in these key areas increased.
This question will be the focus of a future study.
Hanley says that stroke patients are typically told to
"learn to live with" their disabilities, unlike
heart attack patients and others who are often prescribed
lifestyle changes and exercise programs to
help recover function. Most stroke rehabilitation programs
focus on short-term improvement, ending
just a few months after a patient has had a stroke.
Consequently, over the following years, patients'
functional improvement plateaus and fitness often wanes,
factors that could increase the chance of a
second stroke.
"Many stroke survivors believe there's nothing to be
gained from further rehabilitation, but our
results suggest that health and functional benefits from
walking on a treadmill can occur even decades
out from stroke," said Macko, professor of neurology at the
University of Maryland School of
Medicine, noting that one of the patients in the study had
significant improvement 20 years after a
stroke. "We believe exercise gives individuals a way to
fight back against stroke disabilities."
This research was organized by the University of
Maryland Veterans Medical Center, and the
fMRIs were performed at the F.M. Kirby Research Center for
Brain Imaging at Kennedy Krieger, a
research institute affiliated with Johns Hopkins. Funding
by the National Institute on Aging, Claude D.
Pepper Older American Independence Center, University of
Maryland, U.S. Department of Veterans
Affairs, France-Merrick Foundation, Johns Hopkins
University, Eleanor Naylor Dana Charitable Trust
and Deutsche Forschungsgemeinschaft supported this work.
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