Connect with us


There’s New Data on How Antibiotics Affect Your Workout



“], “filter”: { “nextExceptions”: “img, blockquote, div”, “nextContainsExceptions”: “img, blockquote”} }”>

It’s no surprise that most people don’t feel great at the gym when they’re taking antibiotics. After all, if you’re taking them, that generally means that you’re either ill or just getting over an illness. But lately there’s been a surge of scientific interest in the idea of a gut-muscle axis, which posits that the microbes in your intestines are affected by physical activity and, in turn, affect your ability to perform physical activity. That raises an interesting question: do antibiotics, which wipe out large swaths of your gut flora, have a direct effect on athletic performance?

There have been a bunch of studies supporting the idea of a two-way gut-muscle axis, mostly in mice. Transplanting fecal bacteria from unusually healthy older humans into mice makes them stronger. Eliminating gut bacteria in mice with a wide-spectrum antibiotic reduces running endurance. Most prominently, in 2019, a lactate-eating bacteria found in the poop of Boston marathoners made mice faster. But when you move past the headlines, the actual research remains confusing and contradictory: every study seems to find a different magic microbe.

RELATED: The Microbiome and Athletic Performance

The good news, then: two new studies on the effects of antibiotics on exercise reach similar conclusions. There are still plenty of caveats—both studies are in mice, for one thing. But they suggest an interesting twist: the biggest athletic effect of antibiotics may be on the brain, not the muscles.

The first study, led by Monica McNamara and Theodore Garland of the University of California, Riverside and published in Behavioural Processes, compared two different types of mice. One was the famous High Runner line. Back in 1993, researchers began selecting mice who showed unusually high levels of voluntary wheel running and breeding them with each other. The mice in the UC Riverside study are from the 89th generation of this program, and they now choose to run about three times as much daily as mice from the control group, who come from the same original group of mice but weren’t selectively bred for running.

After two weeks of baseline wheel-running, the mice were put on broad-spectrum antibiotics (meaning they wiped out most gut bacteria rather than just certain strains) for ten days. Here’s what their average “running log” looked like, measured in revolutions of the wheels in their cages:

(Illustration: Behavioural Processes)

The daily distance drops by 21 percent in the High Runner mice, and doesn’t return to normal during the subsequent 12 days. In the control mice, on the other hand, nothing seems to change. Neither group showed any evidence of being sick: their weight and food consumption were unaffected. This suggests that some part of whatever it is that’s been bred into the High Runner mice is affected by antibiotics.

One possibility is that this is a gut-muscle axis effect. The High Runner mice have some sort of microbial advantage—something like the lactate-eating microbe from Boston marathoners—that makes running physically easier for them, which is why they run so much. Take that edge away, and running isn’t as much fun, so they do less of it.

The other possibility is that it’s the gut-brain axis in action. McNamara cites some previous research showing that the gut microbiome can influence motivation and reward circuitry in the brain: antibiotics affect how certain amino acids are absorbed from the gut into the bloodstream, after which they travel to the brain where they’re transformed into brain chemicals such as dopamine and serotonin. McNamara’s experiment can’t distinguish between these two possibilities, but either way the motivation to exercise seems to be blunted.

RELATED: What Inspires These 7 Outdoor Athletes

The second study, led by Noah Hutchinson and Jeffrey Woods of the University of Illinois at Urbana-Champaign and published in Medicine & Science in Sports & Exercise, has a similar setup. They compared normal lab mice with and without broad-spectrum antibiotics, plus a group of “germ-free” mice that were specially bred from birth to have no microbiome at all. In this case, the researchers were interested in how the antibiotics affected training adaptations: after six weeks of voluntary wheel-running, would the antibiotic and germ-free mice gain as much fitness as the control group? Their hypothesis was no.

