Vigorous and frequent aerobic exercise during the early stages of Parkinson’s disease may help delay, at least temporarily, the progression of the motor symptoms commonly associated with the condition, a new study reports.

The study also found high-intensity exercise to be safe for people with Parkinson’s.

Both of those findings are potentially important. Although past research has suggested that high-intensity endurance activities might protect against Parkinson’s, it had been thought — until now — that such activity might be too physically stressful for people with the neurodegenerative disease.

Yet the findings, which were published this week in JAMA Neurology, come with an important caveat. The new study — a phase 2 randomized clinical trial — was small and followed people for only six months. Larger, longer phase 3 randomized trials will need to be conducted to confirm these findings and to determine if the effects can last for more than a few months.

Still, the study’s authors are enthusiastic about their findings. While waiting for the larger studies to be conducted, they say, doctors may safely prescribe high-intensity exercise for their patients with Parkinson’s.

“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’s that simple,” said Daniel Corcos, the study’s senior author and a professor of physical therapy at Northwestern University, in a released statement. 

More than 1 million people are living with Parkinson’s in the United States, and about 60,000 Americans are diagnosed with the disease each year, according to the Parkinson’s Foundation. The condition develops when cells in an area of the brain that controls movement become impaired or die. Symptoms can include tremors, limb stiffness and trouble with balance. There is currently no cure for the disease, and although various drugs are used to help control its symptoms, their effects often wear off over time.

Study details

For the new study, Corcos and his colleagues recruited 128 people, aged 40 to 80 years old, who had been diagnosed with Parkinson’s within the past five years but were still in the early stages of the disease. None were taking medicine for their condition, and none were regularly engaged in exercise of moderate or higher intensity.

A third of the participants were randomly assigned to a four-times-a-week exercise program that involved moderate-intensity physical activity — specifically, walking on a treadmill at a speed and incline that kept their heart rate at 60-65 percent of their maximum.

Another third were assigned to a similar exercise program, although this time they walked at a speed and incline that kept their heart rate at 80-85 percent of their maximum.

The remainder of the participants — the “controls” — were not assigned to an exercise program, but were instructed to continue with their normal daily activities.

Before and after the six-month study, the participants were asked to rate the severity of their Parkinson’s disease symptoms on a 0-108 scale that is commonly used by researchers. At the start of the study, the average score in each of the three groups was about the same (around 20). After the study, the scores of the people in the control group had declined, on average, by more than three points — a drop that is considered clinically significant.

By comparison, the scores of those in the moderate-intensity exercise group declined by an average of 1.5 points — an amount that means the exercise was “futile” as a treatment for Parkinson’s, the study’s authors point out.

The scores of the people in the high-intensity exercise group, however, showed almost no decline at all — strong evidence that the treatment worked and made a difference in those participants’ quality of life, say the researchers. 

“We are stopping people from getting worse, which is significant, particularly if we catch them early in the disease,” said Corcos.

Further research needed

Again, this is a Phase 2 clinical trial. A larger — and longer — study is needed to confirm its results. Also, the exercise in the study involved only treadmill training. It’s not clear if other forms of exercise would have similar results.

Importantly, the treadmill training appeared to be easily tolerated by the participants. Although the people in both exercise groups dropped down to an average of three (rather than four) exercise sessions when they were doing it on their own (after the first couple of weeks of the study), few stopped altogether.

“Several lines of evidence point to a beneficial effect of exercise in Parkinson’s diseases,” said Dr. Codrin Lungu, program director at the National Institute of Neurological Disorders and Stroke, in the released statement. “Nevertheless, it’s not clear which kind of exercise is most effective.”

The current study “tries to rigorously address this issue,” he added. “The results are interesting and warrant further exploration of the optimal exercise regimes for Parkinson’s.”

In the meantime, Parkinson’s patients who want to start a vigorous exercise program should, of course, consult with their physician first.

FMI: You’ll find an abstract of the study on JAMA Neurology’s website, but the full study is behind a paywall.