Antibiotics Can Ruin Your Motivation and Endurance

The elimination of intestinal microorganisms reduces the motivation and ability to exercise.

According to a recent study, antibiotics destroy essential gut bacteria, destroying motivation and endurance in athletes. According to a mouse study conducted by the University of California, Riverside, a significant element that differentiates athletes from sedentary people is their microbiome.

This study is one of the few to look at how gut bacteria also influence voluntary exercise habits. While other studies have looked at how exercise affects the microbiome, this one looks at the opposite. Both athletic prowess and motivation are necessary for voluntary exercise.

The researchers’ results were recently published in the journal behavioral processes.

“We believed 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, a UCR evolutionary physiologist whose lab studied conducted the investigation. “Our study reinforces this belief.”

The researchers used fecal samples to show that, after 10 days of antibiotic treatment, the gut bacteria of two groups of mice — those bred for high levels of running and some that were not — were reduced.

Both groups of mice showed no symptoms of disease after antibiotic therapy. Therefore, the researchers were convinced that damage to the microbiota was to blame when the running of the wheels in the athletic mice was reduced by 21%. The tall running mice also failed to regain their running behaviors 12 days after the antibiotic treatment ended.

Both during and after treatment, the behavior of normal mice did not change significantly.

“An occasional athlete with a minor injury would not be affected much. But in a world-class athlete, a small setback can be magnified much more,” said Monica McNamara, a UCR doctoral student in evolutionary biology and first author of the paper. “That’s why we wanted to compare the two types of mice.” Eliminating the normal gut microbiome could be likened to an injury.

One way the microbiome might affect exercise in mice or humans is through its ability to transform carbohydrates into chemicals that travel through the body and affect muscle performance.

“The metabolic end products of bacteria in the gut can be reabsorbed and used for fuel,” Garland said. “Less good bacteria means less available fuel.”

In the future, the researchers would like to identify the specific bacteria responsible for increased athletic performance. “If we can identify the right microbes, there’s the potential to use them as a therapy to help average people exercise more,” Garland said.

Lack of exercise is known to be a major risk factor for 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 it successfully.

“Although we are studying mice, their physiology is very similar to that of humans. The more we learn from them, the better our chances of improving our own health,” Garland said.

Certain foods can also increase desirable gut bacteria. While the research on “probiotics” develops, Garland recommends that those interested in promoting overall health maintain a balanced diet in addition to regular exercise.

“We know from previous studies that the high-fat, high-sugar Western diet can have a negative effect on gut biodiversity and probably, by extension, on athletic ability and possibly even exercise motivation,” Garland said.

Reference: “Oral Antibiotics Reduce Voluntary Exercise Behavior in Athletic Mice” by Monica P. McNamara, Marcell D. Cadney, Alberto A.Castro, David A. Hillis, Kelly M. Kallini, John C. Macbeth, Margaret P. Schmill, Nicole E. Schwartz, Ansel Hsiao, and Theodore Garland Jr., May 4, 2022, behavioral processes.
DOI: 10.1016/j.beproc.2022.104650