TORONTO - Tai chi, the Chinese exercise regimen based on slow, rhythmic body movements, can improve balance and reduce falls in people with mild to moderate Parkinson's disease, researchers say.

In a study published in the New England Journal of Medicine on Wednesday, U.S. researchers found that the regular practice of modified tai chi movements was more beneficial for people with Parkinson's than either stretching or weight-resistance training on a number of measures.

The study involved 195 participants with Parkinson's, who were randomly assigned to one of three exercise groups -- tai chi, resistance training or stretching. Patients took part in 60-minute sessions twice a week for 24 weeks.

"After six months of training with tai chi, participants reported less falls compared to people in the stretching group, and there was no difference between the tai chi group and the resistance training," said lead author Fuzhong Li, a senior research scientist at the Oregon Research Institute.

"Falls are a significant issue for people, particularly in advancing stages," Li said from Eugene, Ore.

Tai chi was superior to stretching on all measures and outperformed resistance training for stride length and functional reach, two areas of movement that are impaired by the disease, the authors report.

Parkinson's is a neurodegenerative disease that occurs with the loss of dopamine, a chemical that carries signals between the nerves in the brain. The disorder is marked by such symptoms as tremor, slowness and stiffness, impaired balance and muscle rigidity.

While there is no cure and the disease is progressive, there are medications to help control symptoms, and people can live for years with the disease. More than 100,000 Canadians are estimated to have Parkinson's. Canadian actor Michael J. Fox is perhaps one of the more well-known faces of people with the disease.

"We always encourage exercise whether we have a disease or not," said Li. "But for people with Parkinson's disease, particularly early-stage, the study that we did really suggests that tai chi can maybe either prevent or help ease some of the movement disorders, ease the symptoms.

"So if you have a problem walking, with tai chi we show people walk better ... and through tai chi they become more mobile ... they get up quicker, walk faster, make more efficient turns and are able to sit down and complete mobility tests quicker."

Carole Hartzman of Bedford, N.S., was diagnosed with Parkinson's in 2003 and has tried many kinds of exercise, including tai chi, to try to better manage some of her symptoms.

"The important thing about tai chi is the fluidity of movement and the balance part, because balance is so essential and it's what we lose with Parkinson's," said Hartzman, 70. "And I have entered into the part of Parkinson's which is governed by an inability to initiate movement.

"You all of a sudden can't move forward and there you are and you're about to be thrown forward because the momentum is there, but the feet are not picking up and moving you.

"That's something that's significant and that the tai chi may be able to deal with."

Quincy Almeida, director of the movement disorders research centre at Wilfrid Laurier University, said the U.S. study suggests that pushing the limits of stability with tai chi movements may make patients feel more physically secure -- and perhaps more independent.

"It certainly is a promising finding," Almeida said Wednesday from Waterloo, Ont.

"It is impressive that with only two sessions a week for 24 weeks that they were able to get some of the improvements that they're making note of here."

However, one question that needs answering is whether the effects of tai chi are specific to Parkinson's or would the exercise bestow similar benefits on older people without the neurological disease, a group whose mobility and balance also diminish over time.

Almeida said his centre has been doing similar studies of different kinds of exercises in people with Parkinson's, but there is not yet a body of scientific evidence proving that regular physical activity can delay the progression of the disease.

Still, there are secondary effects -- cardiovascular disease, for instance -- that can be prevented with exercise, he said, explaining that some people with Parkinson's withdraw socially because of their symptoms.

"So when somebody chooses to stay within their home because they're afraid that people are going to notice the tremor in their hand or ... they don't go out on the golf course anymore ... cardiovascular and other sorts of issues start to develop because of being inactive."

Li said the study participants doing tai chi had improvements over the 24-week exercise period, and when researchers assessed the patients three months later, those benefits had persisted.

But that doesn't mean the improvements would continue to be maintained: the program needs to be kept up, he said.

"I would like to see this as a lifelong exercise program, as an integral part of disease management."

Hartzman, a retired university Spanish instructor, said she isn't deluding herself that tai chi will halt the progression of her disease, though she would be elated it that happened.

"But I, like everybody else, wants to be as mobile as I can -- for as long as I can."