No matter how much you exercise, sitting for extended periods of time and for cumulative amounts of time (i.e., sitting for long periods many times a day), may be harmful to your health. Several studies have found an association between sitting time and things we’d rather avoid. They include 1) metabolic syndrome1 (defined as changes in 3 of the 5 following biomarkers which themselves increase the risk of heart disease, diabetes and stroke: being overfat by waist size, having high blood fat levels (triglycerides), high blood sugar, high blood pressure (or being on medicine to treat either of those), and/or low HDL cholesterol levels); 2) an increase in death from any cause2; and 3) difficulty completing self-care activities3, e.g., dressing, eating.
Most studies, including those whose outcomes I just mentioned, adjusted for physical activity and found that independent of how often a person engages in exercise, sitting for multiple 1-hour periods each day is bad for health. Sedentary behavior - sitting around doing stuff - is a risk factor by itself - independent of physical activity/exercise. A person who eats a plant-based diet, does not smoke, exercises everyday... still needs to ‘not sit’ for long periods of time. What I mean to emphasize is that even if you go to the gym, play golf, run, etc., an hour or more every day, the more you sit, the greater your risk for poor health. When I suggest you sit less and you say, “but I golfed 18 holes this morning” that is like my suggesting you don’t smoke and you saying, “but I golfed 18 holes this morning.” Golfing does not protect you from the consequences of sitting 6 hours a day any more than it protects you from the consequences of smoking. Spending more than a few hours a day in sedentary behavior puts you at risk for poor health. (I am not sure that any scientist has quantified what amount of sedentary behavior is actually safe, so we just have to go with ‘less is better.’)
In addition, one of the studies showed that the association between sitting and poor health was influenced by total sitting time, AND whether or not that total time was split up. In other words, if two people sit for 8 hours a day, but one of them takes short physical activity breaks every hour, the one taking the breaks will have less disease or markers of disease (e.g., inflammation, abnormal blood sugar) than the constant sitter.4 This is assuming that they both exercise the same amount and are alike in other ways.
The latest study on sedentary behavior and poor health investigated the association between sitting time and the ability to complete Activities of Daily Living. I would like to share a few details about that self-care study today. First the citation and link:
Dunlop, D., Song, J., Arnston, E., Semanik, P., Lee, J., Chang, R., & Hootman, J. M. (2014). Sedentary Time in US Older Adults Associated With Disability in Activities of Daily Living Independent of Physical Activity. Journal of physical activity & health.
In this study, Dunlop and colleagues found an association between time spent in sedentary activity, defined as (sitting while) watching TV, working or playing games on the computer, reading, playing cards, etc., and difficulty completing Activities of Daily Living (ADLs).
Dunlop et al evaluated responses from a nationally representative sample of US adults over the age of 60 who were randomly selected to participate in one year of the National Health and Nutrition Examination Survey, NHANES. Their study sample included more than 2000 adults who were all over age 60. Each of the participants wore an activity monitor for 7 days. From the information generated by the monitors, the researchers could tell when the people were being still - as opposed to the people reporting when they were still. (To be clear, the accelerometers were not perfect. For example, the monitors did not detect if a person was riding a bicycle and I think the ones used in this study could not be worn in water.) The outcome that these researchers evaluated was ADLs. This is an important outcome because older adults who do not have trouble with their ADLs are more likely to be able to live independently. ADLs for this study included getting dressed, getting in and out of bed, walking and eating.
The take home message from this study, the one that you can apply to your life right now (even if you, like me, are under age 60) is that in this sample of older adults, for every additional hour of sedentary activity (sitting at the TV, computer, playing cards, reading) there was a 46% greater chance of having difficulty with one or more of the ADLs I listed in the above paragraph.
The researchers also studied the percent of total time in sedentary activity per day as a predictor of ADL problems. In this case, for every 10% increase in time spent sedentary, there was about a 70% increase in the chance of ADL problems. I didn’t see (in the article) what the comparison was or the absolute value, which bothers me a little. But for simplicity, if you and I are just alike, every hour more that I sit than you sit, my risk of having ADL trouble increases by almost 50%.
The authors of the study hope that physicians will start asking their patients how much time they spend in sit-down activities and encourage them to take activity breaks. One idea the authors/researchers had is for someone to lead a physical ‘activity’ before and after a book club or bingo meeting. I LOVE it.
1. Bankoski A, Harris TB, McClain JJ, et al. Sedentary activity associated with metabolic syndrome independent of physical activity. Diabetes care. 2011;34(2):497-503.
2. Katzmarzyk PT, Church TS, Craig CL, Bouchard C. Sitting time and mortality from all causes, cardiovascular disease, and cancer. Medicine & Science in Sports & Exercise. 2009;41(5):998-1005.
3. Dunlop D, Song J, Arnston E, et al. Sedentary Time in US Older Adults Associated With Disability in Activities of Daily Living Independent of Physical Activity. Journal of physical activity & health. 2014.
4. Healy GN, Dunstan DW, Salmon J, et al. Breaks in Sedentary Time Beneficial associations with metabolic risk. Diabetes care. 2008;31(4):661-666.