Time for another guest post from Paul Ingraham, his second. He contributed a post last November about stretching myths. Paul is a former massage therapist and current health science journalist and copyeditor for ScienceBasedMedicine.org, and creator of the excellent website PainScience.com. His website has an extensive collection of well researched ebooks and articles on a wide variety of topics related to common therapies for chronic pain and athletic performance, especially overuse injuries like injuries like IT band syndrome and plantar fasciitis. Paul recently contacted me to say he wants to do a post that "criticizes the idea of trigger points,” which is interesting, because he’s written a whole book about trigger points. I told him do whatever you want, just make sure the title of the post sounds like a Chuck Norris movie. Read the result below ...
The Bamboo Cage - Immobilization and Muscle Pain
Muscle often feels uncomfortable — stiff, sore, aching — but it is still unclear why that is, or even if it’s the muscle that is actually hurting. The problem may be in our minds, not our meat. This may be more literally true than it seems: not “all in your head,” but just a deeply neurological phenomenon. It may be that so-called “muscle pain” is a function of the central nervous system and the behavior of nerves, and not unhappy muscle tissue.
For instance, consider how intensely uncomfortable it is to be immobilized. Being stuck actually hurts — tissue responds to stagnation with discomfort and then pain, and it can become extremely unpleasant long before there is anything physiologically wrong with your tissue. Stay immobilized for too long, and stuckness can become torture — literally!
Actual torture by immobilization, as in a cramped bamboo cage, is the most macabre and extreme example of how much we hate to be stuck. (There is a memorable depiction of immobilization torture in The Bridge on the River Kwai, and unfortunately such methods are not just a Hollywood invention.1) As with relentless drops of water, immobilization can cause great pain and suffering without doing any apparent physical harm. Why? Such extremes of human experience are often instructive.
The same effect can be reproduced in a few minutes at home. Try this simple experiment:
Position yourself comfortably, but place one muscle group in a moderate stretch, something you can sustain without effort (for instance, your hand bent backwards, your fingers comfortably hooked onto something, stretching your forearm flexors). Don’t move. Wait. The stretch will become somewhat unpleasant for most people within a few minutes, and bloody awful within a half hour. Again, why? The muscle cannot possibly be damaged — not that quickly.
Now … imagine several hours like that.
Never bet against the importance of nerves and brains
More than a decade ago, Vancouver pain researcher Chan Gunn suggested an interesting mechanism for pain that might help us to understand why stagnancy is uncomfortable, and immobilization torturous. Here’s a translation of his idea from neuro-speak into English:2
Tissue health depends on a normal flow of nerve impulses. If nerves are impaired, tissue can become paradoxically super-sensitive. Once the sensitivity sets in, tissue may become over-sensitive to all kinds of stimulation, and not just injury. Ordinary stretch and pressure, for instance, could become painful.
Sound familiar? That is just how many people feel when they have “muscle pain”. Whether Gunn is right or wrong about the particulars is not important — it’s this kind of thinking that may be useful in understanding so-called “muscle pain”. If this is anything like how muscle pain actually works, you can see quite clearly that it’s not quite right to think of it as a “muscle problem”.
Gunn used his idea as a way to explain “trigger points,” the sensitive patches of muscle that people popularly call “muscle knots.” His explanation is outside the mainstream of trigger point science (if there is any such thing) and was summarily dismissed by Dr. David Simons, one of the pioneers of this field, who wrote: “Neuropathy can be, but is not always, a major activating factor.”3. Simons’ dismissal was basically, “it’s not the whole story, it’s too simple,” which is always easy to agree with. But I think his dismissal was entirely too quick, and ever since then pain science has relentlessly affirmed the importance of neurological dysfunction and central dis-regulation.4
Basically, when it comes to pain, never bet against the importance of nerves and brains.
What is immobilization pain trying to tell us?
Gunn’s idea depended on the phenomenon of “denervation supersensitivity,” in which muscles that have been cut off from their nerve supply become extremely sensitive to acetylcholine, the neurotransmitter that triggers muscle contraction. They become sensitive to it because there’s hardly any of the stuff coming from the nerve! Muscle cells literally build more receptors, coating their surfaces with them — a vivid example of how nerves can actually change the tissues they are attached to.5 With all those receptors, the muscles are “listening” very carefully for acetylcholine — they seem to be saying, “Hey! Where’s the acetylcholine?” And then they react strongly to any that they do get. (The same thing takes place in many different contexts: we get more sensitive to all kinds of signalling molecules when there’s a shortage, or insensitive when there’s a surplus.)
This phenomenon occurs in response to obvious nerve injury. It’s possible — unproven but plausible — that something analogous to denervation supersensitivity could also occur when there’s simply a lack of sensory variety and stimulation, which amounts to sensory boredom. Muscles might become very sensitive to nerve impulses as we stagnate, like an eager dog who lunges at the slightest movement that might herald a ball throw. That eagerness to contract, that “itch to move,” could become intense and start to burn like pain.
