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

TED11:24Added Aug 30, 2026

Can a five-minute walk change how you feel all day? Exercise scientist Keith Diaz shows how your body is built for the kind of movement that modern life has quietly erased — and suggests something refreshingly doable: making time for small doses of movement sprinkled throughout the day, as a way to boost your brain and body. (Recorded at TED2026 on April 15, 2026)

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Contributed by 刘嘉琪

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  1. 00:04My favorite job ever was as a summer-camp counselor,
  2. 00:08where I was basically paid to play games with kids all day.
  3. 00:11We played capture the flag, running bases, dodgeball,
  4. 00:14went swimming in the pool every day.
  5. 00:16And at the end of the day,
  6. 00:18I'd be tired, but in a good way.
  7. 00:20Not mentally drained, but physically tired.
  8. 00:23A satisfied kind of tired
  9. 00:25where I'd use my body to complete a hard day's work.
  10. 00:28Flash forward,
  11. 00:30and my job today looks very different.
  12. 00:33(Laughter)
  13. 00:35Even though I'm an exercise scientist,
  14. 00:37I don't get to actually do any exercise at work.
  15. 00:40Instead, my days consist of staring at a computer screen
  16. 00:43and sitting in countless meetings.
  17. 00:45The transition for me to office work was jarring.
  18. 00:49I no longer had those same feelings of satisfaction
  19. 00:51at the end of the day's work.
  20. 00:53I was still tired, exhausted, actually,
  21. 00:55but I hadn't used my body at all.
  22. 00:58And this shift that I experienced, I'm not alone in feeling.
  23. 01:02We are living in the most sedentary era in modern history.
  24. 01:07In a single year,
  25. 01:09the average adult will now spend a full 187 days,
  26. 01:12over half of the year,
  27. 01:14sitting or physically idle.
  28. 01:18The bad news is that our bodies weren't designed for this.
  29. 01:21I know because I've spent my career as a scientist
  30. 01:24studying the harms of being highly sedentary.
  31. 01:26And what scientists have found is that being highly sedentary
  32. 01:29increases your risk of diabetes,
  33. 01:32cancer, dementia,
  34. 01:34heart disease and ultimately early death.
  35. 01:38Worse, this is true even if you exercise regularly.
  36. 01:44To put it simply,
  37. 01:45being highly sedentary, as many of us are,
  38. 01:49is toxic.
  39. 01:52Let's start with the healthiest people among us
  40. 01:54to use as an example.
  41. 01:56In one study,
  42. 01:57when highly trained endurance athletes were forced to bed rest,
  43. 02:01their aerobic fitness levels dropped by about 20 percent
  44. 02:05in just three days.
  45. 02:08What took them months to build
  46. 02:11was erased in a matter of a long weekend
  47. 02:14with no movement.
  48. 02:15This isn’t unique to highly trained endurance athletes.
  49. 02:19If you took a regular, typical, healthy adult
  50. 02:22and forced them to 40 days of bed rest,
  51. 02:24their heart would show changes similar to 50 years of aging.
  52. 02:31Now, this isn't about missing a workout or two.
  53. 02:34Exercise only makes up a tiny fraction of your day.
  54. 02:38The toxicity comes from when movement begins to disappear from your life.
  55. 02:44And this begs the question,
  56. 02:46why isn't exercise alone enough?
  57. 02:51Part of the answer lies in our muscles.
  58. 02:54Our muscles are more than just a machinery that power movement.
  59. 02:58They're also really important for regulating things like our metabolism.
  60. 03:02Let's use blood sugar as an example.
  61. 03:08Our muscles are like sponges for blood sugar.
  62. 03:12When we regularly use and contract our muscles,
  63. 03:16they're like a moist sponge,
  64. 03:17soaking up the sugar from the bloodstream.
  65. 03:20But when we don’t regularly use and contract our muscles,
  66. 03:24like a dry and shriveled-up sponge,
  67. 03:26not really good at soaking up anything.
  68. 03:28Now here's the key.
  69. 03:30When we exercise,
  70. 03:32it rewets the sponge,
  71. 03:34but eventually that sponge dries out
  72. 03:37if you get little to no movement the rest of your day.
  73. 03:40So what do we do?
