Moderate to vigorous physical activity such as swimming, jogging, or bicycling reduced the risk of developing Parkinson's disease compared to light physical activity such as walking around the room—for men. The same association was not significant among women, according to a review and meta-analysis of eight studies published online in JAMA Network Open on September 21.
The cause of Parkinson's disease is unknown, but researchers hypothesize that both genetic and environmental factors are involved. Many studies have suggested that engaging in physical activity and adopting other healthy habits can reduce the risk of developing the disease, but these studies have varied in sample size, ethnicity, and other characteristics, leading to inconsistent results.
To address these inconsistencies, a team of researchers evaluated eight prospective studies that involved 544,336 people, including 2,192 patients with Parkinson's disease, who were followed for an average of 12 years.
The researchers split participant data, such as sex, geographic location, follow-up, sample size, and study quality into subgroups to make comparisons between them.
Since each study had different cutoffs for high versus low activity levels, the researchers used a measure called metabolic equivalents (METs)—the rate of energy expended during activity versus the rate at rest—to assess physical activity and determine the number of minutes per week spent in moderate or vigorous exercise.
Data from all eight studies showed that those who were the most physically active had a 29 percent lower risk of developing Parkinson's disease than those who were less active or not active at all, with a stronger association seen among men than women. In fact, with each increase of 10 MET-hours a week of moderate to vigorous physical activity, men reduced their risk by 17 percent.
Overall, the beneficial effect of physical activity on the risk of Parkinson's disease was exclusive to men. The researchers hypothesized that men and women may have different biological responses to physical activity. They did note, however, that because there weren’t many women in the study, they wouldn’t conclude anything about physical activity and the risk of Parkinson’s disease for women.
The researchers believe their findings may encourage physicians and health care policy makers to develop guidelines and recommendations about the amount of physical activity that may reduce the risk of Parkinson's disease.
Further research with a larger sample size and detailed analysis of physical activity is warranted, the study authors say, to establish more evidence regarding the association between physical activity and Parkinson's disease risk.