Too Much Sitting Is Killing UsJanuary 3, 2012
Studies say that even moderate to vigorous exercise doesn’t counteract the damage.
A study published in the American Heart Association’s journal Circulation showed that each extra hour of television watching (the ultimate sitting sedentary activity) per day was associated with an 18% increase in deaths from heart disease and an 11% increase in overall mortality. People who watched TV for at least four hours a day were 80% more likely to die of cardiovascular disease than those who watched two hours or less, and 46% more likely to die of any cause.
We have smart readers, and many of you will immediately ask: “Weren’t there other factors, not just sitting, that resulted in this outcome?” Yet that doesn’t seem to be the case. There are specific reasons why sitting, in itself, appears to be dangerous. The message seems to be to move around. But if you aren’t moving around, stand or lie down, which humans have done throughout their history. Avoid sitting in a chair, an activity that is relatively new for human beings and not at all good for us.
Surprising as it is, the increase in heart and mortality risk observed in the Circulation study affected people who met exercise guidelines—and were independent of eating habits as well! Studies reported significant associations between total sedentary time with blood glucose, blood lipids, and adiposity, even in people who performed moderate to vigorous exercise several times each week.
Animal studies also show that how much time we are sedentary is related to how well our bodies process fats. The studies in rats show that leg muscles only produce the lipase lipoprotein (fat-processing) molecule when they are being actively flexed—that is, when standing or, better still, walking around—and low levels of the molecule are associated with health problems, including heart disease. In short, sitting makes this important molecule slow down. In fact, actively contracting the muscles produces a whole suite of substances that have a beneficial effect on how the body uses and stores sugars and fats.
“Many people, on a daily basis, simply shift from one chair to another—from the seat in the car to the chair in the office to the chair in front of the television,” said to the lead author of the study. “Even if someone has a healthy body weight, sitting for long periods still has an unhealthy influence on blood sugar and blood fats.”
It should be noted that sitting too much is not the same as exercising too little. They do completely different things to the body. Standing recruits specialized muscles designed for low-intensity activity—muscles that are very rich in enzymes. The lipoprotein lipase enzyme grabs fat and cholesterol from the blood, burning the fat into energy while shifting the cholesterol from LDL (the bad kind) to HDL (the healthy kind). When you sit, the muscles are relaxed, and enzyme activity drops by 90% to 95%, leaving fat to camp out in the bloodstream. Within a couple hours of sitting, healthy cholesterol plummets by 20%.
A Canadian study reached a similar conclusion. After adjusting for potential compounding factors (smoking, exercise levels, etc.), the study found that the longer people sat, the higher the risk of mortality from all causes except cancer.
The good news is that inserting breaks into your sedentary periods can help. Periodically taking time out from your computer, desk, television, and driving time to walk, move around, stretch, and flex your muscles, is good for you. These spurts of activity are associated with a smaller waist circumference, lower body mass index, and lower blood lipid levels, and better glucose metabolism.
A stand up desk might be a good idea as well. Don’t have room for one? Too expensive? Then pile some books or something else on top of your existing desk and put your laptop where you can type standing up when you want to, either often or as a break.
At ANH-USA, we believe that true health comes from a combination of diet (and supplements), exercise, and lifestyle. Politically, so much is happening regarding supplements and diet that we spend most of our newsletter space focusing on those areas. But science tells us that our lifestyle choices—simple decisions made daily—can make a huge impact on our health, for good or for ill.