  74. 03:42Well, we need to keep the sponge moist.
  75. 03:49Now I’m not going to tell you that we need to move all day.
  76. 03:54Instead, I'm going to suggest that we follow the lead
  77. 03:56of an unlikely place.
  78. 03:58The tobacco industry.
  79. 04:00(Laughter)
  80. 04:01In their early days, cigars were their primary product.
  81. 04:05But this was the industrial age.
  82. 04:08Millions were working in factories,
  83. 04:10and those workers only got short breaks from their lines.
  84. 04:13Certainly not long enough to smoke a cigar.
  85. 04:15Thus, the cigarette became the primary focus of the tobacco industry
  86. 04:21so that these workers could get their fix in small, short doses,
  87. 04:24a few minutes at a time throughout the day.
  88. 04:28And if sitting truly is the new smoking,
  89. 04:32as the saying goes,
  90. 04:34then what better way to fight back
  91. 04:36than to use the approach of the tobacco industry?
  92. 04:38But instead of smoke breaks,
  93. 04:41“movement breaks.”
  94. 04:43Short bouts of movement, a few minutes at a time,
  95. 04:47sprinkled in throughout the day.
  96. 04:50If our muscles need regular use to function optimally,
  97. 04:53then outside of any exercise time,
  98. 04:55we need to be contracting them frequently through movement.
  99. 04:59The question that we asked in my lab is,
  100. 05:02what’s the least amount of “movement breaks” that we need
  101. 05:04in order to offset the harms of being highly sedentary?
  102. 05:08And the answer we found
  103. 05:11was a five-minute walk every half hour.
  104. 05:14This reduced the blood sugar spike after eating by about 60 percent.
  105. 05:19That's the size of reduction you would expect to see
  106. 05:21if you put someone on medication
  107. 05:23to manage their blood sugar levels.
  108. 05:26The cool part is that our participants weren't sprinting or even walking fast.
  109. 05:31This was a stroll, they were walking at two miles an hour.
  110. 05:37Now I want to be honest.
  111. 05:39What I’m proposing to you as the answer to our modern sedentary lives
  112. 05:45are five-minute breaks every hour or every half hour.
  113. 05:49The truth is that when I found out that this was the answer,
  114. 05:53I was disappointed.
  115. 05:54My immediate reaction was,
  116. 05:55there's no way people are going to do this,
  117. 05:57largely because I couldn't realistically do it myself.
  118. 06:00And so part of me wondered whether this should be the end of the road
  119. 06:03for my research on movement breaks.
  120. 06:05But rather than argue with the data,
  121. 06:08I decided to press forward
  122. 06:10and put it to the test in the real world.
  123. 06:13With a little help from public radio,
  124. 06:14we had over 20,000 people try our experiment
  125. 06:17to take movement breaks throughout the day,
  126. 06:19anywhere from every half hour to every two hours for two weeks.
  127. 06:22And to my surprise,
  128. 06:24the vast majority of people liked taking movement breaks.
  129. 06:28Many wanted to keep going.
  130. 06:30We had tapped into something that people were craving,
  131. 06:34an antidote to our toxic modern lives.
  132. 06:38But what really surprised me
  133. 06:40is that when we asked people what they liked about movement breaks,
  134. 06:44very few touted the physical health benefits.
  135. 06:46Instead, what they liked
  136. 06:49was how the movement breaks made them feel.
  137. 06:53They loved that they felt energized,
  138. 06:56that they no longer felt like they were in this brain fog throughout the day,
  139. 07:00that they were able to actually better focus at work.
  140. 07:05And this really resonated with me and my experiences
  141. 07:07as an office worker
  142. 07:08and how the exhaustion impacted my life.
  143. 07:11I remember when my kids were younger
  144. 07:13and I'd come home from my office job,
  145. 07:15I’d open the door
  146. 07:16and they'd greet me with energy and enthusiasm,
  147. 07:18and want me to immediately start playing with them,
  148. 07:21and I just didn't have it in me.
  149. 07:23I was too drained from the day.
  150. 07:26And that's one of the most striking findings that we see in the lab.
  151. 07:29Over the course of sitting all day with no movement,
  152. 07:31people's mood plummets
  153. 07:33while their fatigue builds and builds.
