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Is sitting as dangerous as smoking?
Rebecca Goldin Ph.D and Michael Adams, July 27, 2011
We look at the numbers from a surprising health claim

San Francisco’s CBS affiliate recently claimed that sitting down for prolonged periods of time was “just as dangerous” for your health as smoking. As smoking is the number one cause for preventable death in the United States, the implication is, inescapably, that your desk job is literally killing you. Unsurprisingly, it turns out that the harm from smoking is far greater than any harm found through sitting; the twist is that the two are only comparable when it comes to heart disease.

CBS 5 interviewed Dr. David Coven, a cardiologist with St. Luke’s-Roosevelt Hospital Center in New York, who said that recent research had shown sitting for long periods of time could result in heart disease, obesity, diabetes and cancer. The workplace environment was a particular culprit, and the suggested solution included walking around in the office.

The segment cited several studies to support the claims. The most recent and primary study mentioned only looked at how many hours were spent on “screen time” (that is time spent watching television, playing video games, etc.) outside of work. Published in the Journal of the American College of Cardiology, this research only looked at time spent outside of work and ignored time spent sitting at work. As would be expected, the study showed greater health problems for those who spent more time in front of a screen.

CBS 5 also mentioned an older study from the journal Medicine and Science in Sports and Exercise, which examined sitting at the workplace. It questioned participants as to how much of the day they spent sitting down. The responses could be almost none of the time, a quarter of the time, half the time, three quarters of the time, and almost all the time. The study included 7,278 men and 9,735 women between the ages of 18 and 90 who took part in the 1981 Canada Fitness Survey. Factors such as obesity, smoking, sex and age were all taken into account. The researchers followed up after 12.9 years. There were 951 deaths in men and 881 deaths in women. Of these deaths, 759 were from cardiovascular disease, 547 were from cancer, and 526 were from other causes.

This study concluded that those who sat for longer periods of time did have a higher chance of dying from cardiovascular disease or other causes, although it did not affect the rate of death from cancer. The deaths from cardiovascular diseases in men increased by 25 percent for those who sat three quarters of the day and by 35 percent by those who sat all day. In women these numbers were 77 percent and 81 percent compared to those who sat almost none of the day. Still, smoking is even riskier than sitting, increasing the risk of coronary disease from 100 to 300 percent according to Cardiovascular Consultants.

This study also did not carefully consider the possibility that people with weaker hearts or health problems are more likely to sit a lot than people without – in other words, it may not be that sitting is causing the problem, but that it is only indicative of the problem. While the authors controlled for many factors, no observational study can take into account the possible unmeasured factors that can be playing a role in the final outcome. However, the authors do point to other evidence that sitting itself is the problem, especially in reference to activity restriction studies.

A study published in the American Journal of Epidemiology that examined the effects of a sedentary lifestyle on cancer did find an increase in the cases of cancer of the colon and rectum. Participants who spent ten or more years in sedentary work had twice the chance of getting distal colon cancer and 44 percent increase in the risk of getting rectal cancer.

But according to the Center for Disease Control and Prevention, only 39.7 women out of 100,000 get colorectal cancer and among men the number is 52.7 out of 100,000. So doubling the risk is not all that significant. Most of these cases occur at older ages as well. Furthermore, if diagnosed early, there is a 90 percent survival rate. 

In contrast, people who smoke increase their risk of lung cancer 10 to 20 times, and 90 percent of lung cancer deaths in men and 80 percent in women are caused by smoking.  The absolute risk of getting lung cancer in one’s lifetime is 1.3 percent among male nonsmokers, and about 17.2 percent for male smokers. According to, smoking is the leading cause of cancer and death from cancer. The different types of cancer caused by smoking include cancer of the lung, esophagus, larynx, mouth, throat, kidney, bladder, pancreas, stomach, and cervix. Other dangers caused by smoking are heart disease, stroke, aortic aneurysm, chronic bronchitis, emphysema, asthma, and cataracts.

The net result is that smoking causes more than 440,000 deaths each year in the United States. It would be hard to imagine the day in which a chair carries the kind of shocking imagery that cigarette packs will soon have to warn people of the harm they will incur by, um, sitting down.




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