Maintaining physical fitness remains one of the most proven approaches to modestly slow the progression of aging. The large study noted here provides an example of the long-term benefits of exercise. The scientists observe a reduction in Parkinson's disease incidence in more active individuals. This is a pattern observed in near all age-related conditions, a good argument for putting in the time and effort needed to remain physically fit and active as one moves into later life.
The study included 95,354 female participants, mostly teachers, with an average age of 49 who did not have Parkinson's disease at the start of the study. Researchers followed participants for three decades during which 1,074 participants developed Parkinson's disease. Over the course of the study, participants completed up to six questionnaires about types and amounts of physical activity. Researchers assigned each activity a score based on the metabolic equivalent of a task (METs), a way to quantify energy expenditure. For each activity, METs were multiplied by their frequency and duration to obtain a physical activity score of METs-hours per week. For example, a more intense form of exercise like cycling was six METs, while less intense forms of exercise such as walking and cleaning were three METs. The average physical activity level for participants was 45 METs-hours per week at the start of the study.
Participants were divided into four equal groups of just over 24,000 people each. At the start of the study, those in the highest group had an average physical activity score of 71 METs-hours per week. Those in the lowest group had an average score of 27 METs-hours per week. Among the participants in the highest exercise group, there were 246 cases of Parkinson's disease or 0.55 cases per 1,000 person-years compared to 286 cases or 0.73 per 1,000 person-years among participants in the lowest exercise group.
After adjusting for factors such as place of residence, age of first period and menopausal status, and smoking, researchers found those in the highest exercise group had a 25% lower rate of developing Parkinson's disease than those in the lowest exercise group when physical activity was assessed up to 10 years before diagnosis. The association remained when physical activity was assessed up to 15 or 20 years before diagnosis. Results were similar after adjusting for diet or medical conditions such as high blood pressure, diabetes, and cardiovascular disease. Researchers also found that 10 years before diagnosis, physical activity declined at a faster rate in those with Parkinson's disease than in those without, likely due to early symptoms of Parkinson's disease.