Like many health-conscious folks, I slip in a workout whenever I can, aiming to really sweat about three or four times a week. The rest of the time, though, I pretty much sit -- at my desk, in the car, on the couch in front of the TV. All that sitting may be increasing my odds of heart disease, according to a study published Tuesday in the European Heart Journal.
The study involved nearly 4,800 American volunteers who agreed to wear accelerometer devices to measure how much time they spent sitting and how many breaks they took to get up and walk around; after accounting for exercise, the researchers found that those who spent the most time being sedentary were more likely to have larger waists, worse cholesterol and insulin levels, and higher levels of dangerous inflammation -- all risk factors for heart disease -- compared with those who were the least sedentary.
The researchers also found that those who got up the least often for mini-breaks had higher heart disease risks than those who got up the most.
"This is perhaps the most convincing evidence yet that prolonged sitting is dangerous to our health," says Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital, who was not involved with the study. "It may be an independent risk factor for heart disease, even after accounting for structured exercise."
Manson and her colleagues previously found in the Nurses' Health Study that women who watched the most TV had the highest likelihood of being obese and developing diabetes. She says she carves out time, beyond her 30 minutes of daily exercise, to get up and walk the corridors around her office for a few minutes every hour or so.
"Being sedentary is a huge problem in modern times," Manson says. "Many of us feel shackled to our computer, and really have to make a conscious effort to take breaks." She recommends setting an alarm to go off throughout the day to remind yourself to get up and move. "It's gotten so bad that many people will use e-mail to communicate with colleagues down the hall rather than getting up to talk to them face to face."
Guilty as charged.
But I'm inclined to change my habits after learning from the study what prolonged sitting may do to my body. Those fewer muscle contractions that the body gets from being immobile may result in more fats circulating in my bloodstream and a reduced sensitivity to the hormone insulin, a precursor to diabetes. It also lowers the rate of calorie-burning and probably contributes to age-related muscle loss.
While daily exercise is certainly crucial for avoiding these problems, so, too, is taking frequent breaks from sitting. As the Australian study authors write, "these findings ... highlight the importance of considering prolonged sedentary time as a distinct health risk behaviour that warrants explicit advice in future public health guidelines."
Manson agrees and says doctors need to talk to their patients about how dangerous it is to sit and sit. Companies should think about installing treadmill desks that allow you to walk and type at the same time, and, at the very least, have more meetings where folks stroll around the conference table rather than sit.
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