Seating Position

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The Proper Sitting Position

The secret to Oregon Aero’s maximum-comfort seating is the way it shifts the hips, pelvis and back into the proper position, creating a smooth lumbar curve. Photos and x-rays show how our seating systems work and why other seating is painful.

Comfort: Proper Lumbar Curve & Pelvic Position

smooth lumbar curve                                         
  • Painless sitting!
  • Pelvis rotated forward.
  • Smooth lumbar curve.


     
    
                     

 
  • Smooth lumbar curve.
  • Shoulders and head shift effortlessly into painless position. 
  • Shown with SoftSeat® Portable Seat Cushion, but same painless seating occurs with all Oregon Aero® Seating Systems.
  

 

A carefully placed pelvic rotator repositions the pelvis, which restores the lumbar curve. A gentle lumbar cushion (not one that pushes hard) stabilizes the lumbar curve. When this is done, the head and shoulders move back to an effortless, painless, upright position. No more slouch, no more pain! Oregon Aero complies with all applicable FAA regulations by supplying FAA-approved seating and other parts to the public and OEM’s. The Oregon Aero Engineering Department has an FAA “Seat” DER on staff to support our customers.

X-Ray:  Sitting in an Oregon Aero® Ejection Seat Cushion

*While the x-rays and data compare ejections seats, the same improvements will occur with any Oregon Aero sest system, compared to conventional seating.

X-ray of Person Sitting In the Oregon Aero APECS™ I Ejection Seat Cushioning System


 

Here’s an actual x-ray of a person sitting in an Oregon Aero® Seat Cushion. The position is ideal for painless sitting and occurs with all Oregon Aero seating. This position also produces resistance by the spine to injury from a vertical acceleration in the straight-up “Z” axis of the spine.

Click on image to enlarge.

Line A: Horizontal datum (point from which other data is measured).
Line B: Angle of the pelvis relative to the Line A. Angular difference from the horizontal datum (Line A) is +13°. Ideal position.
Arc XX : Radius of the lumbar spine, 24.5 cm. Ideal position.
Line C-1: Surface of the vertebra relative to Line D-1, the surface of the adjacent vertebra (i.e., angular measurement of the vertebrae relative to each other). Angular difference is 9°. Ideal position.
Line C-2: Surface of the vertebra relative to Line D-2, the surface of the adjacent vertebra (i.e. angular measurement of the vertebrae relative to each other). Angular difference is 7°. Ideal position.

 

Why Are Other Seats Painful?

 Bad Seating #1
  • Our body weight lands on the pelvis’ ischial 
    tuberosity (the "sits bones") but the center of 
    gravity of the upper body is behind the sits bones — SO
 
  • The pelvis is rotated back, down and around the sits bones. This flattens the lumbar spine and compresses the anterior (front) of the disks at the lumbar spine (see two closeup photos), causing pain.
 Bad Seating #3
  • Anterior surfaces of wedge-shaped lumbar disk compressed to parallel position by pelvic rotation back and down.
  • Undesirable, painful position.
  • Produces low back strain, pain.
  • Remember: disks are naturally wedge-shaped.
  • See x-ray of conventional/stock cushion.
bad seating #4
  • Using cushion to push on the lumbar doesn’t overcome gravity!
  • Pelvis tipped back and down.
  • Anterior surfaces of wedge-shaped lumbar disk compressed to parallel position.
  • Undesirable relative surfaces of adjacent vertebrae.
  • Painful position.
  • Produces low back strain, pain.
  • See x-ray of conventional/stock cushion.
Bad Seating #5
  • Our instinctive response is to try and place pressure under the pelvis by slouching or using some kind of lumbar support, but this results in a complete curvature of the spine, compressing all of the disks up to the neck.
 
  • Does this slouching position look familiar? All of us have experienced it. 
    Note the top of the spine is rotated forward. This is felt as a tendency for the head and chest to fall forward and compress the diaphragm area of the upper abdomen. So — with great effort — we try to sit straight and pull our shoulders back. All of this is our clue that the pelvis is rotated back and down and that our back will hurt eventually, no matter what we do with lumbar cushions.

Oregon Aero designs all our seting to provide a gentle rotation of the pelvis. This rotation restores the lumbar curve and removes the compression strain from the spinal disks. 

X-Ray: Sitting in a Stock Ejection Seat

xray of person sitting in stock ejection seat


The position shown in this x-ray produces low back strain and pain. This position also diminishes by 50% the spine's ability to withstand a vertical acceleration in the straight-up "Z" axis of the spine.

Click on image to enlarge.


Line A: Horizontal datum (point from which other data is measured).
Line B: Angle of the pelvis relative to the Line A. Angular difference from the horizontal datum (Line A) is -6.5°. Undesirable, painful position.
Arc XX : Radius of the lumbar spine, 76 cm. Undesirable, painful position.
Line C-1: Surface of the vertebra relative to Line D-1, the surface of the adjacent vertebra (i.e., angular measurement of the vertebrae relative to each other). Angular difference is <1°, not even measurable. Disks are compressed. Painful position.
Line C-2: Surface of the vertebra relative to Line D-2, the surface of the adjacent vertebra (i.e. angular measurement of the vertebrae relative to each other). Angular difference is <1°, not even measurable. Disks are compressed. Painful position.

 Comparative Data:
Oregon Aero X-Ray Vs. Conventional Seating X-Ray

*While the x-rays and data compare ejections seats, the same improvements will occur with any Oregon Aero sest system, compared to conventional seating.

Data Number Considered Ideal for Painless Sitting & Injury Resistance Oregon Aero® Seat Cushion System Conventional/
Stock Seat
Pelvic Angle 12° - 13° +13° -6.5°
Lumbar Radius 24 - 25 cm 24.5 cm 76 cm
Relationship of adjacent lumbar vertebrae 7° - 9° 7° - 9° <1°