Sensible advice for aches, pains & injuries
For blind and low-vision visitors, an audio version of this article is freely available on request to visually impaired visitors. Please email requests for audio to and I will send a download link within a day. There are audio versions of seven other popular articles on the site.  This image is linked to a page with more information, or see slash   audio.

The pain is real!

But are “trigger points”? The more I learn, the more I wonder.

Trigger Point Doubts

Is there really such a thing as a muscle “knot”?

updated (first published 2012)
by Paul Ingraham, Vancouver, Canadabio
I am a science writer, the Assistant Editor of, and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about

An audio version of this article is freely available to visually impaired visitors. Please email requests for audio to and I will send a download link within a day, but usually much faster. There are audio versions of seven other popular articles on the site.An audio version of this article is freely available to visually impaired visitors. Please email requests for audio to and I will send a download link within a day, but usually much faster. There are audio versions of seven other popular articles on the site. audio version available infoThis is one of seven articles available in audio format as a free bonus for e-boxed set customers. For more information, see Audio Articles.

I don’t want to believe. I want to know.

Carl Sagan

Why do I feel the need to challenge the clinical concept of trigger points? Because the science of trigger points is weak and has yet to produce a proven, reliable way to treat pain. Because many serious, earnest experts have declared their annoyance with dogma and wild speculation about trigger points. Because it’s all a bit half-baked … after decades in the oven.

And yet my ebook about trigger points and myofascial pain syndrome is my best-selling product. It is my meal ticket: it literally pays my rent, buys my food, and keeps the lights on. This website would not be 10% of the resource that it is without those sales. I wrote it because, during my 10-year stint as massage therapist — 2000–2010, R.I.P. — I got more therapeutic mileage out of the idea of trigger points than any other clinical concept. Or so it seemed. In my experience, I was able to help more people in that way than any other, by far — good bang for treatment buck.

And there’s the problem: I don’t trust “my experience” farther than I can throw it, and I take it as an article of faith that I misunderstood the meaning of many of my clinical experiences. I was never an over-confident therapist. I was prone to earnest self-deprecation and making a virtue of candid confessions of my limitations. And yet I wrote an entire book based more or less on my experience. Experiences like the one I’ll describe in the next section.

We know something is going on, and it is often labelled “trigger point” pain, wisely or unwisely. No one doubts that: not me, not the harshest skeptics, not anyone. What is in doubt is the explanation, the nature of the beast. Although this might seem to contradict the purpose of my book, it does not: armchair speculation about the biology of trigger points should not discourage anyone from rational exploration of their treatment options. The purpose of this article is to address the reasonable and fair questions of skeptics about the science of trigger points. In any case, I do not conclude or condemn anything at this time — I just question and consider. I hope readers will respect the fact that I’m willing to ask the tough questions, even if they aren’t superficially good for my bottom line.

The ultimate trigger point treatment anecdote

The three most dangerous words in medicine: in my experience.

Mark Crislip, MD

A few years ago, during a family visit, my wife’s uncle was suffering from a sickening ache on the front of his shoulder, like a toothache in his anterior deltoid. He was a weathered, cheerful former farmer who’d lived hard and wasn’t the sort to complain or ask for help, especially from his nephew-in-law the massage therapist — a profession that probably seemed a bit strange to him. However, he was pale with pain, and I’d never seen him so subdued, so he accepted my assistance without much fuss. A quick clinical quiz determined that the problem had been worsening steadily over a few weeks, and had driven him to the doctor where it had been chalked up to arthritis. And yet the pain was off the charts in a joint that is rarely afflicted by arthritis, and had been worsening much too quickly for that diagnosis. If this was arthritis, it was certainly an odd example of the breed! He’d also been told it might be bursitis, a common misdiagnosis that was an even worse fit.

I recognized the signs of what I knew as an active muscle knot or “trigger point.” I recognized the signs of what I knew as an active muscle knot or “trigger point.” (And, honestly, I would probably still call it that today — for lack of a better term. This naming problem will come up again.) I recognized the location as being strongly characteristic of a typical pattern of referred pain from the infraspinatus muscle, and one of the more dramatic examples of that odd phenomenon: poke the shoulder blade in back, but feel it in the deltoid muscle on the front of the shoulder. I prodded the infraspinatus just so, and sure enough he responded with surprise: “Yeah, hey, wow, that’s it! I can really feel that in the front of my shoulder.” I rubbed the spot with a practiced thumb for all of five minutes, and …

He was cured. Immediate, total, permanent pain relief. I fixed him in less time than it takes me to make coffee.

