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Sedentary behavior linked to mortality risk

 March 13, 2024 at 11:44 AM PDT

S1: Welcome in San Diego , it's Jade Hindman. Today we are focusing our show on wellness. Will tell you about the dangers of sitting still too long and ways to change that. This is Midday Edition , connecting our communities through conversation. We spend a lot of our lives sitting in our modern lives. We sit to work , we sit to drive , you name it , we sit. But sitting too much can be harmful and can even take years off of our lives. New research out of UC San Diego looked into the impacts of sitting , and looked at what impact it had on older women , and found striking results. Steve Wynn is the study's co-author and fellow with UC San Diego School of Public Health , who focuses on the science of longevity. Steve , it's so good to have you with us today.

S2: Thank you for having me.

S1: Glad to have you here. Also , Andrea Lacroix joins us. She's a professor at UC San Diego School of Public Health , where she's been part of the Women's Health Initiative , which is a national effort to better research women's health. Andrea , great to have you back here on midday.

S3: It's great to be back. Thank you so much.

S1: Glad to have you both here , Steve. This study really analyzed women's activity levels and the amount of time they sat. What were you looking to answer with this research ? Right.

S2: Yeah. So with sedentary behavior that sort of defined as low energy expenditure while sitting or reclining while we're awake , you know , we spend so much of our time sitting and really is more than just the flip side of being active. You can still be active. You can still walk for a half hour a day or run for an hour a day , but still sit for , you know , 12 plus hours a day. And so we really wanted to examine sort of the adverse outcomes that can come with , you know , higher total sitting , but also just sort of that prolonged sitting. Hmm.

S1: So how did you track their activity levels for so long ? Because you did this over years , right ? Correct.

S2: Yeah. So this this study started sort of around 2012 to 2014 , where a study participants , older women in this case wore an activity monitor around their hip for about a week. And then from there we're able to follow these study participants , you know , for as long as ten years or longer to see their their health trajectories. Yeah.

S1: What role did technology play in all of this , especially in getting accurate data. Right.

S2: Right. Yeah. So I guess the two important aspects that I want to mention is that we used an activity monitor , which is sort of always collecting data , and it's not reliant on , you know , your individual recall. So , you know , I might forget that I sat for an hour here or there or , you know , a questionnaire that I'm filling out that asks about my activity and , you know , sort of sedentary behavior might not even ask about it. And the second part to that is that we applied an AI algorithm called the Chap algorithm , which stands for the Convolutional Neural Network hip accelerometer posture algorithm , which is a little bit of a mouthful.

S1: But it sounds like. It.

S2: It. It gets the point across. But what that algorithm really does is it sort of gets at that posture to try and get a better estimate of , you know , an individual's sitting time and , you know , sitting behaviors , current commonly used methods , sort of used activity intensity cut points , which do a great job. But they might count certain behaviors that don't result in movement but are not quite sitting. So for example , standing up , you know , standing and sitting or not the same. So we really want to get a better measurement of sitting. And we're able to get it with both the activity monitor and with the AI algorithm that we applied.

S1: So how beneficial I got to ask. Now since you mentioned standing , how beneficial is standing actually I mean , you're not walking , right ? Yeah. So you're not sitting.

S2: Actually , I think the way you described it is fantastic. It's not quite it's not sitting , but it's not quite walking , you know. But our group did publish research previously showing that higher amounts of standing were associated with lower risk of mortality. So , you know , it's sort of this opposite direction that we're seeing with sedentary behavior. So if you've got a measure that's , you know , kind of unintentionally counting some standing , you're kind of mixing some things up and , you know , you might not get the best estimate of how harmful sitting might be. Huh.

S1: Huh.

S3: So when you're standing up , you've got to use your brain to balance if you're standing still , especially actually walking forward is probably a more natural movement than standing still for long periods of time. You can feel your muscles tighten a bit to hold you in position. You can see the blood in your body has to make its way against gravity up. All these things are happening when you stand. And we we do see a benefit for total and cardiovascular disease mortality , just like Doctor Nguyen saw for sedentary behavior.

S1: This study focused on older women. What age group is that and why did you really want to focus on that group specifically ? Okay.

S3: Great question. The women in the study were all 63 to 99 at the time we did this study. I was in my early 50s , but now I'm 66 , so I'm right square in that age range. And and the participants in this study were part of the larger Women's Health Initiative program , which enrolled initially 160,000 women between 1993 and 1998. And there was a large group of women in San Diego who were part of the Women's Health Initiative and who are still a part of it. So I want to thank anyone in the audience who's a part of Y for all that they've contributed to knowledge of women's health. This study was started as a line item in the federal budget to address the fact that there had not been studies , long term prospective studies , or very many randomized trials that focused on women initially in the 50 to 79 year age range. And now we're learning so much about these women as they have been in this particular physical activity. Study followed for ten years with a little margin around that , and some of them have lived to be over 100 already. And it's super exciting to learn how we stay healthy. In addition , how we stay resilient to the many challenges that aging does bring inevitably with it. And so Doctor Nguyen's study is really exciting because it really shows that by getting up and moving around more often , we can reduce our risk of mortality. And that's pretty cool.


