Gut bacteria and exercise together shape muscle aging
Muscle loss in older age is usually attributed to inactivity. But the composition of gut bacteria appears to play an equally important role. New research outlines how the two factors interact and together determine how quickly muscle deteriorates with age.
Sarcopenia is the progressive loss of muscle mass and strength that accompanies aging. It is a primary driver of frailty in older adults and raises the risk of falls, functional decline, and early death. Exercise is the most established protective factor. But the gut microbiota, the community of bacteria living in the large intestine, appears to exert a comparable influence.
Gut bacteria shift unfavourably from midlife
A narrative review discussed via Fight Aging! finds that the gut microbiome begins shifting in an unfavourable direction as early as the mid-thirties. Bacteria that produce pro-inflammatory compounds increase in number. Bacteria that supply beneficial metabolites, including short-chain fatty acids (compounds that feed gut cells and dampen inflammation), decline. That shift appears to interact directly with muscle aging, according to the researchers.
Exercise does not only benefit the muscles directly; it also shifts gut microbiome composition in a more favourable direction. In turn, certain gut bacteria appear to support muscle metabolism and recovery after physical activity. The relationship runs in both directions.
What can be done now
Faecal transplantation from young to old animals extends life and improves health in animal models, but what the ideal microbiome composition looks like for preserving muscle in humans remains unknown. Probiotics can shift the gut microbiome temporarily, but with limited control over the specific outcome. The researchers emphasise that exercise and microbiome health are mutually reinforcing, and that both are needed. Even physically fit people eventually experience muscle loss. A better understanding of the gut-muscle axis may offer new targets for future therapies.
Search terms to explore further: sarcopenia gut microbiota interaction | short-chain fatty acids muscle metabolism aging | frailty microbiome exercise