Researchers are discovering that getting enough exercise and spending too much time sitting may be two different issues when it comes to your brain health. In fact, a study published in 2025 found that greater sedentary time was associated with changes in brain structure and cognitive functioning, even among people who are meeting recommended exercise guidelines.
Now that caught my attention
Welcome to RenewHer, a podcast for women over 50 ready to reignite their energy and explore what's next. I'm Genell Lemley, brain fitness coach. Here, you'll hear real stories from women taking on new challenges after 50, along with brain health tips to boost focus, energy, and the mindset to move forward with confidence.
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Hey there, and welcome back to RenewHer. Think about how much time you spend sitting during a typical day. Maybe you start your morning with a walk, or you head to the gym, take a fitness class, or go for a bike ride. You make exercise a priority because you know how important it is for your health.
But then think about the rest of your day. Maybe you're sitting at your computer for several hours, driving to appointments, reading a book, having dinner, or relaxing in front of the television. Even if you've exercised, you may have spent a significant portion of your day sitting. And here's something I find fascinating. Researchers are discovering that getting enough exercise and spending too much time sitting may be two different issues when it comes to your brain health.
In fact, a study published in 2025 found that greater sedentary time was associated with changes in brain structure and cognitive functioning, even among people who were meeting recommended exercise guidelines. Now, that caught my attention because most of us have heard about the importance of regular exercise, but how often do we think about what we're doing during all those hours when we're not exercising?
Today, I want to explore what researchers are discovering about prolonged sitting, why it may matter for our brains, and whether that daily workout is enough to offset the hours we spend sitting.
Here's something we don't always think about. You can be physically active and still have a sedentary lifestyle. That may sound contradictory, but consider someone who exercises for 45 to 60 minutes every morning. That's a wonderful habit, and depending on the type and intensity of exercise, she may be meeting the recommended guidelines for physical activity. But if she spends most of the remaining day sitting, she's also accumulating a significant amount of sedentary time.
Researchers distinguish between these two behaviors. Physical activity involves movement that increases energy expenditure. Sedentary behavior generally refers to time spent sitting or reclining while using very little energy.
So exercise and sedentary behavior aren't simply two ends of the same spectrum. They're different aspects of how we spend our days. And I can relate to this. I exercise almost every day, but when I think about how I spend the rest of my day, I realized I'm actually more sedentary now than when I worked in the corporate world. Back then, I spent plenty of time sitting in meetings, but at least I had to get up, walk down the hallway, or go to another conference room.
Now, working from home, I can spend hours sitting at my computer without really needing to get up. And until I came across this research, I hadn't given that much thought. But researchers have been looking more closely at whether both physical activity and sedentary behavior matter when it comes to cognitive aging. And what they're discovering is worth paying attention to.
In May 2025, researchers from Vanderbilt University Medical Center and the University of Pittsburgh published a study in Alzheimer's and Dementia, the Journal of the Alzheimer's Association. They examined four hundred and four adults aged fifty and older. Participants wore devices that measured their activity over a week. Researchers also evaluated their cognitive abilities and examined brain scans collected over a period of several years. And here's what makes this study particularly interesting.
Approximately eighty percent of the participants were meeting the recommended guidelines for moderate-to-vigorous physical activity. In other words, most of these people were exercising. Yet the researchers still found an association between greater sedentary time and less favorable brain health outcomes.
People who spent more time sedentary tended to show poorer performance on certain cognitive measures. And over time, greater sedentary behavior was associated with faster shrinkage of the hippocampus. If you've listened to RenewHer for a while, you may remember hearing me talk about the hippocampus. It's a region of the brain that plays an important role in learning and memory, and it's also one of the areas affected by Alzheimer's disease.
So when researchers observed a relationship between greater sedentary time and faster shrinkage of the hippocampus, it raised an important question: Could the hours we spend sitting matter for our brain health, even if we're getting regular exercise?
Now, this study doesn't prove that sitting caused those brain changes. Researchers were observing relationships, not assigning people to different amounts of sitting and measuring the consequences. But what makes the findings noteworthy is that the associations were observed in a group where most participants were already physically active. And this isn't the only research pointing in that direction.
In twenty twenty-three, a study published in JAMA, J-A-M-A, examined nearly fifty thousand adults aged sixty and older. Researchers used wearable devices to estimate how much time participants spent sedentary each day. They then followed participants for an average of almost seven years to see who developed dementia, and they found a significant association.
People who accumulated more sedentary time each day had a higher incidence of dementia. The relationship became particularly noticeable at higher levels of sedentary time. For example, researchers found that dementia occurred at a sixty-three percent higher rate among people who spent about twelve hours a day sitting, compared with those who spent a little over nine hours sitting. That's a substantial difference.
It means that dementia occurred at a higher rate in that group compared with the group who spent less sitting. And importantly, the researchers accounted for participants' moderate-to-vigorous physical activity, along with a number of other health and lifestyle factors.
