New research shows that by killing essential gut bacteria, antibiotics wreak havoc on athletes’ motivation and endurance. The mouse study conducted by UC Riverside suggests that the microbiome is an important factor separating athletes from couch potatoes.
Other studies have looked at how exercise affects the microbiome, but this study is one of the few to look at the converse -; how gut bacteria also impact voluntary exercise behaviors. Voluntary exercise involves both motivation and athletic ability.
The researchers’ methods and results are now detailed in the journal Behavioral processes.
“We thought that 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 Theodore Garland, physiologist at evolution of the UCR in whose laboratory the research was conducted. “Our study reinforces this belief.”
The researchers confirmed through fecal samples that after 10 days of antibiotics, gut bacteria were reduced in two groups of mice: some elevated for high levels of running, and some not.
Neither group of mice showed signs of pathological behavior following antibiotic treatment. So when wheel travel in sports mice was reduced by 21%, the researchers were certain that damage to the microbiome was responsible. Moreover, the high runner mice did not regain their running behavior even 12 days after the antibiotic treatment was stopped.
The behavior of normal mice was not significantly affected either during treatment or after.
Occasional exercise with a minor injury would not be affected much. But on a world-class athlete, a small setback can be amplified much more. That’s why we wanted to compare the two types of mice.”
Monica McNamara, UCR PhD candidate in evolutionary biology and first author of the paper
Knocking out the normal gut microbiome could be compared to an injury.
One of the ways the microbiome could affect exercise in mice or humans is its ability to convert carbohydrates into chemicals that pass through the body and affect muscle performance.
“The metabolic end products of bacteria in the gut can be reabsorbed and used as fuel,” Garland said. “Less good bacteria means less fuel available.”
In the future, researchers would like to identify the specific bacteria responsible for increasing athletic performance. “If we can identify the good microbes, there’s the possibility of using them as therapeutics to help average people exercise more,” Garland said.
Lack of exercise is known to be a major risk factor for certain aspects of mental health, including depression, as well as physical health, including metabolic syndrome, diabetes, obesity, cardiovascular disease, cancer and osteoporosis. Many in the public health community would like to promote exercise, but few have found ways to do so successfully.
“Although we study mice, their physiology is very similar to that of humans. The more we learn about them, the better our chances of improving our own health,” Garland said.
Certain foods can also increase desirable gut bacteria. As research into “probiotics” grows, Garland recommends those interested in promoting overall health maintain a balanced diet in addition to regular exercise.
“We know from previous studies that the Western diet, high in fat and sugar, can have a negative effect on the biodiversity of your gut and probably, by extension, on athletic ability and perhaps even motivation to exercise,” Garland said.