How a Marathoner's Microbiome Boosts Performance
Groundbreaking research reveals a surprising new player in athletic performance: the gut microbiome
For decades, athletes and scientists have focused on the heart, lungs, and muscles as the keys to athletic performance. But groundbreaking research reveals a surprising new player: the gut microbiome. In a fascinating discovery, scientists have found that elite athletes host a special microbe that turns exercise-induced waste into a powerful performance enhancer, uncovering a hidden athletic advantage that begins in the gut.
This story starts with marathon runners and their gut bacteria, leading to a remarkable finding that could change how we understand human performance.
At the center of it all is lactate—a molecule long misunderstood as merely a fatigue-causing byproduct of intense exercise.
The discovery of a bacterium called Veillonella reveals that lactate is not the body's waste product we thought it was, but rather a valuable fuel source that, with the right gut microbes, can significantly boost endurance.
For nearly a century, lactate (often mistakenly called "lactic acid") was viewed primarily as a fatigue-causing waste product that builds up in muscles during intense exercise 9 . This misconception dates back to 1920s experiments with frog muscles in oxygen-free jars 9 .
The modern understanding, pioneered by scientists like George Brooks and his "lactate shuttle" theory, reveals that lactate is not a dead-end waste product but an important energy source that muscles and organs can use directly as fuel 9 .
Muscle Production
Fuel for Heart
Brain Energy
During intense exercise, working muscles produce lactate, which can then be shuttled to other muscles, the heart, liver, and brain as a preferred energy source 9 .
This revised understanding of lactate as a valuable metabolic intermediate set the stage for the remarkable discovery of how our gut microbes interact with this energy-rich compound.
The story begins when researchers noticed something peculiar about the gut bacteria of marathon runners. When scientists analyzed stool samples from 15 athletes who ran the 2015 Boston Marathon, they made a curious finding: one type of bacteria showed a significant increase in abundance after the marathon compared to before the race 1 6 .
The bacterium was from the genus Veillonella, and it appeared to thrive in the post-marathon environment 1 6 . This correlation was intriguing, but correlation doesn't equal causation.
The critical question remained: was this simply an interesting observation, or was Veillonella actually contributing to athletic performance?
To test whether Veillonella was merely associated with exercise or actually contributing to performance, researchers designed an elegant experiment with mice 1 6 . They isolated a specific strain of Veillonella atypica from one of the marathon runners and introduced it into mice, using another bacterium (Lactobacillus bulgaricus) that cannot metabolize lactate as a control.
How does a gut bacterium make mice run longer? The answer lies in a sophisticated metabolic partnership between host and microbe.
To further solidify these findings, the research team performed shotgun metagenomic sequencing on additional cohorts of elite athletes, including ultra-marathoners and Olympic trial rowers 6 . The results consistently showed that after exercise, athletes had higher levels of every gene required for the metabolic pathway that converts lactate to propionate 6 .
To uncover these findings, scientists employed sophisticated laboratory tools and materials. The table below outlines some key resources essential to this field of research.
| Research Tool | Function in the Research |
|---|---|
| Shotgun Metagenomic Sequencing | Analyzed genetic material from athlete gut microbiomes to identify bacterial genes and metabolic pathways 1 6 . |
| 13C3-labeled Lactate | Tracked how lactate moves from blood into the gut; the "heavy" carbon atoms allowed researchers to follow the lactate's pathway 1 6 . |
| Liquid Chromatography-Mass Spectrometry (LC-MS) | Precisely measured metabolites like lactate and propionate in blood, gut contents, and bacterial cultures 1 6 . |
| Germ-Free or Gnotobiotic Mice | Mice with controlled gut microbiomes allowed researchers to test the specific effects of Veillonella by comparing them to control bacteria 1 6 . |
| Generalized Linear Mixed Models (GLMMs) | Statistical method that accounted for individual variations while identifying significant changes in bacterial abundance related to exercise 6 . |
Advanced sequencing techniques revealed microbial genes and pathways.
Isotope labeling allowed precise tracking of lactate metabolism.
Controlled experiments with mice established causality.
While this research began with elite athletes, its implications extend far beyond the running track. The discovery reveals a previously unknown aspect of human physiology: an internal "metabolic sink" for lactate in our gut 6 . This system may help the body manage lactate more efficiently during physical exertion.
Stanford researchers discovered that a molecule called lac-phe (formed from lactate and the amino acid phenylalanine after intense exercise) acts as an "anti-hunger" signal, helping explain how exercise contributes to weight control 5 .
The ongoing exploration of lactate's roles continues to yield surprises. Recent studies show that lactate not only serves as fuel but can also influence gene expression through a process called lactylation, where lactate molecules modify proteins and histones, potentially affecting how cells read DNA 2 . This epigenetic mechanism represents another exciting frontier in understanding lactate's full biological significance.
The discovery of the Veillonella-lactate partnership represents a paradigm shift in human physiology. It reveals that our physical capabilities aren't determined solely by our own cells but are enhanced by the trillions of microbial partners we host. This hidden athlete within—the gut microbiome—works in concert with our bodies to optimize performance in ways we're only beginning to understand.
Future research may explore how to safely harness this microbial partnership to help not only elite athletes but also patients with metabolic conditions or others who struggle with physical endurance. What's clear is that the road to better performance may not lie solely in training harder but in better understanding and nurturing the microbial ecosystems within us.
As we continue to unravel the complex dialogue between our bodies and our microbes, each discovery reminds us that we're not solitary organisms but complex ecosystems—and that peak performance, like health itself, emerges from partnership at the most fundamental level.