Strokes are caused when something like a clot or a hemorrhage disrupts blood flow to the brain. More importantly, this blocks the flow of oxygen to brain tissue. When this happens, the stroke victim is often left disabled. Up until a few years ago, doctors believed that this kind of disability was irreversible. Rose Hoban reports, they're now discovering that's not necessarily the case.

In the past few years, researchers have been testing ways to help stroke patients regain movement and strength. Doctor Andy Luft worked with a team from the Johns Hopkins University in Baltimore. They recruited stroke patients from a local Veterans' Affairs Hospital and gave half of them an intensive exercise regimen. The other half got a regimen of stretching.

"We were training them in the VA hospital on a treadmill program for six months, which is three times a week for about an hour," Luft says. "We studied them before and after the six-month training program and we assessed walking and cardio respiratory fitness."

Luft and his colleagues found that the treadmill patients were able to walk faster than the other group of patients who only did the stretching exercises. They also had better heart and lung function after the training.

After the training, the researchers put patients who were getting treadmill training into a brain scanner, and had them move their legs as if they were walking. "That will show you all the brain areas involved in this movement, and likely involved in walking," Luft explains. "We compared before and after training and sought changes reflecting what we called plasticity in the brain."

Essentially, what Luft and his colleagues were seeing was that the brain managed to 'rewire' the neuro circuits that control walking as patients got treadmill training. He says they're not sure exactly how this takes place, but he suggests that it might be that the brain taps into some very primitive areas during the retraining process. And Luft says the retraining has to be very intense in order to be effective.

"Through this training after stroke, these evolutionarily old regions are reactivated and may be able to compensate," he says, adding that these kinds of results show that people might be able to regain abilities after losing them to stroke.

His research is published in Stroke: Journal of the American Heart Association.