Endurance Athletes And Their Lactate-Consuming Athletic Gut Bacteria
There are hypotheses that athletes, particularly endurance athletes can alter their microbiome to include species of bacteria which aid in and flourish from their athletic pursuits.
The human microbiome (the microorganisms that reside within the human body) is known to influence human health. Previous research has associated exercise with changes in the microbiome, but the effects of these changes on athletic performance have remained unknown.
The scientific body understands that not only does the human microbiome influence health in sometimes startlingly strong ways, but also that certain behavioral changes in lifestyle, diet, and environmental factors can alter the species of bacteria which live in and upon the human body.
A study published online this week in Nature Medicine. suggests specific bacteria in the gut microbiome of elite runners may contribute to enhanced athletic performance.
Lactate: Friend, Foe, and Fuel
Aleksandar Kostic from the Joslin Diabetes Center in Boston Massachusetts and his colleagues used their city’s famous marathon to study the bacterial changes in the participants’ microbiome.
Analyzing stool samples from 15 runners of the Boston Marathon, Kostic et al. found that the bacterial genus Veillonella became more abundant in the stools of marathoners post-exercise. This was later replicated in a cohort of 87 human athletes.
In another experiment, strains of Veillonella from the marathon runners was isolated and administered to 16 mice, who were found to outperform control-group mice by 13% on laboratory treadmill tests for fitness.
What was also interesting was that Veillonella possessed all the genetic equipment necessary to consume lactate.
Anyone who spent time in and around athletics in high school will recognize the word lactate, as it’s traditionally been seen as a marker for muscle fatigue and exhaustion. Lactate is a metabolite that’s sometimes confused with lactic acid, a byproduct which does in fact cause muscle fatigue.
Otto Meyerhoff, the German biochemist who was awarded the Nobel Prize for Medicine in 1922 for his study of glycolysis was the first to study lactate in detail. Conducting experiments on a frog in a jar, he found that when he stimulated the muscles in the amphibian’s leg to move, they would produce lactate. Over time the lactate would build, and the frog leg would enter an acidotic state, meaning it was full of lactic acid.
He concluded that lactate must be a sign of fatigue in muscles. But modern science understands that lactate is produced as a form of preferred energy for muscle cells in an aerobic state. Dr. George Brooks Ph.D. has wrote extensively on this topic.
He explains that as an energy source, lactate is taken to the mitochondria through a pathway known as the lactate pathway, where upon it undergoes oxidation. The burn associated with muscle fatigue is the result of passing beyond what Brooks called the lactate threshold: the level at which lactate clearance falls behind the speed of lactate production.
Humans who aren’t well-trained to take in and utilize oxygen the way a marathon runner can, obviously have less oxygen in their body for the purpose of oxidizing lactate in their mitochondria. Meyerhoff’s frog was in an oxygen-deficient environment stuck in its jar, therefore the lactate could not be oxidized and so turned into lactic acid.
Professional endurance training has been shown to lead to a doubling in the numbers of both mitochondria and lactate transporters, meaning there are more places for the lactate to go and more transporters to take it there.
Dr. Brooks found that when inundated with lactate, incubated muscle tissues up-regulate 600 genes associated with things like mitochondrial biogenesis and protein synthesis, suggesting that it is getting one’s body acclimated to using lactate as an energy source over long periods which causes this doubling effect.
Dr. Brooks’ research might be enhanced by the work of Aleksandar, as the new studies punctuates another form of lactate utilization for the benefit of aerobic exercise.