You read the title correctly—there were no typos, just a little poetic license and an attempt to get people to hear me, ‘even after all my logic and my theory.’ So, I know people are up in arms about athletes kneeling, but how much we ALL spend sitting should concern us more.
We spend an average of 9-10 hours per day sitting (1).
Our technological advances have allowed the world to transition from a world of manual labor to one of sedentary desk jobs. TV, binge-watching, computers, smartphones, and social media haven’t helped either. We went from ‘hunter-gatherers’ to ‘sitter-watchers.’ How unhealthy is our culture of prolonged sitting? Is there anything we can do to decrease the risks from sitting for extended periods of time? As an evidence-based doc, I went to PubMed to look this sit up and quickly realized two things—this sit is dangerous and I should probably change some sit in my own life.
How dangerous is too much sitting?
These are questions I struggle with myself. Outside of when I’m doing procedures and walking around the hospital, my job as a doctor has its sedentary moments. Multiple studies show that sitting for long stretches is a risk factor for all types of diseases that one should avoid if possible. Let’s address a few major conditions with sitting as a risk factor.
A study published in the Journal of the National Cancer Institute found an association between excessive sitting and an increased risk of colon cancer and uterine cancer (2). The authors concluded that every 2-hour increment of daily sitting increased the risk of colon cancer by 8% and the risk of uterine cancer by 10%. This doesn’t mean that sitting causes these malignancies. The opposite is also true, moving around is not 100% protective against these cancers. Sitting too much is just one possible risk factor for these diseases.
If you are trying to figure out ways to reduce risk your risk of these cancers, sitting less should be one item (not the only item) on your checklist.
Considering that colon cancer is the 3rd most common cancer in both men and women and uterine cancer is the 4th most common cancer in women, we all should seriously think about how much we sit. For my fellow gastroenterologists, when we find polyps, maybe we should advise on physical activity (and diet) in addition to providing our recommendations for when to repeat a colonoscopy? On a brighter note, the study did not show a connection between sitting and several other cancers including prostate, ovarian, breast, stomach, kidney, and esophageal cancers.
An elegant study published in 2013 sought to determine how both sitting and physical activity affects fat deposition throughout the body (3). They used CT scans to measure fat in various organs/locations throughout the body. Not surprising, they found that physically active people had smaller fat deposits in the belly (visceral), muscles (intermuscular), under the skin (subcutaneous), and in the chest cavity (thoracic). On the other hand, in less active people, they found that a significant correlation with each hour of daily sitting and an increased amount of fat around the heart (pericardial fat), but not in other places.
Sedentary, skinny people should read this closely—sitting may lead to fat around the heart, but not in visible areas like the belly and under the skin. The way you look may not reflect what’s going on inside you. The author’s concluded, “the association between sitting and pericardial fat could partially explain the link between sitting and coronary disease [heart disease].”
There is a multitude of studies linking weight gain with sitting and TV watching. The reason for the relationship is simple. Sitting burns fewer calories compared to almost every other activity. Let’s thank Michelle Obama for the Let’s Move Initiative before it’s ‘repealed and replaced.’
How much sitting is too much?
I couldn’t find a straightforward answer. Oddly, medical guidelines regarding physical activity only focus on how long and how intense people should exercise. Guidelines dealing with how long we can safely sit do not exist. Most of the studies I saw looked at varying durations of sitting and the impact of interrupting sitting.
Here are some highlights to give a frame of reference for how long we shouldn’t sit.
3 hours per day
According to a review of multiple studies dealing with sitting, “Watching TV for 3 hours or more per day was associated with increased mortality regardless of physical activity, except in the most active [people]” (4).
Less than 4 hours per day
In a New England Journal of Medicine study, people who sat less than 4 hours per day had a lower risk of heart attacks compared to individuals who sat 16 hours per day (5).
Greater than 6 hours per day
An English study demonstrated that people who watched television for greater than 6 hours per day were 1.48 times more likely to be centrally obese (have a beer belly) compared to individuals who watched less TV, regardless of physical activity (6).
