For patients with mild-to-moderate Parkinson’s disease, moderate exercise in the form of walking may improve disease symptoms, according to a new study.

In new research published in Neurology, researchers recruited a group of 60 adults with mild-to-moderate Parkinson’s disease. The participants took part in 45-minute moderate-intensity walking sessions, three times a week. The average walking speed was about 2.9 miles per hour and participants exercised at 47 percent of their heart rate reserve, which is indicative of moderate intensity aerobic exercise.

Over the six month study, participants wore heart monitors and completed questionnaires that measured fatigue, mood and quality of life.

By the end of the study period, the exercise routine improved participants’ motor function and mood by 15 percent, reduced tiredness by 11 percent, improved attention/response control by 14 percent and improved motor function by an average of 2.8 points— a clinically important difference.

According to the Parkinson’s Disease Foundation, Parkinson’s disease is a neurodegenerative disorder that affects nearly one million people in the U.S. Symptoms include  tremors of the hands, legs and face, slowness of movement, stiffness of limbs and impaired balance and coordination.

Researchers noted that safety was the biggest priority in their study and that they were very selective in choosing their participants.

“Our exercise program was administered after a careful selection of candidates who did not have dementia, who were able to walk independently without a cane or walker, and who did not have heart or lung disease or other serious medical/orthopedic problem,” study author Ergun Uc, associate professor of neurology and neuroscience at the University of Iowa Carver College of Medicine, told

He noted that the study’s findings are therefore only applicable to those who meet participant criteria.

There currently are no standardized exercise recommendations for Parkinson’s and any fitness plan must be developed by a trained specialist and approved by the patient’s physician, Uc said.

While the study did not address the reasons why disease symptoms were improved, Uc hypothesized it could be attributed to a number of mechanisms. First, that exercise may have improved the brain’s neuroplasticity, or its ability to regenerate and repair itself, and therefore may have mitigated the results of degeneration caused by Parkinson’s. Another possible explanation is that exercise boosted the body’s oxygenation and improved the body’s overall energy metabolism. Additionally, exercise may have some positive effect on the dopamine system— the main system that is deficient in Parkinson’s patients.

Uc noted that their research was a phase I/II study that did not have a control group. Researchers are working on getting a grant for a phase III study, which would be able to address exercise safety and efficacy more definitively.  

“There is an important need to identify safe exercise programs that produce long term, clinically meaningful benefits with no safety hazards proven by well-designed, long-term, randomized, controlled clinical trials with large sample sizes,” Uc said.