More than one in seven cases of Alzheimer's disease could be prevented if people who are physically inactive started getting regular doses of exercise, a new report suggests.

The Ontario Brain Institute commissioned the research paper examining 55 studies on physical activity.

"This is the strongest evidence to date that physical activity makes a significant difference to the management and the development of Alzheimer's disease," Dr. Donald Stuss, president and scientific director of the Ontario Brain Institute, told reporters.

Study author Prof. Michael Rotondi of York University's School of Kinesiology and Health Science in Toronto said they found people over age 65 who were physically active were about 38 per cent less likely to develop the degenerative brain disease than those who were physically inactive.

The researchers strongly recommended the Public Health Agency of Canada's guidelines to maintain 150 minutes of moderate to vigorous physical activity per week — half an hour, five times a week — that can even be done in 10 minutes bursts. Moderate to vigorous activity makes breathing harder while still allowing a person to sing. 

When Statistics Canada measured Canadians' physical activity levels, 85 per cent of adults weren't meeting the recommendation. 

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Socializing while learning an exercise has multiple health benefits, experts say. (Eric Risberg/Associated Press)

Since the evidence isn't yet clear on what type of activity is most effective, Laura Middleton, an assistant professor of kinesiology at the University of Waterloo in Ontario suggested people do whatever they enjoy and whatever will continue to keep them moving. Some studies suggest that starting to become physically active earlier in life such as the teen years may have greater benefits for cognition, Middleton said.

"Live an active life, ideally throughout the day, and start doing it as soon as possible," Middleton said.

Exercise gets the circulation going to allow more glucose and oxygen to get the brain regardless of cognitive impairment, said Dr. Tiffany Chow, who treats people with Alzheimer's and prescribes exercise for them at Baycrest in Toronto.

The social stimulation of going out to a gym class or taking a walk with a friend offers others benefits.

"Just being with other people who are enjoying something with you takes away the isolation that can contribute to apathy, more cognitive impairment and feelings of depression," Chow said in an interview.

Stuss pointed to British Columbia's Minds in Motion program for people with dementia and their caregivers as a model. The fitness and social program is offered in 22 communities in the province, and participants have shown elevated mood and cognitive boosts, he said. 

Brisk walking, running, swimming, dancing are examples of aerobic exercise that have been studied the most. Getting physical activity throughout the day, such as by parking at the furthest spot from the entrance, doing chores at home or taking the stairs whenever possible, is also recommended, said Christa Costas-Bradstreet, relations manager for Participaction Canada.

The Alzheimer's Society of Canada projects that the number of cases will more than double to 1.25 million by 2038. Improving physical activity levels is a strategy for prevention and delaying onset of Alzheimer's disease, Middleton said.

With files from CBC's Laura MacNaughton