Why you can have lower back pain into extension and flexion

Posted on January 9, 2017


When someone with a lower back issue leans over / bends down, they’ll usually have pain in one of two ways. On the way down, or on the way up.

Pain on the way down is often a sign of pain into flexion. The lower back rounds => person has pain => “flexion intolerant.”


Spine is rounding.

There are some, often those who have an extensive lifting background, who may lean over with too much extension. They’re the ones who somewhere along the way learned flexion was bad, but they started overcompensating:

But most of the time when leaning over the lower spine will flex.

Then those who have pain on the way up are usually the extension people. The back is (again, usually) going from flexion to extension when one stands up. So the person starts to have pain when this happens. And or they have pain at the very top of the motion, because they lean too far back into excessive extension (example in video above) => “extension intolerant.”

Perhaps the main attraction of categorizing like this is it right away directs intervention. You’re a new client of mine, I see when you flex your back you tend to have pain => “flexion intolerant” => let’s avoid flexion & embrace extension.

Where instead of focusing on the hills in this exercise, we focus on the valleys,

Because not only will this person have pain into flexion, they’ll probably enjoy being put into extension.


But then there are those people. The ones who have pain when they lean over into flexion and when they come up into extension. What do we do? If we avoid extension then are we putting the person into flexion? Or vice versa? Which is also painful? Do we ask this person to invisibly cast their spine so it doesn’t move from neutral? “Flexion-extension intolerant” isn’t as clearly directed! It’s like the spine is saying,


It’s important to back up and reiterate this does happen. At a decent frequency. This is where the most important sentences of Shirley Sahrmann’s book are relevant:

“Alignment is not, nor is it anticipated to be, correlated with low back pain. Structural changes in vertebral alignment occur with aging, but these changes are not always clinically obvious. The patient with spinal stenosis usually has a flat lumbar spine, yet extension is a cause of the symptoms […]

This variability in test results is one of the reasons for using a combinatorial rather than algorithmic examination.”

-> No doubt there will be pain science / posture articles in 2017 talking about the rough relationship between posture and pain. Yeah, people like Sahrmann -whom the criticism is often directed at- and those who genuinely read her book, already know this. Her book is from 2001.

While Sahrmann’s system does still categorize people into flexion or extension impairment, what she’s saying is you need to take each movement as its own issue. If you were to take someone through twenty lower back assessments (different movements), add all the times someone had flexion vs extension pain, a person will still tend to heavily be in one camp, but you won’t know that only through one movement (or one posture). And regardless, you don’t call someone an extension pain person, then have them do a ton of flexion even into a flexion movement that causes pain. You have to combine this assessment with that assessment. Not add a point for this one but subtract a point from that one, then stick to whatever tallied the most.

This is where the lower back can be much harder than other joints. It’s harder to assess because it might take you until the 20th movement assessment to realize, “Alright, in 19 instances this person has pain if they do X. But in number 20 if it’s they do Y.”

-> I’ve had people where it took me until the 87th minute of a 90 minute assessment to really see where somebody was having issues. Granted, I could have found out in the first minute if the order of the assessment was different, but I still would have done the other 87 minutes to see if there were other issues.

This can also be very hard for the person experiencing the pain. “Define me!”

A regular conversation I have with clients is,

“Why does my back hurt?”

“When you move X way that causes pain. If we avoid X, we can avoid pain.”

“Gotcha.” [not really] “So what’s the problem?”

“You moving X way. You do X too much, too often. We need to correct that.”

“So what do we stretch?”

“We need to change how you move.”

“So what do we strengthen?”

“We change how you move X way.”

It’s a very different view than,

“You ruptured a disc. You need rest.”

“You strained your back. Take some ibuprofen to decrease inflammation.”

“Your back muscles are weak. Do X exercise to strengthen them.”

“Your hip flexors are tight. Do Y to stretch them.”

Instead it’s,

“When you lean over, change it A way.”

