From - http://www.todaysdietitian.com/newarchives/040113p46.shtml
With regard to physical activity, research suggests moderate to vigorous exercise may have a neuroprotective effect, reducing the risk of PD development, slowing progression, and improving mobility in those already diagnosed with the disease.
In rats with chemically induced PD, treadmill exercise was found to suppress the loss of dopamine-producing neurons. In another animal study, exercise strengthened weakened muscles and partially recovered the loss of dopamine-producing neurons in rats.'
'While a direct cause and effect relationship hasn’t been proven between physical activity and a reduced risk of PD, the evidence is more clear that physical activity benefits patients with PD. Research indicates that cardiovascular fitness improves cognition among PD patients. Cognitive impairment occurs in about 25% of patients with early PD and eventually develops into dementia in most patients over the long term.The Parkinson’s Disease Foundation recommends regular physical activity to maintain and increase mobility among PD patients.Three 20-minute exercise sessions per week have been recommended as a reasonable goal. Ideally, an exercise program would include aerobic, strengthening, and stretching exercises'