VR motion sickness, 10,000 step goals, benefits of ice baths : Short Wave Another week comes by, and luckily so does our roundup of science news. This time, we've got some questions about better understanding our health: Why do some people get motion sickness from virtual reality (VR) content? Do we really need to walk 10,000 steps a day? And is there real science behind ice baths?

This week, Sacha Pfeiffer, legendary reporter and occasional host of NPR's All Things Considered, who joins our hosts Emily Kwong and Regina G. Barber to demystify and (in some cases) debunk the science of this week's health headlines.

We love hearing what you're reading and what science catches your eye! Reach the show by emailing shortwave@npr.org.

Some people get sick from VR. Why?

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You're listening to SHORT WAVE...


KWONG: ...From NPR.

Hey, SHORT WAVErs. Emily Kwong here.

REGINA BARBER, BYLINE: With Regina Barber.


KWONG: What's up, Sacha? Thank you for being back on our show.

PFEIFFER: Oh, you're welcome. It's fun to do this with you.

BARBER: And you may know Sacha as a legendary investigative reporter and occasional host of All Things Considered.

KWONG: And, Sacha, you're here to join us for another science news roundup...


KWONG: ...Where we get to chat about three stories we've gathered for you from the latest science headlines, research papers and just quirky things we find on the internet - that kind of stuff.

PFEIFFER: And I'm looking at a list of the three stories you want to talk about, and I see a sort of health, recreation, fitness theme here.

BARBER: That's very astute. Thank you for picking up on that. We're talking about counting steps, ice baths and something called virtual reality sickness.


KWONG: We're going to jump into those ice-cold waters, Sacha, in just a minute. You're listening to SHORT WAVE from NPR.


KWONG: OK, Sacha, to recap, our three stories we've got for you today are counting steps, ice baths and virtual reality sickness.

PFEIFFER: Start with that last one first. What is virtual reality sickness?

BARBER: Yeah. VR sickness, for short, is a lot like motion sickness, which I get in cars and boats when I read.

KWONG: Same.

BARBER: What's happening in our bodies, though, is that we're noticing inconsistencies between what we're seeing and what our bodies are feeling. Our bodies are actually accelerometers, and there are structures inside our ears and our joints that tell us when we're speeding up and slowing down. But if your visuals don't line up with what you're actually feeling, you can start to feel sick. And in this case of the car, your body is feeling like you're accelerating, but your eyes and your immediate surroundings in the interior of the car - it's not moving.

PFEIFFER: Oh, yes. This definitely happens to me. It's why I can't read in cars, which is really frustrating when you're looking for ways to pass a lot of time, but you just end up feeling queasy.

BARBER: I know. I - long car rides - it's just a struggle. It's horrible.

PFEIFFER: So have scientists gotten interested in this because gaming has gotten so prevalent and more people end up in these virtual reality situations where they don't feel great?

BARBER: Yeah, absolutely. There is just VR games and training, and there's a large population that just can't experience this because they just get too sick. So scientists are trying to figure out why some people are more susceptible than others.

And let me just clarify here. This virtual reality sickness is slightly different from the motion sickness we just talked about because instead of our bodies feeling like we're moving and us seeing that we're stationary, it's the opposite. Our bodies are actually stationary, and our visuals are the things that are moving.


PFEIFFER: This sounds like there could be some fun experiments involved. How do scientists study this?

BARBER: Yeah, so it actually is. So I talked to one researcher - Michael Barnett-Cowan at University of Waterloo - about this, and he says they asked people to take a visual test before playing a VR game for 30 minutes. And this test involved looking at a luminous vertical line when your head is tilted. This creates an optical illusion. And they asked if that vertical line looked tilted or straight up and down.

MICHAEL BARNETT-COWAN: And then they play their game and they come back.

BARBER: And they report whether they feel sick, and they retake this visual test to see if their perception of that visual line has changed.

BARNETT-COWAN: And if they didn't really change at all in those two settings, those were the people who got more sick. The people who changed were less sick, and it didn't matter the direction.

PFEIFFER: So, Regina, what is the scientific takeaway there?

BARBER: So basically, people who had no change in how they perceived things before and after - their bodies never got the time to kind of reconcile the difference between their visuals and their bodies' accelerometers. Researchers are still trying to figure out why some people can adapt to this kind of VR experience quicker than others. There's also still so many unknowns, like how do you figure out how to mitigate these effects? So we really need more studies to get to that one goal to make VR accessible for many more people.

KWONG: Yeah. I mean, what's interesting about health, period, is that everyone's body is so different. Everyone experiences the world in a different way. The VR story is a perfect example.

And the example I have has to do with updating a long-held popular health claim, which is that we should be taking 10,000 steps a day. It is a number built into all kinds of apps and wearable fitness trackers as this daily aspiration that we all should be striving for. But, Sacha, that 10,000 step claim is not based in science. It's actually based in marketing.

PFEIFFER: Why am I not surprised?


PFEIFFER: So what's the marketing history of this?

KWONG: It's pretty fascinating. In 1965, a Japanese company was selling pedometers, and the Japanese character for 10,000 just so happens to look a bit like a person walking. So the company sold their pedometer as the 10,000 step meter, and that number kind of stuck without much research to support it.


