Sitting is complex, but well worth understanding if you do it in your work, or for long hours. Especially computer based work where it’s easy to be distracted from the stresses in your body by the virtual world or complex tasks.
Chairs have a short history in our culture and none of that lineage is about the body as we understand it now. With a growing proportion of a growing population involved in sedentary tasks, sitting badly is becoming a bigger problem; going as far as the recent quote “sitting is the new smoking”.
So we’ve been thinking about sitting and experimenting with office set-ups over the last couple of years, and the outcome is our Work-stool which has seen a recent update resolving design and production issues.
As the name indicates this stool is for seated work, but the name also means that it is work to sit well, but the health benefits are worth it.
First thing you’ll notice is the work-stool is high. Knees should be lower than the hips to encourage the correct curves in the spine, and balance in the big leg and postural muscles. Why are legacy chairs so low giving all the wrong angles in the posture? Of all the elements in chair design history this might be a factor: chairs are designed to fit under a desk. Desk heights? designed to fit in through a standard door sideways.
So forget ergonomic task chairs, no matter how fancy they are they are stuck in a paradigm that is not anatomically supportive.
The Work-stools premiss is: you are going to have to work to sit well but this brings strength, and when you tire you can easily shift or get up, which is a very healthy thing to do. The body is not designed to be still for long periods, despite what is expected since school — wriggling in your seat is necessary and healthy. The higher perch position is good for this as it gives your feet and legs enough purchase on the floor to make these shifts. Fatigue in a particular muscle group held in one position for a long time can be alleviated by sharing the work around; even tiny shifts can help change these static loads; so you want a chair that makes shifting easy. Firm surfaces are best for shifting on, upholstery just bogs you down.
With new understandings of the body at seated work you’ll realise the work surface has to be high to accommodate balance and ease in the body. Then follows computer screen which has to be at eye height to encourage horizon focused head & spine. Focus below the horizon alters the natural curves of the spine, which it is perfectly capable of, but not for sustained hours. Also keyboard at elbow height is a good thing.
Below is an outline of a legacy chair compared to our Work-stool. These are some of the ideas that informed our design:
- flattens lower spinal curve and so unbalances the curves above, adding stress to the shoulders and neck
- compression of the front of lower disks
- tilts pelvis backwards so weigh not passed directly to sit-bones (ischium)
- this creates torque or offset load on sacrum and illio-sacral joint (load focal behind sit bones — the sacrum is like a keystone in a stone arch, in this case the whole arch tilted back)
- compression of the gut — reduced blood flow and digestion / peristalsis
- compression of hamstring — reduced blood supply in area and blood flow to lower leg, numb bum and cold feet sound familiar?
- shortening of hamstring
- no firm structural connection to ground: no purchase with feet or legs to shift or engage core
- seat upholstery or texture resists bum shifts
- natural curve of spine — balance in upper spine shoulders /neck / head
- weight borne by sit-bones — as the structure of the skeleton is designed for
- load through vertical axis — vertebra to sacrum to pelvis to sit-bones to work-stool to ground
- core control, deep postural muscles engaged
- waterfall edge of seat no compression under thigh
- firm structural connection to ground with legs and feet to shift and help engage core
- little shift resistance in shape and surface texture of seat
- round small top allows femur / thigh to range sideways
- frees upper body to move
- requires work: muscle & postural engagement to sit well but this is strengthening and healthier
Using the skeleton as a metaphor for the complex structural elements of the body — the system through which weight is controlled and transferred to the ground; the diagrams below illustrate the key ideas above.
View our Work-Stool