Extended Sitting: Why researchers see health impact & What you can do

Put aside thoughts of whether or not you meet recommendations for walking or other moderate activity, and answer two questions of newly recognized importance:  How many minutes a day do you spend butt-in-chair or-car? And of that time, how much is extended sitting versus up-and-down?

Are too much sitting and too little activity independent health risks?

The potential relevance of these two questions to your risk of cancer and other chronic diseases was one of the major topics emerging from last week’s research conference held by the American Institute for Cancer Research (AICR).

Since I’ve been back from the conference, I’ve been plowing through  the latest findings. There’s enough here that I will be making some simple changes in my life, and will be more intentional about encouraging them in my work with clients and in speaking.

On average, Americans spend 58% of waking hours sitting.  We know we can have major health impact when we find ways to work in 30 to 60 minutes a day of moderate activity (such as brisk walking). This research on “sedentary behavior” looks at the impact of what we do the rest of the day.

First, there’s the impact on weight control. Researchers measure the calories burned in various activities in units called METs.  If you switch two hours of sitting to light activity or standing, you’ll burn calories equal to what you’d burn with an extra 30-minute walk.

The impact of sitting time goes beyond calorie-burning.  Research now shows that, unlike sitting, when we’re standing or even squatting,  isometric muscle contraction is producing measurable electrical and enzyme activity. This leads to reductions in blood sugar and triglycerides and increased production of HDL (“good” )cholesterol.

Even among people who get 30 minutes of moderate-to-vigorous activity five or more days a week, more TV time is linked with larger waist size, and especially in women, higher fasting blood sugar and triglycerides.  A U.S. study that followed people for 21 years found that those spending more time watching TV and in the car (more than 23 hours combined weekly compared to less than 11 hours) showed 64% more deaths from heart disease.

Now researchers have devices people can wear that measure time spent at various levels of activity.  In one study, 2.3 additional hours sitting each day was associated with 21% higher fasting triglycerides and 32% higher insulin. These results are compatible with three earlier studies.  If confirmed in further research, this has major implications, since high levels of insulin seem to promote growth of cancer.  This combination of elevated triglycerides and insulin is associated with metabolic syndrome, a key risk factor for diabetes and heart disease.  Researchers  examining the data concluded that light-intensity activity may have a protective effect, and that sedentary time may independently contribute to breast cancer risk.

First take-home message:  whether or not you’re already getting the recommended 30 to 60 minutes of moderate-to-vigorous activity daily, look at how much time you are sitting each day, and how you might step that up a notch to boost light activity.  Some people and companies are transitioning to either treadmill desks or “sit to stand” desks. Some less costly swaps to decrease sitting time:

When can you stand instead of sit?

• Telephone time:  Stand – or pace when possible – while on business calls. For social calls, use your cell phone while going for a walk.
• Get off public transportation one stop early; park your car at the far side of parking lots.
• Skip the drive-through:  Better to stand in line for your coffee, banking or dry cleaning than to sit in line.
• When you need a mental break, walk to a colleague’s office to share a joke rather than sending one of those chain emails.  Or simply stand up and perhaps do a few stretches.

Second take-home message: work short breaks into your sitting time.  Research highlighted at the AICR conference shows that the simple act of breaking up extended periods of sitting with even a few minutes of standing and moving helps.  A recent analysis of the huge U.S. NHANES population database shows that even after adjusting for time spent more actively and total amount of sedentary time, those who had more breaks in sedentary time instead of more large blocks of sitting showed 20% lower levels of a marker of chronic, low-grade inflammation and waist size nearly two inches smaller. Thus these breaks could be important, since this type of inflammation and excess abdominal fat are both linked to increased risk of several types of cancer, as well as heart disease and diabetes.

What creative ways can you develop to insert breaks in your “sit time”? Here are a few I’m trying:

• Put the telephone across the room from your desk at work and from where you sit when relaxing at home.  Each time you make or answer a call, you’ll at least get a standing break, and perhaps will remember to stand or walk throughout the call.
• When watching TV, each commercial means time to get up.  Do crunches for a stronger belly or stretches to improve flexibility.  Or take this time for one task like putting in a load of laundry, packing tomorrow’s lunch or taking a quick walk around the kitchen with a sponge or broom.
• Stand rather than sit as you sort through the daily pile of mail.
• If you check email on a laptop, put it on a counter or bookshelf so you can stand as you check it.  If you can check email on a hand-held device, stand as you screen it; then sit only to reply to those that require a lengthy response.

This is an emerging field that needs more research. But since there is no downside to making changes in sitting time and breaks, it makes no sense to wait when the implications of our current sedentary way of living are potentially so significant and wide-ranging.

Let’s talk:  Please comment below to share steps you’ve tried (or are considering) to cut into your total sitting time or to insert breaks in it.

References:
Healy, GN et al. Sedentary time and cardio-metabolic biomarkers in US adults:  NHANES 2003-06.  Eur Heart Journal, 2011.
Warren, TY et al. Sedentary behaviors increase risk of cardiovascular disease mortality in men.  Med Sci Sports Exerc, 2010.
Lynch, BM et al. Associations of objectively assessed physical activity and sedentary time with biomarkers of breast cancer risk in postmenopausal women: findings from NHANES (2003-2006).  Breast Cancer Res Treat., 2011.