This discovery could lead to a probiotic for human consumption that helps maintain strength and fitness during aging.
This study has been published in the prestigious scientific journal Gut.
Scientists from the University of Almeria and the University of Granada, together with researchers from Leiden University Medical Center (LUMC, the Netherlands), have identified an intestinal bacterium of the genus Roseburia associated with stronger muscles and better physical condition.
The results support the concept of a gut-muscle axis. “Overall, our findings provide solid evidence confirming the existence of a gut-muscle axis, in which this identified bacterium positively regulates muscle metabolism and muscle strength,” says Jonathan Ruiz, professor in the Department of Physical Education and Sports at UGR and researcher at the Joint University Institute for Sport and Health (IMUDS).
Additionally, scientists have observed that the bacterium is less abundant in older adults than in younger adults, suggesting that its levels may decrease with age, a period in which muscle loss occurs.
“This opens up the possibility that the bacteria under investigation could be used as a probiotic to help maintain muscle strength during aging,” explains researcher Borja Martínez Téllez from the University of Almería.
The relationship between gut bacteria and muscle performance
The team analyzed whether certain gut microbes are associated with muscle strength and physical condition. To do this, they studied stool samples from 90 healthy young adults (18-25 years old) and 33 older adults (65 years old or older).
Participants in the experiments also performed several physical fitness tests, including hand grip strength, leg strength, and upper body strength (pectoral muscles), and their maximum oxygen consumption, an indicator of cardiorespiratory capacity, was measured.
Of the numerous bacterial groups found, the genus Roseburia is prominent, as its abundance is associated with increased muscle mass and strength. In particular, one species—Roseburia inulinivorans—shows an association with physical fitness.
Older adults who had this bacteria demonstrated 29% greater hand grip strength in experiments than people who did not have this bacteria. In young adults, greater amounts of this bacterium are associated with both greater hand grip strength and higher cardiorespiratory capacity.
Other species of the Roseburia genus present different patterns: Roseburia intestinalis is related to leg and upper body strength in young adults, while Roseburia facies and Roseburia hominis show no significant correlation with the indicators studied.
Assessment of gut-muscle connection
To find out whether Roseburia could directly affect muscle function, researchers conducted experiments on rats. After temporarily reducing their gut microbiota with antibiotics, the animals were given human strains of bacteria once a week for eight weeks.
Mice that were treated with the bacteria had about a 30% increase in the grip strength of their front legs, compared to animals that did not receive it.
In addition, the mice developed a higher proportion of large muscle fibers and type II muscle fibers, which are fast-twitch fibers, in the calf soleus muscle, which are important for strength and power. These changes were also accompanied by metabolic changes in proteins and enzymes that are important for muscle energy production.
boundaries
The researchers point out several limitations. In experiments with mice, human strains of Roseburia did not permanently colonize the intestine, and the study did not directly evaluate certain biological mechanisms such as inflammatory pathways or neuromuscular signaling. Therefore, long-term research will be necessary to determine whether R. Changes in the levels of inulinivorans may lead to or result from improvements in muscle function.
The study was led by Ramón y Cajal researcher Borja Martínez-Téllez from the Department of Nursing, Physiotherapy and Medicine at the University of Almería, in collaboration with UGR professor Jonathan Ruiz and researcher Patrick CN Renson (LUMC). Scientists from the University of Groningen (Netherlands) and other Spanish institutions in Valencia and Cadiz also participated in the work. The project was funded by the Martín Escudero Foundation, the Health Research Fund of the Carlos III Health Institute, and the Leiden University Funds.
Bibliographic references:
Martínez-Téllez B, Schönke M, Kovinev A, García-Dominguez E, Ortiz-Alvarez L, Verhoeven A, Gasesa R, Vich Villa A, Ducarmon QR, Jiménez-Pavón D, Gómez-Cabrera MC, Wiersma R, Smits WK, Gira M, Ruiz JR, Renson PCN. Roseburia inulinivorans increases muscle strength. Intestine. 2026. (IF = 26.2; Gastroenterology and Hepatology, D1). DOI: DOI: 10.1136/gutjnl-2025-336980
Contact:
Borja Martínez-Téllez
Department of Nursing, Physiotherapy and Medicine
University of Almeria, CIBEROBN
Email: @email
Phone: 950 21 41 15
jonathan ruiz ruiz
Department of Physical Education and Sports Science
Faculty of Sports Sciences
University of Grenada
Joint University Institute of Sports and Health (iMUDS), Ibs.Granada, CIBEROBN
Email: @email
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