Is There an Exercise-Intensity Threshold Capable of Avoiding the Leaky Gut?

Area of Science:

• Exercise Physiology
• Gastroenterology
• Molecular Biology

Background:

• Endurance athletes exhibit a high prevalence of gastrointestinal disorders, impacting performance and health.
• Intense exercise, particularly ultramarathons and triathlons, is linked to increased pro-inflammatory cytokines and proteins.
• A common consequence is increased intestinal permeability, or 'leaky gut', characterized by mucosal degradation.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying exercise-induced leaky gut.
• To identify safe exercise thresholds for preserving gastrointestinal integrity.
• To review the role of gut microbiota in mitigating exercise-induced gastrointestinal effects.

Main Methods:

• Analysis of molecular biomarkers such as lactulose/rhamnose ratio, tight junction proteins (occludin, claudin), lipopolysaccharides (LPS), and intestinal fatty acid-binding protein (I-FABP).
• Review of studies investigating the effects of vigorous endurance training (e.g., 60 min at 70% max work capacity) on intestinal permeability.
• Examination of contributing factors like altitude, temperature, hydration, age, and trainability.

Main Results:

• Vigorous endurance training is shown to induce leaky gut responses.
• Several molecular markers indicate increased intestinal permeability and mucosal degradation post-exercise.
• Factors beyond exercise intensity, including environmental and individual variables, may exacerbate these effects.

Conclusions:

• Understanding exercise-induced leaky gut mechanisms is crucial for defining safe training limits.
• Moderate exercise and dietary interventions (probiotics, prebiotics) may enhance intestinal health.
• The gut microbiota plays a significant role in the gastrointestinal response to physical activity.