I’m sure you’ve heard of the community of microorganisms living inside you called the gut microbiota. These microorganisms are as alive as you and I. It’s easy for us to pretend that they’re not there because they’re invisible to the naked eye, but I can assure you, there are literally trillions of little guys scurrying around inside of you right now as you read this article.

One would expect that our workouts have absolutely nothing to do with these critters. After all, these microbes live in our colon and so it would make sense that they’re mostly involved in our food processing and digestion. But then again, they’re also intertwined with our immune system, metabolism, hormonal balance, and even communicate with our brain. It seems the more we learn, the more that we realize that human health always comes back to the gut.

And this is true for exercise too. We all agree that exercise is good for the body. It helps with weight loss, increases your metabolism, boosts your mood and energy levels, reduces your risk of chronic diseases like diabetes, hyperlipidemia, hypertension, and can even improve your memory. We celebrate the health benefits of exercise!

Here’s what’s cool… Recent studies are suggesting that our gut microbes may be responsible for some of those health benefits. In mice we see exercise induce dramatic changes in the gut microbiota, with more bacteria that produce short chain fatty acids like butyrate. These are generally considered to be health promoting bacteria. Believe it or not, there was a forty percent increase in healthy microbes with exercise. We also see improved intestinal integrity, in other words reversal of “leaky gut.”

Recently, they convinced a team of professional rugby players to provide stool specimens in the name of science. When they compared the poo of these elite athletes to sedentary controls, they found increases in gut microbial diversity and more microbes that produce short chain fatty acids. In other words, they validated the findings from the mouse study.

Short chain fatty acids are a postbiotic produced from fibre. When we consume fibre, it passes untouched through our small intestine until it reaches our colon. This gets our microbes into a feeding frenzy. They process and digest the prebiotic fibre, and in the process release short chain fatty acids like butyrate, acetate and propionate. These SCFAs have been associated with a myriad of health benefits: weight loss, improved immune system, lower cholesterol, protection from diabetes, even improved memory. Sound familiar? Yes, those are many of the health benefits that we get from exercise.

So what we find is that Mother Nature rewards us for our hard workout with advantageous changes to our gut microbiota. We’ve heard of the brain-gut connection, but this is the muscle-gut connection. Our movement can improve (or harm) our gut microbes. And when we do it properly and stay active, the payoff is getting more SCFAs from the fibre in our diet.

I love that the currency of health is more SCFAs. It shows us that even the benefits of exercise come back to the gut. It also helps explain why you can’t outwork a bad diet. If you exercise, but you don’t consume adequate amounts of dietary fibre from plants, then you won’t be able to activate your gut microbes to create the SCFAs your body needs to stay healthy. The bottom line is that optimal health will always be the product of both diet and exercise. Hope to see you at the gym, folks!