Your Chair’s Tilt Angle and Sciatica
The number of work tasks focused around sitting at a computer has increased markedly over the past few decades. Every day a large proportion of employees sit for hours on end at their workstation. Often many of these people can suffer from a variety of posture related injuries. The neck, shoulder, back and a variety of repetitive strain injuries can be attributed to your working position. To prevent these issues, your workstation or work environment must be tailored to your individual needs. A recent study conducted by the Irish heart foundation found that the average person in Ireland sits down for 7.3 hours a day. (1)
Sciatica, what is it?
As people work, over time it can be an accumulation of pressures or compression that lead to all sorts of pain, discomfort and other health issues. Sciatica can present as low back pain which often radiates down the back of the legs due to compression of the sciatic nerve. (2)
“Sciatica can present as low back pain which often radiates down the back of the legs due to compression of the sciatic nerve”
How Ergonomics can help!
Thankfully, there are other methods we can use to reduce the amount of time spent sitting in one position. With the ever-evolving knowledge of Ergonomics leading the development of office furniture, we can now use our equipment to help us vary our working position. Most people just sit in their work chairs and never wonder how they might be used to benefit their position and possible symptoms. Imagine you are sitting on the solution to your back pain all this time!
One of the simplest and most beneficial features is the tilt mechanism. This feature is built into almost every office chair found in the average workplace. The tilt function will allow you to change your seated position intermittently throughout the day to change the pressure points put on your back. Sitting for too long in a static position can put extra pressure on the structures surrounding the sciatic nerve. Maybe your normal position isn’t the one for you. Often people sit the way they “think is right” rather than what is “right for them”. People often sit too straight rather than at the angle that works best for their back. In our world, we describe this as “off-loading posture” and this can “significantly shift the centre of the force and the peak pressure from the back onto your thighs.” (3) It’s a much better idea to let your legs take the pressure than your back! When using the tilt mechanism, it will significantly decrease the contact area on the seat and increase that of the backrest, which in turn leads to a decrease in the low back muscle activities. (3)
However, it is important that the chair is set up correctly to suit the individual. Studies have shown that the ideal sitting angles are between 100 degrees and 110 degrees to reduce spinal disc pressure. (4, 5)
“Studies have shown that the ideal sitting angles are between 100 degrees and 110 degrees to reduce spinal disc pressure. ”
Below is the simplest guide to Tilt Tension function on your chair:
Tilted too far back: You will be sitting with little back support. The muscles in your back will only support you for a short period before it becomes achy and uncomfortable because they simply must work too hard to keep you upright
Tilted Too Far Forward: Can cause compression and feel like the chair is forcing you too far forward, encouraging you to sit away from the backrest in a more slumped/forward position with poor posture.
Summary
Comfort – back should feel like little or no pressure and comfortable. Back tension, even low level can increase pressures and lead to other problems developing in the long term.
Angles – consider sitting at a more reclined angle, between 100 and 110 degrees to reduce the pressure which is put on your back.
Click/Tap For References ↓
Peul, W C., Van Houwelingen, H C., Van den Hout, W B., Brand, R., Eekhof, J., Tans, J., Thomeer, R., & Koes, B W. (2007) Surgery versus Prolonged Conservative Treatment for Sciatica. New England Journal of Medicine; 356:2245-2256.
Makhsous, M., Lin, F., Bankard, J., Hendrix, RW., Hepler, M., & Press J. (2009) Biomechanical effects of sitting with adjustable ischial and lumbar support on occupational low back pain: evaluation of sitting load and back muscle activity. BMC Musculoskeletal Disorders. https://doi.org/10.1186/1471-2474-10-17 10:17.
Harrison, D., Harrison, S., Croft, C., Harrison, D., & Troyanovick, D. (1999) Sitting biomechanics Part I: Review of the Literature. Journal of Manipulative and Physiological Therapeutics; 22(9): 594-609.
Harrison, D., Harrison, S., Croft, C., Harrison, D., & Troyanovick, D. Sitting biomechanics, Part II: Optimal car driver's seat and optimal driver's spinal model. (2000) Journal of Manipulative and Physiological Therapeutics; 23(1): 37-47.