Effects of physical exercise on myelin sheath regeneration: A systematic review and meta-analysis

Abstract

Objectives: This study aimed to verify the effects of physical exercise (PE) on myelin sheath regeneration (MSR). News: The databases searched were MedLine/PubMed, Lilacs, and Scielo. Articles not related to the effects of PE on MSR, concentration of proteins and other factors linked to myelin regeneration, and studies that used medicine concomitantly with PE were defined as exclusion criteria. After removing duplicates, applying exclusion criteria, and checking the reference lists, 21 studies were added to this review and divided in two groups: i) articles assessing the effect of PE on permissiveness of environment in central nervous system to MSR and ii) articles assessing the effect of PE on regeneration of myelin sheath components. The random effect model was used to the meta-analysis of myelin sheath thickness (MST) and G ratio because Cochran's Q test showed high heterogeneity. In the first group, low-intensity physical training was the most common PE adopted among the interventions and resulted in improvement of permissiveness on central nervous system environment. The studies in the second group, low-to-moderate PE was the most prevalent protocol adopted among interventions. Additionally, this type of training enhanced MST and maturation. Regarding to meta-analysis, PE was associated with the MST [0.11 (0.05–0.17) μm, P < 0.001] and G ratio [−0.04 (−0.06 – −0.02), P = 0.009], although the high (I2 = 77.1%) and moderate (I2 = 65.0%) heterogeneity, respectively. Conclusion: The results suggest that moderate continuous exercise could potentially enhance MSR and improve concentration of myelination-related proteins and as a result, its practice is encouraged to both prevent and treat demyelination.