Microbiota, Training, and Inflammation: when your gut determines your performance

They say “the gut is the second brain”. That’s nice, but incomplete.
In reality, it’s also a trainer, a physical therapist, a logistician, and sometimes… a discreet saboteur.
(If the gut wore shoes, it would probably choose Vibrams, because “connection to the ground is life”.)

We train to improve our performance, well-being, and energy.
And yet, many regular athletes feel the opposite:
chronic fatigue, slow recovery, stagnation, or even loss of motivation — even though “everything is done correctly”.

An unpleasant surprise?
It’s not always the muscle or the nervous system that’s the problem, but a forgotten organ working undercover: the gut microbiota.

Depending on how you train, eat, and recover, this ecosystem can boost your adaptation… or trigger silent inflammation that slows your progress, without pain, without obvious signs, just that “hey, I’m not progressing anymore despite my efforts.”

Which raises a simple, but unsettling question:
👉 What if your performance isn’t in your muscles, but in your gut?

The gut microbiota is not static. It can evolve — depending on diet, lifestyle… and physical activity. Several studies show that regular, even moderate, training is associated with greater microbial diversity (Varghese, S., 2024).

This microbial diversity is a bit like a reserve of "bacterial good vibes": more species = more metabolic, immune, and digestive functions available.

And exercise seems to promote this richness.

One of the key functions of the microbiota: producing essential metabolites — especially short-chain fatty acids (SCFAs) such as butyrate, propionate, acetate.

These compounds play a role in:

• gut lining health
  
  

• inflammation regulation
  
  

• metabolism
  
  

• recovery
  
  

In short, everything that contributes to sustainable performance (Mailing, L.J., 2019).

When training is intense, prolonged, in heat, with dehydration, the intestinal barrier can be compromised: the lining weakens, the junctions "open", the protective mucus decreases — and compounds like endotoxins (LPS) can pass into the blood.

Result: systemic inflammation, often invisible: fatigue, slowed recovery, decreased performance (Dmytriv, T.R., 2024).

Several aggravating factors contribute to altering the balance of the microbiota and compromising physical performance.

• long/high volume exercise
  
  

• heat and dehydration
  
  

• low-fiber diet
  
  

• frequent consumption of ultra-processed foods
  
  

• lack of recovery

A context that, combined, can create a pro-inflammatory environment unfavorable to performance.

💡 These mechanisms — heat, dehydration, heat stress, redistribution of blood flow, intestinal permeability — are explored in detail in our article:
👉 Hyperthermia, Dehydration and Performance

This article shows how prolonged effort in extreme thermal conditions can trigger major physiological disturbances, including:

• hyperthermia
  
  

• decreased plasma volume
  
  

• digestive ischemia
  
  

• hormonal disruption
  
  

• cognitive disorders
  
  

• increased risk of intestinal permeability
  
  

This link between thermal stress and gut health places the gut at the heart of performance.

"If my stomach doesn't hurt, my gut is fine."

Reality: Intestinal permeability can increase without digestive symptoms. Inflammation, on the other hand, manifests as fatigue, slow recovery, and stagnation.

"The microbiota is just about diet."

Reality: Training directly alters the microbiota — composition, diversity, metabolism.

"Performance = muscle + mental."

Reality: Performance = muscle + mental + gut. And the third is often the weakest link.

This "silent inflammation" — even moderate — can affect:

• recovery
  
  

• adaptation
  
  

• metabolism
  
  

• energy
  
  

• training resistance
  
  

It's not as dramatic as an injury — but it's remarkably effective at sabotaging your progress (Varghese, S., 2024).

The microbiota and the gut communicate with the brain via the gut-brain axis.

This link influences:

• mood
  
  

• stress
  
  

• motivational fatigue
  
  

A "tired" or dysbiotic gut can undermine the motivation to train, regardless of willpower (Dmytriv, T.R., 2024).

• avoid "volume + heat + dehydration" combinations

• consider hydration and recovery
  
  

• avoid prolonged fasted training
  

A varied diet including different food groups can help support a balanced microbiota and limit certain pro-inflammatory factors.

• Fibers (vegetables, legumes, fruits, whole grains)
  
  

• Omega-3s (fatty fish, seeds, nuts)
  
  

• Polyphenols (fruits, vegetables, tea, cocoa)
  
  

• Fermented foods (depending on tolerance)
  
  

And above all:

• limit ultra-processed foods (industrial meals, snacks, sodas, refined oils, additives), which are pro-inflammatory and detrimental to the microbiota.

Regularly adopting these habits can contribute to a more stable gut environment, favorable to well-being and long-term performance.

1. 500–700 ml water + electrolytes before long/intense sessions
   
   

2. Vegetables + omega-3 source with every meal
   
   

3. Avoid ultra-processed foods before/after training

The gut microbiota, intestinal barrier, inflammation, and performance are not separate elements.
They form an integrated system.

Training the body also means training the inner ecosystem.

Protecting the gut means investing in:

• recovery
  
  

• resilience
  
  

• longevity
  
  

• sustainable performance
  
  

👉 The muscle doesn't train alone. It trains with the gut and influences the quality of the microbiota.

• Varghese, S. (2024). Physical Exercise and the Gut Microbiome: A Bidirectional Relationship Influencing Health and Performance. Nutrients, 16(21), 3663. https://doi.org/10.3390/nu16213663

• Dmytriv, T.R. (2024). Intestinal barrier permeability: the influence of gut microbiota, nutrition and exercise. Frontiers in Physiology. https://doi.org/10.3389/fphys.2024.1380713

• Mailing, L.J., Allen, J.M., Buford, T.W., et al. (2019). Exercise and the Gut Microbiome: A Review of the Evidence, Potential Mechanisms, and Implications for Human Health. Exercise and Sport Sciences Reviews, 47(2):75–85. https://doi.org/10.1249/JES.0000000000000183

• Cullen, J.M.A., Shahzad, M., Dhillon, S. (2023). A systematic review on the effects of exercise on gut microbial composition and function in humans and animals. Frontiers in Physiology. https://doi.org/10.3389/fphys.2023.1292673

• Yoon, E.J., et al. (2024). Effect of long-term endurance exercise on gut health, inflammation and intestinal barrier in non-athletes. International Journal of Molecular Sciences, 25(19):10742. https://doi.org/10.3390/ijms251910742

• Aya, V., et al. (2023). Effects of exercise and physical activity on gut microbiota in older adults: a systematic review. BMC Geriatrics. https://doi.org/10.1186/s12877-023-04066-y