Exercise not shown to reduce women's risk of developing multiple sclerosis

A large, new study shows no evidence that exercise may reduce a woman's risk of developing multiple sclerosis (MS). The research is published in the September 28, 2016, online issue of Neurology, the medical journal of the American Academy of Neurology. Previous small studies had shown conflicting results.

"We wanted to find out if exercise lowered the risk of developing MS in women," said study author Kassandra Munger, ScD, of the Harvard T.H. Chan School of Public Health in Boston, Mass. "Our study did not provide evidence to support it."

Researchers evaluated data on more than 193,000 women who participated in the Nurses' Health Study and Nurses' Health Study II and were followed for up to 20 years. The women completed regular questionnaires about their physical activity and also about their activity as teens and young adults. During the study, 341 women developed MS.

Researchers calculated the total hours of physical activity per week, took into account the type of exercise for each woman and adjusted for age, ethnicity, smoking, supplemental vitamin D, place of residence at age 15 and body mass index at age 18.

"Overall, there was no consistent association of exercise at any age and MS," Munger said. "Exercise has been shown to be beneficial to people with the disease, but it seems unlikely that exercise protects against the risk of developing MS."