Once again, voluntary wheel running was reduced in the antibiotic group by 22 percent, and was 26 percent lower in the germ-free group. Here’s what their daily mileage tallies looked like (squares are the control group, circles are on antibiotics, and triangles are germ-free):

(Illustration: Medicine & Science In Sports & Exercise)

But their response to this training tells a slightly different story. In a treadmill test to exhaustion, the antibiotic mice improved similarly to the non-antibiotic mice (their improvement was slightly smaller, but the difference wasn’t statistically significant, and would be expected anyway since they chose to run less during the training period). Moreover, tests of gene expression and muscle properties also found that the antibiotic group fared just as well.

The germ-free mice, on the other hand, didn’t improve as much after the training period. Since the antibiotic group wasn’t affected by its lack of microbiome, this suggests that the germ-free mice had some sort of pre-existing developmental deficit thanks to growing up without a microbiome that compromised their ability to respond to training.

The practical takeaway, according to Hutchinson and his co-authors, is that if you need to go on antibiotics in the lead-up to an important competition, it’s unlikely that it will affect your training adaptations or your performance. I think that’s a reasonable and reassuring position, bearing in mind all the uncertainties inherent in applying mouse studies to human behavior.

But it’s the apparent change in motivation to exercise that really intrigues me. Is there something there that helps explain who among us ends up as a High Runner? If so, can we manipulate it? It’s easy to see how you could get caught up in the excitement around potential new probiotic supplements that alter not just your ability but also your desire to exercise. Garland, in a UC Riverside press release, hints at that possibility. But his advice, for now, is suitably grounded in the current reality. If you want a healthy microbiome, he suggests, you should eat a balanced diet and exercise regularly.


For more Sweat Science, join me on Twitter and Facebook, sign up for the email newsletter, and check out my book Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance.

Continue Reading

Recent News

Crypto Staking Crypto Staking
Crypto19 hours ago

Is it Possible To Make Money On Crypto Staking in 2024?

In the modern world, cryptocurrencies and blockchain technologies are becoming increasingly popular, attracting the attention of investors and users from...

Lake Como Lake Como
Wedding19 hours ago

How to Choose the Right Location for a Marriage Proposal in Italy and Lake Como

Proposing marriage is a unique and memorable moment in a couple’s life. Choosing the right location is crucial to creating...

Personal Injury Lawyer Personal Injury Lawyer
Law4 days ago

Finding the Best Personal Injury Lawyer in Lumberton, NC

Personal injury law is designed to protect individuals who have been harmed due to the negligence or wrongful actions of...

WhatsApp Business WhatsApp Business
Business5 days ago

Running WhatsApp Business with Pro+VPS for Android Emulator

WhatsApp Business is one of the most powerful tool for Business to manage customers communication. Running it can enhance the...

Civil Partnership Visa Civil Partnership Visa
Finance6 days ago

Civil Partnership Visa vs Spouse Visa: Which One is Right for You

Choosing the right visa to join your partner in the UK can be confusing. Two common options are the Civil...

Crypto Crypto
Crypto7 days ago

Staked Crypto – A Step-by-Step Guide for Beginners

Ethereum staking has become an increasingly popular way for cryptocurrency holders to earn passive income through staking rewards. In this...

Ethereum Staking Ethereum Staking
Crypto1 week ago

Maximizing Ethereum Staking Rewards: Tips and Tricks

Are you looking to maximize the potential of your Ethereum holdings? Stake Ethereum using OkayCoin and take advantage of the...

Wedding Wedding
Wedding1 week ago

4 Wedding Services You Can Quickly Check Off Your To-Do List

Organizing a wedding might like arranging a large-scale symphony, in which each element must work together to produce a beautiful...

Luxury Shopping Luxury Shopping
Lifestyle1 week ago

Luxury Shopping in Ibiza: A Guide to the Finest Boutiques

Ibiza is synonymous with lavish lifestyles, sun-soaked beaches, and electrifying nightlife. But beyond the party scene and stunning seascapes, the...

Indian Brides Indian Brides
Fashion2 weeks ago

Top Trends in Diamond Necklaces for Indian Brides

As Indian brides gear up for their big day, the selection of the perfect diamond necklace is crucial. Diamond necklaces...