What Sitting All Day Does to Your Brain and Body | Keith Diaz | TED

00:04My favorite job ever was as a summer-camp counselor, where I was basically paid to play games with kids all day. We played capture the flag, running bases, dodgeball, went swimming in the pool every day. And at the end of the day, I'd be tired, but in a good way.

00:20Not mentally drained, but physically tired. A satisfied kind of tired where I'd use my body to complete a hard day's work. Flash forward, and my job today looks very different. (Laughter) Even though I'm an exercise scientist, I don't get to actually do any exercise at work.

00:40Instead, my days consist of staring at a computer screen and sitting in countless meetings. The transition for me to office work was jarring. I no longer had those same feelings of satisfaction at the end of the day's work. I was still tired, exhausted, actually, but I hadn't used my body at all.

00:58And this shift that I experienced, I'm not alone in feeling. We are living in the most sedentary era in modern history. In a single year, the average adult will now spend a full 187 days, over half of the year, sitting or physically idle. The bad news is that our bodies weren't designed for this.

01:21I know because I've spent my career as a scientist studying the harms of being highly sedentary. And what scientists have found is that being highly sedentary increases your risk of diabetes, cancer, dementia, heart disease and ultimately early death.

01:38Worse, this is true even if you exercise regularly. To put it simply, being highly sedentary, as many of us are, is toxic. Let's start with the healthiest people among us to use as an example. In one study, when highly trained endurance athletes were forced to bed rest, their aerobic fitness levels dropped by about 20 percent in just three days.

02:08What took them months to build was erased in a matter of a long weekend with no movement. This isn’t unique to highly trained endurance athletes. If you took a regular, typical, healthy adult and forced them to 40 days of bed rest, their heart would show changes similar to 50 years of aging.

02:31Now, this isn't about missing a workout or two. Exercise only makes up a tiny fraction of your day. The toxicity comes from when movement begins to disappear from your life. And this begs the question, why isn't exercise alone enough? Part of the answer lies in our muscles.

02:54Our muscles are more than just a machinery that power movement. They're also really important for regulating things like our metabolism. Let's use blood sugar as an example. Our muscles are like sponges for blood sugar. When we regularly use and contract our muscles, they're like a moist sponge, soaking up the sugar from the bloodstream.

03:20But when we don’t regularly use and contract our muscles, like a dry and shriveled-up sponge, not really good at soaking up anything. Now here's the key. When we exercise, it rewets the sponge, but eventually that sponge dries out if you get little to no movement the rest of your day.

03:40So what do we do? Well, we need to keep the sponge moist. Now I’m not going to tell you that we need to move all day. Instead, I'm going to suggest that we follow the lead of an unlikely place. The tobacco industry. (Laughter) In their early days, cigars were their primary product.

04:05But this was the industrial age. Millions were working in factories, and those workers only got short breaks from their lines. Certainly not long enough to smoke a cigar. Thus, the cigarette became the primary focus of the tobacco industry so that these workers could get their fix in small, short doses, a few minutes at a time throughout the day.

04:28And if sitting truly is the new smoking, as the saying goes, then what better way to fight back than to use the approach of the tobacco industry? But instead of smoke breaks, “movement breaks.” Short bouts of movement, a few minutes at a time, sprinkled in throughout the day.

04:50If our muscles need regular use to function optimally, then outside of any exercise time, we need to be contracting them frequently through movement. The question that we asked in my lab is, what’s the least amount of “movement breaks” that we need in order to offset the harms of being highly sedentary?

05:08And the answer we found was a five-minute walk every half hour. This reduced the blood sugar spike after eating by about 60 percent. That's the size of reduction you would expect to see if you put someone on medication to manage their blood sugar levels.

05:26The cool part is that our participants weren't sprinting or even walking fast. This was a stroll, they were walking at two miles an hour. Now I want to be honest. What I’m proposing to you as the answer to our modern sedentary lives are five-minute breaks every hour or every half hour.

