The gut microbiome is a critical regulator of host metabolism, immunity, and the gut-brain axis. Exercise is a promising non-pharmacological modulator of microbial ecology, yet human evidence remains heterogeneous and the translational gap persists. This narrative review synthesizes mechanisms, human and animal evidence, and future directions for the exercise-gut microbiome axis.PubMed, Scopus, Web of Science, and SID were searched for articles published between January 2000 and February 2025. Keywords included exercise, physical activity, gut microbiome, gut microbiota, short-chain fatty acids, and gut-muscle axis. From 218 initial records, 89 original studies (47 human, 42 animal) met inclusion criteria and were critically appraised.Exercise modulates the gut microbiome via splanchnic hypoperfusion, hyperthermia, altered transit time, and immune-mediated barrier regulation. Moderate-intensity continuous training consistently increases alpha diversity and enriches butyrate-producing taxa (,) and mucin-degrading. High-intensity interval training transiently increases intestinal permeability in untrained individuals but, following adaptation, stimulates butyrate production via lactate cross-feeding metabolism-a recent breakthrough. Effects are transient and reversible upon detraining. Animal models establish causality through fecal microbiota transplantation; human randomized controlled trials demonstrate modest, intensity-dependent, and highly individualistic responses. Emerging evidence supports the gut-muscle axis in sarcopenia and personalized exercise prescription guided by microbiome profiling.Exercise shows promise as a low-cost modulator of the gut microbiome for enriching health-associated taxa and improving metabolic outcomes. Definitive evidence linking exercise-induced microbial shifts to enhanced athletic performance in humans remains lacking. Future research requires diet-controlled randomized controlled trials with ≥12-week interventions, shotgun metagenomics, and mechanistic validation of the gut-muscle axis in humans. Background/Objectives: Methods: Results: Conclusion: Faecalibacterium prausnitzii Roseburia hominis Akkermansia muciniphila
