Then I’ll begin. 2020 has been a strange year for many of us. A lot of us have lost the commute to work and we are spending longer than ever sitting in front of a screen, often in places that were not designed for office work.
We were not great at how we sat in chairs. We slouched and adopted a head forward posture. Now we have to contend with people trying to work with chairs that were not designed for office work, some even forced to use the sofa or the bed. It has been a challenge.
A few weeks ago I had someone complain to me about their sacrum being sore through all this sitting. I didn’t say anything at the time but the comment kept chipping away at the back of my brain.
You shouldn’t be sitting on your sacrum.
Your sacrum is a wedge shaped bone at the back of your pelvis, so called because it used to be believed that it was the sacred part of the body that if planted could grow into another body (!). It is often described as a key stone structure that sits between the two halves of the pelvis and that gravity acts on it to wedge the two halves of the pelvis apart. A belief that is clearly not the case if you look at the position of the pelvis from the side where it can be seen that the sacrum is more like the roof of the pelvic cavity that the back wall – I digress.
It can be seen from this image though, that if you were sitting then you shouldn’t be on your sacrum. So what should you be sitting on?
Your pelvis is made up of three bones, The ilium, the pubis and the ischium. (It is a long standing point of disagreement as to whether the sacrum is part of the pelvis or not). These three bones fuse in childhood to give us the distinctive hip, or pelvic, bone. At the bottom of the pelvis, on the ishium, we find a bone lump which anatomists call a tuberosity. These tuberosities are called your ischial tuberosities, because they are on the ishium. The exercise industry has decided to make it all a lot simpler and refers to these structures as your sit bones – because you sit on them.
There are a number of muscles that attach to your ischial tuberosities. If you sit on a hard surface and rock backwards and forwards you may be able to sense when you are on your sit bones but if you have a reasonable amount of body fat (and we all need body fat) it may be a challenge to actually palpate them.
The ischial tuberosities divide the area between your legs into two triangles which anatomists refer to as the urogenital triangle, because it contains the openings of the urinary system and the genital opening, and the anal triangle because … it’s self explanatory.
When you are sitting on your chair you ought to be balanced on your ischial tuberosities thinking about your weight going down through the urogenital triangle rather than the anal triangle. As you sit like this your head will come back into a position over your neck and you ought to get less strain on your neck and shoulders and most of all … no pressure on your sacrum.
Let’s hope we will soon all get back to our ergonomically designed chairs and we can sort out all the aches and pains brought on by home working.