This is the second in a series in which we've been asking how much exercise we really need.
A very high proportion of people now spend a lot of their work day sitting at a computer.
And many of us also spend a good deal of leisure or social time sitting in front of a computer, tablet or television.
Recent research suggests that sedentary workplaces and lifestyles take a very large toll on your health and can even shorten your life.
Many of us assume that regular cardio and/or strength exercise will protect us from the risks that come from sitting too much.
Sadly, that assumption turns out to be overly optimistic.
However, it's also surprisingly easy to slash the adverse impacts of being desk- or couch-bound.
Findings from the latest research could make a big difference to your health and longevity, so read on!
"Sitting disease” and its risks
There's plenty of evidence that moderate-to-intense exercise plays a key role in preventing heart disease, obesity, diabetes and even some forms of cancer.
However, even if you get the recommended 30–45 minutes a day of exercise, that still leaves about 15 hours a day in which you're simply going about the business of life.
New research is investigating the effect our non-purposeful activity during the day.
In other words, how active are we when we're not actively exercising?
Unfortunately, research shows that most people spend only 1-5% of their waking day in moderate to vigorous activity of any kind.
The remaining time is what you would call "incidental” activity – the routine comings and goings of the day.
And of the remaining hours, up to 55% of the average person's day is spent sitting or lying down, with no meaningful activity.
What researchers are finding is that how much we move, or don't move, during this incidental, non-exercising time can have a big impact on our overall health.
Does sitting "undo” exercise?
For a long time, researchers made the (probably false) assumption that simply not exercising was causing health problems such as heart disease and obesity.
While they recognized the risks of not working out, it didn't occur to them to specifically study the effects of being sedentary … independent of a lack of exercise.
Now, research is beginning to reveal the possible negative consequences of being chronically sedentary, regardless of the amount of daily moderate exercise.
The preliminary findings show that by itself, lengthy periods of sitting (without much standing or light physical activity), cause serious health harm… whether we exercise regularly or not.
An in-depth review of the available evidence found that physical inactivity like sitting has its own unique effects on the body.
Early findings indicate real health benefits to interrupting sedentary time, and that this benefit is important in addition to other, moderate activity.
Research published earlier this year, based on the largest the nutrition survey in the world, shows that vigorous exercise does reduce the risk of death for people who typically are sedentary for long periods of time.
However, the research shows that that the benefits of a daily workout are significantly undermined if you spend the remainder of your day being relatively sedentary.
So whether you exercise or don't, sitting for long periods is a real health hazard.
Promising findings suggest an easy remedy for sitting's bad effects
So, what can you do to protect yourself against the negative effects of lengthy periods of seated work or leisure?
Scientists at the University of Utah School of Medicine recently studied the health benefits of interrupting seated time with brief breaks, by examining the activity patterns of 3,626 men and women who participated in the U.S. National Health and Nutrition Examination Survey for 2003-2004 (Beddhu S et al. 2015).
Looking at a two-year period, they compared the death rates of people who either engaged in periodic "low-intensity” activity (such as standing) throughout the day, or periodic "light-intensity” activity (casual walking, gardening, or cleaning).
While there was no death-prevention benefit for trading two minutes of sitting with two minutes of low-intensity activity (such as standing), they did see a 33% lower risk of dying when two minutes of sitting was traded for light-intensity activity (casual walking, gardening or cleaning).
And people who would been diagnosed with chronic kidney disease were 41% less likely to die during the study if two minutes of sitting was routinely interrupted by two minutes of light-intensity activity.
(Chronic kidney disease afflicts about 6% of people under age 60, and about 18% of people over age 60. Some 26 million American adults have CKD, and millions more are at risk. The two main causes are diabetes and high blood pressure.)
More evidence that quick breaks can counter sitting's bad effects
The Utah team's results were echoed in a very similar examination of data from the U.S. National Health and Nutrition Examination Survey for 2003-2004, published by German scientists earlier this year (Schmid D et al. 2015).
As the German team wrote, "Both high levels of sedentary time and low levels of moderate to vigorous physical activity are strong and independent predictors of early death from any cause.”
According to similar epidemiological studies, breaks for light-intensity physical activity may help prevent loss of bone mineral density, and improve health outcomes for breast cancer survivors.
The bottom line: Get off yours briefly, every hour
The take away seems clear: in addition to 2½ hours of moderate exercise per week, you should add two minutes of walking, cleaning or gardening to every hour of your day.
Regular, brief breaks for light-intensity activity appear particularly critical when you're sedentary for long periods.
Remembering to do that can be the hardest part.
Just get one of the many available computer apps that will alert you when a predetermined amount of time has past ... or just set an egg timer!
- Beddhu S, Wei G, Marcus RL, Chonchol M, Greene T. Light-Intensity Physical Activities and Mortality in the United States General Population and CKD Subpopulation. Clin J Am Soc Nephrol. 2015 Apr 30. pii: CJN.08410814. [Epub ahead of print]
- Chastin SF, Mandrichenko O, Helbostadt JL, Skelton DA. Associations between objectively-measured sedentary behaviour and physical activity with bone mineral density in adults and older adults, the NHANES study. Bone. 2014 Jul;64:254-62. doi: 10.1016/j.bone.2014.04.009. Epub 2014 Apr 13.
- Hamilton MT, Healy GN, Dunstan DW, Zderic TW, Owen N. Too Little Exercise and Too Much Sitting: Inactivity Physiology and the Need for New Recommendations on Sedentary Behavior. Curr Cardiovasc Risk Rep. 2008 Jul;2(4):292-298.
- Lynch BM, Dunstan DW, Healy GN, Winkler E, Eakin E, Owen N. Objectively measured physical activity and sedentary time of breast cancer survivors, and associations with adiposity: findings from NHANES (2003-2006). Cancer Causes Control. 2010 Feb;21(2):283-8. doi: 10.1007/s10552-009-9460-6. Epub 2009 Nov 1
- Schmid D, Ricci C, Leitzmann MF. Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: the NHANES study. PLoS One. 2015 Mar 13;10(3):e0119591. doi: 10.1371/journal.pone.0119591. eCollection 2015.
Srinivasan Beddhu, Guo Wei, Robin L. Marcus, Michel Chonchol, and Tom Greene