He drinks organic Swiss chard every 42 minutes. He refuses to be in the same room as plastic. He vomits on gluten-containing products. He wears Power Bar-sponsored spandex and bikes his 43-mile commute to work (and tells you about it). He does 3 sets of 12, even during sex. And afterwards, he asks if you mind standing up while cuddling.
He’s Mr. Extreme (“That Guy” ‘s cousin). You may know some version of him, or even have a little bit of him in yourself. There’s something about reading a hot topic and stepping it up 24 orders of magnitude that seems to really drive our cars, instantly making us feel in control, superior, healthy…Moderation is for pussy cats who can’t hack the real deal.
But today’s blog is not about the mental issues Mr. Extreme and his devotees cultivate in their organically obsessive brains. Today is about the fact that last month his self-centered butt donated all the chairs in your house to his worst enemies…Is Mr. Extreme finally onto something? Or is he just secretly wishing for varicose veins because he heard they are the next badge of health?
You’ve all heard about it in the numerous blogs and NYT articles: sitting is killing us. After all these years of yelling at us to go exercise more, we finally went out and joined a gym, and figured out a way to clock our 30-45 minutes of moderate activity most days of the week. (OK, maybe…and sometimes…) We thought we had that checked off our lists, and those finger-shaking health experts would just leave us the heck alone. But now, it turns out “Haha, suckers! It’s what you do the REST of the 23 hours that actually matters even more.” Doesn’t matter how much you work out. Sitting for the rest of the day is worse.
Mr. and Mrs. Extreme slid off their chairs they were so excited. The rest of us, through tears of frustration, hurled our hailed gym memberships off the nearest cliff and unfriended our Zumba teachers on Facebook.
What’s wrong with taking a load off?
Nothing, except we do it for too long. It started out with some correlations between reported time spent sitting and watching television and risk of cardiovascular mortality…even if those reporting the most time spent seated did regular exercise.
But you know that correlation is not causation, so researchers started taking people and forcing them to sit in lab rooms for 24 hours without moving. One study measured insulin action in 12 people who spent 3 separate days (either sitting or standing) in their sad little room (1). The subjects’ insulin action was lower when they sat for 24 hours compared to when they either stood for most of the day in the room, OR sat for the 24 hours but also ate less than the other two conditions (so eating less attenuated the change). Other studies show “moderate quality” evidence that uninterrupted sitting can result in not-so-cool changes in triglyceride levels, insulin sensitivity, and glucose tolerance (3).
What the hell am I supposed to do? Get a convertible so I can stand while I’m driving? Ask my boss if I can stand during the meeting so that everyone thinks I’m a self-important social reject? Cancel movie nights with my SO because I am afraid of dying in my chair?
Causing car accidents, losing your job, and weirding out friends is a sure fire way to worsen your health.
This is a relatively new area of research, and no guidelines for sedentary behavior, or an actual consistent definition of what “sedentary” means, have been ironed out.. And just because doing one thing all the time is bad, it doesn’t necessarily mean that doing the opposite all the time is good.
In fact, there has been a chunk of research exploring the occupational hazards and long-term effects of prolonged standing. It is associated with chronic plantar heel pain, varicose veins, chronic venous insufficiency, preterm birth, distal lower leg symptoms (like night leg cramps), and the progression of carotid atherosclerosis. Prolonged standing can increase the pooling of blood in your lower extremities, increase the occlusion of blood flow, increase pressure on your joints, and increase muscular fatigue (and not necessarily in the muscles you want to fatigue). Mentally, people report decreased motivation and concentration, and increased perceived fatigue with prolonged standing.
OMG! So should I levitate?
I guess the point is NOT that you’re doomed and whether you sit or stand you will slowly kill yourself in different ways; the takeaway is that that neither should be done for too long of a time period. (Oh gawd! That lame moderation message again! My extreme all-or-nothing mind is exploding!) Mindlessly standing in an off-balance posture x 40 hours a week might develop or exacerbate some muscular and neurological imbalances. But uninterrupted sitting all the time can have negative metabolic consequences.
You’re not helping…
Research has shown that interrupting sitting with breaks negates of the effects of prolonged sitting (2). One study showed that 2-minute breaks every 20 minutes were adequate. However, the breaks were spent ambulating at 1.9 mph, and the researchers did not try longer periods between the breaks, nor did they explore standing breaks in this study. It seems that taking a walk break every 20 minutes would hurt productivity and focus. No study to my knowledge has yet looked at standing for 2 minutes instead.
What about laying down? Can I alternate between standing and laying down, just swapping all my chairs for beds?
I’m with you! Meetings on cots sounds perfect. The research has been done on sitting since that’s what people tend to do at work. But some researchers have been defining sedentary as “less than 1.5 METS”, or less than 1.5 times the amount you burn in bed rest; so laying down unfortunately fits in that category.
