Exercise expert explains benefits of movement
Host Amber Smith: Upstate Medical University in Syracuse, New York, invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith.
People who sit for long hours at work and at home have a greater risk of developing dementia than people who don't sit for long hours. That's according to recent research published in the Journal of the American Medical Association, and it's in line with other research that is focused on the dangers of sitting.
Here with me to help us understand what this may mean is Dr. Carol Sames. She's an exercise physiologist at Upstate, where she teaches students in physical therapy and in physician assistant studies.
Welcome back to "The Informed Patient," Dr. Sames.
Carol Sames, PhD: Thanks so much, Amber. Glad to be here.
Host Amber Smith: Now, this study sounds a little bit alarming, but I don't want to overreact. Have you had a chance to look this over?
Carol Sames, PhD: Yes, and actually it's in line with a lot of research that is now starting to come out in an attempt to look at the association between sedentary lifestyle and later-life onset of dementia.
Host Amber Smith: And so the authors are from credible institutions, and they worked with good quality data?
Carol Sames, PhD: Yeah. The authors here were from UCLA, University of Arizona and University of Grenoble in France. And they were basically looking at the United Kingdom Biobank, and this is a data set that's been going on for a long period of time. They started following people and, essentially, seeing what happens to them as they get older.
And so they took a subset of that data, and it was about 49,000 adults. And these adults were all over the age of 60 years old. And they did not have a diagnosis of dementia. They were living in England, Scotland or Wales. And they had been wearing what we call an accelerometer, which is just an activity monitor on their wrist. And they had had that on their wrist 24 hours a day for a seven-day span.
So, in terms of sample size, very robust. And the accelerometer data is better quality, it's more accurate and reliable than, say, giving me a questionnaire and asking me how much activity do I do, because we know that people tend to exaggerate what they're doing, and by wearing this accelerometer it, pretty much doesn't lie.
Host Amber Smith: So did the researchers show a strong association between sedentary behavior and increased risk of dementia?
Carol Sames, PhD: It was interesting what they found. They actually found this nonlinear association, so up to 9.5 to 10 hours of sedentary time in a day. They actually didn't find an association between sedentary behavior anddementia. But, at 10 hours and greater, there was a very strong relationship. In fact, the risk greatly increased for the development of dementia. For people who sat more than 10 hours a day, their risk of developing dementia within the next seven years was 8% higher than if they sat fewer than 10 hours. So somehow, 10 hours was a cutoff point where you saw a strong association.
Host Amber Smith: Was there also an association between physical activity and lower rates of dementia? Did they look at it that way, too?
Carol Sames, PhD: So interestingly, what they did is, when they were looking at the data, they controlled for physical activity. So, they didn't want that to be a variable that could impact the results, so they controlled for it. However, when they looked back on the data, they found that even in individuals who were active, if they sat more than 10 hours a day, they had an increased risk of dementia. So to say that physical activity was protective, they could not make that claim if people were sitting more than 10 hours a day.
So it wasn't protective. If I got up and walked this morning, and then I've decided that I'm going to sit for the next 11 hours, it didn't end up adding any benefit.
Host Amber Smith: That's really interesting. Was there anything besides activity level that may have accounted for the lower or higher rates of dementia in the people they studied?
Carol Sames, PhD: Right now the whole concept of trying to determine cause of dementia ... this study was looking at an association, so it's not causal. So we really don't know the exact mechanisms. Clearly, when we are active, from a physical activity standpoint, we get increased blood flow. To be able to say precisely what is going on when we are inactive for 10 hours or more in a day, it's difficult to be able to say, what are the exact mechanisms? And so that's really where the research needs to go. We also know from a physical activity standpoint that physical activity reduces inflammation and insulin resistance. And that in turn can lead, with higher levels of inflammation and insulin resistance, we have an increased risk of cardiovascular disease and Type 2 diabetes and obesity. So, there is an interplay there, but I think the take-home message here is, by being active, I'm not protected if I sit for long periods of time in a day, so 10 hours or more, and this was cumulative time, so this wasn't one bout of 10 hours or more. This was waking hours, 10 hours of accumulated sedentary time.
Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith, talking with Dr. Carol Sames. She's an exercise physiologist at Upstate, and she teaches students in physical therapy and in physician assistant studies.
Let's talk about how activity, or the lack of activity in the human body, may influence dementia risk. When we're active and our hearts are pumping and blood is flowing more quickly through our body, how does that affect the development of dementia? Do we know?
Carol Sames, PhD: The exact mechanism is not quite known. However, we have enough research to send us in the right direction. So we know that individuals who are more active, they have less inflammation, they have less insulin resistance. And so that's beneficial.
