Sitting on the Job Static Load, Chronic Pain

By Bob Price
Published: May 7, 2008
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Prolonged sitting adds to the static load on our musculoskeletal system and can impact the circulatory system. From offices to industry, mechanization and automation has changed the way most of us do our jobs.  For many this involves more sitting. The act of sitting is not often viewed as a health and safety concern.  Still we’ve all felt stiffness in our back, pains in   our neck or shoulders and tingling in our toes after sitting for prolonged periods.  In fact, people who sit at work for extended periods of time run a high risk of low back pain and injury, second only to people who perform heavy lifting tasks.

What are the associated risk factors?

Sustained Posture:  The human body was designed for movement not for static postures such as sitting.  Prolonged sitting adds to the static load on our musculoskeletal system and can impact the circulatory system.

Awkward Posture:  Twisting, bending and reaching can result from poorly designed work stations.  These actions force the spine into a non-neutral position that can damage the spinal discs and increase the demands on the muscles and ligaments.

Localized Contact Stress:  Sea height that forces compression of the upper thighs on the underside of work surfaces is a common example of localized stress. The underside of the legs may also be subject to contact stress when a seat is not contoured downward.

Repetition:  Seated workers in a range of sectors including the office environments may also be exposed to the harmful effects of repetition.  The combined risks presented by sitting and repetitive work puts additional pressure on the muscles, ligaments and other parts of the musculoskeletal system.

How does the human body respond to sitting? 

Musculoskeletal System:  Sustaining any static posture such as sitting, increases the demand on the muscles, ligaments and other soft tissues of the musculoskeletal system.  Sitting alters the normal curvature of the spine and puts pressure on the discs.  This pressure can cause herniated discs, premature deterioration of discs, and overall spinal degeneration resulting in chronic back pain and possible nerve damage which could eventual lead to permanent disability.

Circulatory system:  Sitting restricts the circulation of blood to the lower extremities causing swelling, pain, numbness and tingling in the legs and feet.  Other potential health concerns include edema, varicose veins and blood pooling.  Deep-vein thrombosis (DVT)  is another health concern linked with the pooling of blood, which is the formation of large blood clots usually in the veins of the legs.  Clots that become mobile and result in blockages in the lungs, brain or heart may have fatal consequences. 

How can sitting be made less hazardous?

It must be understood that the human body CANNOT be altered to fit the needs of work or the workstation.  Instead, chairs, work surfaces and other aspects of workstations and job design must take into account the physical capability of workers. 

In Ontario specific regulatory protection for those who must sit for extended periods of time is limited to workers in the health care sector.  In the meantime workers are using the existing legislation such as general duty clauses in the occupational Health and Safety Act to call for preventative action in their workplaces.  The act states that “employers shall take every precaution reasonable in the circumstances for the protection of workers” and “provide information, instruction and supervision to a worker to protect the health or safety of the worker”.

Union Gas does have an independent contractor that can perform ergonomic assessments of your workstation if requested.  Contact your local steward, or your Joint Health and Safety Union rep to make arrangements. 

For additional information on this and other Health and Safety related issues visit:  www.whsc.on.ca   www.ohcow.on.ca   www.ccohs.ca



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