Sitting: As Bad As Smoking?!

Hi, I'm Wendy Zuckerman, and this is Science Versus, and I'm here sitting on my butt. Today, on the show, we are taking a look at how bad it is to just sit, because for years now, we've been hearing that sitting is so incredibly bad for our health, that it does bad as public health enemy number one. Smoking! Sitting is the new smoking. You're actually taking years off of your life, even if you work out. Too much sitting could increase your risk of dying from cancer associated with a greater risk for cardiovascular disease. If you sit too much, like we're doing right now, you apparently raise your risk of dying. So, how bad is sitting all day, really? What is the groundbreaking science telling us about this? And if it is that bad, what are we supposed to do about it? When it comes to sitting, there's a lot of. You're actually taking years off of your life. And then there's science. Science Versus sitting is coming up to staff to the break. Welcome back today. We are finding out how bad it is to be sitting all day as I sit in the studio, Michelle Dange, producer at Science Versus, tell me how bad this is, because it's comfy. Hey, Wendy. Wendy, how much do you sit a day? Are you worried about it? I sit so much. I sit so much a day. I'm extremely worried about what you're about to tell me. That could be days where I am locked in and riding, and I sit for basically nine hours at a time. And for years now, I've been seeing headlines about how bad this is, and I've always been too terrified to do the research and find out why. So, I'm very nervous about what you're about to tell me. Why did you want to do this episode? Well, I'm worse than you. I think I sit those nine hours, and then I also sit outside of work. I'm often watching Taskmaster on YouTube. We're playing video games, so yeah, I was worried about that. And we're not alone. You know, the average person in the US and Australia sit six to nine hours a day. We are not alone, but we're in the top percentile. 60s and 60s to nine hours. That's what we are going to find out. So, let's begin with this claim around sitting big as bad as smoking. Where did it come from? Is it true? Yeah. So, I'm going to bring you back to one of the studies that helped kick off all these headlines. That started like 20 years ago, I want you to meet one of the authors behind those studies, Professor David Dunston. He's the head of the Physical Laboratory at the Baker Heart and Diabetes Institute in Melbourne. Back in the mid-2000s, David did this study where to measure what was going on with sitting. He looked at TV time as a proxy. Okay. So, around this time, like people weren't really worried about sitting as a problem, because the focus is really on getting out there to move. There's this recommendation that just come out to exercise two and a half hours a week. Right. But David was wondering, even if people are hitting that exercise targets, there's still a lot of other hours of the day that we could be sitting on our bumps. So, him and his team analyzed a bunch of data where we had people's TV time and look to see what happened. They tracked people's health across six years, and this is what they found. We make the comparison of people who are watching higher amounts of TV versus those who are watching lower amounts of TV. There is an increased risk of premature mortality or early death. So, overall, in the study, they found that each hour of TV time correlated with an 11% increased risk of dying, and this even held up, even if people had been exercising. So, here's David again. That relationship appeared to remain true, even when you started to adjust for things like age and sex and even physical activity. And when you said an 11% increase of death, I mean, we all have 100% risk of death that's coming for all of us, but you mean within the course of the six-year study? Right. The people who were sitting more were more likely to have died within that time. Wow. And so, after this, scientists realized that there's this whole new category of people. The active counts potatoes. This is that whole notion that you can be physically active, meet the guidelines, but also spend a large chunk of your time essentially sitting. Yes. That's us, Michelle. Yeah. So, in David's study, for example, they found that for every hour that you sit, there's an 18% increased risk of dying from cardiovascular disease and a 9% increased risk of dying from cancer. Other studies have also found associations to things like stroke and diabetes. And this metanalysis from the Lancet actually gathered all these studies up and found that even if you exercise about 30 minutes a day and you sit more than four hours a day on average, you still see an increased risk of all cause mortality. And this is where we get these headlines that sitting is the new smoking. Mm-hmm. It's like every time one of these studies comes out, both studies as these results, you get a new headline. Right. And so, it's really stuck with us year after year. Does it increase your risk of death as much as smoking? It doesn't. So, if you look at the actual numbers, heavy smoking is roughly four times worse than sitting a bunch. Okay. And so, what exactly is