How Does Exercise Affect Our Microbiome? A Gastroenterologist Explains

When it comes to exercise and your health, you'll be hard-pressed to find someone who will dispute that it's good for your health. Study after study has proved the benefits—weight loss, improved mood and cognitive function, stronger bones and muscles (duh!), deeper sleep, and lower risk of heart disease and various types of cancer. Not to mention it can help you discover sex that's off the charts.

ICYMI, the power of the microbiome—which are nearly 40 million bacteria strong inside your gut—has been a hot topic lately. Sure, they aid in digestion and, yes, they also help with the absorption of nutrients. Your gut microbiome also promotes glorious bowel movements that are so good you'll want to tell your friends. (But, yeah, it could make for awkward conversation, so maybe keep that one to yourself.)

It also contributes to your metabolism, balances hormones, strengthens the immune system, and helps keep your mind sharp and mood optimistic. There's very little that occurs in the body that does not involve those microscopic microbes inside our colon in some fashion.

All of that is to say that your gut microbiota is basically the director, producer, and star when it comes to the movie featuring an inside look at human health. It's common to think of diet as being the chief determinant of the microbiome because it comes into direct contact with and is processed by gut microbes. After all, the idea that something—like exercise—that never directly enters our intestine could influence our microbial makeup seems much more far-fetched.

Here is what we know: During a 2016 study, researchers discovered that exercise caused dramatic gut microbiota changes1 in mice. They specifically noticed increased microbial diversity, improved intestinal integrity, and more short-chain-fatty-acid (SCFA)-producing microbes.

What's all of that mean? Well, since I know you're a fan of gut health like I am, you can probably guess that it's pretty powerful. Let's unpack it.

Microbial diversity2 is generally considered an indicator of gut health. A more diverse microbiota is more adept at doing what you need it to do. A less diverse microbiota is less capable, and it comes as no surprise that loss of diversity has been associated with the onset of diseases3 such as Crohn's disease, ulcerative colitis, type 1 diabetes, obesity, and even colorectal cancer.

Another aspect of the study was that oh-so-gorgeous boost in SCFA-producing microbes. As you might know, SCFAs are key to gut health. Not only do they reverse leaky gut themselves, but they also have myriad healing effects throughout the body, including an improved immune system and decreased cancer risk.

So, exercise has the ability to strengthen your gut and enhance SCFA release, which is great news. But does it work both ways? Do microbes play any role in exercise performance?

A recent study5 would suggest that, yes, indeed they do.

Nature Medicine5 published the study, noting that researchers identified a specific bacterial strain called Veillonella atypica that was dramatically increased in marathon runners post-marathon. What's cool is that this particular bacteria has the ability to break down lactic acid, which is the acid that builds up in muscles during endurance exercise. Makes sense, right?

When the scientists transferred this particular bacteria into mice, they found that the recipients had improved treadmill run time performance. Yes, they performed better athletically based purely on the presence of this microbe.

 Sure, it's an exciting finding in the world of marathon running, but what I'm most excited about is to see what we find when we study different sports. Is there a special microbe that enhances the start/stop movements in basketball or that promotes muscle recovery after a vigorous workout? My guess is the answer will be yes—but only time will tell.