Is Sitting the New Smoking?

How much time do you spend sitting each day? Considering that excessive sedentary time is ubiquitous in Western societies, for most people, the total amount of time spent sitting could be cut in half, or even in quarters.
 
"Sit less, move more" is the maxim worth repeating, especially with the growing body of evidence suggesting how detrimental prolonged sitting is for your body. A multitude of chronic metabolic diseases, including diabetes, obesity, cardiovascular disease, cancer, even premature death, have been directly associated with prolonged sitting time. According to several long-term studies, no matter how much you exercise, sitting for extended periods of time significantly increases your risk of disease and death, by any cause. 

The Relationship Between Sitting and Mortality

Due to its prevalence, researchers set out to examine the association between daily, sedentary behavior (its total volume and accrual in prolonged, uninterrupted bouts) and all-cause mortality.
 
Researchers shadowed nearly 8000 participants, age 45 or older, for an average of four years and observed that that sedentary behavior, on average, accounted for about 12.3 hours of an average 16-hour waking day. After analyzing the compiled data, the results of this observational experiment postulate a direct relationship; as total sedentary time increases, so does your risk of dying early than expected. Researchers have observed the participants' risk of metabolic morbidity and all-cause mortality grew in tandem with total sitting time and sitting stretch duration - no matter their age, sex, race, body mass index or exercise habits. In other words, prolonged sitting is a risk factor for all-cause mortality, independent of overall levels of moderate to vigorous physical activity. Furthermore, those who sat for more than 13 hours per day had a 2-fold (or 200%) greater risk of death compared to those who sat for less than about 11 hours per day (Diaz et al., 2017).
 
The current exercise guidelines, established by the US Centers for Disease Control and Prevention, recommend adults perform moderate-intensity aerobic exercise for two hours and 30 minutes every week, plus resistance training exercises on two or more days a week. Even this recommendation, however, doesn’t address the importance of reducing sitting time in addition to increasing physical activity levels (Van der Ploeg, Chey, Korda, Banks & Bauman, 2012).
 
Fortunately enough, the recommendations established by the researchers are, perhaps, more clear; take a movement break every 30 minutes. The researchers also determined that people who sit for less than 30 minutes at a time have the lowest risk of early death. According to the researchers, those who frequently sat in stretches less than 30 minutes had a 55% lower risk of death compared to people who usually sat for more than 30 minutes at a stretch. In addition, people who frequently sat for more than 90 minutes at a stretch had a nearly two-fold greater risk of death than those who almost always sat for less than 90 minutes at a stretch.
 
If you have a job, obligation, or lifestyle where you have to sit for prolonged periods, the findings of this research recommend one behavior change could reduce your risk of death: take a movement break every 30 minutes
 
While a standing desk might be helpful for those who work desk jobs, there is limited evidence to suggest that standing is a healthier alternative to sitting. Just taking a look at the anatomy of the human body, it is clear that it is designed for dynamic movement, not remain static.

Each Hour Spent Sitting Decreases Your Life Expectancy by 2 hours

In 2016, Dr. Mercola interviewed Kelly Starrett, who has a Ph.D. in physical therapy and is the author of "Deskbound: Standing Up to a Sitting World." In "Deskbound," Starrett quoted research from Dr. James Levine estimating for every hour you sit down, your life expectancy decreases by two hours.

For comparison, every cigarette smoked reduces life expectancy by 11 minutes, which explains why some are now calling sitting the new smoking. For all intents and purposes, prolonged sitting may actually be far worse for your health than smoking.

Starrett even mentioned a study that found office workers who smoked to be healthier than non-smokers simply because they got up every 30 minutes or so and walked outside to have a cigarette.

In the end, it is clear that the human body is designed to move, and is not designed to stay in any fixed position.

Take Away: Sitting and Standing are Tools

The body is designed to move​. Standing is not inherently better than sitting, and sitting is not inherently worse than standing - they are both tools. However from a metabolic perspective, standing is perhaps better, due to the relative rate of energy expenditure. Given this, it is not recommended to stand all day, or vice versa.

What is most important, is how, or the way in which, you are sitting or standing. How is the quality of your sitting or standing position? How are utilizing your chair or the floor? If you are standing in an array of compromised positions, such as, for example, with an inwards collapsed knee or foot, or disengaged glutes, you are exacerbating the same patterns that result in physical discomfort. Sitting and standing are both tools, so it is important to ask yourself, "How am I using this tool?"

To ensure proper posture, if you are going to be sitting, sit on the front edge of your seat, or the ischial tuberosity (the "sit bones" or bony protrusions located on your rear), with your hips located higher than your knees and your core activated. This position activates the spinal chain setting the sacrum and lumbar spine with a normal curve. If you are going to be standing, equally distribute the weight between your feet, stacking your spine while activating your glutes and core, with your shoulders back and down (not hunched forward), and your head neutral (not forward or looking down).

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References

Diaz, K., Howard, V., Hutto, B., Colabianchi, N., Vena, J., Safford, M., Blair, S. and Hooker, S. (2017). Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults. Annals of Internal Medicine, 167(7), p.465. https://doi.org/10.7326/M17-0212
 
Scutti, S. (2018). Yes, sitting too long can kill you, even if you exercise. [online] CNN. Available at: https://www.cnn.com/2017/09/11/health/sitting-increases-risk-of-death-study/ [Accessed 31 May 2018].
 
Van der Ploeg, H., Chey, T., Korda, R., Banks, E. and Bauman, A. (2012). Sitting Time and All-Cause Mortality Risk in 222 497 Australian Adults. Archives of Internal Medicine, 172(6), p.494. https://doi.org/10.1001/archinternmed.2011.2174