Physical activity from doing chores and commuting can help reduce the risk of Parkinson’s disease, suggests a new study published in Brain: A Journal of Neurology.

To examine the link between exercise frequency and Parkinson’s disease risk, researchers at the Karolinska Institutet in Stockholm, Sweden, monitored about 43,370 men and women for an average of 12.6 years. Researchers noted that “a medium amount” of physical activity was associated with a lower chance of developing the condition, which starts with a tremor or shaking of a limb, often on one side of the body.

The National Institutes of Health (NIH) estimates that Parkinson’s disease impacts 500,000 people in the United States and that 50,000 new cases are reported each year. While scientists have posed various theories for the cause of Parkinson’s, none has been proven.

In their study, researchers in Sweden used the Swedish National March Cohort to analyze various physical activities— from household to commuting, occupational activity, leisure time exercise, and total daily physical activity. Study participants included about 27,860 females and about 15,500 males, all of who responded to a questionnaire.

The study authors defined a medium frequency of physical activity as six hours of exercise, according to a news release. A low frequency translated to less than two hours of exercise.

Compared with study participants who had low physical activity, those who had spent more than six hours per week on the same types of activities had a 43 percent lower risk of developing Parkinson’s disease, according to a news release.

Leisure-time exercise— dedicated time at the gym, for instance— alone was not associated with Parkinson’s disease risk, the researchers noted.

“Our study has a number of strengths,” lead researcher Karin Wirdefeldt, an epidemiology, biostatics and clinical neuroscience professor at Karolinska Institutet, said in the news release. “This was a prospective study including both males and females, and all information on physical activity was assessed before the disease occurrence, making recall bias and reverse causation less likely."

Another key finding, Wirdefeldt said, was that researchers considered the entire spectrum of daily energy output instead of dedicated exercising.  

“The protective effect of physical activity was further supported when we summarized all available evidence from published prospective cohort studies,” Wirdefeldt said in the news release. “These findings are important for both the general population and for the healthcare of patients with Parkinson's disease."