A link between how exercise affects the gut microbiome was established through previous trials and researchers have now been able to see how the gut affects exercise. Scientists from the University of California at Riverside found when antibiotics kill off bacteria in the gut it can also kill an athlete’s motivation and endurance.
Researchers worked with two groups of mice to determine how the gut microbiome affects voluntary exercise behaviors, which includes motivation and athletic ability. They discovered a direct correlation in athletic mice but there appeared to be no discernable difference in regular mice.
"We believed an animal's collection of gut bacteria, its microbiome, would affect digestive processes and muscle function, as well as motivation for various behaviors, including exercise," said UCR evolutionary physiologist Theodore Garland. "Our study reinforces this belief."
Scientists used a group of mice that were bred for high levels of running and a group that was not. They were all on antibiotics for 10 days and afterward were checked to see what remained of their gut bacteria. Fecal samples showed the antibiotics wiped out almost all of the intestinal bacteria from the mice.
None of the mice exhibited any outward signs of sickness or adverse reactions to the 10 days of antibiotics. But afterward, the athletic mice saw a 21 percent reduction in wheel running, which the researchers attributed directly to the damaged microbiome. And those mice did not even recover their previous performance capabilities 12 days after the antibiotics had been stopped.
The behavior of the other set of mice did not appear to be affected much at all. It was only in the mice which were bred for enhanced athletic performance.
"A casual exerciser with a minor injury wouldn't be affected much," said researcher and study author Monica McNamara. "But on a world-class athlete, a small setback can be much more magnified. That's why we wanted to compare the two types of mice."
She equated killing off the normal gut bacteria to an injury. A possible way the gut microbiome may affect exercise is through the process of transforming carbohydrates into substances that impact muscle performance.
"Metabolic end products from bacteria in the gut can be reabsorbed and used as fuel," Garland said. "Fewer good bacteria means less available fuel. If we can pinpoint the right microbes, there exists the possibility of using them as a therapeutic to help average people exercise more."