My uncle-in-law spent the rest of that weekend swinging his arm around, chuckling, and saying things like “Who knew?” and “Well, damn, ain’t that something!” He brought it up every time we visited after that. He mentioned it the last time I saw him, just recently, near death — it was his defining memory of me.

That is the most dramatic treatment anecdote of my career. It was not an unusual sort of clinical experience — I had many similar ones — but it was the high water mark, the best of the best, the most unqualified victory I ever had over pain. The “magic hands” myth was at full power, because the spot I chose to treat was so oddly remote from the pain, so counterintuitive. Nothing is better for a massage therapist’s reputation! It seemed like a miracle to him not only that I cured him, but that I did it by pushing a spot on “wrong” side of his shoulder.

Drawing of a thumb pressing down on a trigger point.
Drawing of a thumb pressing down on a trigger point.

The trouble with empiricism

Experiences like that were good enough for me when I was a massage therapist … but I’m not a massage therapist any more. My career has taken a strange turn from massage therapy to science journalism, and it has exposed me to countless worrisome examples of seriously flawed clinical reasoning … most of them shored up with anecdotes like that.

Experience is not enough. Things are not always what they seem, and the mind is afflicted with many common reasoning errors and illusions. Throughout history, people have believed goofy things based on “experience.”1 It has become my job to study and understand those mistakes. Many of my own beliefs, one by one, have fallen like timber, hacked down by new critical thinking skills. I no longer believe 90% of what I did in my first couple years of selling therapy.

Empiricism is supposed to urge that people be distrustful of authority and go out to look directly at the world. But of course this is a fantasy. It is a fantasy in the case of everyday knowledge, and it is an even greater fantasy in the case of science. Almost every move that a scientist makes depends on elaborate networks of cooperation and trust. If each individual insisted on testing everything himself, science would never advance beyond the most rudimentary ideas.

Peter Godfrey-Smith, Theory and Reality: An Introduction to the Philosophy of Science

The low-hanging empirical fruit is gone from medicine. The handily tested theories are all gone. All the challenges left in health care are the slow-motion and multifactorial, the microscopic, subtle and psychological — messy etiologies. No one will ever discover the one true cause of chronic pain the way Dr. John Snow proved with a simple test that cholera was coming from a polluted well: he removed the pump handle, and the cholera stopped. The handily tested theories are all gone. All the challenges left in health care are the slow-motion and multifactorial, the microscopic, subtle and psychological — messy etiologies.Simple, no? Goodness, no, not even that was straightforward: to prove that cholera wasn’t in the water, some smartass skeptic drank a glass of the stuff … and got away with it, because he just happened to be immune, a rather unlikely coincidence. So he was convinced of an utterly wrong answer by experience — and then he convinced a lot of other people at the time.

Today we face vastly more complicated medical puzzles, and yet deeply flawed and biased personal experience is still constantly used as the main justification for treatment methods. Beware!

Trigger point science is a bit half-baked

For years, the introduction to my book clearly stated that “trigger points are good, hard science.” Hmm. Not quite. There is quite a lot of science, and some of it is interesting and good science — generally better than fascia science, I believe2 — but as a whole it certainly doesn’t add up to much. There are too many serious problems. (I changed the phrasing of the introduction early in 2012.)

Here’s a good example of a particularly scathing expert opinion: Dr. Fred Wolfe, a rheumatologist, calls trigger point science a kind of pseudoscience, “cargo cult science” and “pseudo-pseudoevidence based medicine,” in which the so-called evidence “never reaches the level of evidence, and assertions, ‘facts,’ definitions, and beliefs are derived without testing or without adequate scientific basis.”3 That double-pseudo is quite the slap: he’s saying that trigger point science is even worse than (single pseudo!) pseudoevidence-based medicine, or medicine based on rather low quality evidence.4 This is from an articulate expert, one who worked with Travell & Simons directly, and yet he is quite exasperated with the so-called science of trigger points, and by no means is he the only one.