Greater than 12.5 hours per day
A recent study in the Annals of Internal Medicine assessed the impact of sitting on mortality in 7985 people monitored with accelerometers over four years (7). The researchers showed that sitting for 12.5 hours with sedentary bouts of 60 to 89 and 90 minutes or greater was associated with an increased risk of death. The investigators also discovered that sitting in sessions of 1 to 29 minutes was associated with less risk of dying (mortality) despite a high total duration of sitting. They recommended trying to get up every half hour.
Is there anything we can do to decrease the health risks from sitting too long?
- Moderate to vigorous exercise for 60 to 75 minutes per day may cancel out the risk of sitting 8 hours/day based on a study in the Lancet (4). Speeding walking is a good example of moderate exercise, whereas playing basketball is a type of vigorous exercise. The Harvard School of Public Health has a list of other examples of moderate and vigorous exercises on their website.
- Standing or stepping (Chicagoans— I just mean stepping, not a dance you do at the Grand Ballroom on Tuesdays) for 2 hours per day may help according to one study (8). The standing desks are an attractive option for people who sit at work all day.
- Getting up every 30 minutes and moving around may also make a difference.
- Fidgeting may help according to one analysis of the Women’s Cohort Study. Women who fidgeted and sat 5-6 hours daily had a lower risk of mortality compared to non-fidgeters who sat the same amount of time. The only caveat to the study is that fidgeting is not clearly defined, nor is it easily measured.
What’s the bottom line on why sitting is bad for you?
- Sitting and watching TV all day isn’t healthy and their risks include more than just weight gain.
- If you have to sit, getting up periodically is better than uninterrupted sitting.
- Moving and fidgeting are better than sitting still (tell that to my elementary school teachers).
- Moderate exercise may decrease the risks of sitting.
- MLK had it right in one of my favorite quotes, “By all means, Keep Moving.”
Sit Wisely and Share Some Knowledge.
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- Dunstan DW, Howard B, Healy GN, Owen N. Too much sitting–a health hazard.
Diabetes Res Clin Pract. 2012 Sep;97(3):368-76.
- Schmid D, Leitzmann MF. Television viewing and time spent sedentary in
relation to cancer risk: a meta-analysis. J Natl Cancer Inst. 2014 Jun 16;106(7).
- Larsen BA, Allison MA, Kang E, Saad S, Laughlin GA, Araneta MR, Barrett-Connor
E, Wassel CL. Associations of physical activity and sedentary behavior with
regional fat deposition. Med Sci Sports Exerc. 2014 Mar;46(3):520-8.
- Ekelund U, Steene-Johannessen J, Brown WJ, Fagerland MW, Owen N, Powell KE,
Bauman A, Lee IM; Lancet Physical Activity Series 2 Executive Committe; Lancet
Sedentary Behaviour Working Group. Does physical activity attenuate, or even
eliminate, the detrimental association of sitting time with mortality? A
harmonised meta-analysis of data from more than 1 million men and women. Lancet. 2016 Sep 24;388(10051):1302-10. doi: 10.1016/S0140-6736(16)30370-1.
- Manson JE, Greenland P, LaCroix AZ, Stefanick ML, Mouton CP, Oberman A, Perri
MG, Sheps DS, Pettinger MB, Siscovick DS. Walking compared with vigorous exercise for the prevention of cardiovascular events in women. N Engl J Med. 2002 Sep 5;347(10):716-25.
- Smith L, Fisher A, Hamer M. Television viewing time and risk of incident obesity and central obesity: the English longitudinal study of ageing. BMC obesity.
- Diaz KM, Howard VJ, Hutto B, Colabianchi N, Vena JE, Safford MM, et al. Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults: A National Cohort Study. Ann Intern Med.
- Healy GN, Winkler EA, Owen N, Anuradha S, Dunstan DW. Replacing sitting time
with standing or stepping: associations with cardio-metabolic risk biomarkers.
Eur Heart J. 2015 Oct 14;36(39):2643-9. doi: 10.1093/eurheartj/ehv308. Epub 2015
- Hagger-Johnson G, Gow AJ, Burley V, Greenwood D, Cade JE. Sitting Time,
Fidgeting, and All-Cause Mortality in the UK Women’s Cohort Study. Am J Prev Med.
2016 Feb;50(2):154-60. doi: 10.1016/j.amepre.2015.06.025. Epub 2015 Sep 23.