There is an emerging field of study called the Science of Sedentary Behavior. The focus is on Inactivity Physiology, and the results are raising some concerns about an epidemic of metabolic disorders. The thinking is that too much sitting is creating a new health risk distinct from too little exercise.
We know that inactivity is bad.
- In 1700 the Italian physician Bernardino Ramazzini published A Treatise on the Diseases of Workers. This book detailed the ill effects of many jobs including “the maladies affecting clerks”. Ramazzini said they suffer from general ill health because of constant sitting. Ramazzini also noted; “potters and weavers, who exercise the arms and feet, (…) this keeps them in better health.”
- In the 1950’s a study of London bus operators found that the conductors who climbed up and down the double-decker bus stairs all day had half as many heart attacks as the drivers who spent 90% of their day seated.
- A more recent study (3) followed a group of 17,000 Canadians for a period of 12 years. Researchers found that those who sat the most had a 50% increased risk of early death compared to those who sat the least. This increased risk remained even after controlling for age, smoking, obesity, and exercise.
We thrive on movement.
- Early evolutionary science shows that we were walkers. Early humans walked as much as 6 to 12 miles/ 10 to 20 Km per day in search of food and water.
- Several thousand years ago humans began domesticating animals and raising crops. This hard physical labor produced a more stable food supply and moved our species forward.
- A couple of hundred years ago the industrial revolution and more mechanized work reduced the physical demands placed on many workers. This was heralded as a major advancement for mankind.
- Very recently more work has become automated, now a majority of western workers sit at computers or operate automated systems for work.
Many of us are now sitting all day.
The US Dept of Education estimates that 81% of the US population has internet access at home, and Wikipedia estimates there were 1 Billion computer users globally in 2008. Many of us are knowledge workers who spend much of our time sitting.
Not only do we sit all day at work on our computers, we also sit at breakfast, on our commute to work, all day at work, on the commute home, at dinner, and then we sit to watch TV in the evening. Many of us are sitting 10 hours per day, some even more. It appears that even the recommended 30 minutes of exercise most days per week will not offset inactivity for the other 15 hours of our waking day.
Obesity is becoming epidemic in much of the world.
- From 1960 – 1980 US obesity rates were flat at 15%
- From 1985 – 2009 US obesity rates have steadily increased
- The latest data from 2009 shows:
- Nine states have obesity rates greater than 30%
- Twenty-four states have obesity rates above 25%
- Only one state, Colorado, has an obesity rate at or below 20%
Obesity significantly increases health care costs. According to the Rand Report on obesity, the health risks of obesity are worse than smoking, heavy drinking, and living in poverty. By comparison, only aging from 30 to 50 is associated with more health care costs than obesity.
Enter Metabolic Syndrome aka Sitting Disease:
The National Institutes of Health define metabolic syndrome as a group of risk factors that occur together and increase the risk for coronary artery disease, stroke, and type 2 diabetes. Being a “syndrome” means the causes and mechanisms are not fully understood, but this condition is closely associated with obesity, and now appears to also be associated with inactivity.
Researchers from the university of Missouri-Columbia believe that some key fat burning enzymes become inactive within hours of sitting. These enzymes are different from those activated with exercise. Standing, walking and engaging the postural muscles of the leg seem to be effective at restarting these fat burning enzymes.
What can the ergonomist do?
- Encourage movement; regular posture changes are recommended.
- Avoid prolonged static postures—either sitting or standing.
- Identify standing & walking opportunities in your work. Stand when the phone rings, stand to read documents, walk to speak with colleagues, etc.
- Provide sit to stand accessories or workstations (even if these are shared stations) for temporary touchdown work
- Encourage standing or even walking meetings
- Ramazzini. A Treatise on the Diseases of Workers?
- Morris et al. Coronary heart-disease and physical activity at work. Lancet 1953?
- Katzmarzyk et al. Sitting Time and Mortality from All Causes, Cardiovascular Disease, and Cancer. Med Sci Sports Exerc. 2009
- Behavioral Risk Factor Surveillance, CDC. http://www.cdc.gov/brfss/index.htm?
- Rand Report on obesity http://www.rand.org/pubs/research_briefs/RB4549.html?
- Hamilton et al. Too Little Exercise and Too Much Sitting. Current Cardiovascular Risk Reports 2008?
Gene Kay has a Masters degree in Exercise Science and is a Certified Ergonomics Associate. He has been designing web-based ergonomics programs for 10 years, and owns the ErgoAdvocate Ergonomics Training program. Gene has served as the American Express Global Ergonomics Manager, a Rehab Services Manager, and is Past-President of the Upper Midwest Chapter of HFES.
This article originally appeared in The Ergonomics Report™ on 2011-09-21.