The more I read the more I doubted. The book [the Travell & Simons “Bible”] represented opinion, not science. None of the trigger points or their treatments were validated; none were tested for reliability. There were almost no studies … just testaments. Most of the perpetuating factors were plain wrong, and represented outdated, overthrown junk science.

Dr. Fred Wolfe, rheumatologist, describing his reaction to the “bible” of trigger points

The perpetuating factors were the first things that bugged me about those books, too. Dr. Patrick Wall, a British neuroscientist and “the world's leading expert on pain,” also saw trouble in trigger point land, and referred to it harshly when he wrote his foreword to what is something of a “sequel” to the Travell & Simons text:

Hopefully we are emerging from an era of fantasy explanations for real phenomena. The authors certainly have to face a community of therapists who are obsessionally committed to explanations for disease and for therapy unsupported by a scrap of evidence except for their claimed therapeutic success.

Professor Patrick D. Wall, FRS, DM, FRCP, in the Foreword to Muscle Pain: Understanding its nature, diagnosis and treatment

I feel the need to challenge trigger points as a concept because I don’t trust my own experience any more, and because the science of this kind of pain is more limited and less illuminating than I once thought. Although there’s definitely a phenomenon in need of explaining — there are sensitive spots, people do hurt, the pain is real — much less can be said with confidence about the nature of that phenomenon than I would like. So I am planning a series of updates to the book with the general goal of presenting the notion of a “trigger point” as a weak metaphor — much like the more obviously quaint “muscle knot” — more than an actual known thing that resides in meat. It will become a book more about muscle pain than trigger points. Fortunately for me, muscle pain — the sensations of stiffness, aching, or even agony in muscle — is a worthy topic, whatever the etiology, however it works. So I still have a book, and it is still worthwhile.5

I will also condemn cultish and dogmatic promotion of trigger point therapy as a panacea — which is much too common — and leave my readers with no doubt that many common practices under the banner of myofascial pain syndrome are nonsense or dangerously close to it. I am already critical of some of the worst offenders, but I will get harder still. I will get hate mail and hateful comments on Facebook … and much of it will cite “experiences” like my own. Won’t that be ironic?

A few things I only want to have to say once

Many of my customers, friends, colleagues, and mentors are watching this process with considerable interest. It’s not every day that someone seriously questions the validity of his own meal ticket! I have a few ground rules for this process, things I only want to have to say once:

Plus one more point that is a little too much for a bullet point …

A key premise for doubt: pain cannot be “in” meat

The main reason and underlying assumption for my trigger points doubts is mainly that they may not be what they seem to be. Clearly they seem to be “muscle pain,” but it’s not at all clear that there is anything wrong with the muscle itself. Muscle pain effectively communicates a subjective experience — one that I constantly endure — but that doesn’t mean the muscle is where the trouble is.

Pain is an experience generated by the brain, based on pre-conscious processing of many signals (not just dumbly reporting whatever nerve endings detect in the tissue).7 So what seems to be muscle pain could be more akin to phantom limb pain, a ghostly projection, and not an “issue in the tissue.” This possibility has the potential to explain quite a bit about the phenomenon of so-called trigger points. Even if there is a tissue issue, it might not be all that important — just the tip of an etiologic iceberg.

Even the clearest localization of pain in one area may, in fact, be originating from a distant area …. The reference of pain implies the existence of convergence of inputs within the spinal cord. This leads to the necessary involvement in central neural circuits in the simplest of peripheral disorders. It also leads to the possibility that the basic disorder is entirely central …

Professor Patrick D. Wall, FRS, DM, FRCP, in the Foreword to Muscle Pain: Understanding its nature, diagnosis and treatment

The texture of the problem

It is not clear that the phenomenon of trigger points — sensitive spots — are actually associated with any readily diagnosable physical, clinical sign like tissue hardness. But supposedly they are! Supposedly every trigger point is a painful, tight patch of muscle tissue — a palpable lump or muscle “knot.” This is taken for granted by most of the world’s massage therapists. But are muscles actually tight or hard where they hurt? Believe it or not, it’s not clear, and this is one of the main ways that the science of trigger points is pretty half-baked. It could have and should have been clearly answered a long time ago … but it really hasn’t been.