S3: I mean , in general , if you study younger groups of people , they just fortunately don't die. So when the outcome is mortality , it makes sense to say , we think that this is an important behavior for healthy aging. We don't think it influences risk of death , you know , in young people. Uh. Because they just don't happen to die , which is a good thing. Um , but we think it's a lifelong behavior that has good benefit for preventing other diseases. And we think once you get old and in the age group where your rates of mortality , your risk of mortality goes up. You know , we we have the data right in front of us that show it's associated with lower risk.

S1: Well , I mean , yeah , because it all begs the question of , you know , does what I do right now , today impact me once I do get into that older age group ? And you'd hope so. Absolutely.

S3: It's never too late , I think , to change your behaviors , to elicit more healthy outcomes in the future. So we shouldn't think that it's too late for me to make any positive health changes. I one of the things that Doctor Nguyen and I have talked so much about is how how enticing it is in our daily lives to sit a lot , and how fascinating we've created a world , you know , where you can scroll for hours or watch TV or play video games , and how acclimated we've gotten to long sitting. And this does start. You know , this does have health consequences even in younger people with respect to overweight and obesity and cardiovascular risk. And then when you get older , these same behaviors we find to be associated with mortality. Mhm.

S4: Mhm. Steve.

S1: Steve. So you know I want to dig into the details here. What did the research find when it comes to sitting and mortality. Yeah.

S2: Yeah. So women with you know a little over 11.5 hours per day of sitting had a. 57% higher risk of all cause mortality and is 78% higher risk of cardiovascular disease death compared to women who had less than about nine hours and 20 minutes of sitting per day , which , you know , these are meaningful increased risks of of death. It's nothing to sneeze at.

S1: I think many people are interested in this area of looking into factors that lead to a longer life , but as researchers , I imagine this requires a lot of time to produce studies to fully see what helps us live longer. What do you what do you make of that ? Yeah , these.

S2: Studies do take a very long time. I mean , as Doctor Lacroix mentioned , you know , the Women's Health Initiative was starting in the early 90s , and here we are decades later , still in contact with a lot of these women , you know , to find out whether a certain behavior or a therapy or something might , you know , relate to longer life or better health. You really have to follow them for that period of time. And look at these , you know , specific health outcomes like mortality. Mhm.

S1: I mean , but what does constant movement do for us. Sure.

S2: Sure. So while we're moving our muscles are contracting , our muscles are taking up glucose. So we've got certain benefits to our metabolism there. You know certainly when we're standing up our blood flow is a little bit better. You know blood's not pulling around. It's fighting the force of gravity. And so while we're sitting , you know , our muscles are not contracting , our muscles are not taking up glucose. And that has consequences for metabolism. You know , our blood flow is also impaired while we're sitting. And so all of these things can sort of have negative effects on our metabolisms and lead to certain conditions , including diabetes and hypertension and heart disease , which from there increase our risk of death.

S1: Now it just creates dysfunction in your body is not working as it should be when you're just sitting all the time. Exactly. All right. Well , I think you you found that the negative effects of sitting long were present , even for people who were active and exercised. So tell me about that.

S2: This was one of the noteworthy findings of this study. You know , it didn't matter whether , you know , women had sort of high , you know , even moderate to vigorous intensity physical activity or low amounts. There was always a higher risk of death that traveled with higher sitting. Hmm.

S4: Hmm.


S2: You know , you don't have to get up and go run , although certainly encouraged. But you can kind of just stand up and stretch out a little bit and maybe kind of walk around , you know , your home or maybe go outside for a few minutes and come back in and.

S4: Then , okay.


S3: And it's not really constant motion that you have to aspire to just , you know , if you're if you're watching TV or , or doing a project , any kind of natural break , take the opportunity to , to get up and and move around a bit. And you know , I , I'm in this age group now. I am guilty of sitting too long. But one of the interesting things that you said , Steve , is that the comparison group , the women who sat the least , sat less than about nine hours.

S2: That gives.

S3: You a lot of time to sit when you think about. It.

S4: It.

S1: When I think about it , nine hours and 20 , about.

S2: Nine hours , 20.

S1: Minutes , nine hours , 20 minutes , eight of those hours. I'm sleep. Right. Oh , this.

S2: Is during a wake. So we we.

S1: Took our sleep time. Yeah.

S2: This is this is while you're awake. Okay.

S1: Thank you for clarifying that. Yeah , yeah. Because to me that's really important.

S2: That is super important to know.

S5: Yeah yeah yeah. Okay.

