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I prefer extension: Back pain self-help exercise based on “directional preference,” but only “centralizers” need apply (Member Post)

 •  • by Paul Ingraham
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Funny thing about back pain…

Some back pain patients, especially the ones that also have leg pain, will feel quite a bit better when they move or position themselves in specific ways. For example, you might notice that leaning backwards repeatedly eases your leg pain — either it stops shooting quite so far down the leg, or it even disappears for a while. In some cases, pain right in the back itself might back off.

A minor visual pun, graphics of a road sign that reads “good sign.”

“Centralization” is a good sign (yuk yuk).

This well-documented phenomenon is cryptically known as centralization — because the pain retreats from the periphery into the centre of the body. It’s an odd term. A better term would probably be “focalization” (hat tip to David Poulter), but “centralization” is extremely well established.

The centralization thing happily happens in roughly 40% of people with back pain — happy because it is strongly linked to better outcomes.1 You want to be a centralizer! If you experience centralization, that is an official Good Sign.

It’s also relatively low-hanging fruit, an easy clue that can guide your way out of pain, by telling you what kind of exercises might be most useful. While far from guaranteed, it’s an intriguing phenomenon and principle that applies to a lot of patients… and it’s even somewhat evidence-based! An embarrassment of riches.

Photo of a woman stretching in yoga cobra pose, at home or in yoga studio with big window and bright light, a lush house plant, and a tree outside.

Yoga’s “cobra” pose is an excellent example of a simple back extension exercise — which might be your (directional) preference. Extension is the direction most back pain patients prefer, if they have any preference.

This is a members-only post and is crafted a bit more for patients than pros — less dorky, more practical. There will be a sequel later this summer that dives deeper (and more critically) into The McKenzie Method® of Mechanical Diagnosis and Therapy® (MDT). Meanwhile, I wanted to share this more useful highlight — a “one weird trick” that the average person can extract from MDT relatively easily.


This-a-way feels better: the “directional preference”

Whatever repeated or sustained movement or posture triggers centralization is your directional preference. In other words, if your pain “centralizes” when you bend backwards repeatedly, then your “directional preference” is extension. You prefer moving in that direction.

Strangely cryptic terms for something that really boils down to feeling better when you move one way rather than another.

This simple concept has become a staple of physical therapy for back pain. It comes from the McKenzie Method of “Mechanical Diagnosis and Therapy” (MDT), created by New Zealand physical therapist Robin McKenzie (1931–2013) — one of the best known “systems” in the body-fixing business. It’s a sprawling empire, but this chapter zooms in on the one thing that MDT is almost defined by: extension exercises.

Or flexion for a few people.

And maybe side-bending for a handful.

Dr. Stephen May is a researcher strongly associated with MDT (he literally “wrote the book” on it, with McKenzie). In an interview for PT Pro Talk (episode 95), he said:

“I don’t think there’s anything like it in terms of its high prevalence rate, its potential to indicate a good prognosis, and its potential to indicate a management strategy. And if a clinician doesn’t take such a gift into account they would seem to be shooting themselves in the foot in a very daft way.”

My follow-up post later this summer will push-back against that cockiness a little. But, for now, I think there’s enough truth in Dr. May’s opinion that some DIY experimentation is fully justified: it’s evidence-based enough, easy enough, cheap enough, and safe enough that it should be in everyone’s bag of tricks.

Simple self-help for back pain based on centralization and directional preference

Self-help, really? Based on this rather technical-sounding phenomenon? Well, McKenzie himself published self-help books about it: Treat Your Own Back. So I think it’s fair game.

A 2004 trial asked “does it matter which exercise?” Meaning, does it matter if you exercise in the direction of your directional preference, versus the other way? 72% of the people the researchers worked with had a directional preference, and those folks did better harmonizing with their preference than clashing with it… regardless of what that preference was. That is, if they preferred extension — as most do — then extension exercises produced much better results than flexion. But it was vice versa if they preferred flexion.2

Simple illustration of a woman swinging her hips in a circle.

There are three directions to prefer: back (extension), forward (flexion), or the side as illustrated here. Sidebending is the rarest directional preference & this image emphasizes its simplicity. Just… bend to the side!

Nifty little study. Unfortunately, it is also an isolated bright spot in a generally disappointing literature on the McKenzie method. But it’s something.

Patients can and should exploit this concept by testing themselves for centralization and a directional preference, and then spending time in moving and resting in that preferred direction. Obviously not everyone will succeed at this, but quite a few will, and it’s quite safe to experiment with. In more detail…

There is no step three

Step One: Test for centralization by cautiously experimenting with a variety of spinal movements and positions, looking for clear signs of your symptoms contracting into the center of the problem — less pain sprawl, and relief that persists for at least a little while. There is no need to do anything intensely, or to repeat anything that obviously makes you feel worse.

In the best-case scenario, this is easy and obvious and you can confirm it in minutes. In the worst-case scenario, it might take several sessions of experimentation over a few days to pick up on the signal. If there’s no sign of centralization after a few days, it’s time to give up: you are not a centralizer! (Not yet, anyway. It can change! You can re-test every week or two.)

Only centralizers should proceed to step two.

Step Two: Once you have determined that you have a clear directional preference… use it! Spend time every day moving your spine that-a-way. Or resting with your spine curved in that direction. If it hurts or makes things worse, just stop — the whole idea here is that you’re emphasizing something that makes your back feel better. Not worse.

And that’s the basic self-serve version of exercise therapy for back pain based on centralization and a directional preference.

Of course you can also recruit professional help with this: a professional with MDT training and experience (and there are a lot of them around the world) obviously might be able to suggest many refinements, and that may be worth pursuing. But there’s also nothing wrong with experimenting yourself, and that’s going to be enough for many people.



  1. May S, Runge N, Aina A. Centralization and directional preference: An updated systematic review with synthesis of previous evidence. Musculoskelet Sci Pract. 2018 Dec;38:53–62. PubMed 30273918 ❐
  2. Long A, Donelson R, Fung T. Does it matter which exercise? A randomized control trial of exercise for low back pain. Spine (Phila Pa 1976). 2004 Dec;29(23):2593–602. PubMed 15564907 ❐

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