PRI Vision & Computers–Part Two

As promised, this second part will teach you how to select the right chair for using a computer (or for any prolonged seated activity) and the best position in the chair to keep your body and eyes happy and tension-free!

Let’s start with chair selection.  Here are the things you want in a good chair (see pictures below as well):

  1. The ability to feel your mid-back (the area right under your shoulder blades) hit the chair back without the backside of your calves or knees restricting you from sliding back “into” the chair.
  2. Adjustable arm rests.
  3. An opening in the bottom of the chair back to accommodate your posterior glutes and hips.
  4. A seat that is semi-firm with a rounded edge at the front of the chair seat.  Padding is fine, it just needs to be firm so you don’t “sink” into the middle of the seat.
  5. Height adjustment so that your knees are at the level of your hips, or slightly above them with both feet flat on the floor.  For some of us shorties, this necessitates the use of a block or a taped-up phone book under the feet, otherwise the desk and keyboard tray is too high once seated.
  6. Adjustable seat back that tilts forward or back.

Chair w Arrow Body position in chair Short position in chair

“What if the chair I have doesn’t match your description and my company won’t spring for a new one?”  

Here are a few tricks to make the best of what you have:

  • People 5’4″ & under (like me!) are shorter than what most chairs are designed for.  The telephone book or block under the feet will be a must for most of us.
  • The seat depth (from front to back) will likely also be too large for the knees to clear the front of it and hang down freely.  Use a soft pillow, wider than your torso, positioned so that the top edge of it hits near the bottom of the shoulder blades.  This substitutes for having chair contact at this area as in #1 above, and you should feel as if it’s just a padded chair back with contact in the same area.  Don’t use a lumbar “roll” or “support” that keeps the bottom part or middle of your back pushed forward!  Placed properly the pillow should allow you to slightly round your back while your hands are on the keyboard or mouse.
  • Taller than ~5’8″?  Your chair challenges will be different, and slightly harder to use substitutions since you can’t add more size to a chair easily.  Consider moving the keyboard to the desk top surface from a lower-placed tray to give you more room to bring your chair up high enough.  A chair that has extra adjustment options for the back may help give you a little more useful room in the seat, or one that is designed larger than average is ideal, but these aren’t your typical task chairs available from mass retailers.  Find a local office furniture design firm who orders from more commercially-targeted  manufacturers.  A good designer will be able to steer you in the right direction to meet your body build, and often offers a chance to try the chair in your work environment before ordering one.  (Ours even dropped it off and picked it up for free pre-sale!)  You’ll pay ~$300 or more for a good one, but it will be well worth the investment when you don’t need weekly massages to undo all that tension!

Ok, now that you know what to start with, let’s get to how to use it!

  1. As you sit make sure your mid-back is in contact with the chair back and both feet are flat on the floor (or phone book) with the knees at or slightly above the level of your hips.  If you have on heels, kick them off under the desk so you can feel your feet on the surface under them.  Flat shoes don’t need to be removed.
  2. Round your back slightly without losing the mid-back contact point from #1.  Here’s how:Finding Ribs
  • Put both hands firmly on the bottom of your rib cage.  Don’t push at first, just feel your ribs with your hands.  You want to be able to find the edge of your ribcage curving downward under your fingertips when you push them in slightly, as if giving yourself a “squeeze”.
  • Once you have your hands placed and are not pushing in with your fingers, lean back with your shoulders so that Ribs Upyour back arches.  You should feel the edges of your ribs under your fingertips (without pushing hard) sticking outward and you will see your hands move up slightly as you lean back.  Your low back will move forward as you arch.  This is too much extension of the trunk, based on PRI principles, and is the very position you don’t want!  Ironically, this is the position most lumbar supports will put you in!                                            RJibs Up Side View
  • Now slowly lean forward with both shoulders.  As you do this, begin talking, so that you are encouraged to breathe Shoulder-Hip Alignmentcontinuously as you come forward.  (Say the alphabet, for example.)  You should feel the top half of your back moving forward, and the bottom half moving slightly back, so that your hands are moving down and the edges of your ribs are harder to feel under your fingers.  Your shoulders should now be slightly behind your hips, or close to it.  This is the optimal position and should be the goal!Shoulders in Front
  • Once the edges of your ribs have disappeared from your fingertips without pushing in, keep going forward so your shoulders are farther forward than your hips.  Your mid-back will lose contact with the chair back while your low back will push into it.  You may feel your abs tighten up as you would if you were doing a “crunch” style sit-up.  Your rib edges should be hard to find, and may feel “hunched” over.  This is too far in the opposite direction of extension and doesn’t allow for proper head and neck support.
    Leaning in is typical for many computer users, especially if they subconsciously over-focus their eyes.

    This is what leaning too far forward may also look like.

    Body position in chair

  • Go back to the optimal position described in the second bullet.  You should be able to keep mid-back contact, let your shoulders relax, and breathe easily here.  If you can’t get this with a little practice, or it’s not comfortable, find a PRI-minded therapist or trainer in your area (online at or call them if you don’t find one with the “locate” tool.  They are happy to help!).

Our third and final installment coming up will give you some activities to add to your chair time.  These will help to combat the natural tendencies we all have when we sit for long periods that promote tension.

Until then, Keep Moving Beyond Sight!

Dr. Heidi

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