Microbiota and muscles: these intestinal bacteria that influence your strength

Researchers from the Universities of Almería and Granada, in collaboration with the University Medical Center of Leiden (Netherlands), have highlighted the role of an intestinal bacteria in improving strength and physical condition. The work provides new evidence in favor of an “intestine-muscle axis”: the intestinal microbiota not only plays a digestive role, it also influences metabolism and muscle function.

The intestinal bacteria that strengthens your legs

The study involved stool samples and fitness tests conducted on 90 young adults (18-25 years) and 33 older adults (65 years and older). Among the bacteria studied, it is Roseburia inulinivorans which particularly stands out. Elderly people in whom this bacteria is present display 29% greater grip strength than those in whom it is absent (1). In young adults, a greater abundance of this bacteria is associated with both better grip strength and higher cardiorespiratory fitness.

Researchers have found that the bacteria is less present in older people, which coincides with the period of life when muscle mass naturally tends to decrease.

To confirm a causal link, experiments were carried out on mice. After temporary reduction of their microbiota by antibiotics, the animals received human strains of Roseburia once a week for eight weeks. The result: an approximately 30% increase in grip strength, as well as the development of larger muscle fibers and an increased proportion of type II fibers — the fast-twitch fibers essential for strength and power.

“This opens the possibility that the bacteria studied could be used as a probiotic to help preserve muscle strength during aging”explains Borja Martínez Téllez, researcher at the University of Almería, in a press release (2).

Limitations nevertheless remain: human strains have not long-term colonized the intestine of mice and certain biological mechanisms have not been directly evaluated, which calls for additional longer-term research.

A confirmed “intestine-muscles” axis

The study of the link between muscles, physical strength and microbiota is an emerging area of ​​research. According to a recent systematic review of 12 human studies, microbiota diversity, combined with the presence of butyrate-producing bacteria, appears to be the key to better muscle mass and strength (3). On the other hand, dysbiosis, namely the imbalance of the microbiota, is associated with sarcopenia.

The intestinal microbiota therefore plays an important role in age-related muscle loss. Probiotics and prebiotics could then be potential interventions to improve muscle health in older adults.

Read : Muscles, your greatest life force