We also know that physical activity is associated with some changes in the brain areas. One is the hippocampus, and that's important for memory formation and learning. That's a tertiary way of looking at how activity can be helpful for brain. We also know that physical activity increases this factor called brain-derived neutrotrophic factor, and that is responsible for formation of neurons. And neurons are our brain cells. So, we have an idea of what physical activity can do. But to make that jump from physical activity to dementia, we have sedentary time kind of influencing that interaction.
Host Amber Smith: What about, is there a difference between movement, walking versus strenuous exercise or running, or doing something that's heavy duty? Is there a difference in how protective those might be?
Carol Sames, PhD: The research is still out on that. In this particular study, they included both moderate and vigorous activity. And we certainly know from physical activity research in general, there's been some other studies that have come out, from the Cooper Clinic, for instance, in Dallas, Texas, where they've followed people over time, and they've looked at people's fitness level at midlife and then looked at dementia later in life. And what they found was that as long as people were active, meaning they were just engaged in moderate activity -- and moderate activity is just, you can carry on a conversation; this is not vigorous activity -- they found that there was not a significant difference between moderate or more vigorous activity.
And I find that that's very promising because most people don't want to engage in more vigorous types of activity where it's difficult to carry on a conversation. So this basically is saying we need to get up and move, but we don't necessarily have to get up and move and it be real strenuous.
Host Amber Smith: Well, that is good news, then. So, what is most important to know about what sitting all day does to our body in general and our dementia risk in particular?
Carol Sames, PhD: Well, clearly, the way we were put together and designed, we're not supposed to sit for long periods of time in terms of an accumulation of sedentary time.
So I think really that the take-home message here is that we need to be active. We need to move around. It doesn't necessarily mean that it has to be vigorous activity, but that we cannot sit for long periods of time. And, maybe if we're not sure, we might want to start tracking our sitting behavior. Sometimes we might get caught up in, if we're working, we're sitting in meetings for periods of time, and 10 hours sounds like it's a lot. But maybe when we start to record that, we realize that maybe it's not as much as we think or we get engaged in some TV binge watching, and the next thing you know, five hours has gone by.
So I think really the bottom line is that we need to be moving more and trying, maybe, strategies such as when I'm on the phone, I'm walking around. Is that possible? Can I have a walking meeting, if I'm working? Can I do things that incorporate movement into, maybe, activities that were more sedentary? If I want to listen to a podcast, maybe I should, if I can, take a walk or walk around my home. So try to reduce that cumulative sedentary time.
Host Amber Smith: Well, a lot of people are faithful with working out every day, morning or evening, but then they have jobs where they do have to pretty much sit all day, or that's what they are doing. Short of being able to find more active careers -- I mean, you're talking about walking when you're on the phone and -- are there other things like standing desks? Does it matter if you're, like, standing in front of the computer versus sitting? And are there different ways of sitting that might be less bad for you?
Carol Sames, PhD: So standing desks can be very helpful. But when you stand ... the cutoff in terms of level of moderate activity, standing is a little bit below moderate activity. And nobody has really looked at standing without any associated movement. Like, there isn't any strong research on that. But certainly standing at least will require a little bit more blood flow than sitting.
Some people I know that sit will sit on a stability ball, one of those round balls that kind of require you to stabilize. So instead of just sitting in, say, my LazyBoy rocker-recliner, which I don't have to really do much, sitting on a stability ball is going to require me to have some movement, but again, it's not hitting that threshold for moderate activity. So I think we don't really know how protective that is.
I know a few people at Upstate have the treadmill desks. So clearly if I'm walking, then I'm hitting that aspect of reducing sedentary time. But we're going to see in the next couple of years a lot of research, because this whole idea that sedentary behavior is a separate risk than physical activity is somewhat troubling because we've always said we need to exercise, we need to engage in physical activity, but we're seeing that that is not as protective as we thought, if we end up sitting for long periods of time in the day.
Host Amber Smith: Well, here's another thing that surprises me. You're calling my behavior, actually, sedentary. I would never think of myself as sedentary. But if I sit all day for work, by definition of this study, at least, I mean, I've got sedentary behavior. And so do many office workers. So, what's the takeaway for us?
Carol Sames, PhD: I think the takeaway for us is really that we need to try to engage in more activity, less sitting time while we're awake. And it is a different mindset because I know personally I've always felt that I'm hitting the guidelines, I'm exercising, I'm good. And from the standpoint of all the benefits associated with activity -- and there are many -- we're getting those.
But in terms of dementia risk, maybe not. So maybe that changes the way I think about when I'm not at work. What am I doing at home? Am I trying to be engaged with a little bit more activity? Maybe my idea of working and sitting for eight hours and then coming home and binge watching something for four hours, once in a while could be good, but maybe I don't want to make that a daily pattern.
Host Amber Smith: Well, this has been very enlightening. I appreciate your time, Dr. Sames.
Carol Sames, PhD: Thank you very much.
Host Amber Smith: My guest has been exercise physiologist Carol Sames, who teaches physician assistant and physical therapist students at Upstate.
"The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe.
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