While they say that standing burns significantly more calories than sitting, I’m not totally convinced. If you were to ask an activity caloric estimation chart, it’d tell you that 8 hours of standing burns an extra 380-ish calories more than sitting. However, one study using a more precise caloric estimate found no significant difference between sitting and standing, another found only about a 10-calorie difference every hour, and yet another documented about a 5-calorie hourly difference. So clearly the point of standing isn’t to burn calories, but rather to interrupt the sitting.
What about a treadmill desk?
This is an exciting question that has not fully been explored. Research has thus far shown that some tasks are OK when done at a very slow walking pace, but that other tasks may take more time and be less accurately executed when done during walking. In fact, preliminary evidence not yet published because the researcher is too busy writing nutrition blogs to get her act together and submit it to a journal indicates that walking may actually help creative thinking, but hurt activities that require more focus. So maybe interspersing walking with standing and sitting throughout the day will be the workday of the future (and hopefully soon we’ll know what is performed best in each position :)!)
So what’s the bottom line?
We don’t know the bottom line yet, because nobody has done a dose trial (testing how long is too long) nor a long-term study. What is clear now is that the negative effects of prolonged sitting are ameliorated by taking breaks. So here are some interim recommendations, since research hasn’t ironed it out yet.
- Take a break and stand up every 30 or 40 minutes for maybe 2 minutes. You don’t have to stop working, just stand up. Work standing for a few minutes.
- Lather, rinse, repeat every 30ish-minutes throughout your day, if you can.
- Every hour, if you have the setting for it, walk around for a minute, go pee, or go find out who in the office is wearing something fuchsia (we can only really focus well for 45 minutes at a time anyway!)
- If you miss a break, do not melt down. You can watch a movie without your lipoprotein lipase eating your spleen. You can drive to work without metabolically imploding. If you have to sit for a long time, don’t be glued in one position. Shift a bit. Contract your glutes once in a while. Mr/s Moderation is much happier and healthier than Mr. Extreme, and has more friends as well.
MS, RD, PhD
Footnotes!! And some sources built in 🙂
1. In an elegant study, researchers compared each subject to themselves across three different 24-hour conditions (in a room with a chair, desk, futon, internet-accessible computer, books and magazines, and movies): “NO SIT” where the subjects were restricted in their total sitting time and stood while working on the computer, playing board or card games, and performed standardized activities for set amounts of time like sweeping, folding laundry, and playing darts; “SIT” and “SIT-BAL” where the subjects sat during most of the activities they did. During the NO-SIT and SIT conditions the subjects ate identical number of calories, determined based on their own personal needs calculated using a ventilated hood collecting their respiratory gases and using indirect calorimetry; when in the SIT-BAL condition, subjects consumed 1000 less calories than they had during the NO-SIT and SIT days. Therefore, during NO-SIT and SIT-BAL the researchers decided that the subjects were in energy balance, but during SIT the subjects were in energy surplus. (I am not sure I agree with that, as 1000 extra calories for standing and ambling is a bit generous!)
At the end of the day, it turned out that the NO-SIT spent about 1.1-2.7 METS on a minute by minute basis (pretty low intensity), to somehow make 10,000 steps, and the SIT and SIT BAL expended 24-29% less calories than the NO-SIT condition.
All meals were identical foods, and the macronutrient distribution was about 54% carbs, 29% fat, and 16% protein.
The results were as follows: Fasting plasma glucose was no different among the three conditions, insulin action was 39% lower in the SIT compared to the NO-SIT condition, but the NO-SIT and SIT-BAL condition did not statistically differ from each other (close, but no statistical cigar!) The authors thought close was enough to still conclude that sitting, even with an energy decrease, still wasn’t enough to completely prevent the decline in insulin action (although statistically SIT with caloric deficit was no different than NO-SIT).
Problems with this are low sample size (only 12 people); it was unclear how the NO-SIT condition managed 10,000 steps per day in a small room; they didn’t record or separate out sleep time, nor even mention it, in their results or study design; this was only 24 hours, so hard to extrapolate to longer-term effects; the subjects were all healthy, young, fit people, so it’s unclear if these results can apply to a broader range of folks; finally, this study’s SIT condition is not exactly ecologically valid…most people, other than those suffering a medical condition or injury, will leave a room within 24 hours, even if to walk to their mailbox or go answer a phone.
Here’s the study:
Stephensa, B.R., Granadosa, K., Zdericb, M.T., & Hamilton, B.B. (2011). Effects of 1 day inactivity on insulin action in healthy mean and women: interaction with energy intake. Metabolism Clinical and Experimental, 60, 941-949.
2. This systematic review of 25 independent interventions found what they called “moderate quality” evidence suggesting that acute bouts of uninterrupted sedentary behavior lasting result in deleterious changes in triglyceride levels, insulin sensitivity, and glucose tolerance. The authors noted that of the 25, only 6 of the trials had a randomized design, and actually only 3 had randomized crossover studies, where the same subjects were used in each condition, serving as their own controls. Also, only 4 of the 25 studies actually looked at sitting (non-bed rest) as the sedentary activity, so the effects may not be as large as the systematic review suggest. Finally, the majority of the subjects in all of the 25 studies were healthy, young men.
