A type of intestinal bacteria called rosemary tilt Specifically associated with improving muscle strength in humans and muscle performance in mice, research published online in the journal intestines.
R slope Research shows that it alters certain metabolic processes in the muscles, converting muscle fibers into “fast-twitch (Type II)” fibers designed for short, intense movements such as sprinting or weight training.
R slope Dutch and Spanish researchers suggest that probiotics may have potential as a dietary supplement in the treatment of age-related muscle wasting diseases.
Researchers explain that loss of muscle mass and strength is a major cause of frailty, reduced mobility and function, and poor health, especially in older adults and people with long-term conditions.
A growing body of evidence suggests that gut bacteria are involved in a wide range of health conditions, including metabolic, neurodegenerative and cardiovascular diseases, and may also impact muscle mass and function, the researchers added.
Therefore, they wanted to find out whether specific gut microbial species might be associated with muscle strength, and if so, what the underlying mechanisms might be.
To do this, they analyzed fecal samples from 90 healthy young people (aged 18 to 25) and 33 older adults (aged 65 and older) for the presence of bacteria.
Physical fitness was evaluated using hand grip strength, leg press and bench press performance, and VO2 max (maximum oxygen consumption during exercise), which is an indicator of cardiovascular function.
Among all bacteria found in stool samples, the Roseburia group (genus) was the only one that showed a positive correlation with muscle mass and strength.
R waste and R intestine Species was not significantly associated with hand grip strength or VO2 max in either age group.
However, older adults with detectable symptoms may R slope Their stool samples showed that they had 29% higher grip strength and no increase in peak oxygen uptake compared to those without, indicating better health.
In young adults, R slope There was a positive correlation with both grip strength and VO2 max. and both are relatively abundant R slope and R intestine There was also a positive correlation with leg press and bench press intensity.
The relatively abundant R waste and man’s R was not associated with any measure of muscle strength. This suggests that different Roseburia species may affect different aspects of muscle strength, the researchers said.
Roseburia is also more common in young adults, of whom a proportion of R waste It ranged from 0% to 3.3%. that of R intestine It ranged from 0% to 5.5%. on the other hand, R slope It ranged from 0% to 6.6%.
Among the elderly, the proportion is R waste It ranged from 0% to 2.2%. that of R intestine rranged from 0% to 0.7%; R slope It ranged from 0% to 1.3%.
To determine the causal role of Roseburia in muscle strength, researchers fed Roseburia seeds once a week for eight weeks to 32 mice that were given a cocktail of antibiotics for two weeks to deplete their gut microbiota.
Mice were randomly assigned to one of four groups, three of which received different strains of Roseburia, and one of which received no Roseburia (control group).
None of the Roseburia varieties increased running time to fatigue. However, when compared with the control group, R slope After 4, 6, and 8 weeks of treatment, it caused a significant increase of approximately 30% in forelimb grip strength, a surrogate for muscle function.
Furthermore, the treated mice R slope Compared to other groups, the soleus muscle in the calf had larger muscle fiber size and a significantly higher proportion of type II (“fast-twitch”) fibers, but not when compared to treated mice. R intestine.
Further analysis of the fiber size distribution revealed that the fiber size distribution was relatively evenly distributed in the treated mice, whereas it was relatively evenly distributed in the control group. R slope There were higher levels of larger fibers than in mice treated with other Roseburia species or control mice.
These changes were also accompanied by metabolic changes in proteins and enzymes that are key to muscle energy production.
The researchers acknowledge that their findings have various limitations. In animal studies, none of the human Roseburia species colonized the intestines of mice. Additionally, specific pathways related to inflammation and neuromuscular signaling have not been directly assessed and may be influential.
Long-term studies are needed to determine whether the abundance of R slope They emphasize that it is the cause or effect of changes in muscle function.
Nevertheless, they suggest: “Taken together, our findings provide strong evidence in favor of a gut-muscle axis. R slope Actively regulates muscle metabolism and strength. ”
And they conclude: “Furthermore, we R slope It is lower in the elderly than in the young. Its amount appears to decrease with age, and the prevalence of sarcopenia (muscle loss) increases during this period. R slope As a potential probiotic for maintaining muscle strength. ”
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Reference magazines:
Borja Martinez Telles Others. (2026). Roseburia inulinivorans increases muscle strength. intestine. DOI: 10.1136/gutjnl-2025-336980. https://gut.bmj.com/content/early/2026/03/03/gutjnl-2025-336980