In a nice little 2010 experiment in the Journal of Pain,8 the hardness of the trapezius muscle was tested and compared with sensitive points, before and after intense exercise. The most sensitive spots were not just soft, but the softest spots — the opposite of what most people would expect, and the opposite of what we “know” from trigger point lore. In a dozen healthy patients, the two “typical locations for tender points” were not just soft, but the softest spots in the muscle — the opposite of what most people would expect, and the opposite of what we “know” from trigger point lore. In general, “a heterogeneous distribution of pressure pain sensitivity and muscle hardness was found.” Translation: the conventional wisdom that you’ll find the most pain at “tight” spots in muscles is probably a misleading oversimplification, at best.

Oh, dear. That’s not how a description of trigger points should sound! This is a bit of a problem. It’s not a large experiment, but it didn’t particularly need to be to make this point. Even a small test should have clearly showed that the sorest spots are the hardest — if they really are. The muscle was particularly well-chosen: the trapezius is possibly the most massaged of all muscles, and assumed to be one of the “knottiest” in the human body. If sore spots don’t correlate well with texture in the trapezius, they probably won’t anywhere else either.

Trigger point doubt #1: What if therapists can’t find them?

In the Andersen et al study just discussed, sensitivity was both measured with a therapist’s “magic hands,” and more objectively with a tool: a pressure algometer. Guess what? Thirty percent of the sensitive spots identified by hand were not identified by the more accurate algometer.

Magic hands? Magic algometer, more like.

Diagnostic accuracy is a problem for trigger points. If different professionals cannot reasonably consistently find the same trigger points in the same patients, then trigger point therapy has a practical problem at the least, or a rather dire existential problem at the worst. Either it means that trigger points are quite difficult to detect (that’s the practical problem) … or that they aren’t actually there in the first place (and that would be the existential problem).

This sort of thing is mainly determined using inter-rater reliability tests, which are quite persuasive: when two therapists tested separately point to different spots and say, “Well, there’s your problem,” people can easily see that someone must be wrong. It is difficult indeed to treat what you cannot find. (Although not as impossible as it might seem at first — stay tuned.)

Probably the first reliability study of trigger points was in 1992.9 Dr. Fred Wolfe’s description is more dramatic than an episode of Downton Abbey:

In 1992, we performed a study of trigger points. A group of four myofascial pain experts, selected by Simons and including Simons, blindly examined four patients with MFP. The examiners were allowed to take as much time as they needed; they could examine but not interview the patients. As we had mixed MFP patients with those who had fibromyalgia, it was a blinded experiment. These MFP experts were no ordinary examiners. They were the best. They wrote the book, they did the lectures. But, in the end, they could not find or agree on the trigger points. It was a disaster. The examiners were distraught. After the results were in, they protested and wanted to change the protocol and purposes of the study (post hoc). It wasn’t fair, they said. Glenn McCain, one of the rheumatologists, exploded in outrage. It was intolerable, he said, to alter study results. He was so angry that the opposition stopped. Subsequent delays and disagreements over the methods, results and discussion continued and almost prevented publication. But time took over; people forgot, and the study—a little toned down—came out in the Journal of Rheumatology. If we believed in trigger points and The Trigger Point Manual before, we were a lot less secure in our beliefs now.

For all that, the final wording of the paper does not seem quite like a “disaster,” and of course there is probably another side to the story. You can easily see signs of the tense negotiation over the wording in the abstract. On the one hand, there were “problems with reliability.” On the other hand, with a “more liberal definition of trigger point,” they were indeed found. “Our data are exploratory and tentative” and they “suggest that attention to definition and reliability are required to advance our knowledge.” Ya think?

The data were indeed not enough to settle the question, and 20 years later the reliability evidence remains about the same: inconclusive but discouraging. A 2009 study by Lucas et al surveyed the state of the art: what science has been done so far? It’s a confusing mess, unfortunately!10 Past research has not “reported the reliability of trigger point diagnosis according to the currently proposed criteria” (exactly echoing Myburgh et al from the year before11). The authors also explain that “there is no accepted reference standard for the diagnosis of trigger points, and data on the reliability of physical examination for trigger points are conflicting.” In other words, some studies were somewhat positive, and some were somewhat negative, and after all this time apparently no one quite agrees what we’re looking for (a problem in itself).

