Depending on where in the brain it occurs, a stroke can result in paralysis, difficulties with breathing, swallowing, walking and balance, or problems understanding language. (CBC)

People who have suffered a stroke may benefit from walking on a treadmill years after the brain injury, according to researchers who saw signs of the brain healing itself.

The results, published in Monday's issue of the journal Stroke: Journal of the American Heart Association, suggest the brain retains the capacity to rewire itself when exercised months or years after conventional physical therapy ends.

"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 Dr. Daniel Hanley, a neurology professor at the Johns Hopkins University School of Medicine in Baltimore, who helped lead the study.

A stroke is a brain injury caused by a lack of blood. It happens to 50,000 Canadians each year.

Depending on where in the brain it occurs, a stroke can result in paralysis, difficulty breathing, swallowing, walking and keeping one's balance, or problems understanding language, among other symptoms.

'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.'— Dr. Richard Macko

The study involved 71 people with an average of 63. They all had had a stroke at least six months

before the study began, and on average, it happened four years earlier. When the study started, half of the subjects could walk without assistance, while the others used a cane, walker or a wheelchair.

Regardless of disability, half of the participants walked on a treadmill for 40 minutes three times a week for six months, while the rest did stretching exercises for the same time. Those who were physically impaired because of the stroke used supporting slings or tethers to help them complete the exercises.

Changes in brain activity

Physical therapists increased the intensity of the workouts over time by increasing the speed and incline on the treadmill, although their aerobic capacity was never taxed beyond recommended levels.

The researchers used functional magnetic resonance imaging on 32 subjects chosen equally from both groups to look for possible changes in brain activity during the study.

The scans showed increased activity in the brainstem areas associated with walking in the treadmill group, while no changes were seen in the stretching group.

"This suggests that the brain is responsible for the improvement we saw in patients' walking ability," said study author Dr. Andreas Luft, a professor of neurorehabilitation at the University of Zurich in Switzerland.

"It seems to be recruiting other regions to take on the job of areas damaged by stroke."

Among the treadmill walkers, walking speed improved by 51 per cent compared with 11 per cent among the stretchers. The treadmill walkers also improved their mobility and aerobic fitness by about 18 per cent, while no change was seen in the stretching group, the researchers said.

Most stroke rehabilitation programs focus on short-term improvements and end a few months after someone has had a 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 Dr. Richard Macko, a professor of neurology at the University of Maryland School of Medicine who also helped lead the study.