Chair Series: Seat Pan Blog
Low back pain is a highly prevalent health problem that is associated with enormous costs worldwide. What if it could be helped or altered by your sitting position and more accurately a well hidden feature of an office chair. Repetitive stressing of a body part to the point of injury takes time through the build-up of trauma. (1) Due to the continued increase in the amount of time spent sitting at a desk for work, ergonomists have been developing strategies to try and counteract the negative effect that this is having on the population. This has led to the addition of the seat pan function on the chair. This is the part of the chair that you sit on and it often slides forward and back to provide more or less support to the thighs and low back.
Myth Busting: The Button/Lever on your chair that you never pushed does nothing
Ergonomic chairs come in many shapes and sizes and have numerous functions to help keep you comfortable and supported. Most people understand and use the basic adjustments of an ergonomic office chair, such as the height or recline functions. However, there is much more to them than this and often people do not understand the benefits of using the other functions available to them.
The seat pan is the part of the chair which supports the majority of your weight (your lower limbs), so it makes sense that you have this set up to suit your individual needs. The seat pan function is often hidden or hard to find on the left-hand side of the chair or underneath the front of your chair. Most of the time, even if you find it, nothing happens when you press it because your body weight does not allow it to move. Best way to find out what it does is to stand up, press the same lever but try to slide your seat pan forward and back (rather than expect it to go up and down). I always feel this lever is counterintuitive when sitting in your chair and so we often just disregard it. This is a big mistake as this can play a major role is helping to improve your comfort at the workstation.
The Seat pan helps everything
Firstly, its important to make sure that the seat pan suits you. Some of the things to know about ideal seat pan size:
You should be able to fit 2-4 fingers behind the knees when sitting
Should be deep enough to support most of your upper leg
Not so deep that it contacts the back of your knees when you sit back in your chair
The width of the seat should be at least one inch wider than your hips.
Not be so wide that you cannot rest your arms on the armrests without stretching them out to the side.
Compression of the backs of the knees or tingling in the feet can result from insufficient space. To avoid this discomfort, most people tend to sit perched at the edge of their chair which results in no back support or they slouch which is not ideal either. A proper seat depth setting allows the user to sit all the way back so you can position the curve of the seat to meet the curve of your back when sitting back and utilize the lumbar support on your chair. Simply put, it allows for the correct positioning of the hips which helps everything above and below!
What are benefits of tilting seat pan?
It decreases the load on your lower back and minimizes the risk for lower back pain (2) (3)
Sitting with your thighs in a downward slope increases the activity of your lower leg muscles, and reduces the pressure put on your back
Summary Tips
Seat pan function and size is important
Allow for a 2 to 4 finger gap between the front of the seat pan and the back of your knees
The ability to change seat pan depth and sit more supported can help reduce low back pain
Click/Tap For References ↓
Kumar P N (2018). Musculoskeletal Disorders: Office Menace. Office Buildings:105-126
Salai, M., Brosh, T, Blankstein, A., Oran, A., & Chechik, A. (1999) Effect of changing the sad-dle angle on the incidence of low back pain in recreational bicyclists. British Journal of Sport Medicine. 33(6): 398-400.
Nourbakhsh, M. R., & Arab, A. M. (2002) Relationship Between Mechanical Factors and In-cidence of Low Back Pain. Journal of Orthopaedic & Sports Physical Therapy: 32(9): 447–460. DOI:10.2519/jospt.2002.32.9.447