Benefits of Strength Training for Gut Microbiota

We know that strength training is a pillar of longevity for its role in preserving muscle mass. And that practicing sports regularly, including cardiovascular activity, improves brain health, especially regarding memory. Less known is the role of strength training in gut microbiota health. 

Tamara Pazos, a neurobiologist and science communicator, and the pharmacist and nutritionist Marián García, popularly known as Boticaria García, discussed this interesting connection at a recent gathering of nutritionists, doctors and researchers in microbiota and longevity organized by Activia. A session that had everything: exercise physiology, metabolism and those chemical reactions in which the microbiota plays a lead role.

If you want to contribute to the menu of your gut-friendly bacteria, it is not enough to eat probiotics and prebiotics. It is a good moment to grab the dumbbells and start training.

What feeds the microbiota?

The bacteria in our gut are as discerning as humans and have their preferences when it comes to food. On one hand, there are bacteria from the Bifidobacterium or Lactobacillus strains, which like to ferment the fibers and carbohydrates in our diet. “From those nutrients they produce lactate (lactic acid) and acetate as metabolic waste products,” explained the neurobiologist Tamara Pazos. These bacteria are present in yogurt and kefir.

Then there are other, more gluttonous strains, such as Anaerostipes, Anaerobutyricum and certain species of Eubacterium, which “take advantage of that lactate and transform it into butyrate.”

When these groups live in balance, lactate levels in the intestine remain stable. But if the second group does not perform its function well or is not abundant enough, lactate begins to accumulate. And that’s a problem because lactate is an acid, so the gut pH drops and that acidification kills many of the “good” bacteria. In other words: it ends up translating into intestinal dysbiosis with bloating, gas and other digestive troubles.

Silence: here it is recycled

This peculiar way of recycling energy substrates from our microbiota is called cross-feeding. While an excess of lactate can cause digestive problems, a surplus of butyrate is good news for the colon. “Butyrate is the colon’s favorite fuel and vital to preserve the intestinal barrier,” the neurologist continues.

Here come into play the colonocytes. These are the cells that line the internal wall of the colon and prevent what passes through that tube (toxins, remnants of bacteria or small undigested food particles) from escaping.

Preventing anything from leaving the gut

The scientific term for this is intestinal permeability. If that happens and those substances accidentally end up in the bloodstream, the immune system identifies them as potential invaders and triggers its defense mechanism: inflammation.

That is why it is so important that the colonocytes are healthy, well fed “and tightly joined, forming a solid intestinal barrier,” notes Boticaria García.

And what does a colonocyte eat? Butyrate. “If they are well fed because they have plenty of butyrate, we will avoid a leaky gut. Moreover, a healthy and well-nourished microbiota strengthens the immune system,” adds Pazos.

And, at last, the moment for the dumbbell

All of the above may sound like a biology class lesson. But it is vital to understand the curious relationship between what happens in the gym and our gut microbiota. Boticaria García explains that “while I do my biceps curl or my set of squats I am producing lactate. That lactate travels through the bloodstream to the intestine and, as we have seen, it is loved by our good microbiota bacteria. They take care of transforming it into butyrate.”

So “training not only benefits the arm, it also improves the health of the microbiota.” 

Happy muscle, young brain

If there is something that fascinates Boticaria García, as a good pharmacist she is, it is chemical reactions and the connections between enzymes and metabolites. Without letting go of the dumbbell she recalls that that “butyrate that colonocytes love so much is not only an energy source for cells. It also acts as a signaling molecule that activates the gene responsible for producing BDNF. Then our brain cells start producing more BDNF and there we have more synapses, more neurons and longevity for our brain.

Moreover, she reminds that strength training, “with intensity, but not going overboard, since stress isn’t good either, generates a type of exerkines I like to call superkinases.” These molecules have anti-inflammatory and immunomodulatory effects. “Among those superkinases generated during strength training is irisin. This irisin travels to the brain, crosses the blood-brain barrier and also stimulates the production of Brain-Derived Neurotrophic Factor (BDNF), another exerkine that will make us have more neurons, i.e., more memory,” continues Boticaria García.

Excited by this peculiar double connection between strength training, the microbiota and brain health, she uses an easy-to-understand analogy: “While we train, we are generating a torrent of BDNF through two different pathways, via butyrate produced by our microbiota and via irisin. It’s as if instead of giving a constant drip of signals to the brain, we are fertilizing it.”

To close her talk, she recalls that a healthy microbiota, a brain with strong neural connections, and powerful muscles are three levers that improve our longevity.