More and more studies are finding that extended periods of sitting significantly increase our risk of developing various medical conditions, some of them serious. This is true even for those who exercise regularly. With increased computer use, video game playing and TV watching comes increased sitting. While the currently-recommended 30 minutes of daily physical activity is good for staying healthy, what you do during the remaining 23½ hours each day matters very much also.
The American Institute for Cancer Research recommends setting up your computer to remind you to get up and walk around every 60 minutes.
A study published October, 2011 in the journal Cancer Prevention Research found that for post-menopausal women, taking frequent breaks from sitting is associated with smaller waist circumference and lower levels of C-reactive proteins, both biomarkers associated with elevated risk of some cancers.
The National Health and Nutrition Examination Survey analyzed data of 4,757 participants and found that even short periods of light activity – for example frequently standing up and walking for as little as a minute – reduced biomarkers such as large waist circumference, elevated triglyceride levels and increased insulin resistance, which are linked to heightened cardiovascular disease and may also boost risk of various cancers.
Many components of metabolic syndrome are associated with a sedentary lifestyle, including increased adipose tissue, reduced HDL cholesterol, and a trend toward increased triglycerides, blood pressure, and glucose in the genetically susceptible. Compared with individuals who watched television or videos or used their computer for less than one hour daily, those that carried out these behaviors for greater than four hours daily have a twofold increased risk of metabolic syndrome. [Fauci, Anthony S. (2008). Harrison's principles of internal medicine. McGraw-Hill Medical]
According to Dr. Emmanuel Stamatakis of University College London's Department of Epidemiology and Public Health, the risk of heart disease and premature death from any cause increases significantly for those spending more than fours hours a day watching television, surfing the web, or playing computer games.
The study was published in the Journal of the American College of Cardiology in January of 2011 and involved 4,512 adults who were respondents of the 2003 Scottish Health Survey. It found a 48% increased risk of all-cause mortality and an approximately 125% increase in risk of cardiovascular events among those spending more than four hours a day in front of a screen, and also suggests that even two hours of screen time each day may place someone at greater risk for a cardiac event. The risk appears to be irrespective of factors such as smoking, hypertension, BMI, social class, and even exercise.
Risk of developing breast and colon cancers is significantly increased in those who spend a lot of time sitting, according to research presented in November of 2011 at the American Institute for Cancer Research.