“When you sit, change it B way.”

“When you lay down, change it C way.”

“When you do that, change it Z way.”

The approach is to get people to change how they sit, stand, walk, lay down. (Exercise is still a part of this.) These broadly hit every scenario a person can run into pain. However, they may have three different chairs they use in a day, which is now three different ways they may need to adjust how they sit. If they move throughout the night, they may need to change how they sleep on their back and side. They may need to change how they stand when they hold their kid differently than when typing at their standing desk.

Frankly, this is more work than “give me X exercise for strengthening and Y exercise for stretching.” But it’s why it works so much better. You take the exact movement(s) someone is having issues with and make it so there are no issues. You do this movement by movement. It’s work, but damn near fail-proof.

Reasons pain can happen both directions

The above doesn’t tell us why someone can have pain into flexion and extension. At first it may be counterintuitive, but there are countless scenarios. The most obvious one being you threw your back out so everything is painful. Sprain a knee or ankle badly enough and it doesn’t matter what direction you move, it hurts.

-> Movement classification doesn’t always work well in acute injuries, or big flare ups. Though a pattern typically emerges once the area calms down.

A less obvious way is someone who sits and sleeps for ~23 hours a day in flexion,

->  A fetal position is one example of flexing the spine while sleeping, as the spine is rounded over:

but they also deadlift three times a week with shoddy form, where they’re overextending. In one scenario we have long duration activity causing the problem; in another we have intense exercise causing it. Boom. Potential pain into flexion and extension. Movement is specific.

One thing we know about the spine is being analogous to a column, it handles compression very well.

In the middle above, that’s an after and before sleeping spine. Where we actually compress our spine inches everyday (middle right spine is shorter), by being upright. Subsequently, we tension -stretch- our spine every night as well.

The thing our spine doesn’t love is shear and torsion:

Let’s think about shear. While the above shows opposing lateral stresses, shear can happen forward and backward too.

Progressively zooming into our spine:

We’ll take it from the bottom, where we are only looking at a few vertebrae, and to start we’ll keep the spine as a rigid -it’s not bending- column, despite a real one having curves and likely bending.

What if going forward the spine flexed? That would cause some shear. The purple line is above the orange line because the spine has moved from its rigid state:


Where our rigid column might look like this now:




Below is a before and after, where the orange vertebrae, relative to neutral (our initial rigid spine), has been moved forward compared to the purple which has been moved backward:

In case that’s still tough to see, another before and after. Previously the green line hit both edges. Now it only hits one:

Now the person leans back:



The discs can shear the exact same way!

-> Emphasis on can. Not saying this always happens when somebody flexes and extends.

Relative to their rigid state, purple has moved back / orange has moved forward. After then before:

Flexion and extension are not always specific enough terms for the lower back. The same movement can be occurring at the disc level when flexing and extending. Where instead of flexion or extension intolerant, this person may be “shear intolerant at lumbar segment three and four.”

And why might that happen to someone’s spine? What if somebody happens to sit in a manner that produces excessive shear at that segment? Notice if we put this girl in a chair, how similar her spinal position is to how the male is sitting:

Where you can see his lumbar support, and any lumbar support if positioned a certain way, can produce excessive shear:

Sit in that one way for hours every day, and we have ourselves a mechanism for generating a hypermobile spine segment in a specific direction. We’ve adapted the ability to hinge at one specific location.

The work element of this is it’s a hell of a lot harder to get somebody to stop moving one specific segment of their spine / adjusting a lumbar support by centimeters than it is to tell somebody “stop flexing” or “stop extending,” “stretch this; strengthen that,” / “just add a lumbar support.” But it can be necessary.

-> Or, why adjustable lumbar supports trump one size fits all. Why a towel, which you can roll to your thickness preference, is better than any “oh, you fancy huh?” rigid model.

Movement can be that specific.

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Posted in: Lower Back Pain, Pain