ENHANCING PHYSICAL PERFORMANCE THROUGH MODULATION OF THE GUT–LIVER– MUSCLE AXIS: THE ROLE OF PROBIOTICS

Purpose: This study aims to investigate the interaction between gut, liver and muscle, paying particular attention to role of intestinal microbiota and the impact of probiotics on physical performance. Previous studies have demonstrated that these three organs communicate with each other via hormonal, inflammatory and metabolic signals. During physical activity, muscles release myokines, including IL-6, which improve the liver’s insulin sensitivity, stimulate controlled glucose production and promote lipid oxidation. In turn, the liver receives and integrates signals from the muscles and intestines. It responds adaptively to maintain energy homeostasis, reduce lipid accumulation and improve cholesterol management by directing it towards bile acid synthesis. At the same time, the gut contributes to liver regulation by releasing hormones such as FGF19, which has hepatoprotective effects and modulates energy metabolism. Gut microbiota, which are positively influenced by probiotic intake, play a central role in this axis by promoting better intestinal barrier integrity, reducing systemic inflammation and regulating bile acid composition. This study aims to clarify how strengthening the gut-liver-muscle axis can optimise metabolic health and physical performance. Methods: The study involved 10 subjects, who were divided into two groups: an experimental group (n = 5) who were treated with a multistrain mix of probiotics containing Lactobacillus reuteri, Bifidobacterium longum, Bifidobacterium lactis and Lactobacillus fermentum, and a control group (n = 5), who received no treatment. The intervention lasted 16 weeks. Blood samples were taken to assess the following biomarkers: IL-6, irisin, TSK, FGF19, bile acids and shortchain fatty acids (SCFAs). Results: The results showed a trend of variation in the probiotictreated group compared to the control group. In particular, changes were observed in the plasma levels of IL-6 and irisin, accompanied by modulations in FGF19, bile acids, and short-chain fatty acids (SCFAs). Conclusions: The results suggest that modulating the microbiota through probiotics can influence the gut-liver-muscle axis, optimising energy metabolism, reducing systemic inflammation, and improving physical performance. However, further research need to confirm this finding, involving larger sample sizes, longer follow-ups and more indepth molecular investigations.