I want to cover a subject that to some of you could be fairly confusing and misunderstood.  I have referred to the words flexion and extension multiple times throughout my work and blogs, and I think that it deserves some attention and clarification.  One of the big pitfalls of the fitness/health space is that the language can become a barrier for the passing of knowledge.  Like many fields, language becomes extremely specific and difficult for those without standard education in the field to understand.  One of the things I pride myself on is making complex topics such as how the body compensates in movement for lack of muscular strength/lengthening so that anyone can understand what could be going on with their own bodies.  At the very least, to make the information easy for someone who does not have the background in the field.  That being said, let’s dive into the topic of flexion and extension in regards to the spine.  Keep in mind that just because you have back pain, does not mean you have a flexion or extension problem.  This is an educational post, not something to use as a tool to diagnose medical conditions. But it is something we need to understand and keep in mind!

So what exactly is “flexion”?  Flexion of the spine is easily understood in regards to a visual that you will be familiar with by thinking of someone bending over to pick something up.  Anytime the spine is moving into the C (curved) position such as bending over, we refer to that as flexion.  The spine is “flexing”, and the paraspinal muscles such as your lumbar erectors are also in flexion in this position.  From a functional anatomy standpoint they are being forced to lengthen or stretch out to slow the decent out of spine/trunk.  So when you are sitting at your desk all day in a slouched posture, you are effectively putting yourself into flexion all day.  What that means is that those paraspinal muscles have been loaded all day, and they are not used to being lengthened so overtime they become chronically short.  They are also being loaded all day with the weight of your trunk, as sitting in a slouched position means that your abdominals can not fire effectively to support your trunk. This can lead to other issues, but that is not the point of today’s post.  You will likely catch yourself in flexion during the day if you sit a good amount.  This is one of the things I almost always have to work on with my clients.  This dependence on your lumbar muscles also changes neuromuscular firing patterns as well over time.  Anytime I have a client with back issues I immediately check the way they sit, because most of the time people’s back pain seems to worsen after sitting for long amounts of time, or when attempting to lift objects from the ground.  This is often explainable when we take a look at the individual’s mechanics and ability or lack of ability to fire from the correct musculature because of imbalances.


In regards to extension, it is the exact opposite of flexion.  Think of when someone stretches early in the morning and they push their chest out and increase the curve of their lower back when doing it.  They are effectively creating greater lumbar lordosis (curve) by putting their spine and the muscles associated with it into extension.  Putting the spine into extension creates contraction in the paraspinals to hold this extended position.  The paraspinals are being shortened in this position, not lengthened as they would be in extension.  In simple terms when we put ourselves into extension we are basically flexing our back muscles (lumbar erectors) to create the extension.  While this position is a great stretch, I would argue against putting yourself in that position for any length of time.  Multiple clients of mine have had fairly significant back issues that have been partly generated by a posture that put them into extension throughout the day and when sitting.  Doing this locks those paraspinal muscles for hours at a time. 

So now that we understand these two positions, what can we do with this information?  You may notice that you are either flexion or extension intolerant in your back.  For myself, it has taken years of working on my own structure and musculature to get back to a point where flexion and extension does not create pain.  But regardless of my degenerative disc disease, flexion and extension no longer cause the incredible pain that it once did.  This was done through a complex programming of undoing the muscular dominance of my paraspinals and allowing my glutes to properly fire in hip extension (when my leg is behind me/or when I am standing).  I have done the same with hundreds of people I have worked with including face to face with patients of medical professionals when I have been brought in as a specialist.  Interestingly enough, I have noticed a trend that many people who think they are in good posture, have actually put themselves into extension throughout the day.  Day after day of this habitual pattern eventually creates chronically tight lumbar erectors/paraspinals that ended up generating intense back pain.

So what we can do about it?  While catching yourself slouching at the computer is fairly easy and only requires awareness, there is something we can actually do to test if we are in extension!  This programming is something I give for my clients to work on, and I want to share it with you.  As long as you have no issues with getting on the floor and on your back, you can test this out for yourself.  The movement is simple, and the first part is 100% inspired from Dr. Stuart McGills work.

Lay on your back with your knees up and feet on the floor.  Take one hand and attempt to slide it under your lower back.  Can you easily slide your hand under you? Is there a gap between the floor and your back?  Is your back naturally nearly on the floor when you try this?  If you found that you can easily slide your hand under you, this means you are in an extended position and are not even aware of it.  The natural/neutral position we should be looking for is a position that does not allow your hand to slide under your low back.  Keep in mind that under no circumstances should you attempt to force your back onto the floor.  Since you are so used to being in an extended position, you will likely use your lower paraspinals to push yourself onto the floor.  That is the last thing that we want, and will only further the low back dominance pattern.  The goal is to be able to lower the rib cage from that extended position by using your abdominals – not by flexing your lower back into that position (There is further cuing needed for the pelvis but that’s another issue).  Easier said than done I understand!  There are several progressions of this movement/exercise that can really help reset your posture, that my clients undergo, but this is the very first step.  The first step is always awareness.

I hope all of you are doing well during this time.  With Oregon/WA trying to reopen business, and I am aiming at being able to see clients in person by the end of the month.  If you enjoyed this blog or have a specific subject you would like me to cover, please post in the comments.

Until next time,