Resistance training may strengthen your gut microbiome
People who made the greatest gains in muscle power over eight weeks of resistance training also improved the balance of bacteria in their gut
By David Robson
8 September 2025
Strength training may benefit the gut microbiome
Juliana Yamada/Los Angeles Times via Getty Images
The most visible benefits of lifting weights may be bulging biceps, but strength training could also improve your gut microbiome.
While there is no single combination of microbes that ensures good health, certain configurations are consistently associated with better medical outcomes, such as improved immune function and healthier ageing. These include Faecalibacterium, Akkermansia and Roseburia hominis, all of which produce short-chain fatty acids like butyrate that help protect the gut’s lining and reduce inflammation.
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Our diets clearly play an enormous role, but research has suggested that aerobic exercise – such as cycling or running – may help these microbial species to flourish. This may be through improved blood circulation, hormonal changes or the metabolic byproducts of physical activity, such as lactate. Studies examining the effects of resistance training have produced mixed results, however, with some experiments revealing meaningful shifts, while others found minimal change. “Existing research is relatively limited,” says Matthieu Clauss at the Norwegian School of Sport Sciences in Oslo.
To clear up the confusion, Sven Nahnsen at the University of Tübingen in Germany and his colleagues recruited a relatively large sample of 150 sedentary adults and prescribed them an eight-week training programme that included various resistance exercises, such as lateral pulls, seated rows, chest presses and leg curls.
Unlike the previous studies, the participants were given access to “smart” strength machines that automatically adjust the weight and range of motion according to the participants’ performance, while maintaining detailed records of their progress. “Every single weight that is lifted, every repeat, is recorded digitally, so we have really highly accurate data,” says Nahnsen.
