Gut-muscle crosstalk: The effect of endurance training and probiotic supplementation on intestinal villus structure, postbiotics and VO2max in old male rats

The aim of this study was the effect of endurance exercise and probiotic supplement enriched with amino acid leucine and vitamin D on the gut-muscle axis in aged male rats. For this purpose, 25 male Wistar rats (5 rats in each group) in two age groups of 8 to 12 weeks (young) and 18 to 24 months (elderly) were randomly divided into 5 equal groups of old control (OC), young control (YC), endurance exercise (OE), supplement group (OS) and endurance exercise plus supplement (OES) were divided. The results showed that 8 weeks of endurance training (three times a week) and supplemental oral gavage (5 times a week) caused a significant change in postbiotics (decrease of indoxyl sulfate (IXS) and increase of Short-chain fatty acids (SCFAs)). The role of OS in reducing IXS was more prominent than OE and OES variables; of course, the synergistic effect of OES (P=0.000), caused a greater improvement in the amount of SCFA. Also, Administering the supplement alone and at rest (without exercise) could not cause a significant increase in VO2max (P=0.449). But, the effect of exercise on increasing VO2max index was more effective than OS and even OES. Eventually, the independent variables made a significant difference on the Villus height (VH) (except for the OS group) and number of goblet cells (GC) compared to the OC group (P 0.05).