People who exercise regularly may be less likely to develop Parkinson's disease

People who exercise regularly may be less likely to develop Parkinson's
disease -- but leisurely strolls may not be enough.

That news comes from a study of more than 143,300 U.S. men and women who
were followed from 1992-2001.

When the study started, participants were 63 years old, on average. They
reported their weekly hours of light exercise (walking or dancing) and
moderate to vigorous exercise (jogging, running, swimming, bicycling,
playing tennis or racquetball, or doing aerobics or calisthenics).

A total of 413 participants were diagnosed with Parkinson's disease by the
end of the study.

The most active participants were the least likely to develop Parkinson's
disease in the next decade, according to the researchers, who included Evan
Thacker, SM, of Harvard School of Public Health.

Exercise and Parkinson's

"The most important thing we learned from this study was that high levels of
moderate to vigorous recreational physical activity (like biking, swimming,
aerobics, etc.) were associated with lower Parkinson's disease risk,"
Thacker tells WebMD.

"Those with the highest levels of recreational physical activity at the
beginning of the study had a lower risk of getting Parkinson's disease over
the next 10 years, compared to the people with low levels of recreational
physical activity or none at all," says Thacker.

Thacker will present the study in Boston on May 1, 2007 at the American
Academy of Neurology's 59th annual meeting. How Much Exercise?

The drop in Parkinson's disease risk was only seen in people who got a lot
of moderate to vigorous exercise.

"People who reported the highest levels of recreational physical activity in
the study were doing about the equivalent of 5-6 hours of aerobics or 3-4
hours of lap swimming each week ," says Thacker.

"Their Parkinson's disease risk was 40% lower than the people who reported
zero physical activity, or only light activities like walking," he says.

Exercise Intensity Mattered

"Light physical activity such as walking or dancing was not related to
Parkinson's disease risk at all," says Thacker.

"On the other hand," he says, "higher participation in moderate to vigorous
activities such as biking, lap swimming, jogging, etc., was associated with
lower Parkinson's disease risk."

No particular form of moderate to vigorous exercise stood out as being best.

"The amount of time spent and the overall level of intensity were more
important than the specific activity," says Thacker.

Study's Limits

The study was purely observational. That is, participants weren't asked to
exercise.

The researchers considered participants' age, gender, and smoking -- but
they can't rule out the possibility that other factors influenced the
results.

Thacker and colleagues aren't blaming Parkinson's disease on insufficient
exercise. Their study also doesn't promise that exercise will prevent
Parkinson's disease.

Many factors may affect the odds of developing Parkinson's disease, and
doctors often don't know precisely why someone develops Parkinson's disease.

"Our study is just one piece in a complicated puzzle of discovering what
might prevent Parkinson's disease," says Thacker.

SOURCES: American Academy of Neurology's 59th Annual Meeting, Boston, April
28-May 5, 2007. Evan Thacker, SM, Harvard School of Public Health.