antibiotics may interfere with high-performance running: study

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a group of mice bred for running weren't able to recover to their pre-antibiotic level of ability during the study, but the less athletic mice saw no decrease in running ability.

by chris arnold

published jun 03, 2022

last updated feb 20, 2025

3 minute read

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3 minute read

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antibiotics may interfere with high-performance running: study

researchers say antibiotics can interfere with digestive processes and muscle function. getty

antibiotics have many benefits in the body, like slowing the growth of bacteria and preventing infection. but researchers from the university of california, riverside, say antibiotics can kill essential gut bacteria and decrease athletic motivation and endurance.

“we believed an animal’s collection of gut bacteria, its microbiome, would affect digestive processes and muscle function, as well as motivation for various behaviours, including exercise,” theodore garland, distinguished professor of biology, university of california and principal investigator on the study, said in a statement.

the researchers say that belief is reinforced in their findings, published in the journal behavioural processes.

the team monitored fecal samples from two groups of mice after the animals were provided with antibiotics for 10 days. (the first group of mice was not bred for running, the second was.) they found both groups of mice experienced a decrease in gut bacteria,

the two groups then ran on a wheel, where the researchers saw a decreased athletic performance of 21 per cent in the runner group when compared to their pre-antibiotic distance. none of the mice had shown any signs of illness or impairment before running.

high-performance group not back to pre-antibiotic levels 12 days later

the group of runner mice wasn’t able to recover to their prebiotic level of ability even 12 days after stopping antibiotics. the regular, less athletic group of mice saw no decrease in running ability.

“a casual exerciser with a minor injury wouldn’t be affected much. but on a world-class athlete, a small setback can be much more magnified,” monica mcnamara, first author of the study, said. “that’s why we wanted to compare the two types of mice.”

the researchers theorize that in the high-performance runners, bacteria can help turn carbohydrates into chemicals 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.”

next, the researchers plan on trying to identify which specific bacteria are responsible for the performance impact. it’s possible that if they can pinpoint which bacteria boost performance, it could be used as a therapy to help people exercise more.

fecal microbiota transplants may reverse signs of aging

other types of bacteria have already been transplanted in mice, and have been found to improve age-related health declines when transplanting from a young mouse to an old mouse.

when researchers transplanted fecal microbes from a young mouse to an old mouse, the elderly creatures saw age-associated inflammation in their eyes and central nervous system reduce, as well as benefits to their immune system and eye function.

those researchers, from the quadram institute and the university of east anglia, caution against fecal transplants in humans for the time being, however, at least until it’s deemed to be safe.

people who don’t exercise are known to have an increased risk for mental health issues like depression, as well as physical health issues such as diabetes, obesity, and cardiovascular disease.

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

it’s also possible that the food we eat may play a role in development of desirable gut bacteria. although research into probiotic foods is still new, garland says maintaining a solid diet and exercise routine is key.

“we do know from previous studies that the western diet, high in fat and sugar, can have a negative effect on biodiversity in your gut and likely, by extension, on athletic ability and possibly even on motivation to exercise,” garland said.