New research into the effects of exercise in the management of Parkinson's disease suggests that regular high-intensity physical activity may help to keep disease progression in check.
Parkinson's disease is a neurodegenerative motor system disorder characterized by uncontrolled tremor in various body parts, especially the arms and legs, as well as poor balance and coordination of movements.
In the United States, around 1 million people live with Parkinson's disease and approximately 60,000 new cases are diagnosed every year, according to data from the U.S. National Library of Medicine of the National Institutes of Health (NIH).
A phase II clinical trial, called the Study in Parkinson Disease of Exercise (SPARX), was recently conducted by researchers from Northwestern University Feinberg School of Medicine in Chicago, IL, and the University of Colorado in Denver.
Their findings suggest that high-intensity physical exercise is beneficial for people with early stage Parkinson's disease, as it may delay the progression of symptoms related to motor abilities.
"If you have Parkinson's disease and you want to delay the progression of your symptoms, you should exercise three times a week with your heart rate between 80 to 85 percent maximum. It is that simple."
Study author Daniel Corcos, Northwestern University Feinberg School of Medicine
The results of this study have now been published in JAMA Neurology.
Early intervention may delay symptoms
The authors cite previous research that showed that medication used to treat Parkinson's tends to be less effective over time, and that it exposes people to adverse effects. For this reason, they say, it is important to identify effective alternative treatments that do not involve the administration of drugs.
In phase II of the current randomized clinical trial, Corcos and his team worked with 128 participants aged between 40 and 80. The participants were recruited through various institutions and medical centers across three states (Colorado, Illinois, and Pennsylvania).
The institutions included Northwestern University in Chicago, IL, Rush University Medical Center in Chicago, IL, the University of Colorado in Denver, and the University of Pittsburgh in Pennsylvania.
All participants were still at an early stage of Parkinson's and were not taking any drugs targeting symptoms of this disease when the study was conducted.
"The earlier in the disease you intervene, the more likely it is you can prevent the progression of the disease," Corcos suggests.
The trial compared the effects of moderate- and high-intensity exercise. More specifically, it studied the effects of a physical activity routine on the progression of disease symptoms. The researchers also examined how safe exercising was in early stage Parkinson's.
The study participants were asked to exercise three times every week for a period of 6 months at either moderate (characterized by 60–65 percent maximum heart rate), or high intensity (defined as 80–85 percent maximum heart rate). All the participants exercised on a treadmill.
For consistency, the scientists also referred to a control group that did not engage in physical exercise.
After the program, all participants were rated on a relevant scale from 0 to 108, measuring the severity of their symptoms. Higher scores indicated more acute manifestations of the disease.
High-intensity exercise most effective
Before the start of the trial, everyone had measured a score of approximately 20. However, results differed following the 6-month period, and the differences were dictated by the intensity of the participants' workouts.
While participants engaging in high-intensity exercise continued to score around 20 on the symptom severity scale, those who had engaged in moderate-intensity exercise exhibited worsened symptoms and scored 1.5 points higher.
Meanwhile, those who did not exercise at all scored three points higher, indicating an even more acute worsening of symptoms.
According to the researchers, the three-point difference suggests a significant disparity when it comes to quality of life. Since high-intensity exercise seemed to keep the development of motor symptoms in check, physical activity warrants further research as a potential treatment for Parkinson's disease.
"We delayed worsening of symptoms for 6 months; whether we can prevent progression any longer than 6 months will require further study," says Corcos.
The safety of high-intensity exercise was also confirmed through graded exercises supervised by cardiologists, monitoring how straining the regime would be for the participants' hearts.
'Exercise is medicine'
The researchers acknowledge that their study had some limitations — particularly the fact that the only type of exercise that was studied was treadmill training. This meant that the potential benefits of other types of exercise remain unknown.
However, they point out that the high number of participants as well as the long period of time over which they were observed strengthen the validity of the results. Corcos explains that most studies targeting Parkinson's have fewer participants and do not exceed 12 weeks.
"We gave them [the participants] a proper workout. This is not mild stretching," he says. "This is high intensity. It's part of the idea that exercise is medicine."
Existing studies had already noted that exercise was beneficial for people with Parkinson's disease, but this was the first time that the effects of different intensities had been targeted by research.
"Several lines of evidence point to a beneficial effect of exercise in Parkinson's disease," comments Dr. Codrin Lungu, program director at the National Institute of Neurological Disorders and Stroke.
"Nevertheless," he continues, "it's not clear which kind of exercise is most effective. The SPARX trial tries to rigorously address this issue. The results are interesting and warrant further exploration of the optimal exercise regimes for Parkinson's."