We all know that regular exercise is good for our health and too much sitting isn’t ideal. If you’re like most people, you spend a vast majority of your day sitting down—in your office, commuting to and from work, watching TV in the evening. Research shows that the average American spends nine to 10 hours of their day sitting. Certain occupations, such as telecommunications employees spend an average of 12 hours sitting each day. And, the more sedentary you are at work, the more sedentary you will tend to be at home as well.
Now a new study suggests it’s not just the length of time we spend sitting down but the number of times we get up during that time that can influence our health. The evidence shows that prolonged sitting actively promotes dozens of chronic diseases, including overweight and type 2 diabetes, even if you’re very fit. This is really highly counter-intuitive as it would seem physically fit people could get away with sitting. However, research shows that maintaining a regular fitness regimen cannot counteract the accumulated ill effects of sitting eight to 12 hours a day in between bouts of exercise
The study, published online in the European Heart Journal, examined the total length of time people spent sitting down and breaks taken in that time, together with various indicators of risk for heart disease, metabolic diseases such as diabetes, and inflammatory processes that can play a role in the blocking of arteries. When you sit for lengths of time, disease processes set in that independently raise your mortality risk, even if you eat right, exercise regularly and are very fit; even a professional or Olympic level athlete.
The most recent systematic review looked at 47 studies of sedentary behavior, and discovered that the time a person spends sitting each day produces detrimental effects that outweigh the benefits reaped from exercise. Sitting was found to increase your risk of death from virtually all health problems, from type 2 diabetes and cardiovascular disease to cancer and all-cause mortality. For example, sitting for more than eight hours a day was associated with a 90 percent increased risk of type 2 diabetes. Other research has found that those who sit the most have a 112 percent increased Relative Risk of diabetes, and a 147 percent increased relative risk of cardiovascular events compared to those who sit the least.
The Australian research found that long periods of sitting down, even in people who did a lot of exercise otherwise, were associated with worse indicators of cardio-metabolic function and inflammation, such as larger waist circumferences, lower levels of HDL (“good”) cholesterol, and higher levels of C-reactive protein (an important marker of inflammation) and triglycerides (blood fats).
However, the study also found that even in people who spent a long time sitting down, the more breaks they took during this time, the smaller their waists and the lower the levels of C-reactive protein. Genevieve Healy, MD, from the University of Queensland led the study. “The most significant differences were observed for waist circumference,” she says. “The top 25% of people who took the most breaks had, on average, a 4.1 cm smaller waist circumference than those in the lowest 25%.”
The dangers of being too big around the middle are well-documented. According to the National Heart, Lung, and Blood Institute, high-risk waist circumferences are:
- Over 40 inches for men.
- Over 35 inches for women.
Healy and her colleagues analyzed earlier U.S. data from nearly 5,000 people aged 20 and over. The participants wore a small device called an accelerometer, which monitored the amount and intensity of walking or running. It gave researchers information on sedentary time and breaks in sedentary time. It suggests that plenty of breaks, even if they are as short as one minute, seem to be beneficial.
“The potential adverse health impact of prolonged sitting (which is something that we do on average for more than half of our day), is only just being realized,” Healy says. “Our research highlights the importance of considering prolonged sedentary time as a distinct health risk behavior that warrants explicit advice in future public health guidelines.”
Amy Thompson, Senior Cardiac Nurse at the British Heart Foundation, says in a statement, “This study was a very interesting read and adds to well established evidence that long periods of inactivity are not good for the heart. If you’re sitting for long periods it’s really important you take regular breaks by getting up on your feet. Regular physical activity is essential to protect cardiovascular health.”
To counteract the ill effects of prolonged sitting, the authors of the featured review suggest that you:
- Keep track (with your phone or pedometer) of how much you’re sitting each day, and make an effort to reduce it, little by little, each week until you are moving more than you are sitting
- When watching TV, stand up and/or walk around during commercial breaks or pause a movie and go for a brisk five minute walk
The study suggests even small changes in your office or home could help, like standing up to take phone calls, walking to see a colleague rather than phoning or emailing, and centralizing trash cans and printers so you have to walk to them.