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 We help protect people, your company's most valuable asset January 2003 

In This Issue
Smarter sitting for improved back comfort
Research: sitting posture and movement
New: Personalized Training
Credits and notices

Published by Ergovera Ergonomic Consulting to help you keep up on ergonomic innovations, so you can protect your employees and increase their productivity. Please pass it on to your colleagues and friends.

Recently I discovered the SALLI saddle chair, which has a seat base that looks like a saddle one would use on a horse. The chair positions you in a very upright posture and allows you to scoot around in it quickly. It made me question my beliefs about chairs and sitting postures.

Not wanting to spend money on the SALLI chair quite yet (anything this good is not cheap), I procured a new posture ball (a simple large gym ball one sits on). This ball positions you in an excellent upright posture and allows you to rotate your pelvis and lower-back gently while sitting on the flexible ball. This is fun (says the dancer in me who loves to move), plus, sitting on the ball alleviates static posture and increases lower-back circulation.

Disc compression, swelling in the lower extremities, and back pain have been linked to prolonged sitting - with the lumbar area of the back being the most susceptible. Wanting to explore sitting further, I began to research movement while sitting, including dynamic chairs and posture.

The recent studies I summarize in this issue provide insight on sitting and offer some good tips:

  • Rocking in a chair that has a full-tilt mechanism (i.e. a dynamic chair) prevents swelling in the legs.
  • The greatest postural changes tend to occur during reading tasks, compared to word-processing and CAD work. These tasks can lead to awkward spinal postures.
  • The type of task one does substantially effects postural changes, but the type of chair does not.
  • Dynamic chairs help "the recovery of disc height," which helps relieve disc compression and discomfort.
  • Static postures provoke more pain while movement alleviates it.

So, educate your employees about how to adjust their chairs and the benefits of using the tilt-mechanism to rock periodically. Get them document holders for reading tasks to minimize poor posture. Consider the posture ball (an approximately $40.00 expenditure), especially for anyone who has a chair with a fixed seat base and backrest.

Have a safe and comfortable new year,

Deidre Rogers, RN, MS, CAE

A Norwegian study (Stranden) found that office chairs with a tilt-mechanism that incorporates movements, much like those of a rocking chair, activate vein pumping in the legs. This increases circulation and decreases swelling of the legs. The study showed that upward seat deflection (i.e., front edge of seat base slanted upward) did not cause venous obstruction, as some think it does.

A Netherlands study (Van Dieën et al.) found that when subjects use dynamic chairs, their spinal measurements showed increased stature (i.e., recovery on disc height). This was not seen with chairs that had fixed seat bases and fixed backrests. The researchers also found that a person's task affected body positioning and EMG variables (i.e., muscle activity), while the type of chair did not.

A study done in Spain (Vergara & Page) found that the probability of lumbar pain is greater when the pelvis is rotated forward and there is more lordosis (forward curvature of the spine). Static postures were found to provoke more pain, while small and quick movements alleviated it.


Standen, E. (2000). Dynamic leg volume changes when sitting in a locked and free floating tilt office chair. Ergonomics, 43(3), 421-433.

Van Dieëm, J., Looze, M. & Hermans, V. (2001). Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage. Ergonomics, 44(7), 739-750.

Vergara, M. & Page, A. (2001). Relationship between comfort and back posture and mobility in sitting-posture. Applied Ergonomics, 33(1), 1- 8.

Want to educate your employees about how to adjust their chairs, their monitors, or their keyboard trays? Ergovera can make a simple personalized video that uses your equipment and your workstations. This can be used annually as part of your ergonomic program and for all new employees.

Personalized videos can show how specific tasks should be performed to prevent injuries. For instance, neck position, monitor placement instructions, and vision issues can be discussed together. This way employees learn how to avoid risk factors associated with monitor placement and viewing.

Call Deidre at 831.335.8448 or send her a message now for more info about personalized videos.

Copyright © 2002, Deidre Rogers and Ergovera Ergonomic Consulting. All rights reserved. Reuse in any form must be requested and granted in writing.

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