sitting doing in the body that's so bad? Because it feels nice, you know? It doesn't feel that bad. Right. So, let's start with the heart stuff for this. I spoke to professor Bethany Barron Gibbs. She's from West Virginia University and studies all about the cardiovascular system. And she told me that a big reason that sitting makes a difference here starts with the heart's main job. Love. Aww. But that's not where we're going. What our heart is doing is pumping our blood all the way through our body down to our toes and back and up to our heads and back down, you know, up to our fingers and back up. Okay. But in order to successfully pump blood throughout your body, your heart actually has a very important supporting cast. And a big part of that cast is your muscles. So, after the heart sends blood across your body through your arms, your legs, for example, the muscles in those appendages have to help the blood come back to the heart. Okay. So, your heart is the pump, the engine that's pushing blood around. But then the muscles are helping the blood pump back to the heart. Okay. And the important power players are in your legs. It's your calves and your thighs doing a lot of this work. In order to do this, they have to contract. Yes. That's interesting. They contract around the blood vessels, pushing the blood out. So you have these veins, they call deep veins that run through your leg muscles. So these veins are sitting inside throughout our calves and it has a lot of pressure to push back up. But again, they need to contract to do this and Wendy, what are our legs doing when we're sitting? They look contracting. Not contracting. They're relaxing, just like me. Yeah. So, here's how Bethany put it, right? Your feet are low, your head is high. So, your heart still has to pump blood, you know, against gravity. But you are not using that muscle pump at all. That like helper is not helping. Besides gravity, it's the fact that your legs are in these right angles at your knees and your hips. So that's making it harder for blood to come up as well. And then because of all this, blood starts pooling in your legs. Bethany told me it just kind of sits inside the veins of your legs and feet. And while this pooling isn't great, it can lead to a cascade of other effects in your body. So, what happens is that the blood vessels around your body start to constrict. There's a compensation, which your body's like, "Wait a minute, not enough blood's coming back." And so, your blood pressure has to go up and your heart has to work harder. I just feel it all through my body now, it's like I can feel it. I can feel more, I feel like my shoes are getting tight, Michelle. Yeah. I would like to thank you for your time. sitting for too long already. Exactly. I feel like my heart's going to come out of my chest. It's working so hard. So what? Okay. So this is why sitting is so bad for us. Because so the blood is pooling down by our feet. We're not able to use the muscles in our legs to help squish the blood back up. Our heart is working too hard and we're forcing our bodies to be in this position for hours at a time. Yeah. So even though, you know, I was kind of joking to say, I feel it now as you're describing these symptoms. The truth is, after a full day of sitting, I don't feel any of that stuff. Right. It's just comfy, right? Exactly. I mean, if I felt like my heart was racing and my shoes were tight, I would do something about it. But I don't. I just live my life. So it's actually not that dramatic of a jump when you look at something like systolic blood pressure. It goes up maybe two to three points after sitting for a few hours. It's not something that you can feel, like really feel. Uh-huh. But over time, the idea is it's a signal that your body doesn't like this state that it's in. Over time, we think that's enough to cause long-term damage if this is something that happened over and over and over again. So one thing that can happen is that higher blood pressure can actually start to change the structure of your blood vessels over time. Even just a tiny increase that can still your blood vessels then start to adapt to the state that it's in. So like even the cells inside your arteries inside the walls of your arteries can start to detect this change in this like extra pressure that they're getting stretched out a little bit more. And they don't like that. So they start remodeling their walls to also adapt to this change. Cool. And two of the major building blocks in our blood vessels are actually collagen and elastin. Uh-huh. Here's Bethany. If you have more elastin, things are more elastic and that's easier for your heart. And if you have more collagen, it's different. So the remodeling happens slowly over time as cells get replaced. You know, the vessels might be like, hey, we're getting a lot of pressure around here. We need some more, when we replace, let's replace with collagen. So we're ready to so we can adapt and handle this higher pressure. They want to get stiffer. Because if you got extra pressure, you don't want to keep stretching, stretching, stretching. So you get stiffer blood vessels. I see where this is going. You don't want stiffer blood vessels. And again, this