Can something as common as too much sitting shorten your lifespan? One report titled “Too much sitting—A health hazard” shows that there is evidence linking prolonged sitting with a number of adverse health outcomes, including premature mortality.

In contemporary society, prolonged sitting has been engineered into our lives across many settings, including transportation, the workplace and the home. Due to changes in transportation, communications, workplace technologies and domestic entertainment, there are significantly reduced demands to be active. Especially in the contexts of television viewing, computer and game-console use, workplace sitting, and time spent in automobiles. As a consequence, background level of physical activity is declining. Much of the reduction in activity can be attributed to exposure to environments that demand or encourage prolonged sitting.

There is new evidence that too much sitting (also known as sedentary behavior) is adversely associated with health outcomes, including cardio-metabolic risk biomarkers, type 2 diabetes and premature mortality. Importantly, these detrimental associations remain even after accounting for time spent in leisure-time physical activity.

Studies indicate that time spent in sedentary behavior may be independently associated with increased risk for all-cause and cardiovascular disease-related mortality in both men and women. In one study, each one hour increment in TV time was found to be associated with an 11% increased risk of all-cause mortality and an 18% increased risk of cardiovascular disease mortality. Furthermore, relative to those watching less TV (less than 2 hours/day), there was a 46% increased risk of all-cause and an 80% increased risk of cardiovascular disease mortality in those watching four or more hours of TV per day, independent of traditional risk factors such as smoking, blood pressure, cholesterol, waist circumference and diet, as well as leisure-time physical activity. Time spent in sedentary behaviors is a distinct risk factor for several health outcomes. Prominent within this evidence are relationships of sedentary time with diabetes risk. Recent evidence from studies makes a persuasive case that too much sitting should now be considered an important stand-alone component of the physical activity and health equation, particularly in relation to diabetes and cardiovascular risk.

Importantly, in many of these studies, the associations of sedentary behavior with these adverse outcomes have been shown to persist even when participation in leisure-time moderate-to-vigorous physical activity had been accounted for. In other words, just because you get the recommended amount of exercise (which is a minimum of 30 minutes per day) doesn’t mean you are safe from the negative effects of too much sitting time.

Sedentary behaviors are defined by both their posture (sitting or reclining) and their low energy expenditure—typically in the energy-expenditure range of 1.0–1.5 METs
(multiples of the base metabolic rate). In contrast, moderate-to-vigorous physical activities, such as brisk walking or running, involve an energy expenditure of at least 3 METs. Light-intensity activities are those with an energy expenditure range of 1.6–2.9 METs. These light-intensity activities are the predominant determinant of
daily energy expenditure. Environmental, social and technological changes have resulted in a high proportion of such normal daily light-intensity activity being displaced by time spent sedentary. It is estimated that some 51–68% of adults’ total waking hours are spent sedentary. In contrast, moderate to vigorous physical activities accounts for only 5% of the total time, with the remainder (some 27–44%) being spent in light-intensity physical activity or ‘baseline’ activity. Reduced baseline activity seems to be the primary driver of the negative health effects of increased sitting time.

Adults whose sedentary time was mostly uninterrupted (prolonged unbroken sitting) had a poorer cardio-metabolic health profile compared to those who interrupted, or had more frequent breaks in their sedentary time.

Based on the evidence, this report recommended:

I have a desk job, but I try to get up as much as possible. I get up to fill my water bottle and then to go to the bathroom frequently. This has the bonus of helping to stay more hydrated. I also find that getting up once in a while clears my mind and gives me new insight into a problem that I’m working on. This makes me feel that I am not shirking work just for the sake of more movement—I am still thinking about work as I move around. I also walk about a mile during my lunch break to split up the day. I usually keep my TV time at about 1 hour per day. One area where I could use improvement is phone screen time—I am usually spending over 3 hours a day staring at my smartphone. I could make an effort to walk around a bit when I’m on the phone or take more frequent breaks.

Try to keep track of your sitting time—If you are spending more than half your waking day on your rear end, you may be shortening your lifespan. Get up and move—even if it is only light-intensity activity. Your body will thank you.