Physical Exercise and Gut Microbiota: Implications for Alzheimer's Disease in Experimental Models: A Systematic...

Background and Objectives: The concept of the gut-muscle-brain axis encompasses the intricate, multidirectional interactions between the gut microbiota (GM), physical exercise (PE), and the central nervous system. Within this framework, gut dysbiosis has been implicated in the pathogenesis of Alzheimer's disease (AD). Given that cognitive functions in AD appear to benefit from PE, it is plausible to hypothesize that these improvements may be partially mediated by PE-induced alterations in GM taxonomy. Therefore, the objective of this study is to evaluate the potential effects of PE in the GM and their implications for AD. Methods: A systematic review was conducted in PubMed, Web of Science and Scopus following the PRISMA guidelines up to July 2025 for preclinical controlled trials that assessed the effects of PE on the GM of AD animal models. A random-effects model meta-analysis was performed to estimate the pooled effect of PE on GM frequency or composition. This study received no external funding. Results: Eight studies were included in the systematic review (sample size, n = 126), of which two could be meta-analyzed. We found that PE significantly reduced Actinobacteria abundance (MD = -0.005%; 95% CI, -0.008 to -0.002; p = 0.001) with no statistically significant evidence of heterogeneity (I² = 89.60%, Q = 0.102, p = 0.950) or publication bias observed (Begg's test, p = 0.296), but no significant effects were found for other phylums or genera. Conclusions: PE appears capable of modulating the GM of animal models with AD in a selective and heterogeneous manner. Further studies are needed to clarify the mechanisms by which this is possible and to determinate its impact on the pathogenesis of the disease.