DEATH BY CHAIR

Should We Be Warning Patients about the Dangers of Their Chair?

On September 13, 2010, in Activity & Musculoskeletal Health, by Craig Liebenson

The great Czech neurologist Pr Vladimir Janda stated that we are designed to take over 20,000 steps/day.Yet the average American takes about 6500 steps/day! In fact, Pr Janda probably underestimated how much humans are designed to walk as the  Amish typically take over 30,000 steps a day.  We can say with certainty that 200,000 years of evolution have designed us to walk at least 3x as much as we now do. Our modern lifestyles have led homosapian into becoming homosedentarius. Or, as our German colleagues say homo erectus vulgaris.

What are the culprits? According to a recent summary - Too Much Sitting: The Population Health Science of Sedentary Behavior: Objective Assessment of Sedentary Time: New Findings

• Prolonged sitting
• TV watching
• Computer or internet useage
• Driving

What is the effect of all this sitting? How about the big one -  increased mortality!

Warren TY, Barry V, Hooker SP, Sui X, Church T, Blair SN. Sedentary behaviors increase risk of cardiovascular disease mortality in men. Med. Sci. Sports Exerc. 2010; 42(5):879–85.

If we look at the different modifiable risk factors that shorten life span -

• high blood pressure
• obesity
• alchoholism
• smoking
• sedentarism

Sedentarism affects lifespan more than any of the others! Yet, prevention strategies more frequently focus on the others.

Increased physical activity has been shown to lead to reductions in functional decline (frailty), coronary heart disease (CHD), and disability prior to death along with increased life expectancy have all been demonstrated.

The  Surgeon General has reported  that only 22% of adults in the United States are active enough to derive benefits from activity.  Inactive men 60 years of age who become active have a mortality rate 50% lower than their peers who remain inactive. A study of Harvard University alumni confirmed this result. Men who were initially sedentary, but later began engaging in vigorous sports had a 23% lower rate of mortality than their inactive counterparts (Paffenberger, 1993). A Honolulu Heart program found that retired men who walked >2 miles/day had half the mortality rate (22%) than those who walked <1 mile/day (43%) (Hakim).

Many physicians counsel patients about smoking and body weight, but not about inactivity (Caspersen, 1985).

FOR ADDITIONAL REFERENCES SEE CHAPTER 37 OF REHABILITATION OF THE SPINE (2ND ED).

Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise and physical fitness: Definitions and distinctions for health-related research. Public Health Rep 1985;100:126-131.

Hakim AA, Curb D, Petrovitch H, Rodrigues BL, Yano K, Ross W, et al. Effects of walking on coronary heart disease in elderly men: The Honolulu Heart Program. Circulation 1999;100:9-13.

Paffenberger RS Jr, Hyde RT, Wing AL, et al. The association of change sand physical-activity level and other liefstyle characteristics with mortality among men. N Engl J Med 1993;328:538-545.

Physical Activity and Health: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion; 1996.

Here is a Self-Help article for your patients/clients on how to perform simple microbreaks espoused by Pr.'s McGill & Brugger.MB's – 02

WHAT ARE SOME OTHER EFFECTS OF PROLONGED SITTING?

A Pain In Your Neck?

When we sit our muscles are active at about 4% of their maximum voluntary contraction ability (MVC). Yet, if maintained for over 10 minutes  a negative metabolic state is established (Andersson, Sato). Such low levels of muscle contractions during static work loads can trigger  fatigue and pain in the neck. (Hamilton, Jensen, Veiersted).  Jensen suggested that any sustained static work load of greater than 10 minutes should not exceed 2% of MVC (Jensen).

Andersson GBJ. Occupational biomechanics in Wienstein JN, Wiesel SW, eds. The lumbar spine: the international society for the study of the lumbar spine. Philadelphia, WB Saunders, 1990 p 213.

Hamilton N. Source document position as it affects head position and neck muscle tension. Ergonomics 1996;39:593-610.

