Sitting is killing you. Numerous studies have pointed to the health risks of sitting all day, but here you have in one illustration how prolonged sitting affects our bodies and reminders to interrupt sitting time whenever possible.
The human body simply isn’t built to sit all day at a desk or for hours vegging out on the couch. Many of us spend more time sitting than sleeping. To avoid the health risks, we need not just 30 minutes of daily exercise, the infographic advises, but taking every opportunity to get up during the day.
The Truth About “The Truth About Sitting Down”
After hearing about the benefits of standing desks for a while now, I finally sorted out a standing desk at work last month. It’s just an old desk I found, balanced on top of my original desk, but it puts my keyboard at a perfect height. I have to say, I don’t miss sitting at all. At the end of a long day in front of my computer, my feet hurt much less than my back used to. The only down side is that I tend to look a bit ridiculous when I’m working with headphones on and find myself dancing in place at my desk.
Being an empirical scientist, I know I can’t always trust my own perceptions about the benefits of an intervention. Any sort of change can increase productivity, so I’ve been looking for scientific evidence for the benefits of standing desks. An infographic, Sitting Down is Killing You by MedicalBillingandCoding.org, portrayed the state of research being strongly in favour of standing desks, but how accurate are the claims?
This infographic is much better than most because it includes references in a list at the end of the image, but each specific claim isn’t cited, so I looked up all 12 links to find the evidence behind the pictures (see the list at the end of this article). Let’s take a closer look at a few of the stats.
Sitting Increases Risk of Death Up to 40%?
The first major statistic on the infographic is this:
Sitting 6+ hours per day makes you up to 40% likelier to die within 15 years than someone who sits less than 3. Even if you exercise.
I tracked this claim down to an article in The New York Times, which states:
Alpa Patel, an epidemiologist at the American Cancer Society, tracked the health of 123,000 Americans between 1992 and 2006. The men in the study who spent six hours or more per day of their leisure time sitting had an overall death rate that was about 20 percent higher than the men who sat for three hours or less. The death rate for women who sat for more than six hours a day was about 40 percent higher.
Even from this brief description of the study, you can tell that this statistic is misleading as written. The increase in death rate for men was half this figure, but the infographic gives no hint of a sex difference.
Reading the actual study in the American Journal of Epidemiology provides further clarification. The participants in this study were healthy adults age 50–74 at the beginning of the study, so it’s unclear how the results apply to younger adults.
Additionally, the study only measured non-working sitting time. The exact question was, “During the past year, on an average day (not counting time spent at your job), how many hours per day did you spend sitting (watching television, reading, etc.)?” However, the same panel includes a pie graph that states the average person is sedentary 9.3 hours per day, implying that the dangerous level of 6+ hours of sitting per day is epidemic and includes sitting at work. In actuality, only 9% of women and 13% of men in this study sat for more than 6 hours per day, compared to 49% of women and 43% of men who sat for less than 3 hours per day outside of work.
How Sitting Wrecks Your Body?
The claims made in this panel set off my skeptic alarm immediately. The infographic claims that:
As soon as you sit:
- Electric activity in the leg muscles shuts off
- Calorie burning drops to 1 per minute
- Enzymes that help break down fat drop 90%
After 2 hours: Good cholesterol drops 20%
After 24 hours: Insulin effectiveness drops 24% and risk of diabetes rises
I traced two of these claims to an article in Business Week. The article contains the uncited statements:
When you sit, the muscles are relaxed, and enzyme activity drops by 90% to 95%, leaving fat to camp out in the bloodstream. Within a couple hours of sitting, healthy cholesterol plummets by 20%.
This is your body on chairs: Electrical activity in the muscles drops — “the muscles go as silent as those of a dead horse,” Hamilton says — leading to a cascade of harmful metabolic effects. Your calorie-burning rate immediately plunges to about one per minute, a third of what it would be if you got up and walked. Insulin effectiveness drops within a single day, and the risk of developing Type 2 diabetes rises. So does the risk of being obese. The enzymes responsible for breaking down lipids and triglycerides — for “vacuuming up fat out of the bloodstream,” as Hamilton puts it — plunge, which in turn causes the levels of good (HDL) cholesterol to fall.
So it looks like most of these claims are potentially supported by the evidence, even though they are presented in a fairly sensationalist manner. For instance, the claim that electrical activity in the leg muscles shuts off as soon as you sit down is fully supported by evidence in this graph, but it isn’t at all clear how this statistic relates to general health, as electrical activity normally “shuts off” in any muscle when it isn’t being used.
Standing Desks in the News
While the infographic overstates and mischaracterises some of the evidence (not unusual for infographics), the general conclusion holds true even after a closer look at the sources. There is a huge amount of quality reporting on research on the benefits of standing desks, including several of the links cited in the infographic (and below).
