When stroke victims played virtual reality games in which they imagined they were diving with sharks or snowboarding down a narrow slope, their ability to walk eventually improved, researchers reported in a small study.

About 700,000 people each year experience a new or recurrent stroke, which often impairs one side of the body and walking ability.

Doctors called the findings promising because the patients had all had strokes more than a year earlier, a timeframe when further recovery is unlikely.

While the study size was small and the volunteers relatively young - 10 stroke victims with an average age of 57 - the researchers believe video games may be a good way to keep patients engaged in therapy.

The patients in the study, which appeared in Thursday's issue of the journal Stroke, all had weakness on one side of their body. Researchers randomly assigned them to a control group or a virtual reality group. The control group got no intervention while the virtual reality group used the video training for an hour a day, five days a week for more than a month.

''This was a group of people that you would not expect to improve, and that's what made it interesting that they did,'' said Robert Felberg, director of the stroke program at Ochsner Clinic Foundation in New Orleans.

The three games in which the patient's body is superimposed into the scene were used to build a range of motion, balance, mobility, stepping and walking skills. One game simulated going up and down stairs, another let the patient go deep-sea diving with sharks and the third re-created snowboarding by simulating gliding down a narrow slope, jumping and avoiding obstacles.

The five patients who played the games improved in walking, standing and climbing steps, researchers said. Also, brain imaging done before and after the experiment indicated a reorganization of brain function after the therapy, said lead author Sung H. You, assistant professor of physical therapy at Hampton University in Hampton, Va.

Experts said more study is needed.

''It doesn't show that virtual reality is any better than any other intervention,'' said Allen Brown, medical director of brain rehabilitation at the Mayo Clinic in Rochester, Minn.