“Does resistance training really improve your gut microbiome?”

A recent study sheds new light on how strength training could affect the gut microbiome. In previously inactive adults, eight weeks of strength training actually caused changes in the composition of the gut flora – but not equally in all participants. The decisive factor was how much the participants increased their strength performance, not the frequency or duration of training alone. The research thus shows that individual training adaptations may play a greater role than previously thought. The results were published on The Conversation platform.

The team of researchers at the University of Tübingen studied 150 people who did not normally exercise and who completed strength training two to three times a week over an eight-week period. The results showed that participants with the greatest strength gains – so-called ‘high responders’ who increased their strength by more than 33 per cent – exhibited subtle but significant changes in their gut bacteria that did not occur in others. Two types of bacteria in particular increased: Faecalibacterium and Roseburia hominis. Both produce butyrate, a short-chain fatty acid that provides energy and supports a healthy intestinal mucosa.

It is also noteworthy that the study highlights the complexity of the microbiome: during the course of the study, some bacteria commonly associated with health decreased, while others increased. This underscores the fact that every microbiome is unique and that the same bacteria can play different roles in different people.

The article highlights important limitations: the study cannot prove causality – it cannot be said with certainty whether the bacterial changes caused the increases in strength or vice versa. In addition, diet, which is difficult to control, may have played a role.

Nevertheless, the study opens up new perspectives for research. It adds to growing evidence that lifestyle choices – including how much we exercise – can influence the microscopic world inside us. What can be said with greater certainty is that exercise appears to benefit overall physical and mental health and should be part of a healthy lifestyle, regardless of what it does to gut microbes.

Go to Article on The Conversation

Original publication:

Straub, D., Englert, T., Beller, A., Stadelmaier, J., Stahl, M., Kilian, J., ... & Nahnsen, S. Resistance Training Reshapes the Gut Microbiome for Better Health. (2025) bioRxiv, 2025-08. doi: 10.1101/2025.08.13.670057