A sedentary lifestyle is one of the top ten causes of death in the world. It increases risk factors for non-communicable diseases such as cancer, diabetes and cardiovascular diseases. The World Health Organization recommends to practice regular physical activity for a healthy living. Physical activity can sometimes be even more effective than medication and contribute to prevent or cure a wide range of diseases, such as type 2 diabetes, obesity, or atherosclerosis for example. It may have some benefits on gut health and microbiota.
Muscles and exercises
The human body is made up of three types of muscles:
- skeletal muscles, which are controlled by the individual’s will. These are the ones that are stimulated during physical activity such as running or daily actions
- Cardiac muscles and
- Smooth muscles, found in the blood vessels and the intestine, for example, which contract independently of the individual’s will.
During a physical activity, the contraction of the skeletal muscles results in the production of a number of health-promoting substances. These substances (cytokines, myokines, growth factors) can have a remote action on other tissues or organs. The beneficial effects of regular physical activity include especially an increase in energy expenditure and anti-inflammatory and antioxidant actions.
Benefits for everyone!
Apart from the benefits associated with reducing excess body fat in situations of overweight or obesity, for example, physical activity also helps prevent high blood pressure, and cardiovascular diseases. In addition, mobilizing muscles helps in case of altered capacity to metabolize both sugars (insulin resistance, diabetes) and fats (high levels of cholesterol or triglycerides in the blood, atherosclerosis).
These effects are also beneficial to people suffering from certain diseases affecting the liver (non-alcoholic fatty liver or alcoholic fatty liver) or the intestine (irritable bowel syndrome). In addition, certain forms of cancer, but also anxiety states and mood disorders, including depression, could be reduced by regular physical activity.
Finally, benefits of physical activity can be extended to age-related pathologies such as sarcopenia (loss of muscle quantity and quality). Moreover, staying active on a regular basis would act to prevent the risk of cognitive disorders or dementia.
An active and balanced lifestyle is good for our intestinal health
An active lifestyle and adapted physical activities may have beneficial effects on intestinal function. For example, the time of intestinal transit is reduced. As a result, the contact of possible pathogens with the mucus layer lining the intestinal walls is lowered and, ultimately, the incidence of chronic inflammatory bowel disease and colon cancer is reduced.
However, in case of excess, abdominal symptoms such as bloating, nausea, stomach cramps or diarrhea are notable, especially in high-level athletes. These symptoms can be explained by the increase in internal body temperature, dehydration, excessive use of supplements or anti-inflammatory drugs but also anxiety or a diet rich in simple carbohydrates. These factors can damage the tight junctions between the cells of the intestinal wall and cause a pro-inflammatory response. There would also be an increased permeability to bacteria and toxic substances negatively affecting the immune response.
A distinction must be made between the healthy population and patients with chronic gastrointestinal diseases and disorders. In the latter group, more studies are needed to clarify the likely consequences of prolonged intense exercise on health status.
Physical activity and gut microbiota: a bidirectional relationship
The skeletal muscles and the intestine also engage in a fruitful dialogue. This “gut-muscle axis” has important effects on health and on the body’s physical and athletic capacities, and the ability of the microbiota to regulate skeletal muscle tissue at a distance. Alteration of the gut microbiota due to aging may, through various mechanisms, alter muscle functions. One of the underlying mechanisms would be an increase in intestinal permeability due to microbial alterations. This would result in an increased flow of microbial products into the bloodstream, triggering pro-inflammatory signals. One consequence could be structural alterations in muscles, with a subsequent loss of their functional capacity. Inevitably, these conditions would lead, especially in the elderly, to a decrease in quality of life.
It has therefore become clear that the gut microbiota can affect muscle function. As for the impact of physical activity on the microbiota, it would contribute to positive changes in terms of gastro-intestinal health.
Physical exercises would influence the diversity and relative quantities of bacterial species, even in different nutritional contexts, and modulate the balance of interactions between the host and his microbiota.
Physical exercise would promote a greater diversity of intestinal microbiota, associated with a decreased incidence of high BMI and a lowering risk of metabolic and degenerative diseases. Moreover, a balanced microbiota has a positive impact on the whole body. Thus, the favorable influence of physical activity could improve not only intestinal health, but also many other bodily functions.
The physical activity implies a wide variety of biological responses, including interactions with the brain-gut-microbiota axis, metabolic diet-microbiota-host interactions, and neuroendocrine and neuro-immunological interactions.
Probiotics and prebiotics for athletes?
Scientific studies suggest that consumption of prebiotics and probiotics may help preserve and promote optimal health in athletes by improving metabolism, antioxidant and immune defenses or barrier functions. Daily probiotic supplementation may limit the exercise-induced reduction in the amino acid tryptophan levels. As a result, it could decrease the incidence of upper respiratory tract infections. Furthermore, daily intake of two probiotic strains (Bifidobacterium breve BR03 and Streptococcus thermophilus FP4) would appear to have an anti-inflammatory effect and allow an attenuation of the decline in performance after traumatic muscle work.
In conclusion, consuming prebiotics or probiotics could be a safe and effective way to improve metabolism, immune system, and barrier function. It promotes the proliferation of specific bacteria, such as Bifidobacteria or Lactobacillus, and the production of metabolites, such as short-chain fatty acids. However, further studies are needed to properly assess the dose and type of prebiotics or probiotics needed.
This post is written on the basis of the book “Microbiota”.
“Microbiota” is published in english by the Danone Institute Italy and Danone Institute International. It gathers a mix of historical, anthropological and scientific concepts explaining why research on gut bacteria, from ancient texts to the most recent scientific evidence, is a sector of great interest for science. Thanks to a Q&A structure, 7 recognized experts explain several topics considering the different ages and conditions in life. The book is available in pdf and e-book format (on the Danone Institute International website)
