Physical activity is associated with a host of muscular, cardiovascular and bone-related benefits, and it would appear that it is also beneficial for intestinal health. Conversely, the intestinal microbiota seems to improve physical performance.
Impact of microbiota on sports performance
What if certain intestinal bacteria helped to improve sporting performance?
Researchers have discovered a bacterium, Veillonella atypica, that is capable of boosting sports performance. It is found in large quantities in the faecal samples of marathon runners.
When athletes’ muscles have used up all their glycogen reserves, they ferment to produce energy, producing a waste product called lactate. This molecule is produced during anaerobic respiration and is at the root of the pain caused by stiffness after intense exercise.
According to the scientists, Veillonella is responsible for metabolising lactate. It uses it to generate energy, transforming lactate into short-chain fatty acids (SCFAs). These are used by the muscles as a source of energy.
An experiment showed that when mice were given a Veillonella-based probiotic, they ran 13% longer.
When the intestinal microbiota is balanced, certain bacteria present enable :
- The transport of liquids and solutes across the intestinal barrier and therefore the maintenance of hydration, essential during physical effort;
- Ferment fibres, transforming them into short-chain fatty acids (SCFAs), which serve as an emergency fuel for the muscles during exercise. In addition, SCFAs reduce the inflammation caused by intense physical effort;
- The production of molecules that stimulate the release of dopamine (the pleasure and motivation hormone) during physical activity.
An unbalanced microbiota contributes to overall inflammation in the body, which affects muscle recovery capacity.
Therefore it is advisable to take care of your intestinal flora in order to improve your physical performance. In fact, one study revealed that four weeks‘ probiotic supplementation delayed athletes’ fatigue time by an average of 16% in a treadmill test.
Impact of physical activity on intestinal microbiota
Conversely, physical activity has a positive impact on intestinal health:
- Increased diversity of beneficial bacteria in the microbiota;
- Strengthening of the mucous membrane lining the walls of the digestive tract;
- Improved gastrointestinal motility (contractions of the muscles in the digestive tract needed to move food through it);
- Improved intestinal transit;
- Increased synthesis of molecules that modulate immunity (AGCC).
2h30 of physical activity a week is enough to obtain intestinal benefits. In fact, the improvement in the diversity and richness of the microbiota is linked more to the number of hours devoted to physical activity than to the intensity of that activity.
It would even appear that moderate physical activity is effective in reducing the symptoms of irritable bowel syndrome (IBS).
The intestinal microbiota of athletes is more diverse. In particular, it is richer in beneficial bacteria (Bifidobacterium, Lactobacilli and Akkermansia) and produces more short-chain fatty acids (SCFAs).
However, 90% of athletes taking part in ultra-endurance events suffer from digestive problems. This is because their bodies organise themselves to supply the muscles with the oxygen they need via the bloodstream, to the detriment of the digestive system. In addition, the sympathetic nervous system, involved in accelerating the heart rate, affects intestinal transit. This dual mechanism explains the pain, nausea and diarrhoea experienced.
Nevertheless, even if these discomforts are short-lived, they may cause an alteration in the composition and function of the intestinal microbiota. The more intense the physical activity, the more rapid and profound the dysbiosis, leading to increased intestinal permeability. Numerous bacterial toxins and/or pro-inflammatory molecules could then penetrate the body and have an impact on the athlete’s overall health.
In conclusion, sport has a positive impact on both the quantity and quality of the microbiota. However, you don’t need to engage in overly intense physical activity to reap the benefits – 2h30 a week is enough. On the contrary, at too high an intensity, sport can have a deleterious effect on intestinal health.
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