For the study, 48 people with Parkinson's disease were randomised to progressive resistance exercise, known as weight training, or they were assigned to the exercise known as fitness counts, which includes flexibility, balance and strengthening exercises. The groups exercised for one hour, twice a week for two years.
The severity of motor symptoms, including tremors, was measured using the Unified Parkinson's Disease Rating Scale (UPDRS) after six, 12, 18 and 24 months of exercise. Scores were taken when the participants were not taking their medication.
"While we have known that many different types of exercise can benefit Parkinson's patients over short time periods, we did not know whether exercise improves the motor symptoms of Parkinson's over the long term," Daniel Corcos, the study author from the University of Illinois at Chicago, said.
While both forms of exercise reduced motor symptoms at six months of exercise, participants who did weight training saw a 7.3 point improvement in their UPRDS score after two years while the fitness counts group returned to the same scores they had at the start of the study.
"Our results suggest that long-term weight training could be considered by patients and doctors as an important component in managing Parkinson's disease," Corcos added.
The study will be presented at the American Academy of Neurology's 64th Annual Meeting in New Orleans April 21 to April 28, 2012.