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The Truth About Sitting

exec-chair3Can you believe that an average office worker, throughout his career, spends 80,000 hours sitting in an office chair?  This is an amazing statistic and it helps put into perspective how important it is to have an ergonomic, adjustable chair.

 

The human body is not structured to sit in a chair all day.  Your body requires muscles to work continually to help you sit.  Sitting is harder on your back than standing because when you stand the spine is in a state called lordosis, with pressure evenly distributed along the 24 vertebrae of your backbone.  The blood flow along the spine is unobstructed.  When sitting, you bend the body at a right angle and flatten the lumbar. 

 

It is a misconception that your backbone supports your body.  Your body actually supports your backbone.  The back’s 24 vertebrae and its jelly-like disks offer you flexibility, but not much strength.  When standing pressure is evenly distributed along your backbone.  When you sit at a right angle, the bending of your body flattens the lumbar and causes a state called kyphosis, or uneven pressure on the disks in your back.  This state strains the muscles in that area and causes lower pack pain. 

 

The less you move while sitting, the less your body is able to supply other parts of your body with vital nutrients.  When your lumbar area is nutrient deprived, the fluid-filled disks harden.  As they become less flexible, your body is more vulnerable to injuries caused by motion.  Sitting incorrectly essentially crunches your lumbar area and will gradually erode the disks in your back over time.  Just sitting for 20 minutes can so reduce the flow of nutrients to your disks that they can begin to harden.  If your chair is too soft and cushy, your body doesn’t really move much and your disks pay the price.

 

 

It may seem pretty obvious how to sit in a chair.  However, there are ways to do it that promote a healthier body.  Studies have proven that sitting in a properly adjusted chair that encourages motion reduces cumulative trauma disorders to nerves, tendons, and the neurovascular system.  It is important to continually allow your muscles and bones to find the most stable, healthy position as easily as possible. 

 

One of the most important features of an ergonomic chair is adjustability.  Here are some great adjustment tips from Neutral Posture:

 

If you experience this problem

Caused by:

Try this:

Neck tension, tightness, upper back and shoulders tension. Head too far forward while you type or view your monitor Elevate your monitor so your head and trunk relationship is more vertical.
  Hands and arms not supported while keyboarding. Adjust the chair’s armrests.
Note: ideally ergonomic professionals suggest not resting arms while keyboarding. However in the “real world” we recognize this is often done.
  Head is too far back during monitor viewing.  Tilt the seat and backrest forward so as to keep the head and trunk relationship more vertical.
Hand, wrist and lower arm discomfort The wrist is deviated (turned) in an unnatural position. Set the keyboard or calculator to produce a neutral (straight) position.
  Excessive application of force to the keys Train yourself to reduce excessive keystroke force. Excessive force is not needed or efficient.
Lower back pain discomfort. Lumbar curvature is not being maintained or supported. Bring your chair’s backrest in closer to your back, tilt it forward, or change your lumbar support by increasing or decreasing the air pressure on the chair’s air lumbar support (if you have this.). The backrest should be placed just above the pelvis to provide lower back region support.
  The major thigh muscle is pulling on the spine because your feet are dangling or unsupported. Lower your chair and or use a footrest so that the feet support both their own weight and the weight of the lower legs only.
  Increased disc pressure because vertebrae do not have equidistance spacing. This results in stretching the muscle, tendon and ligament system. Open up trunk/thigh angle towards the neutral position.
Buttock discomfort Sitting too far forward in the seat pan and not using the footrest. Sit deeper in the chair. It may be necessary to adjust the backrest by tilting the angle.
  Pressure is too great on the buttock/ischial tuberosities (the bony parts of the pelvis where we sit on. Raise the chair height and increase the pressure naturally for the thigh. Back of the thighs should touch the seat pan.
Thigh discomfort Too much pressure on the thigh because the chair is too high and legs are dangling Lower chair height so the feet support themselves and the lower legs only.
  Too much pressure on the popliteal area (the soft tissue area behind the knee) from the seat pan. Sit further forward in the seat pan and adjust backrest further forward.
Lower leg/foot discomfort Too much pressure in the popliteal area (soft tissue behind the knee) from the seat pan so that circulation is restricted to the lower leg and feet. This puts pressure on the nerves to the lower legs and feet. Sit further forward in the seat pan and adjust the backrest further forward.
  Infrequent posture changes in the feet and lower legs. Utilize a well designed footrest to promote movement and frequent posture changes.