More recently, the BBC, in collaboration with researchers at the University of Chester, published the results of a small study on the benefits of standing at work: Calorie burner: How much better is standing up than sitting? On the basis of data from 10 volunteers with normally sedentary jobs at an estate agents who stood for 3 or more hours per day, they concluded:
If you stand for three hours a day for five days that’s around 750 calories burnt. Over the course of a year it would add up to about 30,000 extra calories, or around 8lb of fat.
“If you want to put that into activity levels,” Dr Buckley says, “then that would be the equivalent of running about 10 marathons a year. Just by standing up three or four hours in your day at work.”
So I’ll be sticking with my standing desk. It’s certainly easier than a marathon!
Breakdown of Citations in the Infographic
- http://bjsm.bmj.com/content/43/2/81.full (Owen, Bauman & Brown (2009). Too much sitting: a novel and important predictor of chronic disease risk? British Journal of Sports Medicine): reviews research on the health risks of sitting. Contains the chart used for “Average Physical Activity (Waking Hours)” in the panel, “Sitting increases risk of death up to 40%”.
- http://www.bls.gov/tus/charts/ (The American Time Use Survey): This website “collects information about the activities people do during the day and how much time they spend doing them” and probably contributed to several of the graphs.
- http://www.ajcn.org/content/72/6/1451.full (Energy expenditure of nonexercise activity. American Journal of Clinical Nutrition): Researchers measured changes in energy expenditure with fidgeting-like activities. They found that sitting still increases energy expenditure by 5.6 ± 1.6 kJ/minute (80 ± 23 calories/hour) above resting, while standing still increases it 6.1 ± 1.7kJ/minute (87 ± 24 calories/hour).
- http://fitness.families.com/blog/how-many-calories-do-you-burn-while-walking (Blog Post): Provides average calories burned per minute by walking for several weight categories.
- http://www.businessweek.com/magazine/content/10_19/b4177071221162.htm (Your Office Chair is Killing You, Business Week): Source of the claims about enzyme activity and cholesterol changes (uncited to research).
- http://www.nytimes.com/2011/04/17/magazine/mag-17sitting-t.html (Is Sitting a Lethal Activity? The New York Times): The source for several claims on the “How sitting wrecks your body” panel (see above).
- http://atvb.ahajournals.org/cgi/content/full/26/4/729 (Levine et al. (2006). Non-Exercise Activity Thermogenesis. Arteriosclerosis, Thrombosis and Vascular Biology): Contains the observation that “Obese individuals appear to exhibit an innate tendency to be seated for 2.5 hours per day more than sedentary lean counterparts.”, which reports data from Levine et al’s 2005 Science paper, Interindividual variation in posture allocation: possible role in human obesity. This study measured the activity of 20 self-proclaimed “couch potatoes.” who were lean (BMI = 23 ± 2 kg/m2) or mildly obese (BMI = 33 ± 2 kg/m2) and found that “obese participants were seated for 164 min longer per day than were lean participants” and “lean participants were upright for 152 min longer per day than obese participants”.
- http://diabetes.diabetesjournals.org/content/56/11/2655.long (Hamilton, Hamilton & Zderic (2007). Role of Low Energy Expenditure and Sitting in Obesity, Metabolic Syndrome, Type 2 Diabetes, and Cardiovascular Disease. Diabetes): An academic review paper of research on inactivity. Provides evidence for the claim that electrical activity in leg muscles shuts off when sitting.
- http://well.blogs.nytimes.com/2010/07/14/phys-ed-the-men-who-stare-at-screens/ (The Men Who Stare at Screen, The New York Times blog): Reports on some research. No specific statistics from the infographic are apparent.
- http://www.cdc.gov/pdf/facts_about_obesity_in_the_united_states.pdf (US Center for Disease Control): Source for “Between 1980 and 2000, obesity rates doubled among adults” and “About 60 million adults, or 30% of the adult population, are now obese.”
- http://msnbc.msn.com/id/39523298/ns/health-mens_health/ (Why your desk job is slowly killing you, Men’s Health): Source for the claims that sitting rose 8% from 1980–2000, “A 2006 University of Minnesota study found that from 1980 to 2000, the percentage of people who reported exercising regularly remained the same—but the amount of time people spent sitting rose by 8 percent”, and the claim that people with sitting jobs have twice the rate of cardiovascular disease, “people who sat for almost the entire day were 54 percent more likely to end up clutching their chests than those who sat for almost none of the time.”
- http://news.bbc.co.uk/2/hi/6187080.stm (Sitting straight ‘bad for backs’, BBC News): Source for entire “Take the extra step” panel. “When they looked at all test results, the researchers said the 135-degree position was the best for backs, and say this is how people should sit.”
Originally posted 2017-04-17 03:32:57.