On the bright side, perhaps it means that this isn’t over, and there might still be hope for the reliability of trigger point diagnosis. On the other hand, it’s quite discouraging that the evidence is so conflicted and definitions and standards remain so unsettled after so long. If trigger point science was solid and diagnosis reasonably reliable, the data would not be conflicting. And the conclusion of the Lucas paper certainly seems disappointing and completely at odds with what professionals are out there doing every day:

Physical examination cannot currently be recommended as a reliable test for the diagnosis of trigger points.

So, should we give up? Is it futile to grope about for trigger points in muscle? Let’s ask a radar operator first. From radar science, we learn that reliability isn’t everything.

Bogey at 10 o’clock! Reliability isn’t everything

Diagnosis is detection

“Signal detection theory” started with radar in WW II, and is relevant to many modern diagnostic challenges.

Difficulty detecting something does not mean it isn’t there or that it isn’t worth trying. Lots of things worth looking for are hard to find, the process plagued with inaccuracy and false positives and negatives.

Like enemy fighters.

Signal detection theory” started with radar in WW II. There was a painful trade-off that afflicted the technology: you could dial up the sensitivity of the radar to be sure of detecting every invading plane, but then you’d end up scrambling your pilots to defend against invading geese as well. Or you could dial it down to prevent those false alarms … but then you’d (disastrously) miss genuine enemies.

It’s a hell of a dilemma, and as unavoidable as gravity: it crops up everywhere that anyone tries to separate “signal” from “noise,” with any attempt to detect anything indirectly. It is the same as the trade-off between diagnostic sensitivity and specificity in medicine. Both are highly desirable, but you tend to get more of one only at the expense of the other. Just replace “enemy fighters on radar” with “tumours in MRI scans,” and you see how similar these problems are. Radar operators were “diagnosing” invading planes. Radiologists are detecting invading pathologies.

If trigger points are a detectable phenomenon, how hard might it be to detect them? All indirect detection challenges are tricky by nature. Consider this fascinating recent example, where researchers discovered that fMRI studies of brain activity frequently “find” signals “when there wasn’t really anything happening.” Uh oh! Brain activity signatures are real, but detecting them is … well, “difficult” doesn’t really do it justice.


Genuine R-O curve napkin scribbles

To bone up on my signal detection theory, I asked my buddy Dr. Rob Tarzwell to give me a brain dump on the subject over beers, and he drew this here receiver operator curve diagram on a napkin. Rob is a former air force man and a rare double-speciality physician — psychiatry and nuclear medicine — so he’s absurdly qualified to scribble on this topic. The upshot? The graph demonstrates the natural trade offs between specificity and sensitivity, and that more expertise can only get you so far. In other words, some things are just bloody tricky to detect, and subtle nodules in muscle may well be among them. Also: I am blessed with frighteningly smart drinking buddies. See the Facebook discussion about this scribble.


Genuine R-O curve napkin scribbles

To bone up on my signal detection theory, I asked my buddy Dr. Rob Tarzwell to give me a brain dump on the subject over beers, and he drew this here receiver operator curve diagram on a napkin. Rob is a former air force man and a rare double-speciality physician — psychiatry and nuclear medicine — so he’s absurdly qualified to scribble on this topic. The upshot? The graph demonstrates the natural trade offs between specificity and sensitivity, and that more expertise can only get you so far. In other words, some things are just bloody tricky to detect, and subtle nodules in muscle may well be among them. Also: I am blessed with frighteningly smart drinking buddies. See the Facebook discussion about this scribble.

Palpatory pareidolia: dialing up sensitivity

The problem of detecting lumps in muscles is greatly complicated by pareidolia, a proven and common kind of illusion in which we perceive what we want or expect, rather than what is real. It literally happens to the best of us. Pareidolia occurs in any situation where humans are trying to interpret unclear signals, and it is always amplified by a clear bias. And financial interest. And it certainly applies to diagnosing anything by feel — “palpation.” It is certainly possible — maybe even likely — that I misinterpreted the biological meaning of what I felt. Day in. Day out. For years.For a much more detailed discussion of this, see Palpatory Pareidolia: Sensory illusions, wishful thinking, and palpation pretension in massage and other touchy health care. This section is just a quick summary of PP as it applies to the question of trigger point.

