Why Sitting Too Much Is Not Good for You
Barbara Van Tine | July 27, 2017
Reviewed by John Edward Swartzberg, M.D.
Because of our deskbound jobs, seated entertainment habits, and reliance on cars we’ve become increasingly sedentary in recent decades. The average adult sits for nearly eight hours a day, according to the 2003/2004 National Health and Nutrition Examination Survey (NHANES). As we get older, we tend to increase our sitting time: Some studies estimate that people over age 60 spend up to 10 hours a day sitting.
Sitting is linked to heart disease and more
Multiple observational studies have linked prolonged sitting to:
- Cardiovascular disease
- Muscle and joint problems
- Breast, colorectal, endometrial, and ovarian cancers
Scientists have long known about the harmful health effects of prolonged sitting. In an important 1953 study researchers reported that double-decker bus drivers in London were more prone to heart disease and premature death than bus conductors, who were more physically active.
The amount of time you spend sitting does matter
That long, robust walk you took after breakfast doesn’t clear you to spend the rest of the day lounging on the sofa. Prolonged periods of sitting — regardless of any daily exercise regimen — still may reap serious harm to your health. Unfortunately, it might not be only a matter of how physically active you are but also how much time you spend sitting. Accumulating evidence suggests that reducing sitting time could be nearly as beneficial as increasing activity time.
Sitting too much? Blame the boob tube
Studies involving hours of watching television seem to support the argument that regular workouts don’t offset sitting. An analysis involving 16 studies of more than 1 million adults mostly 45 and older, published in September 2016 in The Lancet, associated three or more hours a day of watching TV with dying prematurely. Even the most active adults lost some positive effects of exercise when their TV viewing surpassed five hours daily.
What sitting does to your muscles
At least one reason why prolonged sitting contributes to heart disease despite regular workouts, some experts say, is the lack of muscular contraction that occurs while sitting. This can lead to a slowed metabolism and low energy expenditure. Little muscular contraction can also suppress a molecule called lipoprotein lipase, causing a rise in triglycerides and blood sugar and lowering production of high density lipoprotein (HDL), or “good” cholesterol.
8 hours of sitting a day vs. 4 hours
If you’re still not convinced that you should get up and move more often to fend off “sitting disease,” consider this recent finding: A 2015 study of 195,000 Australians found that people who sat for more than eight hours a day were less likely to report excellent overall health and quality of life than those who sat fewer than four hours.
What might help if you sit too much
Just two minutes of casual walking around the room or your home each hour might help prolong your life. In 2015, researchers at the University of Utah associated two-minute bouts of walking with a 33 percent decreased risk of dying prematurely. Overweight, sedentary adults who had diabetes improved their glycemic control when they interrupted seven hours of sitting with three minutes of easy walking on a treadmill or simple resistance activities (such as half squats and knee raises) every 30 minutes.
Break up sitting time
In a study published in September 2015, researchers coached 36 adults 60 and up to spend an average of 27 fewer minutes a day sitting, over eight weeks. Participants said they felt better able to tackle everyday tasks as a result. They could also walk faster and had fewer symptoms of depression. Breaking up sitting time may help protect older adults against cognitive decline by better controlling glucose levels and improving blood flow to the brain, according to a 2017 Australian study.
The benefits of fidgeting
Tapping your feet may help counter the decline in vascular function caused by prolonged sitting, suggests a small study published in May 2016 in the American Journal of Physiology—Heart and Circulatory Physiology. One adverse effect of uninterrupted sitting is the alteration of blood flow in the legs, which may contribute to circulatory and metabolic problems.
Small movements add up
To test the effect of on vascular function, researchers had 11 young adults stay seated at a desk and tap one heel rapidly for a minute, then rest it for four minutes, repeatedly over the course of three hours, while the other foot stayed still. Blood flow in the lower leg of the fidgeting foot was markedly improved, while blood flow in the stationary leg was reduced. It’s not known whether the same effect would occur in older people with poorer circulation.
Sit less, move more
Although observational studies can’t prove that briefly interrupting long stretches of sitting will improve health, there seems to be little downside to sitting less and moving more. Even if you’re able to carve out 30 minutes or more a day to devote yourself to regular exercise, it’s still not a bad idea to complement your workouts by intermittently standing up and moving around, especially if you spend long hours sitting, whether at a desk, in front of a computer or TV screen, or in a car.