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An Open and Closed Case

An explanation for a strange duality of muscle sensation observed in massage therapy

Paul Ingrahamupdated ARCHIVEDThis page has been archived. Archived pages are rarely or never updated. Most featured articles on are updated regularly over many years, but not archived pages.

Most of the muscles of the human body can be broadly classified into two straightforward categories:

These categories are not of much significance physiologically, and they are not taught in anatomy classes. Flexors and adductors have nothing functionally important in common, and there is usually no reason to consider them together. Likewise, extensors and abductors do not seem to share anything except their “opening” function, which is not particularly interesting in itself.

And yet they do share something of interest.

Pain intensity

Early in my career as a massage therapist, I was curious about what my clients’ massages felt like. Intensity is the most important thing to know about any painful sensation during a massage. If it hurts a lot, with only modest pressure, we make the assumption that the tissue must be in some kind of rough shape.

But this assumption is not necessarily safe. Assumptions rarely are.

It’s common for people with dysfunctional tissue to be numb to pain, probably as a kind of defense mechanism. Just because they’ve cut it off from their consciousness doesn’t mean it’s healthy.

So already the clinical value of the client’s subjective experience is getting confusing, and we’ve barely scratched the surface.

Sharp or dull? Pain quality

The challenge of interpreting sensations gets much hairier when you consider pain “quality.” Many people don’t know how to begin describing pain quality without a little practice. But ask a leading question like, “Is the pain sharp or dull?” and you’ll usually get a confident answer. And then some people go on to describe painful sensation using a variety of interesting adjectives.

There’s a lot of variety in those descriptions. It’s clear that not everyone experiences the same sensations during a massage. There are patterns, but any given person might use new and different words to describe their sensations in response to the same stimulation.

Why are there such differences? Are they important? Years later, I still don’t know for sure. But some interesting clues are slowly emerging. For one thing, the sharp/dull duality is undeniable. The pain of a muscle knot comes in these two basic flavours.

Dull pain is …

Sharp pain is …

What’s the difference between sharp and dull?

I learned from a mentor in school that a “hot” or “sharp” muscle knot tends to indicate an especially bad “trigger points,” a really stubborn old curmudgeon of a knot that will release slowly or maybe not at all. Although I took it as gospel at the time, I have slowly come to believe that it can’t be that simple. I have encountered plenty of hot/sharp trigger points that were easily treated.

Yet the sharp/dull duality is striking, and rarely ambiguous.1

Why? What do the sharp ones have in common? What do the dull ones share? There’s only one thing I’ve noticed:

Pain quality in the protective muscles

Noticing the sharp/dull duality for the first time was quite the eye-opener. It seems like a bit of a philosophical gold mine.

Body-closing muscles might be an ideal habitat for unpleasantly painful trigger points just by virtue of their job. “Closing” has a negative connotation: no one wants to think of himself or herself as “closed” emotionally, and we certainly don’t want to be closed physically. The foetal-position is powerful body language in an adult: we rarely go there, except perhaps partially, in bed.

It seems like an elegant truth that the muscles that do this job of folding us up like a baby might be “corrupt” or vulnerable in some way.

Pain quality in the opening muscles

“Opening,” of course, enjoys the opposite reputation. Everyone wants to be open, or at least seem that way. An open posture indicates everything from exhilaration — the Toyota “oh what a feeling” jumper, for instance, fully extended and abducted! — to sexual receptivity, confidence and relaxation, happiness and friendliness. We spend our whole lives unfolding from our original posture — or trying to, or wishing we could. Closing may not be “bad,” but it is something most of us are constantly trying to grow out of, to leave behind. And opening may not be “good,” but it does seem to be what we are working towards, and what we get the most pleasure from.

In a family photo shoot recently, we spontaneously tried posing with our arms in the air and our mouths really wide open. Although the situation was ordinary, and not unusually happy or exciting, the effect on the pictures was incredible. Anyone looking at them would think we were having the time of our lives: just because our arms were in the air and our mouths were wide open! That’s the power of the open posture.

But opening and closing are not actually virtuous and evil, of course. They are yin and yang, an integral human duality, forces in equilibrium and all that jazz. It wasn’t long before I thought this was all sounding a little too simplistic. It turns out there is probably a better explanation.

Fear of opening

Here is an alternative view: opening may be appealing, but it’s also scary.

There is a lifelong dynamic tension between the security and comfort of closing, and the vulnerability and stimulation of opening. Despite our moralizing idea that opening is “good,” it still gives us the existential heebie-jeebies. To be open is exposed, physically and emotionally. Opening is dangerous!

