Numerous studies have shown that, in addition to its other benefits, regular moderate physical exercise increases diversity among the bacteria in the intestine, favoring beneficial species. However, this is only the case for regular exercise, since ceasing all activity may lead to an imbalance in the intestinal microbiota (dysbiosis).
Avoid excessive exercise
The opposite situation also has its dangers. Whether you are an amateur or a professional, training too intensely or disproportionately to your level may lead to a dysbiosis, which can be all the more sudden and acute the more intense the activity. Such dysbioses may result in increased intestinal permeability, which, by allowing bacteria and their components to pass into the bloodstream, can lead to inflammation in the body. They may also be the cause of abdominal pain, nausea and diarrhea that certain people experience during extreme exertion.
A gut-muscle axis?
The most likely hypothesis is that the muscles and intestinal bacteria communicate via a gut-muscle axis. This communication is thought to work both ways: the gut microbiota influences muscular health and physical exercise modulates the composition of the microbiota. In humans, although supported by the link between intestinal dysbioses and various muscle-related metabolic alterations (protein synthesis, release of molecules promoting muscle development, etc.), this hypothesis remains tentative.
The immune system: at the crossroads of the gut-muscle axis?
Shaped by the intestinal bacteria, the immune system may also play a key role in muscular health. By helping to build a strong immune system, a “healthy” gut microbiota may influence the gut-muscle axis and the health of our muscles, especially among people having an active lifestyle. Conversely, a dysbiosis caused by a negative interaction with the immune system may promote muscular disorders. This is one more hypothesis that needs to be verified if we are to finally understand the relationship between exercise, the immune system, the gut microbiota and muscular health.