Jensen BR, Schibye B, Sogaard K, Simonsen EB, Sjogarrd G. Shoulder muscle load and muscle fatigue among industrial sewing machine operators. Eur J Applied Physiology 1993;6:467-475.

Sato H,  Ohashi J, Owanga K, et al. Endurance time and fatigue in static contractions. J Human Ergol 1984;3:147-154.

Veiersted KB, Westgaard RH, Andersen P. Pattern of muscle activity during stereotyped work and its relation to muscle pain. Internat Arch Occup Environ Health. 1990;62:31-41.

Back Pain From Just Sitting?

Prolonged sitting is one of the most deleterious activities most people engage in. After only 3 minutes of full flexion of the spine ligamentous creep or laxity occurs which persists even after 30 minutes of rest! (Gunning, McGill). These ligaments are responsible for protecting our discs so it is no wonder that trivial early morning flexion (putting on socks) or bending after sitting for a prolonged period (picking up a pencil) can lead to a severe disc problem with nerve irritation (Adams and Hutton)

According to Bogduk and Twomney, "After prolonged strain ligaments, capsules, and IV discs of the lumbar spine may creep, and they may be liable to injury if sudden forces are unexpectedly applied during the vulnerable recovery phase."  Once a tissue is strained, it has difficulty returning to its original length.

Wilder showed that the motor control signature associated with low back pain involves – a slow reaction time, decreased peak torque output (power), and increased after discharges when irregular load is handled (sustained elevated muscle tension). Prolonged sitting was shown to further disturb these variables and a brief walking break to improve them again.

Solomonow et al have demonstrated that the creep reaction may be much more stubborn than previously believed.   Reduced muscle activity with spasms were found during static flexion periods during a 7 hour recovery period. Multifidus spasm and acute inflammation of ligaments were noted. The dysfunction was reported to outlast the period over which strain occurred by 60X!

Adams, M.A., Hutton, W.C., Gradual disc prolapse, Spine 1985; 10: 524‑531.

Bogduk N, Twomney L. Clinical Anatomy of the Lumbar Spine and Sacrum, 3rd edn. Edinburgh: Churchill Livingston, 1997.

Gunning, J., Callaghan, J.P., McGill, S.M., The role of prior loading history and spinal posture on the compressive tolerance and type of failure in the spine using a porcine trauma model, Clin. Biomech 2001;16:471-480.

McGill SM, Brown Creep response of the lumbar spine to prolonged full flexion. Clinical Biomechanics 1992;7:43-46.

Solomonow M, Hatipkarasulu S, Zhou B, Baratta RV, Aghazadeh F. Biomechanics and EMG of a common idiopathic low back disorder. Spine 2003:28:1235-1248.

Wilder DG, Aleksiev AR, Magnusson ML, Pope MH, Spratt KF, Goel VK. Muscular response to sudden load. A tool to evaluate fatigue and rehabilitation. Spine 1996;21:2628–39.

ACTIVITY THROUGHOUT THE LIFESPAN

Most people when they have a problem or as they age tend to associate activity with risk. Yet, doing "too little too late" is often more dangerous than doing "too much too soon". If a person has a problem with activity they should seek a health care professionals advice. But, when people are sedentary they often do not have symptoms until it is too late.

Fall prevention is an obvious example. The mortality risk in an elderly person is greater than from cancer or heart disease! Simple exercises such as basic Tai Chi have been shown to reduce fall risk and thus mortality in the coming year in seniors.

Abenheim L, Rossignol M, Valat JP, Nordin M, Avouac B, Blotman F, Charlot J, et al. The role of activity in the therapeutic management of back pain: Report of the International Paris Task Force on Back Pain. Spine 2000;25:1S-33S.

Wolf SL, Barnahart HX, et al. Reducing frailty and falls in older persons: An investigation of Tai Chi and computerized balance training. JAGS 199;44:489-497