05:49The truth is that when I found out that this was the answer, I was disappointed. My immediate reaction was, there's no way people are going to do this, largely because I couldn't realistically do it myself. And so part of me wondered whether this should be the end of the road for my research on movement breaks.

06:05But rather than argue with the data, I decided to press forward and put it to the test in the real world. With a little help from public radio, we had over 20,000 people try our experiment to take movement breaks throughout the day, anywhere from every half hour to every two hours for two weeks.

06:22And to my surprise, the vast majority of people liked taking movement breaks. Many wanted to keep going. We had tapped into something that people were craving, an antidote to our toxic modern lives. But what really surprised me is that when we asked people what they liked about movement breaks, very few touted the physical health benefits.

06:46Instead, what they liked was how the movement breaks made them feel. They loved that they felt energized, that they no longer felt like they were in this brain fog throughout the day, that they were able to actually better focus at work. And this really resonated with me and my experiences as an office worker and how the exhaustion impacted my life.

07:11I remember when my kids were younger and I'd come home from my office job, I’d open the door and they'd greet me with energy and enthusiasm, and want me to immediately start playing with them, and I just didn't have it in me. I was too drained from the day.

07:26And that's one of the most striking findings that we see in the lab. Over the course of sitting all day with no movement, people's mood plummets while their fatigue builds and builds. And that's because our muscles have a symbiotic relationship with our brains.

07:43They're in constant communication. Our biological need to contract muscle is more than just about physical health and metabolism. It's also foundational to mental and brain health. The promising news is that in our real-world experiment, our participants only averaged four to five movement breaks a day.

08:03Far below our lab-tested prescription. And yet, they still reduced their feelings of fatigue by about 25 percent. And we see this play out in the lab as well. Something as small as a one-minute walk every hour can still largely offset the impact of sitting all day on your mood.

08:24So even small, short, infrequent movement breaks can counter some, not all, but some of the hidden costs of our sedentary lives. Now one of the biggest concerns I often hear from employers and schools about movement breaks is they worry that it’s disruptive, that it'll hurt productivity and performance.

08:46But movement doesn't mean you have to stop working. You can have walking meetings, pace around while you're on a call, get walking pads, or simply just move around while thinking. But the bigger idea and concept with movement breaks is that when you compare brain activity after movement versus after sitting, the differences are so striking.

09:08The brain after movement looks like one certainly far more ready to learn and to work. And yet, somewhere along the way, we decided that sitting and staring in front of a computer screen for eight hours straight is the best way to work. And that's where the real challenge lies.

09:23Productivity culture, convenience culture, and technology are reengineering our lives and steadily removing the need for movement. We can have groceries delivered, and robots vacuum our floors without ever getting off the couch. And the consequences of this reengineering are that we now often see movement -- (Laughter) As an inconvenience.

09:49[My laptop is dying. But my charger is all the way upstairs] We see it as an interruption. We see it as something to avoid. I saw this play out with my daughter recently when I had to drive her to our local library. But when we got there, the parking lot was full, so I had to park a little further away in the street, and she immediately started complaining that I had parked so far away.

10:13Now mind you, the place I had parked may have added an additional 20 seconds of walking to her life. Not a mile. Twenty seconds. But that moment hit me. Movement had become an inconvenience for my daughter too. So I gave her a classic dad lecture.

10:31And this was met with a preteen eye roll. (Laughter) But a few days later, we were leaving a stadium and I was taking the escalator down. And as I'm going down, I see something pass by me and I look and it's my daughter, taking the regular set of stairs -- happily taking the regular set of stairs -- smiling at me as she goes by.

10:50It was a small victory. And if my eye rolling preteen can make this shift on occasion, then I have hope for the rest of us. Because movement breaks are ultimately about something bigger. They're about seeing those small moments in your day when you have the opportunity to move, to see them not as inconveniences, but as a way to reconnect our bodies and our brains so we're not living some tired, drained version of ourselves.

11:18Thank you. (Cheers and applause)