This systematic review and meta-analysis examines the effects of exercise on the gut microbiota (GM) of adults. The study aimed to quantitatively assess the impact of exercise on GM diversity using a meta-analysis approach. A total of 25 studies with 1044 participants were included, covering various types of exercise interventions and control groups. The results showed that exercise interventions significantly increased the alpha diversity of adult GM, particularly the Shannon index, with a weighted mean difference (WMD) of 0.05 (95% CI 0.00, 0.09). Exercise also altered the GM composition, decreasing Bacteroidetes and increasing Firmicutes, indicating a shift in the Firmicutes/Bacteroidetes ratio. Subgroup analyses revealed that females and older adults exhibited more significant changes in the Shannon index and observed operational taxonomic units (OTUs). The study concluded that exercise may be a promising way to improve GM in adults, with the Shannon index showing a significant increase. However, the effects on GM diversity varied across different measures, suggesting that exercise's impact is more pronounced in evenness rather than richness. The findings highlight the need for further research to explore the nuanced relationships between different types of exercise and GM composition, considering individual variations and long-term effects.This systematic review and meta-analysis examines the effects of exercise on the gut microbiota (GM) of adults. The study aimed to quantitatively assess the impact of exercise on GM diversity using a meta-analysis approach. A total of 25 studies with 1044 participants were included, covering various types of exercise interventions and control groups. The results showed that exercise interventions significantly increased the alpha diversity of adult GM, particularly the Shannon index, with a weighted mean difference (WMD) of 0.05 (95% CI 0.00, 0.09). Exercise also altered the GM composition, decreasing Bacteroidetes and increasing Firmicutes, indicating a shift in the Firmicutes/Bacteroidetes ratio. Subgroup analyses revealed that females and older adults exhibited more significant changes in the Shannon index and observed operational taxonomic units (OTUs). The study concluded that exercise may be a promising way to improve GM in adults, with the Shannon index showing a significant increase. However, the effects on GM diversity varied across different measures, suggesting that exercise's impact is more pronounced in evenness rather than richness. The findings highlight the need for further research to explore the nuanced relationships between different types of exercise and GM composition, considering individual variations and long-term effects.