Physical activity in multiple sclerosis: a comparative study of vitamin D, brain-derived neurotrophic factor and...

Previous studies suggest beneficial effects of exercise in multiple sclerosis (MS). However, knowledge on the effects of physical activity on the immune system is limited.

To assess potential relationships between cardiorespiratory fitness, cognitive function, and immune parameters in physically active and inactive MS patients.

We identified 83 patients with relapsing-remitting disease, an unrestricted walking range, and stable interferon-β treatment from our data base. Based on the subjective report of physical activity, the lower/inactive (n = 21) and upper/active quartiles (n = 21) of patients were selected. We assessed the frequency of T cells, B cells, NK cells, monocytes and regulatory T cell populations by flow cytometry, measured brain-derived neurotrophic factor and vitamin D serum levels by ELISA, and conducted spiroergometry and transcranial sonography.

Physical activity and cardiorespiratory fitness were not associated with brain-derived neurotrophic factor, frequency of T regulatory cells or any other immune cell subpopulation. However, we found a positive correlation of vitamin D serum levels with cardiorespiratory fitness.

Overall, we found no negative effect of physical activity on the immune system. The association between vitamin D and cardiorespiratory fitness most likely reflects longer hours of sunlight exposure in active patients, suggesting a desirable 'side- effect' of physical activity.