# Resistance Training Reshapes the Gut Microbiome in a Longitudinal 8-Week Intervention in Sedentary Adults

## TL;DR

Resistance training can change the gut microbiome, especially in people who gain more strength, leading to healthier bacteria linked to anti-inflammation and better gut function.

## Contribution

This study shows resistance training induces time-dependent gut microbiome changes, particularly in individuals with significant strength gains.

## Key findings

- Resistance training caused significant microbial shifts in participants with ≥33% strength gains.
- Faecalibacterium and Roseburia hominis, linked to health benefits, were enriched in high responders.
- Microbial changes correlated with strength improvement, suggesting a link between gut health and physical fitness.

## Abstract

The gut microbiome plays a critical role in metabolism, immunity, and aging. While endurance training has been shown to beneficially modulate the microbiome, the effects of resistance training remain less clear, with some studies reporting minimal changes. This project aims to investigate whether structured resistance training elicits significant changes in gut microbiome composition and diversity in sedentary, healthy adults. 150 participants (85 female, 63 male), between 24 and 61 years of age, completed an 8-week supervised resistance training program between May 2022 and July 2023 in the cities of Tübingen and Rottenburg, Germany. Session-level training data, including weights and repetitions, were recorded alongside metrics like load and compliance. Fecal samples were collected throughout the study period at designated timepoints for 16S rRNA gene amplicon sequencing to assess microbiome composition and for metabolomics analyses to evaluate microbial metabolic activity.

No differences in microbial diversity were observed, and there were no significant changes in microbial community composition or fecal metabolomics across all participants post-training. However, within-individual microbial community changes significantly correlated with strength improvement (Pearson correlation coefficient r = 0.167, p = 0.0004), and significantly stronger shifts in beta diversity were observed in participants with ≥ 33% average strength gains compared to those with ≤ 12.2% gains (Kruskal-Wallis rank sum test, p = 0.08). In these high responders, differential abundance analysis revealed time-dependent microbial changes, with 27 taxa enriched or depleted by week 8 of training (ANCOM-BC2, ≥ 2-fold change, p ≤ 0.05). Notably, Faecalibacterium and Roseburia hominis—both associated with a healthier, anti-inflammatory microbiome—were significantly enriched. Many differentially abundant taxa belonged to the Lachnospiraceae family.

Resistance training drives significant, time-dependent gut microbiome changes, particularly in those demonstrating greater improvements in strength. These shifts mirror endurance training effects and may reflect improved overall health.

The online version contains supplementary material available at 10.1186/s40798-026-00990-6.

Our results indicate that resistance training can induce meaningful, time-dependent shifts in the gut microbiome, particularly among sedentary individuals who experience substantial strength gains.Notably, we observed enrichment of key health-associated taxa, including Faecalibacterium and Roseburia hominis, both linked to anti-inflammatory effects and improved gut function.These findings suggest that resistance training may contribute to gut health in conjunction with physical fitness, supporting its broader application in health promotion strategies and future microbiome-focused research.

Our results indicate that resistance training can induce meaningful, time-dependent shifts in the gut microbiome, particularly among sedentary individuals who experience substantial strength gains.

Notably, we observed enrichment of key health-associated taxa, including Faecalibacterium and Roseburia hominis, both linked to anti-inflammatory effects and improved gut function.

These findings suggest that resistance training may contribute to gut health in conjunction with physical fitness, supporting its broader application in health promotion strategies and future microbiome-focused research.

The online version contains supplementary material available at 10.1186/s40798-026-00990-6.