Rachel Carlson

They carry oxygen throughout people's bodies and transport waste.

So damage to those red blood cells can trigger inflammation or lead to anemia.

They're not talking about us.

That meant trail runners who raced either 24 miles, so a little under a marathon, or who raced 106 miles in ultramarathon.

One of the study authors, Travis Nemkov, put it like this.

When you're doing something like running, your body needs more oxygen.

And that means blood is circulating through your body more quickly, which can lead to the breakdown of red blood cells.

Well, Travis and the researchers do not know whether this extreme amount of exercise is bad.

The study was very small.

It only looked at 23 runners.

And it doesn't tell us anything about the long-term impact of these kinds of races.

And then more broadly, Travis says definitely do not stop doing regular exercise.

It's the best tool we have to keep our bodies healthy and age well.

And Mary Louise, thank you so much for joining us today.

It was my total pleasure as always.

And for more science stories just like this one, follow Shortwave on whatever app you're listening to.

I produced this episode with Jordan Marie Smith and Hannah Chin.

It was edited by Christopher Intagliata, William Troop, and Rebecca Ramirez.

And I'm Rachel Carlson.

Thanks for listening to Shortwave, the science podcast from NPR.