Gut Microbiota and Endurance Performance: A New Frontier in Sports Science

In 2015, a Harvard University study found that Boston Marathon runners harbored a specific bacterium in their guts—Veillonella atypica—that was rarely found in others. When researchers transferred this bacterium to mice, the mice’s endurance improved by approximately 13%. This finding stunned the sports science community and opened up a new field of research: the relationship between gut microbiota and athletic performance.

Gut Microbiota Basics

Scale

The human gut contains approximately 100 trillion bacteria, belonging to over 1,000 species. The total weight of these microorganisms is about 1.5–2 kg, and their gene count is 150 times that of the human genome.

Athletes vs. General Population: Gut Differences

Multiple studies have compared the gut microbiota of professional athletes and sedentary individuals:

Mechanisms by Which Gut Microbiota Affect Cycling Performance

1. Energy Metabolism

Short-chain fatty acids (SCFAs):
Propionate and butyrate produced by gut bacteria fermenting dietary fiber:

• Propionate can enter circulation and serve as a substrate for gluconeogenesis (synthesizing glucose)
• Butyrate is the primary energy source for gut epithelial cells
• Some studies suggest that a higher abundance of propionate-producing bacteria in athletes’ guts may support endurance

2. Immune Modulation

A stronger immune system = fewer illnesses = more consistent training:

• Good gut microbial diversity is associated with a stronger immune response
• High-training-volume cyclists (at increased risk of immunosuppression) particularly need gut health support

3. Inflammation Control

Chronic low-grade inflammation is a major enemy of recovery:

• Gut bacteria help regulate systemic inflammation levels
• Microbial imbalance (dysbiosis) is linked to chronic inflammation

4. The Gut-Brain Axis

The gut and brain are directly connected via the vagus nerve:

• Gut microbiota influence the production of neurotransmitters (serotonin, dopamine)
• May affect perceived exertion (RPE) during exercise
• The “gut feeling” during cycling is partly determined by microbial status

The Impact of High-Intensity Cycling on the Gut

Cycling itself is a stressor for the gut:

Exercise-Induced Gastrointestinal Syndrome

During high-intensity cycling (>70% VO2max):

• Gut blood flow decreases by 50–80% (blood is redistributed to muscles)
• May lead to increased intestinal permeability (“leaky gut”)
• Bacterial endotoxins (LPS) may enter the bloodstream, triggering inflammation
• Gastrointestinal discomfort is a common issue in long-distance cycling and triathlon events

Strategies for Optimizing Gut Microbiota

Dietary Strategies

Increase dietary fiber:

• Target: 25–35 grams of dietary fiber per day
• Diverse sources: vegetables, legumes, whole grains, fruits
• Taiwan recommendations: oats, brown rice, sweet potatoes, legumes, and a variety of vegetables

Fermented foods:

• Yogurt, kefir
• Taiwanese traditional options: fermented tofu, kimchi, miso soup
• Research shows: one serving of fermented food per day can increase microbial diversity

Reduce ultra-processed foods:

• Emulsifiers and preservatives may disrupt gut microbiota
• High-sugar diets promote the proliferation of harmful bacteria

Probiotic Supplementation

Research-supported strains:

Notes:

• Probiotic supplementation requires consistency (effects disappear after stopping)
• Individual responses vary greatly
• Choose products with third-party certification

Training-Related Strategies

Progressive increases in training load:

• Sudden large increases in training volume (especially high-intensity) negatively affect gut microbiota
• Following the principle of progression also protects gut health

Post-exercise replenishment:

• The post-training “metabolic window” also applies to gut health
• Recovery meals containing protein and prebiotics support gut repair

The Gut Advantages of the Taiwanese Diet

Traditional Taiwanese cuisine contains many gut-friendly elements:

• Tofu and legumes: quality plant protein and dietary fiber
• A variety of vegetables: diverse polyphenols and fiber
• Fermented foods: traditional fermented products such as soy sauce and fermented tofu
• Sweet potatoes: quality prebiotics that promote the proliferation of beneficial bacteria

Conclusion

Gut microbiota research is the most exciting new frontier in sports science. Although the era of “eat this bacterium to make you faster” has not yet arrived, the association between a healthy, diverse gut microbiota and better endurance performance, faster recovery, and stronger immunity is becoming increasingly clear. Starting today, eat more dietary fiber and fermented foods—invest in your “gut competitive advantage.”

Related Reading

• Microbiome Research in Cycling: The Impact of Endurance Training on Gut Microbiota
• Gut Microbiota and Endurance Performance: Your Gut Bacteria May Be Stealing Your Power
• The Association Between Gut Microbiota Composition and Endurance Performance: A Study on Energy Supply from Short-Chain Fatty Acids
• Exercise and Gut Microbiota: An Emerging Performance Factor—The Second Engine from Endurance to Recovery