is not something that happens after you sit for one day, but it's something that could start to change over months or years of sitting. And there is this one other big reason that sitting is bad for us that we'll go through quickly. Let's go stick the knife in even further. And that's that when you sit for a long time, it leads to more glucose hanging out in your blood. And that's also because your muscles are so inactive. Muscles love to gobble up glucose as their main source of energy and fuel, right? Right. But when they're not doing anything, like when we're sitting for a long time, that glucose just ends up hanging out in the blood, especially after a big meal. And that then leads to the production of insulin, right? To then pull out. Yeah. So you get bigger glucose spikes, then you get your body pumping out insulin. And then you know, this kind of stuff happening again and again can lead to things like insulin resistance and even type two diabetes down the line. Ooh. And surprisingly, that all can kind of weaves into why we might be seeing an increased risk of cancer as well. How come? Because insulin actually plays a big role in how cells grow and divide. And so if we have a bunch of it, it might be helping out cancer cells. That you have these more more insulin spikes, potentially triggering cells to grow in ways that they shouldn't, which is basically what cancer is, right? The cells dividing growing too quickly. Right. So that's one small thing that could be going on with cancer. Coming into this chat, I mean, I, yeah, I suspected you were going to tell me still sitting for nine hours a day is bad. But I was desperately hoping that because some days I'll go for a run, maybe an hour or something. And I was, and in my mind, I'm thinking, this is an excellent day. Good on me for going for a run. But from everything you've told me about the science here, that it's the sitting, I've still got four hours on either side of that run of just blood ruling glucose hanging out in my blood. That run did not save me from the perils of sitting, didn't it? Well, actually, it depends. Yeah. And that, that big meta-analysis we talked about before from the Lancet, they found that 30 minutes of exercise a day didn't cancel out the effects of sitting. But it turns out if you exercise a lot, like they were talking like 60 to 75 minutes a day of moderate to vigorous exercise, like exercise, like gets your heart pumping. Yeah. That this can actually cancel out the effects of sitting. All right. So, so this is, as big as big sitting over here, big sitter over here, this is all very bad news. But what I'm also hearing is that the body can adapt, right? I mean, not it is adapting to the state of sitting, but that means it should be able to adapt to a new, healthier state, right? Is there a way we can reverse this, reverse this damage that we're causing our body? Yeah. Is there anything we can do to stop it? So, after the break, we're going to look at whether we can just stand up to fix all our sitting problems. Excellent. Coming up. Welcome back. We've just heard that sitting is really bad for our heart over time increases our risk of death. It's all looking bad for the big sitters out there. Like me, but Michelle Dang, producer at science versus has promised us a solution, a way to get out of our sitting woes. Michelle, take it away. Yeah. So, can breaking up your sitting with standing help? Well, Bethany, who we heard from earlier, actually did a whole randomized control trial on this. Right. In it, she actually recreated a bunch of workers, desk workers who sit a lot, and she broke them into two different groups. Uh-huh. And one of them, they were coached to change positions throughout the day and stand up more, and they were giving standing desks. And then they coached them for three months. They also looked to see if there were any changes in their blood pressure over this time. They coached them. They were like, you can keep standing or it was all about the sitting and standing, the sitting and standing. They weren't encouraged to just stand for as long as possible. Yeah, it was about breaking up their sitting with like 15 to 30 minutes of standing per hour. Uh-huh. That's a real hassle. That gets in the way of work. Yeah, it's like a constant reminder, right? Yeah, yeah, yeah. It's every half an hour, which standard was supposed to mean, sitting and standing. Okay, but it's for our health. It's for our heart. So one group was, and then what was the control group? So the control group were just, they didn't get the coaching, and they carried on as usual. They're you and me. Where are the control groups? Yes. So on average, at the end of the study, the people who got coached, they did stand more, and they dropped their sitting by about an hour a day. Oh, wow. Okay. Yeah. But it turns out that this did not help their blood pressure. Oh, no. So I was already such a hassle and it didn't work. I know. Dan, they were still sitting too long. Well, here's the other thing that Bethany discovered from this study. She found that for the people who stood the most, their arteries were actually stiffer than the people who were sitting a lot. And it wasn't such a big change