KWONG: The person to piece together this history for public health purposes is Dr. I-Min Lee, Harvard Medical School professor and epidemiologist at Brigham and Women's Hospital.

I-MIN LEE: For many folks who are older, I think 10,000 steps can be very daunting.

PFEIFFER: I think 10,000 steps is - what? - 5 miles. So I can see how for - especially if you're older, that would feel like a big distance.

KWONG: Yeah, it's a lot. So to figure this out - and I read about this in a recent article from Scientific American - Dr. Lee and fellow researchers a few years ago tracked more than 16,000 women 45 years and older who all wore a pedometer over four years. And they found that at 4,400 steps a day, study participants did have significantly lower mortality rates. But after only 7,500 steps, it kind of leveled out.

PFEIFFER: Meaning suddenly they weren't seeing as much health benefit from it?

KWONG: Yes, exactly.


KWONG: So as we get older, our movements become less efficient, and each step requires more energy.

PFEIFFER: Ah, aging. Every time I hear more news about aging, it seems bad. Here's some more.

KWONG: No, no, no. But here's an upside. Think of it this way, right? It means that you need fewer steps to reap the same health benefits.


KWONG: So Dr. Lee's ultimate recommendation if you're older, if you're over, say, 65 is getting between 6,000 and 8,000 steps a day is more than enough to result in real health outcomes. And if you're sedentary or your area isn't safe to walk in, even a modest increase - just some walking every day - will significantly improve your cardiovascular health and your life expectancy.

LEE: Getting some steps is always better than getting fewer steps.

KWONG: And this nuance matters to me. It just means that as our bodies change, our expectations for ourselves should change, too. And ranges are better than hard-and-fast numbers.

PFEIFFER: All right, so we've covered virtual reality sickness. We've covered counting steps. You said you also wanted to talk about ice baths.

BARBER: Yeah. So we're talking about cold water immersion. That's the phenomenon where people are jumping into cold lakes, taking freezing showers or sitting in tubs of ice cubes.

PFEIFFER: I have an older - I had - he's no longer alive - an older Finnish friend who loved to do that. He would dunk himself into cold water. I always thought it must feel excruciatingly uncomfortable, but he really thought it was good for him.

BARBER: Yeah, it scares me a little bit, but people have been promoting this on social media, saying that it gives them, like, more energy and it improves their mood.

KWONG: I - to be honest, I love them, too. My fiancé and I are hosting a polar plunge the morning of our wedding next month. We're getting 100 people to run straight into the Maine ocean for fun.

PFEIFFER: (Laughter).

BARBER: Oh, my gosh.

KWONG: So I'm there. I'm there for the social benefits, you know?

PFEIFFER: And are there actually any health benefits to this?

BARBER: Yeah. Even though the practice is old and traditional, there's a lot of people that do it around the world, like your Finnish friend, the research on cold immersion is new. There's just not a ton of studies to back up these anecdotal claims of health benefits.

KWONG: Yeah. Most of the research that's been done on cold water immersion is on elite athletes. And we do know that cold water affects circulation. Like, when you get in the bath, your blood vessels constrict, and then when you get out, they enlarge, and that kind of supercharges the removal of lactic acid and other waste products because that blood is full of oxygen and nutrients, and it lowers inflammation. But the thing is we don't know if cold water immersion is better at healing muscles than, say, other kinds of active recovery, like walking or cycling between workouts. It seems like there's lots of things that can help our muscles heal.

PFEIFFER: I think one of you said that some people do it because they believe it improves mood. Do we know if there's any scientific backing for that?

KWONG: There is a lot of anecdotal evidence, but as far as research studies go, it's hard to say whether it causes an improved mood. And this happens all the time, like the research with the pedometer. There's all these health claims out there that become very popular, but it takes a while for the research to catch up and bring that nuance to the conversation because everyone's bodies are so different.

BARBER: Just to underscore that, there's a paper that caught my eye. And this paper is what we call in science a literature review. This one looked at 104 studies examining health benefits of cold water immersion. And the problem is there's so many variables, like temperature of the water. And there's just not a clear consensus because in a lot of these studies, you just can't clearly say that they have health benefits because the people might have been already healthy.

KWONG: But my consensus is that doesn't mean it isn't fun. It's actually, I would argue, more fun than a bouquet toss at your wedding. So maybe you should try it.

BARBER: I would not argue that.

PFEIFFER: Different definitions of fun for different people.


KWONG: Thank you again to Sacha Pfeiffer, Christopher Intagliata and Kai McNamee for letting us share some headlines. The segment you just heard also airs on the radio on All Things Considered.

BARBER: Yep, you're going to hear us on the radio every two weeks. So if there's a science story in the news you want to hear us break down, hit us up at shortwave@npr.org.

KWONG: This episode was produced by Liz Metzger, with Kai McNamee. It was edited by our managing producer, Rebecca Ramirez, Brent Baughman and Christopher Intagliata. And Brit Hanson checked the facts.

BARBER: Our senior director of programming is Beth Donovan, and our senior vice president of programming is Anya Grundmann.

KWONG: I'm Emily Kwong.

BARBER: And I'm Regina Barber. Thanks for listening to SHORT WAVE from NPR.


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