People who sit for over eight hours a day are more susceptible to premature death no matter whether they work out regularly, analysis of 47 prior studies by a team at the University of Toronto suggests.
It is fairly well-established that sitting for hours increases the risk of diabetes, heart diseases, dementia and cancer, leading to premature death. What is surprising is that regular exercise does not decrease the risk.
When people stand, some muscles work hard to maintain the posture and the body also releases hormones to burn fat. But when sitting, the metabolism is not as active and sedentary behavior increases the secretion of hormones that disturb the control of blood sugar levels.
For these reasons, those who sit for over eight hours a day have a 14 percent higher risk of being hospitalized than their more active counterparts and are 90 percent more likely to develop diabetes, according to the study.
The researchers offered the unhelpful suggestion that sitting should not take up more than four or five hours a day, citing guidelines by the Public Health Agency of Canada.
But they did offer some tips to decrease sedentary time. "Taking a one- to three-minute break every half-hour during the day to stand (which burns twice as many calories as sitting) or walk around" is one way to reduce sedentary time, as is "gradually reducing daily sitting time by 15 to 20 minutes per day, aiming for two to three fewer sedentary hours over a 12-hour day."