This is supported in rat trials (where they unload or tie up the rats hindlimb); after 18 hours of sedentary behavior, the rats experienced a 75% reduction in triglyceride uptake as well as near total cessation of lipoprotein lipase activity.
Here’s the study:
Saunders, T.J., Larouche, R., Colley, R.C., & Tremblay, M.S. (2012). Acute sedentary behavior and markers of cardiometabolic risk: A systematic review of intervention studies. Journal of Nutrition and Metabolism, 2012, 712435.
3. Another study was a bit more ecologically valid than the one described in footnote #1. The population used were overweight or obese adults from 45-65 years old, compared to the healthy and younger population used in the study described above. Even though prolonged sitting is associated with premature cardiovascular and all-cause mortality, frequent interruptions or breaks from sedentary time, that lasted on average 4 minutes are shown to provide a benefit, above and beyond adiposity and leisure time exercise!
So these guys looked an uninterrupted sitting and compared it with short 2 minute breaks consisting of light or moderate intensity walking in overweight middle-aged adults. Everyone did all three conditions in randomized order with a week in between. All participants sat for 2 hours (and they had a venous catheter in their arm for the entire trial). They then consumed a 3,195 calorie drink of about 75 grams of carbohydrate and 50 grams of fat. Then the remaining 5 hours were spent in one fo the following conditions: uninterrupted sitting, where they minimized excessive movement and only got up to go to the bathroom; sitting + light-intensity activity breaks, where they rose every 20 minutes throughout the 5 hours to get 3 2-minute breaks per hour, and the break was walking on a treadmill at a pace of 1.9 mph; or a sitting + moderate-intensity activity breaks (same number of breaks) with walking on the treadmill at around 3.6 – 3.9 mph.
Turned out that the light intensity break was just the same as the moderate intensity break for reductions in post-eating glucose and insulin (indicating indirectly that the insulin was more effective?). You’d like to see this study with a standing break done as well, and the authors suspect similar benefits would be found, as some animal studies imply that it is primarily important to interrupt the contractile inactivity in postural muscles, as opposed to actually walking or expending more energy. Also, the study did not look at switch cost for attention for ecological validity. My guess is that dashing sitting with standing every 20 minutes for 2 minutes would result in less mental focus interruption.
Here’s the study:
Dunstan, D.W., Kingwell, B.A., Larsen, R., Genevieve, N.H., Cerin, E., Hamilton, M.T., Shaw, J.E., Bertovic, D.A., Zimmet, P.Z., Salmon, J., & Owen, N. (2012). Breaking up prolonged sitting reduces postprandial glucose and insulin responses. Diabetes Care, 35(5), 976-983.
About inactivity physiology:
Yates, T., Wilmot, E.G., Khunti, K., Biddle, S., Gorely, T., & Davies, M.J. (2011). Stand up for health: Is it time to rethink the physical activity paradigm? Diabetes Research and Clinical Practice, 93(2), 292-294.
Standing vs Sitting caloric burn (not a huge difference according to these studies!):
Lanningham-Foster, L., Foster, R.C., McCrady, S.K., Jensen, T.B., Mitre, N., & Levine, J.A. (2009). Activity promoting games and increased energy expenditure. Journal of Pediatrics, 154(6), 819-823.
Speck, R.M., & Schmitz, K.H. (2011). Energy expenditure comparison: A pilot study of standing instead of sitting at work for obesity prevention. Preventive Medicine, 52(3-4), 283-284.
Steeves, J.A., Thompson, D.L., & Bassett, D.R. (2012). Energy cost of stepping in place while watching television commercials. Medicine & Science in Sports and Exercise, 44(2), 330-335.
Effects of prolonged standing studies:
Bahk, J.W., Kim, H., Jung-Choi, K., Myung-Chui, J., & Inseok, L. (2012). Relationship between prolonged standing and symptoms of varicose veins and nocturnal leg cramps among women and men. Ergonomics: Special Issue: Gender, Women’s Work and Ergonomics, 55(2), 133-139.
Freitas, S., Wieczorek, S.A., Marchetti, P.H., Duarte, M. (2005). Age-related changes in human postural control of prolonged standing. Gait & Posture, 22, 322-330.
Irving, D.B., Cook, J.L., & Menz, H.B. (2006). Factors associated with chronic plantar heel pain: a systematic review. Journal of Science and Medicine in Sport, 9(1-2), 11-22.
Marshall, P. W.M., Patel, H., & Callaghan, J.P. (2011). Gluteus medius strength, endurance, and co-activation in the development of low back pain during prolonged standing. Human Movement Science, 30, 63-73.