Ergonomic Seating

Ergonomic Seat Pan Angle – Adjusting the Lumbo-Pelvic Angle

Lower back pain is a global problem. Its rate has increased steadily over the last several decades, with now more than 637 million individuals suffering around the world. 1

What has also been steadily increasing is the act of sitting. People are working from home more than ever, especially with the recent coronavirus outbreak, forcing people to self-isolate to reduce the spread of the disease. Even before COVID-19, businesses and individuals have increasingly adopted computer-based platforms that increase screen time. Engaging with screens are a large part of life for many and presents a new reality of work life.

What do we know about the origins of lower back pain?

Lower back pain is considered multifaceted with intervertebral disc degeneration (IDD) being the most probable leading cause. IDD is a precursor to many commonly known conditions, with only some of them being disc herniation, spondylosis and lumbar spinal stenosis. 2 A common radiological finding within IDD and the other related spinal conditions are the reduction of spacing between the vertebra. Or, in other words, disc height loss. So how does disc height loss occur?


Disc height loss is normal through the day/night cycle. As humans, we lose approximately 20% of the fluid from our discs over the day to regain it at night, when we lie down to sleep. 3 The regaining or recovery of the fluid and respective height is imperative for the health of the disc. If we do not recover the height, this leads to a state of compression and resulting pain. On the flip side, if discs regain too much fluid, this also results in over expansion as we see with astronauts. Problems also incur if one lies in bed for too long.


So we need a balance—a balance of compression and decompression to our spines. If there is an excess in either direction, problems can arise. To minimize over-compression, we have to look at our postural behaviours. And one act that we just do too much of is sitting. We know that sitting causes disc compression and height loss as the spine undergoes the movement of flexion. 4. And why does the spine round into that posture? Well, the main reason is because of traditional seat pans 5 which cause the lumbar spine to round and causing increased pressure on the disc. 6

So what is it about sitting that is so different?

If you look carefully at a single motion segment (vertebra-disc-vertebra complex), each vertebra is separated by three joints. The largest and most important anatomical structure in the fight to resist compression is the intervertebral disc, which supports about 80 percent of the load in the standing posture. The remaining 20% load is distributed through the facet joints. Lumbar Model - Intervertebral Disc and FacetsProfessional LxH Dynamic Disc Model

I often describe this using a tricycle as a metaphor. The big tire on the front is like the disc, and the two facet joints are similarly like the two little tires. Sitting will place all the pressure over the big tire on the front of the tricycle, which increases the pressure on it. And over time, because the disc is a hydraulic structure, water will squeeze water out of it, reducing its height.

Neutral Loading

Office Chairs and Lumbar Alignment

To optimize sitting alignment during sitting, researchers have looked at lumbar supports to balance the motion segments of the spine. 7 These groups of researchers asked one question: Which office chair feature is better at improving spine posture in sitting? What they did was evaluate 28 participants, measuring by x-ray postures in four different chair conditions: control, lumbar support, seat pan tilt and backrest with scapular relief. They concluded that not one of the four stood out with regards to improving lumbar flexion, but the angled seat pan did improve pelvic posture significantly. They also discussed how the tilting seat pan did reduce flexion in the lumbar spine and suggesting that this may still be of practical significance. 8


Ergonomic Seating from Dynamic Disc Designs Corp.

At Dynamic Disc Designs, we are introducing ergonomic seating. Some may know the CEO, Jerome Fryer BSc DC, who has, from an early start in his career, observed the increasing trend of global sitting. In 1998, he made a simple observation during his training years as a chiropractor. And this simple observation of self-decompression led to two publications in The Journal of Bodywork and Movement Therapies and also The Spine Journal.

With the knowledge gained, he thought it was time to bring it to others.

With an adjustable seat pan and a saddle orientation to keep your hips in a more neutral position, the Ergonomic Saddle – Task Chair will optimize lumbopelvic posture. A 12-degree seat pan tilt is adjustable to each user’s unique lower back.

Seat Pan Angle Adjustability
Adjustable Tilt