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Short Wave

Could Running Change Your Brain?

Fri, 04 Apr 2025

Description

Running an entire marathon takes a lot of energy. Neuroscientist Carlos Matute knows this: he's run 18 of them. He wondered how runners' bodies get the energy they need to make it to the finish line. His new research in the journal Nature Metabolism may be the first step in answering the question – and suggests their brains might be (temporarily) depleting a fatty substance that coats nerve cells called myelin. Have other questions about the brain? Let us know by emailing [email protected]! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

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Transcription

Chapter 1: Who are the hosts of this episode?

11.084 - 23.042 Rachel Carlson

You're listening to Shortwave from NPR. Hey, Short Wavers, Regina Barber here. And Rachel Carlson. With our biweekly science news roundup featuring Juana Summers of All Things Considered.

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23.162 - 29.324 Regina Barber

Hey, Juana. Hi, excited to be here. I hear we're talking about one of my favorite things, running, and how running a marathon can change your brain.

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29.944 - 33.986 Rachel Carlson

Yep. Plus, we're talking about fermenting food in space and what it does to its taste.

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34.446 - 41.409 Juana Summers

And scientists have solved a longstanding mystery of how hordes of bats emerging from caves avoid bat-on-bat collisions.

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41.769 - 46.171 Rachel Carlson

I'm intrigued, y'all. All that on this episode of Shortwave, the science podcast from NPR.

53.533 - 63.057 Sponsor Message Reader

Support for NPR and the following message come from Jarl and Pamela Moan, thanking the people who make public radio great every day and also those who listen.

64.656 - 70.099 Regina Barber

All right. Just to start off, tell me about marathon running. I'm training for one myself, so I'm really interested in this story.

Chapter 2: What inspired neuroscientist Carlos Matute to study marathon running?

70.319 - 89.41 Juana Summers

Yeah. Okay. So especially if you're training for a marathon, I think we can both imagine that running one would take a lot of energy. Neuroscientist Carlos Matute told me he's done 18 marathons, so he really knows it's exhausting. And he told me that he wondered, how do runners' bodies get the energy they need to make it to the finish line?

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Chapter 3: How does running a marathon affect the brain's myelin?

89.77 - 108.016 Juana Summers

His new research in the journal Nature Metabolism suggests their brains might be depleting a fatty substance called myelin. So it's sort of like your brain is eating itself when it's running low on energy? Yeah, that's kind of how I was thinking about it. Myelin coats nerve cells and helps electrical signals travel, and it makes up about 40 percent of the brain.

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108.556 - 121.244 Rachel Carlson

And after marathons, they saw that myelin decreased in the runners' brains, especially in the areas of the brain that are important for things like motor coordination, like how we move our bodies, and sensory processing. So after a marathon, there's less myelin. Is that a bad thing?

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Chapter 4: Are the changes to myelin after running permanent or temporary?

121.744 - 130.247 Juana Summers

Well, the changes were all temporary. The researchers followed up with the runners two months after the marathon and scanned their brains again. And they saw that the amount of myelin returned to normal.

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130.467 - 139.43 Rachel Carlson

But there are some neurological diseases where myelin decreases and doesn't return to normal. Carlos thinks studying runners could help us better understand these disorders, like multiple sclerosis.

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Chapter 5: What are the implications of this research for neurological diseases?

139.79 - 146.092 Carlos Matute

It may be useful to develop new lines of treatment for myelin.

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153.474 - 160.418 Regina Barber

Like neurodegenerative diseases. Okay, so for marathon runners or marathon runner hopefuls like me, it sounds like we're all okay to keep on running.

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Chapter 6: What limitations does the marathon running brain study have?

160.698 - 167.121 Juana Summers

Yeah, and the study has a few limitations. One of them is that they only looked at 10 runners' brains, so it was a very small sample size.

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167.721 - 184.553 Rachel Carlson

Another neuroscientist in the field, Yannick Poitelot, Told us the kind of scans the researchers took makes it hard to say, like, for sure that running caused the change in myelin. But he says that this study was really exciting. It's one of the first to show that human myelin could be used as an energy source. And he thinks it could inspire lots of new work in the field.

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185.133 - 191.438 Regina Barber

All right. So next up, we've got fermenting food in space. I'm always good for food story. So what kind of food are we talking about here?

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Chapter 7: What did researchers discover about fermenting food in space?

191.598 - 203.432 Rachel Carlson

Yeah, it was miso. Okay, the paste created from like fermented soybeans or grains. It's used a lot in Japanese cooking. And part of the study is in service of astronaut nutrition. Like how do we make their diets more delicious, more nutritious, more diverse?

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203.979 - 213.307 Juana Summers

And the researchers were also wondering, how does this specific space environment, the space station, shape microbial life in unique ways? And understanding that's important for any kind of space travel.

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213.707 - 229.581 Rachel Carlson

So how did this miso make its way into space? Well, Juana, it almost didn't. I spoke to Maggie Koblenz and Josh Evans, who published their study in the journal Ice Science this week. And Josh reminded me that, like most fermented things, have a really strong smell. And this fact almost stopped them from getting the experiment into space.

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229.901 - 239.685 Unnamed NASA Contact

The MISTA was ready to be put into the shuttle in Houston. And then we got this kind of or Maggie got this like frantic call from someone from NASA being like, your payload is like kind of smelling weird.

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240.906 - 247.489 Regina Barber

But fortunately, once NASA like got the explanation, they launched it anyway. So what did the researchers learn from this fermenting adventure?

Chapter 8: How did NASA handle the strong smell of the miso fermentation experiment?

248.009 - 250.05 Juana Summers

Well, Maggie's big takeaway is that it worked.

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250.353 - 253.516 Unnamed NASA Contact

Fermentation is possible in the International Space Station.

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253.796 - 267.026 Juana Summers

So if this worked, who knows what astronauts could get into next when fermenting stuff in space? Maybe sourdough, kimchi. I guess there's also stinky cheese, but I feel like if I were an astronaut, I'd be a little worried about that one. Personal choice, though.

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268.047 - 275.818 Regina Barber

I mean, as a cook or an attempted cook, I'm sort of curious. Did fermenting this miso in space make it taste any different than making it on Earth?

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276.199 - 293.779 Rachel Carlson

Yeah, it did. When it came back to Earth, it tasted nuttier than the miso from the same batch fermented on the ground. Interesting. Why do they think that happened? So they don't know for sure. It could have been like radiation. It could be microgravity. It could be a combination of all of this. But the leading hypothesis is that it was mostly temperature swings inside the space station.

294.159 - 299.944 Regina Barber

All right, y'all, let's bring it home. We've got to end on bats. You say that scientists figured out how they avoid collisions?

300.504 - 315.195 Rachel Carlson

Yeah. So this was a big mystery that perplexed researchers for a while. Like basically bats emerge from their caves like around dusk all at once. There can be hundreds, thousands or even millions of bats in a group all funneling out together. And for the most part, they don't crash into each other.

315.455 - 335.713 Juana Summers

And just a reminder, bats navigate using sound. It's called echolocation. They send out a vocalization, a call. And then they listen for its echo off objects in their path. But when a million bats are all flying out of a cave together, that's a lot of bat calls that could get mixed up. Here, let's take a listen. Oh, my gosh.

336.013 - 340.978 Regina Barber

Wow, that's incredible. So how did scientists sort of sort out all of these different calls?

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