that it would have been clinically meaningful. But it was definitely in the wrong direction, because their body had to adapt to this new state of standing male. Yeah. So here's, I asked Bethany, like, why does she think this happened? Well, I think that people were standing still at their desk and all the things I told you about sitting and blood pulling and the muscle not being activated and the heart having to work harder. If you stand very still at your desk, it's even worse. You're standing up even taller. So there's even more pressure in the veins of your legs when you're standing, potentially a reason why we see more stiffening in the people who are standing more than sitting. What's really fascinating is that Bethany only saw this link between standing and stiffer arteries when people were standing at work. but outside of work standing was not. It was actually beneficial. And so I think that static standing is not something that people really do a lot of. Like you just, yeah, at home, you think it's like, I don't know, like in the kitchen, maybe you're-- - No, 'cause you're moving, right? You're cooking, you're throwing stuff away, you're going to refrigerator. So your muscles are moving. So I think that in our lives, there's dairy that just like sitting for a long time, that's kind of like an artificially created thing. I think standing still for a long time is also an artificially created thing that's not terribly good for us. - And Wendy, before we move on, I heard something funny from Bethany. It's actually about David Dunston, the researcher we heard about earlier. - Early on in the early days of sedentary behavior research, you know, there was only a couple of us doing it. And we would go to these scientific meetings and then all the sedentary behavior researchers would be standing in the back of the room, right? 'Cause we didn't want to be sitting. - So I remember we'd be standing in the back of the room and I remember one time just standing next to David Dunston and we were like, "Oh, it's like I stand all day, my desk." And he's like, "Oh, yeah, I never sit down." You know, like we were thinking we were really great about how often we use our sedentary behavior. And then I remember I saw him right after I published the study that showed that the ex, like too much standing up at the desk and I was like, "I have to talk to you." I was like, "Listen, don't stand all day at your desk. I don't know if you're still doing that, but don't do that 'cause that's not good for you." - Oh, but they were wrong. - Yeah. - They were wrong, so they thought they were doing the right thing. I used to be a cocky standard too. - And there is one other thing to worry about with standing for a long time and that is back pain. I spoke to one researcher who told me that when they bring people in the lab and have them stand for a long time, about 50% of people are likely to start feeling discomfort and pain and that's around the same as having people sit for a very long time. - Oh, interesting. - I think people often associate back pain with having a crappy posture while you're sitting, but actually standing can be just as bad. - So overall, back pain plus all those blood problems we heard about earlier mean that we also shouldn't stand still for hours at a time. Researchers actually recommend that people who have to stand for work don't stand more than four hours throughout the whole day. - Wait, don't stand for more than four hours a day, but what if you have to? - It's really about those standing still. So if you are someone who has a job or you're at the stand most of the day, it's helpful to think about any moment that you can move around a bit more during the day. - Yeah, okay, so we really need to be moving. - That's the answer, right? That's how you get the muscles in your legs contracting, helping out your heart, preventing a bunch of these things. So then the question becomes, what's the minimum amount of movement you need? In the middle of a work day, I'm not talking about going out and getting exercise through a run. I mean, if you've got a chunk of eight hours, how do you need to break up that day in order to prevent the bad sides of sitting? - Right, yeah. Let's go back to David who did a study on this. And so what he did is he brought people into the lab three different days and had them just sit for seven hours straight. - What if they made it to go to the toilet, by the way? - And they were in the seven hours sitting. - Were they sitting on a toilet? - No, they were sitting in a nice comfy sofa chair. - Okay, okay. - Well, that'd be a crazy study one day, sitting on a toilet for seven hours. - Okay, so they're sitting on a comfy couch, presumably they can get up to pay. - Yeah, so one of those days, it was literally just sitting in the sofa for seven hours straight, with always bad from breaks. - I sure of. - And then another of the days, he had them walk on a treadmill every 20 minutes for two minutes. And so he had them walk at a light pace. - What, a lot of people call posturing around or just light emulation. - And then another day, he had them do the same thing. - Every 20 minutes, walk for two minutes, but at a slightly faster pace. - What did