S1: Okay. Yeah. I mean , you know , when you , when you , um , looked at these findings , did , did you think , you know , there ought to be cultural change , um , here , a different way of living in society.

S2: I was just thinking , like , you know , along with what Doctor Lacroix said earlier , like , it's we we live in this world that we created. It's so enticing to sit and do all these things. But , you know , I think there are changes we can certainly make , you know , sort of standing up a few times every hour , finding those natural breaks to take an opportunity to stand and walk around a bit. You know , I think , you know , there's an entire industry of sort of like standing furniture that , you know , people can purchase standing desks , you know , bike desks , things like that. I think , too , when it comes to the work setting , you know , going from like a meeting in a room where everyone sits down to , you know , if possible , maybe having a standing meeting or a walking meeting. And I think these are certainly things that we can think about. And , you know , there's also a lot of work going on , including by our group , to develop and test interventions to , you know , try and help individuals stand up a little bit more and more often. Andrea.

S1: Andrea.

S3: I would just , you know , have some compassion for there are , as we get older , changes in our bodies that can make it harder to stand up and harder to move around. And indeed , those things register in your body , you know , if it's harder for you to get out of a chair , you know , you do more work , you get more. Intense physical activity out of that movement. But and we we're studying that concept right now. Um , relative physical activity , relative intensity. But whatever works for you , you know , is , is kind of the message we want to get across. You don't have to buy special furniture or gizmos. You don't have to have a machine or a watch beeping at you. It's it's just kind of a habit to get into. Uh , in our intervention studies , we help women in this same age group set goals. Like how how much more do you want to stand up ? How how much more per hour do you want to stand up ? And it really becomes kind of more entrenched in you , um , after you do it for a while , just like any other habit. So I like to , you know , do things. What works for me is very simple stuff like , um , getting a cup of tea , like having a routine where I get a cup of tea and you know what happens 20 minutes after you drink a cup of tea ? You have to get up again. Um , looking at the flowers out the window , chatting with someone if I'm at work. There's so many reasons. I also try to when I talk to colleagues about work or friends about our lives , I try to be strolling while I do that. That's one of my favorite things , is taking walks with friends , um , which reduces my sitting time enormously. And you don't have to walk a mile a minute either. You don't have to stress yourself out. I always say , if it's hard to walk , walk slower , you know , make it less hard. It's all within our power to make it work for us.

S1: All right.

S3: And we found that sedentary behavior still predicted mortality and different levels of those variables. I hope I'm not oversimplifying , Steve.

S2: No , no , that's I think that's spot on. Yeah. It didn't matter if someone had sort of lower physical function or higher physical function. It didn't matter if they had no health conditions or if they had several health conditions , just higher amounts of sitting , prolonged sitting just translated to a higher mortality risks. Wow.

S4: Wow.

S1: All right. I mean , what's next for this research ? Is there anything else that you guys are looking into or or expanding ? Well , Steve.

S3: Is doing Steve is expanding to better understand the mechanisms through which physical activity may reduce the risk of cognitive aging and dementia. Do you want to talk about that ? Sure. Yeah.

S2: Yeah. Yeah. So I started a National Institute of Aging. It's called a 99 or 0 zero award , or a grant to look at how physical activity and sedentary behavior , you know , influences our proteins in our , you know , our body as we can measure them. You know , in blood , but also how that how that influences the risk of dementia and cognitive outcomes. Yeah.

S4: Yeah.


S2: But but you know , we do have pretty compelling data showing that , you know , higher amounts of physical activity and a higher step counts. Um , it's associated with lower risk of dementia. And so , you know , we accounted for , you know , a lot of factors there. And , you know , even after , you know , disentangling health status and cardiovascular disease factors , we still saw that higher activity translated to lower dementia risk. So , you know , with this grant will really be taking a deep look into , you know , whether our plasma proteins are influenced by , you know , the movement that we do. And you know how that plays a role in dementia. Wow.

S1: Wow. That's very interesting. Research will definitely be following up with you on that one. I've been speaking with Steve Nguyen and Andrea Lacroix from UC San Diego School of Public Health and Human Longevity Science. Thank you both for joining us today.

S2: Thank you so much for having me.

S3: Thank you so much.

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Students walk at UC San Diego in this undated photo.
Milan Kovacevic
Students walk at UC San Diego in this undated photo.

New research out of UC San Diego looked into the effects sedentary behavior had on older women. Findings showed that sitting for long hours increased the risk of death, regardless of exercise levels.

Sedentary behavior is defined as sitting or reclining while awake. It is a health risk because it reduces muscle contractions, blood flow and metabolism.

So, take a walk while you listen to Midday Edition, as Jade Hindmon sits down with the UC San Diego researchers behind the study.


  • Steve Nguyen, fellow with UC San Diego’s school of public health who focuses on the science of longevity
  • Andrea La Croix, professor of epidemiology at UC San Diego’s school of public health