Treadmill exercise not only improves the mobility and health of people who have had strokes but also seems to “rewire” the brain—even years after the damage—according to a new study.
“This is really good news for stroke survivors,” says study co-author Daniel Hanley, a professor of neurology at Johns Hopkins University. “It suggests that not only are there improvements that they haven’t yet achieved that they can achieve, [but also] that through research we can find even bigger changes.”
The study, which appears in the journal Stroke, involved 71 people who had had a stroke on average about four years before testing. Researchers asked one group to exercise on a treadmill; the other group received only stretching therapy.
The treadmill users gradually increased the intensity of their exercises over the course of six months; at the study’s end they showed significant improvements in walking speed and fitness. The control (stretching) group showed reduced or no improvement in these measures.
But the changes weren’t restricted to just the heart and lungs. Functional magnetic resonance imaging (fMRI) studies found that people in the treadmill group showed activity increases in regions of the brain associated with walking.
“It was a strong correlation—the brain activity change didn’t occur in the non-paralyzed limb of patients receiving treadmill therapy,” Hanley says. This shows that “some rewiring may be going on and is in part responsible for the walking improvement.”
But what was truly unexpected, he says, was where the activity was found—in the midbrain and cerebellum instead of the cortex, which is associated with many of the brain’s higher functions.
Stroke survivors can take hope from this, Hanley adds, because it offers new potential treatments. “For 80 percent [of stroke survivors], the prime complaint is limited mobility,” he says. Whether through therapeutic drugs or stem cells or robotic circuits, “there are now more sites in the brain that are candidates for intervention than we had before this study.”
Importance of aerobics
“This is a certainly a well-designed, well-prepared, well-conducted study,” says Allen Brown, director of brain rehabilitation and research at the Mayo Clinic in Rochester, N.Y., who was not involved in the study. And the research largely confirms previous work suggesting that aerobic exercise can aid in stroke recovery, he adds.
“It further reinforces that clinicians should support and explore aerobic fitness after stroke, just as they should for everyone, period,” something many patients and even some doctors ignore, Brown says. “The research largely confirms the fact that even in the chronic phase, patients with intense interventions can increase task-specific performance and cardiopulmonary fitness.”
However, more research is needed to determine whether such activity can truly improve walking—the scientists did not assess gait, only fitness—and whether using a treadmill is necessary to see improvement or if any exercise would work.
The brain changes observed also are preliminary—due to the restrictive environment of MRI scanners, researchers could test only for knee-bending, a proxy for walking—and any treatments based on that work would be years away even if they were successful, Brown says. Hanley and his team are planning to address some of these questions soon.
“Whether the brain changes are a cause or an effect of the therapy is an open question,” Hanley says. “More research and more evaluation are needed to be sure if the brain changes are sufficient to cause walking changes.
“We would like to figure out what the right doses of these type of interventions are,” he adds. “Other interventions might result in even bigger improvement in gait and movement.”