Why Sitting Could Be Hurting Your Heart Health

The Negative Effects of a Sedentary Lifestyle

People sitting at desks in office
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You are sitting too much. No, seriously. The mere fact that you are reading this article indicates that you are adept at finding what you want on the Internet, and therefore, are likely to be a person who often uses a computer, and therefore, are likely to be sitting a lot.

Numerous studies have now correlated the time people are sitting (watching TV, working, using a computer, driving, eating) to a greatly increased risk of cardiovascular disease. In addition, sitting time correlates strongly with metabolic syndrome, diabetes, obesity, hypertension, increased triglycerides, and reduced HDL (”good”) cholesterol, and even cancer. Worse, one large meta-analysis published in 2015 indicates that even participation in regular exercise does not mitigate the negative effects of prolonged sitting.

Some investigators have concluded that the prolonged sitting has an impact on cardiovascular risk that is the equivalent of smoking.

The Benefits of Not Sitting

While regular exercise is good for you, what you are doing in the hours you’re not exercising is also important.

An Australian study published in July 2015 reported on 700 subjects who wore activity monitors that collected posture and activity data (i.e., time standing vs. sitting). They found that the more time people spent sitting, the higher their BMIs, glucose levels, waist circumference, triglyceride levels, and the lower their HDL cholesterol levels. Conversely, the longer people spent standing, the more favorable these same measurements were.

The authors suggest, from this evidence, that a “reallocation” of sitting time to standing (or walking) time can greatly reduce risk factors for cardiovascular disease.

Because many studies over the past few years have given similar results, various professional bodies around the world are updating their guidelines to stress the importance of minimizing the time we spend sitting, and maximizing time we spend standing or (better yet) walking.

Why Is Sitting Bad?

Why might sitting be bad for us? Certainly, sitting (or lying down) reduces stress on the cardiovascular system, and allows the heart and blood vessels to “relax.” (This is one reason bedrest is useful for recovering from some medical conditions.) In contrast, standing causes both the heart and circulatory system to work harder, simply to maintain a normal blood pressure. The reduced baseline level of cardiovascular work associated with prolonged sitting may therefore produce relative cardiac deconditioning. More time spent standing, on the other hand, will lead to improved cardiovascular and muscular tone. This all makes sense.

On the other hand, the data collected to date really just show an association between sitting and cardiovascular risk, and do not demonstrate a definite causal relationship. Furthermore, with a few exceptions the studies available to date rely on self-reported information, and other non-objective types of data gathering. It is difficult to make firm conclusions from such data.

Now that everyone’s consciousness has been raised, studies are underway to use objective data (from wearable sensors) to prospectively assess the relationship between posture, activity, and outcomes, and more importantly, whether cardiovascular outcomes can be improved by reducing a person’s sitting/standing ratio. Within a few years we should know for sure.

Bottom Line

While we can’t yet prove that it leads to cardiovascular disease, there are good reasons to avoid prolonged sitting. First, the data available to date, while not conclusive, looks very consistent from study to study. It certainly is compelling enough to have caused medical experts to change activity guidelines. Second, there is nothing to lose by converting sitting time to standing time; it is quite a safe and easy thing for us to do. Third, at the very least, by sitting less you will burn more calories.

So it makes sense to reduce your sitting time, and reallocate that time to standing or walking. Even if you can’t afford a standing desk, you can stand or walk while making phone calls or eating lunch, listen to part of the game while taking a walk, or park your car at the far end of the lot. Using an activity monitor to set daily step goals can also be helpful in reminding you to move around regularly.

Then, by the time the data finally becomes definitive regarding the hazards of sitting, you will have made a very good start.