This makes good biological sense. Stillness is dangerous — a few days in a bamboo cage might well cripple or possibly kill, and there are many more commonplace examples of dangerous stagnation (ask any nurse). Undoubtedly it’s a good survival strategy to have nervous systems fine-tuned to avoid it. The sensory boredom of stillness is a meaningful warning, and doubtless it’s more meaningful still if there’s a constant drone of signals about stretch or pressure or anything whatsoever that is more likely to do damage if sustained, even if it is perfectly harmless in the short term.
As these signals pour in, we undoubtedly get squirmier and twitchier, literally over-eager to move, stretch, anything. The stagnancy alarm might lead to physical changes in the muscle and its subsequent behaviour — i.e. hypersensitivity to stimulation — or it might just be a matter of extreme psychological distress associated with the sensations of being stuck — pain! — or all of the above.
The urgency of that feeling — the loudness of the warning — will be dialled up or down by our brain, modified by our knowledge of the situation, how long we expect it to last, whether panic and thrashing about is a not such a bad idea … or if it would just ruin the meditation. Sometimes people actually practice being still, and are consciously, constructively resisting the urge to squirm — at least for a while. And sometimes they are actually being tortured. Or maybe they just have to work in a chair all day — which is a bit of both.
Breaking the cage
It’s not hard to understand how a good massage could scratch that itch to move, a stimulation-seeking impulse satisfied by hands and thumbs, introducing sensations that signal the end of stagnancy and soften the alarm.
It is often easier said than done to “use it or lose it.” Accidents of anatomy and modern lifestyle make it nearly impossible, even for a healthy person, to keep certain places in the body adequately stimulated — the low back, for instance. For chair-bound office workers, it is almost as though the low back is being tortured, locked in a tiny bamboo cage. Even when we get up to move, not every muscle entirely stretchable, and regardless it’s hard to compensate for so many hours in a chair (although it certainly makes sense to try).
Injury, disease and even emotional constipation can pile on and block our efforts to scratch our itches ourselves.6 The problem becomes much more obvious in the elderly, where these factors have accumulated. When I worked as a student massage therapist in extended care facilities, I had the strong impression that I was lending a helping hand, stimulating tissues on behalf of my elderly clients, helping them do what they desperately craved but literally could not do themselves — one fellow I remember well simply could not reach his swollen feet — or only with such difficulty and discomfort as to defeat the purpose. Our help was, of course, an intense relief for them, like breaking the bars of the bamboo cage that had been built around their bodies by age, arthritis, habit, tension, and every imaginable medical problem.
This is a surprisingly non-meaty vision of how muscles hurt and massage matters. It suggests that muscle pain might be a kind of illusion, that trigger points may be not be what they seem to be, and that pressing on muscle doesn’t “fix” muscle, per se. Instead, perhaps it “just” satisfies the organism’s intense craving for stimulation … a craving which may be far more urgent and important than we usually imagine it to be.
- My father is a Vietnam veteran, so I don’t use the example of bamboo cage torture lightly. Is it a real thing? When I first thought of it, I wasn’t sure where I’d even heard of the idea. My father is not only a veteran but a war historian, so I asked if he could check into this for me. It seems that “tiger cages" were used in WWII, and then again in Vietnam by the North Vietnamese. There are other similar methods. One torture that was used on captured pilots combined severe joint strain with immobilization — their hands were tied behind them, and they were lifted off the floor by a rope and left to hang there, which is a more extreme version of the more common stress positions method, which is much more widely used (at that last link, there’s a picture of a A Viet Cong prisoner being tortured this way by Americans). Of course, regardless of whether bamboo cages were used in this way, it’s obvious that severe confinment and immobilization would indeed be torture. Return to text.
- Gunn. Neuropathic Myofascial Pain Syndromes. Return to text.
- Mense et al. Muscle Pain. 2000. amazon.com, p. 61. Return to text.
- See Pain changes how pain works, which is a translation/summary of Woolf et al. Or see a guest post Todd did for SaveYourself.ca early this year, A tour of ideas from recent pain science. Return to text.
- Merlie et al. J Cell Biol. 1984. “In adult skeletal muscles, acetylcholine receptors are highly concentrated in the postsynaptic membrane, but virtually absent from the rest of the muscle's plasma membrane. After denervation, however, [they] appear over the entire muscle fiber surface.This phenomenon, called denervation supersensitivity, has been studied extensively, with the aim of learning how nerves cause long-term changes in their targets.” Return to text.
- Todd has been writing about the psychological dimension of this recently in his series on Barrett Dorko’s ideomotion therapy. “Dorko hypothesizes that the corrective movements produced by pain are often inhibited by other mental activity, the most likely culprit being mental activity devoted to social concerns. For example, the social need to use appropriate body language could inhibit corrective movements that would send the wrong signals.” It’s a strong theme in my writing as well; I do go on about the relevance of personal growth and emotional maturity to pain and recovery, what I call “healing by growing up.” Return to text.