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If you go to the gym often enough, you might be familiar with protein powders and shakes, but one study thinks that the secret to big gains might actually be your gut bacteria.

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Go to to check out their course on Beautiful Geometry. [♪ INTRO]. If you spend a lot of time at the gym, I have been informed that you’re probably pretty familiar with supplements or protein powders intended to help you make those hashtag gains.

But research published online this week in The Journal of Physiology suggests there may be another important ingredient to muscle gain: Gut bacteria. And while the findings only apply to rodents for now, it could be the start of developing new training supplements for athletes, or therapies to help people rebuild lost muscle mass as a result of age or disease. The study showed that mice need to have an intact gut microbiome to be able to grow muscle with exercise.

That’s the community of bacteria and other microbes living in animals’ guts. The way researchers figured this out was they basically put a bunch of mice into like a crossfit class. Half the mice in the study were given a running wheel kitted out with a mini weight that got progressively heavier over the eight weeks they were training.

It topped out around a third of their body weight, which I imagine is quite a workout! In that exercising group, half the mice were also given antibiotics in their water, which knocked out a bunch of their gut bacteria. The researchers then compared both muscle size and the types of muscle fibers in the different groups.

They saw that, without a healthy gut microbiome, the mouse’s muscles just couldn’t adapt to the training. The researchers wanted to know about three main types of muscle fibers. Type one, also called slow-twitch fibers, which have lots of energy-making mitochondria in them to help with endurance work.

And two types of type two fibers, also called fast-twitch fibers, which are more useful for sprinting or sudden, powerful bursts of movement. Researchers looked for the number and size of these fibers in two calf muscles, the soleus and plantaris, to indicate muscle growth. They saw that type one fibers in the soleus of the microbiome-less mice didn’t grow as much as those of the mice with their guts intact.

The mice with their microbiomes intact also tended to have more of both kinds of fast-twitch muscle fibers in their calves. Plus, there were more of the type 2a fibers in the plantaris of the microbiome-intact mice. And mice who didn’t get antibiotics also had more of the cells that help muscle fibers grow.

Altogether, this shows that mice with healthy microbiomes grew all-around stronger muscle tissue. The benefit wasn’t simply a result of the antibiotic-less mice exercising more. The mice with and without their gut bacteria ran for about the same amount of time.

What the researchers don’t know yet is exactly how a lack of gut bacteria means less gains at the mouse gym. They hypothesized that some compound made by the gut bacteria may be helping muscles get bigger and stronger. Fewer gut bacteria could mean less of this compound, and therefore smaller mouse muscles.

Or it could be that the antibiotics themselves were somehow interfering with muscle growth. Like, they could be making the walls of the gut inflamed and messing with how muscles use certain proteins to grow. But the researchers are fairly confident that didn’t happen, since they didn’t see any increase in inflammatory molecules in the blood of the treated mice.

And it’s still early stages. This is just one study looking only at female mice. Fun fact, according to the literature, they are better runners than males.

It might be a different story for male mice, and that’s to say nothing of humans. The next step would be to identify and isolate these compounds if they exist. Then, to test the muscle-growth idea by giving them to mice and running them through the bootcamp.

If these researchers can identify a bacteria-produced pro-muscle substance, then it could be used to develop a whole new range of treatments for people who suffer muscle loss from diseases like cancer, or for athletes. Still, no reason to change up your pre-workout routine, or to go in search of the microbiomes of the strongest men you know, until we know more. From running muscles to singing muscles: researchers have found a way to predict what zebra finches will sing based on their brain activity.

Specifically, they looked at neurons in an area of the bird brain called the HVC. Those neurons have been linked to how birds learn and sing songs. Three zebra finches had electrodes implanted into their brains in the HVC area.

That made it possible to record their brain activity over time. When the birds sang, researchers recorded their songs using a microphone. They then analyzed those songs and broke them down into motifs, or little snippets of melody broken up by silence.

Then they broke them further down into syllables, or small groups of notes. Using a statistical model that would let them objectively pick out patterns from background noise, the researchers then looked for which parts of the song related to specific spikes in brain activity. These spikes, called local field potentials or LFPs, are a kind of picture of all the signals coming into a neuron and being sent out of it.

And that picture changes as the bird is singing. Different features of the LFPs matched up with different syllables of the birds’ song, as well as the timing of when those syllables played in that song. The researchers could then look at the bird's brain activity and predict, based on the signals that came before, what note the bird was going to sing.

The authors of this study think that this is the first step to helping neuroscientists understand and predict human speech in the same way. In fact, the birds could act as a model developing technology to record and decode brain activity. As sci-fi as that sounds, the hope is that one day, we could make prosthetics for people who have lost the ability to speak through injury or other means.

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