he find? - Yeah, so what he was looking for was what this did to the glucose and their blood. - Okay, the glucose, right, which is a kind of like a proxy for your muscles aren't working in the way that we want them to be because the glucose is hanging around in the blood instead of getting gobbled up by the muscles. - Yes. - That's why it's important. And what he found was pretty exciting. - This is one study where I triple checked, quadruple checked the statistics. So across the same time period, glucose at 25% lower throughout the day, in which we're breaking up that sedentary time. - So it worked. And it actually worked for both the light walking and faster walking. It dropped blood glucose about 25% and the same for insulin. Here's David. - So we were heartened that walking with light intensity led to improvements in the blood glucose control. We then thought, well, this could be beneficial in an opposite situation because if people are walking around the office, that's a break. - Right, and if you're walking to the toilet, that's included. You're walking together. - Yes, yes. I need to be running or running around the office. This is much more practical. - Are you really excited by this funding? I mean, I'm glad it worked, but the implication that every 20 minutes we might have to be moving around. - Well, David told me that that study was sort of his best guess at the time and he understands it's not the most practical. So what he likes to tell people now is take a few minutes to walk every half hour. Instead of 20 minutes. So a little bit better, but that's the best thing you can do. And exactly that. Like Bethany said, she likes to go to the bathroom that's across the building to get those extra steps in. It doesn't take much for you to see the benefits of breaking out that setting with just a bit of movement. - Yeah. And it is absolutely true that when I'm sitting for a long period of time, I'm acting like it's comfy and it's the greatest state of nature. But it's not really after an entire day of sitting. I guess I do feel pretty gross. - Yeah, like you start to start feeling cramped up and sometimes my backstarts are hurt a little bit too. - Yes, exactly. - So it's lean into that and be like, all right, maybe I'm gonna stand up and take a little stroll. - So you're a gamer and you're gonna start pausing the game every half an hour? - I probably should. You probably should. - I mean, it's made me think a lot more about getting up in general when I can afford to. I won't get up during our Zoom meetings, but maybe sometimes we can take walk-and-talk meetings, you know? - We could, we should. We should. - We should have a timer. - Yeah. - We could do it right now, Michelle. We've been sitting for two. Let's do it. - Off we go. - All right. - Here we go. - Here we go. How long do I need to do? This is great. - For two minutes. Are you having fun? Lots of fun. All right. We'll arrive. - I'll also mention, like in later studies, David and other researchers have found that things like simple resistance exercises helps too. So things like squats or glute squeezes, heel raises. So those are things that you could do at your desk. If you can't. - Like a glute squeeze, like right now. Is that just what it sounds like? Just, but I don't know why that's the sound effect. 'Cause I guess the audience can't say anything, even if you're watching. - But there we go. - Wendy's just squeezed her butt. - I did. What else is there? - A squat. - And what was the third one? - Heal raises or calf raises. - Okay, these things can help too. - That's great. - All about getting those muscles going and preventing that pooling from happening. - Excellent. - So how worried are you about sitting now? How are you feeling about your sitting? - Ah, it's good to know the science, it's good. I've been avoiding it for a really long time to really understand the science here. And now that I know it, I feel better. I do feel, I feel like I understand more about what my body is doing day and day out. And that feels good. I don't need to be afraid of the facts, Michelle. And now I'll just sit last move more. I'll make an effort. I will. You've changed me, Michelle. - Oh, so happy. - Thanks, Michelle. - Thanks, Wendy. - That's science versus. Michelle, how many citations are in this week's episode? - There are 63 citations in this week's episode. - 63, and if people want to see them, learn more about the science of sitting, where should they go? - Yeah, just head over to the show notes and find a link to the transcript there. - Great. - Thanks, Michelle. - Thanks, Wendy. (upbeat music) - This episode was produced by Michelle Deng with help from Marilyn Horn at Katie Foster Keys and Rose Rimmelund. We're edited by Blythe Terrell. Wendy Zuckerman, that's me. I'm the executive producer, fact checking by Diane Kelly, video editing and sound by Bobbi Lord, music written by Bobbi Lord, Boomer Hidaka, so Wiley, Emma Munga, and Peter Leonard. Thanks to all of the researchers that we spoke to, including Dr. Caitlin Gallagher. Science versus is a Spotify studio. original you can join us for free on Spotify or wherever you get your podcasts or also on YouTube. I'm Wendy Zuckerman, back to you next time.