  154. 07:36And that's because our muscles have a symbiotic relationship with our brains.
  155. 07:43They're in constant communication.
  156. 07:45Our biological need to contract muscle
  157. 07:47is more than just about physical health and metabolism.
  158. 07:51It's also foundational to mental and brain health.
  159. 07:56The promising news is that in our real-world experiment,
  160. 07:59our participants only averaged four to five movement breaks a day.
  161. 08:03Far below our lab-tested prescription.
  162. 08:05And yet, they still reduced their feelings of fatigue
  163. 08:09by about 25 percent.
  164. 08:11And we see this play out in the lab as well.
  165. 08:14Something as small as a one-minute walk every hour
  166. 08:19can still largely offset the impact of sitting all day on your mood.
  167. 08:24So even small, short, infrequent movement breaks
  168. 08:28can counter some, not all,
  169. 08:30but some of the hidden costs of our sedentary lives.
  170. 08:35Now one of the biggest concerns I often hear from employers and schools
  171. 08:39about movement breaks
  172. 08:41is they worry that it’s disruptive,
  173. 08:43that it'll hurt productivity and performance.
  174. 08:46But movement doesn't mean you have to stop working.
  175. 08:49You can have walking meetings, pace around while you're on a call,
  176. 08:53get walking pads,
  177. 08:54or simply just move around while thinking.
  178. 08:56But the bigger idea and concept with movement breaks
  179. 09:00is that when you compare brain activity
  180. 09:02after movement
  181. 09:04versus after sitting,
  182. 09:06the differences are so striking.
  183. 09:08The brain after movement looks like one
  184. 09:10certainly far more ready to learn and to work.
  185. 09:13And yet, somewhere along the way,
  186. 09:15we decided that sitting
  187. 09:16and staring in front of a computer screen for eight hours straight
  188. 09:19is the best way to work.
  189. 09:20And that's where the real challenge lies.
  190. 09:23Productivity culture, convenience culture,
  191. 09:27and technology are reengineering our lives
  192. 09:30and steadily removing the need for movement.
  193. 09:34We can have groceries delivered,
  194. 09:36and robots vacuum our floors without ever getting off the couch.
  195. 09:40And the consequences of this reengineering are that we now often see movement --
  196. 09:45(Laughter)
  197. 09:48As an inconvenience.
  198. 09:49[My laptop is dying. But my charger is all the way upstairs]
  199. 09:52We see it as an interruption.
  200. 09:54We see it as something to avoid.
  201. 09:58I saw this play out with my daughter recently
  202. 10:00when I had to drive her to our local library.
  203. 10:04But when we got there, the parking lot was full,
  204. 10:06so I had to park a little further away in the street,
  205. 10:09and she immediately started complaining that I had parked so far away.
  206. 10:13Now mind you,
  207. 10:14the place I had parked may have added
  208. 10:16an additional 20 seconds of walking to her life.
  209. 10:18Not a mile.
  210. 10:20Twenty seconds.
  211. 10:22But that moment hit me.
  212. 10:24Movement had become an inconvenience for my daughter too.
  213. 10:28So I gave her a classic dad lecture.
  214. 10:31And this was met with a preteen eye roll.
  215. 10:34(Laughter)
  216. 10:35But a few days later,
  217. 10:37we were leaving a stadium and I was taking the escalator down.
  218. 10:40And as I'm going down,
  219. 10:42I see something pass by me and I look and it's my daughter,
  220. 10:44taking the regular set of stairs --
  221. 10:46happily taking the regular set of stairs --
  222. 10:48smiling at me as she goes by.
  223. 10:50It was a small victory.
  224. 10:52And if my eye rolling preteen can make this shift on occasion,
  225. 10:57then I have hope for the rest of us.
  226. 10:59Because movement breaks are ultimately about something bigger.
  227. 11:03They're about seeing those small moments in your day
  228. 11:06when you have the opportunity to move,
  229. 11:08to see them not as inconveniences,
  230. 11:11but as a way to reconnect our bodies and our brains
  231. 11:14so we're not living some tired, drained version of ourselves.
  232. 11:18Thank you.
  233. 11:19(Cheers and applause)