"We wanted to find out if exercise lowered the risk of developing MS in women. Our study did not provide evidence to support it," said Kassandra Munger, Researcher at the Harvard TH Chan School of Public Health in Boston, in a study published in the journal Neurology.
Researchers evaluated data on more than 193,000 women and 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.
"Overall, there was no consistent association of exercise at any age and MS. 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," Ms Munger added.