“All parts of the body which have a function… if unused and left idle they become liable to disease, defective in growth and age quickly.” Hippocrates Circa 450 BC
We sit all the time. When we’re reading, watching TV or working, chances are you spend more of your waking hours sitting than any other activity. For me, I’m sitting down while writing this blog.
The interest in the effects of sitting has exploded in recent years with many studies indicating that sitting increases ones risk for premature death, heart disease, cancer and diabetes. One study reported that for every two hours of TV viewing, the risk for diabetes increased by 20%, for heart disease by 15% and for premature death by 13%. In addition, work that we have done has shown that just the ownership of a sedentary device such as a computer, TV or car was associated with a greater risk for obesity and diabetes. People who owned all three devices were three times more likely to be obese and twice as likely to have diabetes.
So it’s clear that sitting for long periods of time is not good for us, but what if we’re active when we’re not sitting? We used to think that sitting was just the lack of being physical active but that doesn’t appear to be the case. While the two are related, sitting seems to result in health risks even if someone is active. Many of the studies above took into account the levels of physical activity people did and sitting still increased risk of death. Even in people who were avid exercises and walked briskly for more than 13 hours per week, those who sat for more than six hours per day, had a 20% greater risk of premature death than those who sat for less than three hours per day.
There are a number of biological changes that occur in our body when we sit for too long; our energy needs go down and our muscles no longer require the same amount of sugars and fats that they use during activity. Certain enzymes are shut down leaving sugars and fats to circulate in our blood stream- higher levels of blood sugars and fats are risk factors for diabetes and heart disease. The good news is that even getting up and walking around for as little as two minutes every 20 minutes over a five hour sitting period has been shown to reduce blood sugars by more than 20% compared to continuous sitting.
As a solution, many people have turned to and advocated the use of standing desks in a way to reduce sitting time. This is based on the premise that if sitting is bad for you, then anything else other than sitting most be good for you. Standing desks definitely do reduce sitting time, there is no doubt about that, and standing does burn more calories than sitting, however, the difference is negligible. The not so good news is that standing also creates its own set of health problems. While we don’t have long-term studies on standing like we do in sitting, standing for long periods may lead to back pain, and can increase risk for varicose veins. In addition, sitting is better at stabilizing our body for when we need to do computer work or other fine work like drawing. Standing doing these activities can lead to greater muscle and skeletal fatigue. Some people do have offices in which they have standing and sitting desks, or sit-to-standing desks. Either option is costly but is it really needed?
The bottom line isn’t so much that sitting in itself is bad, it is prolonged inactivity whether sitting or standing. Sitting and taking a 2 minute walk every half hour over three hours is much better than sitting for three hours in a row and most likely better than standing for that period of time as well.
An easy way to remind yourself of the need to get up and walk around is to use a cooking timer or the timer on your phone or computer. Set it to go off every 20 to 30 minutes, and get up and walk around for a couple of minutes. Besides improving your health, this may also help fight off any fatigue that prolonged sitting may result in and improve your daily productivity.
In the next blog I will discuss whether exercise is good for weight loss.
This is Part 7 in a series of blog posts entitled Being Active While Living an Active Life.