The association between greater sedentary time and dementia remained. Again, this doesn't establish that sitting causes dementia. But taken together with the twenty twenty-five findings, it gives researchers another reason to investigate sedentary behavior as a potential important factor in brain health.
So what's happening here? Why might the amount of time we spend sitting have anything to do with memory, thinking, or the structure of our brains? Researchers are still investigating the mechanisms, but there are several possible connections.
One involves our cardiovascular system. Our brains depend on a continuous supply of blood carrying oxygen and nutrients, and the health of our blood vessels plays an important role in maintaining healthy brain function.
We know that prolonged sedentary behavior can affect aspects of cardiovascular and metabolic health. For example, extended periods of sitting can influence how our bodies regulate blood sugar, and blood sugar regulation matters because the brain relies on a carefully regulated supply of energy.
Researchers are also studying how sedentary behavior may relate to inflammation and other biological processes involved in brain aging. But it's important to distinguish between what we know and what we're still trying to understand. We have evidence connecting sedentary behavior with several aspects of physical health. We also have studies finding associations between sedentary time and cognitive outcomes.
What we don't yet fully understand is how these relationships develop or how much changing sedentary behavior might alter long-term dementia risk. Still, the broader connection is worth considering. Our brains aren't operating independently from the rest of our bodies. What's happening with our cardiovascular system, our metabolism, and our overall physical health can influence how well our brains function.
Let's return to the question we started with. If you're exercising regularly, can that compensate for spending much of the rest of your day sitting? The answer is that researchers haven't established a simple yes or no, and this is where I think the research becomes especially interesting. Some studies suggest that higher levels of physical activity are associated with better cognitive outcomes, even among people who spend substantial time sedentary.
Other studies, including the 2025 Vanderbilt research, have found associations between greater sedentary time and less favorable brain outcomes, despite high levels of physical activity. So I wouldn't interpret this research as saying your morning workout doesn't count. Regular physical activity remains one of the more important ways we can support our physical health and cognitive functioning as we age.
But the emerging research suggests that a workout may not tell the whole story. It may also be worth paying attention to how we spend the rest of our waking hours. And I think that's a meaningful distinction because we often approach exercise as something we schedule. We go to the gym. We take a walk. We attend a class. And once we finish, we consider our physical activity complete for the day. But perhaps we should also be thinking about movement as something that belongs throughout our day, not just during a designated workout.
So what should we actually do with this information? First, I wouldn't want anyone to come away from this episode thinking they need to stop enjoying activities that involve sitting. Reading, working on a project, having a long conversation over dinner, these are meaningful parts of our lives, and many of them provide cognitive and emotional benefits of their own. The goal isn't to eliminate sitting. It's to become more aware of how much of our day we spend sedentary. And that's something I'm gonna be more intentional about.
I've always assumed that because I exercise regularly, I was doing enough. But after learning about these studies, now I'm not so sure. I don't know that there's a magic number for how often we should get up or how long we need to move, but I've decided that I'm going to make a point of getting up at least once an hour, even if it's just to walk around for a couple of minutes, to get my body moving, break up those long stretches of sitting, and maybe even give my brain a little break from whatever I've been working on.
I'm not suggesting that getting up every hour is some scientifically established formula for protecting our brains. It's simply a change I've decided to make based on what I've learned.
And perhaps it's worth thinking about your own routine. Do you spend several hours at your computer without realizing how much time has passed? Do you sit for much of the afternoon after exercising in the morning? Are there opportunities to incorporate a little more movement into activities you're already doing?
Maybe you can get up and walk around between meetings, take a short walk after lunch, move around while talking on the phone, or simply look for opportunities to spend a little less of your day sitting. Researchers haven't established that standing up every 30 minutes or following any particular schedule of getting up to move around will prevent dementia.
And I don't think we need to turn this into another set of numbers to obsess over. But finding opportunities to move more throughout the day is a reasonable way to support our overall health, and it may be another piece of the brain health puzzle.
What I find most interesting about this research is how it challenges the way we often think about physical activity. We tend to divide our days into exercise and everything else. We exercise because we know it's good for us, and then we go about the rest of our day without necessarily giving much thought of how long we've been sitting. But the researchers are asking us to look at the bigger picture, not just whether we're exercising, but how we're spending the hours in between.
And that's particularly relevant as we get older because maintaining our brain health isn't simply about preventing disease. It's about preserving the abilities that allow us to live the lives we want to live. To remain independent, to travel, to explore, to learn new things, to take on challenges, and to continue pursuing the experiences that make life meaningful.
That's something I talk about frequently on RenewHer. We're not simply trying to add years to our lives. We want those years to be filled with possibility. And caring for our brains and bodies is part of what makes that possible.
So here's something I encourage you to think about this week, not just how much exercise you're getting, but how much time you're
spending sitting during the rest of your day. You might be surprised. And you might discover a few opportunities to add more movement to your everyday routine. Because supporting our brain health may involve more than what we do during our workouts. It may also involve what we do during all those hours in between.
Until next time, stay curious and keep moving.
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