I lack the clinical experience to make this judgement about human nature with much confidence. It seems sound enough, but I can talk myself into anything with some pretty words. Is this really how people work?

Drs. Jock McKeen and Bennet Wong, with decades of experiences working with people in the context of personal growth and bodywork, more authoritatively affirm the idea: they “suspect those particular muscles are exquisitely painful because of the intense fear of opening up, which would be challenged with massage in that area.”2

But how does that work, exactly? If we are afraid to open, why isn’t the sharp/dull duality the other way around? Why wouldn’t it be a relief to massage (soothe/help) the closing muscles, for instance?

The concept of muscle armoring comes to the rescue.

Muscle armor

This fear of opening is eloquently expressed by your muscles. The shape and feel of our “muscle armor” tells the story.

Muscle armoring is the habitual muscular holding patterns that make us feel safer.3 We protect, define and even express ourselves by maintaining a characteristic pattern of muscular tension in our bodies. There is a fuzzy line between muscle armoring, posture and body language: each one influences the others.

Anyone who’s spent more than a few months working hands-on with bodies knows that muscle armoring is a force to be reckoned with. The patterns are usually strong and persistent. Personally, I believe that people rarely change their muscle armoring, and manual therapy is almost useless for that purpose. I believe that only serious injury, dramatic healing experiences and emotional revelations can quickly and permanently alter your body armor.

All muscles — both body closing muscles and body opening muscles — are crucial to body armoring in different ways. The extensors and abductors, which tend to be on the exposed surfaces of the body, are used to create a rigid outer surface, to literally thicken our skin. The trapezius, for instance, which covers most of the upper back, is often hardened like a shell. It is almost like we are trying to imitate a turtle!

Lacking an actual shell, hardening the exterior only provides so much protection, however. Closing the body is a more vital protective posture. Any heavily muscle-armored person tends to make use of the flexors in a big way, not just hardening but hiding the softer, more vulnerable “inner” surfaces of our anatomy: the throat, chest, abdomen, armpits, and groin. Even the backs of the knees and the insides of the elbows are known for their sharp-feeling muscle knots!

The body tends to resent all interference with this carefully cultivated system of self-defense. Although physical manipulation of the body-closing muscles has the potential to feel safe and freeing, the quality of sensation still tends to be more threatening than anything else. Stimulation is interpreted as potentially threatening.

Even the physical location of most of these muscles is awkward. Therapy for them requires a patient to allow a therapist deep into his or her personal space. This alone usually feels disconcerting, to say nothing of the quality of sensation in the tissues themselves.

Meanwhile, I imagine that the body feels relief at softening the “shell” part of our armor. That part of massage therapy is more analogous to taking a heavy load off your back!

The usual mysteriousness

We can make intelligent guesses about these kinds of things, but we can’t know. Perhaps several decades of the right kind of experience in working with bodies could further illuminate the matter — by observing thousands of responses to many different kinds of stimuli — or perhaps not.

It is enough for now just to know that the duality certainly exists. People really do experience pain in these two categories of muscle in remarkably clear and seemingly opposite ways. And the fear of opening does seem to be a likely basic force in human nature, and it goes a long way to explaining why massage in some places feels so much better than it does in others — why a back rub is so much more prized than a belly rub. Among humans anyway!

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter.


  1. Every now and then someone will tell me that a trigger point is somehow “both” sharp and dull at the same time, but this is rare. The great majority of the time, tissue sensitivity is decisively one or the other, without the slightest doubt on the part of the client.
  2. Email correspondence with Dr. Jock McKeen, July 6, 2005. Dr. McKeen wrote: “ … we are cautious about labelling one group good and the other bad.” I replied: “You are, and so am I, but Joe Client has no such caution … And why would that be? What can we make of that observation?” Dr. McKeen replied: “We [Dr. Wong and I] believe that people would rather moralize, and make something ‘bad’ or ‘wrong’ rather than face the existential issues. I suspect those particular muscles are exquisitely painful because of the intense fear of opening up, which would be challenged with massage in that area. [Our job is] to facilitate people moving past the limitations of their moralizing, to face their more ontic life issues. So, in body work, and in other approaches, we are always on the alert to see if we can faciliate a more neutral awareness of "what is" with curiosity, rather than condemning the experience. People don't like this .... they would rather have someone else ‘fix them.’”
  3. Muscle armoring is one of those concepts that probably describes a vivid natural phenomenon, yet will permanently evade any scientific understanding of how people work because you can only observe it by comparing measurable, objective signs (muscle tension) to subjective signs (psychology state). Physiology is a poorer science for it, unfortunately, because we have much to learn about human nature that depends on correlating subjective experience with all kinds of things.