The study also shows treadmill exercise may be better than stretching, the traditional exercise prescribed after a stroke, both for walking and overall fitness.
Researchers at the University of Maryland and Baltimore Veterans Affairs Medical Center compared 37 patients who performed "progressive task repetitive treadmill therapy" with 34 patients who did stretching. The patients had chronic hemiparesis, which is weakness on one side of the body, at least six months after a stroke. The patients had all completed conventional rehabilitation.
The treadmill group was given the goal of three 40-minute sessions per week on the treadmill at 60 percent of their heart rate reserve. They started out slower, adding duration and intensity every two weeks. The exercise program lasted six months.
The stretching group had the same number of sessions, and the length of each session was also the same. They performed a variety of traditional stretches on a raised mat table with the assistance of an instructor.
Researchers measured results in three ways: by looking at brain activity on MRIs, by measuring walking ability, and by evaluating overall fitness level. The treadmill group performed better in all three categories.
Treadmill participants increased their activity in certain parts of the brain by 72 percent on imaging tests. Brain activity changes did not occur in patients who did stretching exercise.
Researchers checked brain MRIs while participants did knee-flexing exercises that mimic walking. The MRIs showed increased blood oxygenation and flow in the brain stem and cerebellum of the stroke survivors who had used the treadmill but not in those who did stretching.
Researchers say the increases in blood oxygenation and flow indicated that the cerebellum and brain stem had been "recruited" to replace some of the walking functions of the cortical brain that had been damaged by the strokes.
"We saw what we call an equivalent of neuroplasticity - a change in brain activation that reflects the brain's adaptability," says Andreas Luft, MD, in a news release. Luft is one of the study's lead authors and a professor of clinical neurology and neurorehabilitation in the department of neurology at the University of Zurich, Switzerland.
The treadmill group also increased their walking speed and their fitness more than those in the stretching group. This is particularly important because stroke survivors' immobility can lead to cardiovascular disease and diabetes.
In the study, published in Stroke: Journal of the American Heart Association, the authors argue that treadmill exercise should be included in long-term therapy programs for stroke survivors.
"It is promising that treadmill exercise can stimulate new or underused brain circuits and improve walking in stroke survivors even after completion of conventional rehabilitation therapy," Luft says.
By Caroline Wilbert
Reviewed by Elizabeth Klodas
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