For many massage therapists, trigger points as a palpable entity are accepted dogmatically, and it is the basis for a lucrative career. If a diagnostician expects to feel trigger points, she probably will. If trigger points really are bumpy, palpatory pareidolia will cause a lot of overdiagnosis. It will be one of the main reasons that diagnosis is hard.

But what if trigger points are not actually palpable at all? Alas, palpatory pareidolia is all-too capable of disguising this fact. Therapists will probably feel them anyway, because they think they should. You may be skeptical, but it is actually almost routine for large numbers of perfectly intelligent human beings to suffer from pareidolia-powered misperception. Our brains really are that weird and fallible. (In fact, pareidolia is nothing.12) This has happened many times in history. If you accept pareidolia as a reality (and you really can’t avoid it), then you also have to assume that therapists will find what they are looking for, whether it is actually there or not. It means that diagnostic sensitivity will be off the charts at the expense of specificity, and so the rate of false positive trigger point “finds” will be off the charts.


Things are not always what they seem.


Things are not always what they seem.

I spent many years overconfidently “detecting” trigger points in tissue, and I am fully, humbly willing to admit that I was probably wrong about many of them, and it could be even worse than that. That does not mean I was wasting my time, or that my clients were not enjoying a perfectly meaningful and useful massage experience. But it is certainly possible — maybe even likely — that I misinterpreted the biological meaning of what I felt. Day in. Day out. For years.

The first principle is that you must not fool yourself & you are the easiest person to fool.

Richard Feynman

Difficult is not impossible

Some clinical phenomena are more difficult to assess and we expect diagnostic reliability to be poorer for them. Obviously one wants to be wary of using this as a lame excuse for poor reliability (special pleading), but neither do we want to ignore the obvious: some diagnosis is just difficult. If trigger points actually cause lumps in muscle tissue, it probably is tricky to find them reliably. Lumps under thick skin are not exactly a palpatory slam dunk!

In attempting to diagnose trigger points by feel, there are many potential false negatives and positives. It may be quite a needle-in-haystack challenge to find a trigger point in muscle, with far more ways to either miss one or be fooled into thinking you’ve found one. This is also true of many medical conditions, which is precisely why palpation is almost never the sole diagnostic method in a medical context.

false negative = It’s there! But it’s hard to feel. It might be too small (microscopic or close?) or too subtle (maybe only 10% firmer than surrounding muscle). Maybe it’s too buried, or adjacent to disorienting anatomy (sometimes hard to tell healthy bumps from the unhealthy ones).
false positive = Mostly caused by normal bumpy stuff in anatomy — decoys! Powered by palpatory pareidolia. Could be pure illusion. Misinterpretation of variations in muscle tone that have nothing to do with trigger points.

For contrast, poor diagnostic reliability for chiropractic subluxations would be considerably more damning, because there are a lot fewer possible subluxed joints in the spine than possible trigger points in muscle — fewer potential false negatives or positives! That means that chiropractors would look a bit ridiculous if they couldn’t agree on a diagnosis when choosing from only five lumbar joints. Pop quiz: can they? Answer:13

Context matters. Poor inter-rater reliability doesn’t mean much on its own, if you don’t know much about the phenomenon you’re trying to detect. But when the phenomenon you’re attempting to detect is debatable and hypothetical in the first place, lacks any corroborating objective evidence, and it all could be explained by pareidolia … then poor reliability becomes a serious basis for concern. Detecting cancers is tricky too, but it’s a lethal certainty that they are there to be found. One of the main reasons that I have “trigger point doubts” is that the detection challenge isn’t the only concern about trigger points.

Mitigating factors: the reliability problem is not in itself a deal-breaker

We do not yet actually have smoking gun evidence of poor reliability: just weak but discouragingly conflicting evidence that cannot actually answer the question. It does not tell us whether trigger points are genuinely lumpy but hard to detect … or non-lumpy in the first place.

The cost of a diagnostic miss may be relatively trivial. It’s ruinous to diagnose a cancer where there is none, but not so much with trigger points.

Diagnostic precision may not be critical to the value of the therapy. Does it actually matter if you know exactly where a trigger point is? Massage can easily cast a wide “net” of pressure, touching most or many trigger points without precision.

With well-established official guidelines and proper training, accurate diagnosis might be a snap, and there is already evidence that skill could make a difference.14 The therapists of the future may pass reliability tests with flying colours. But there are no such guidelines, and most professionals probably do not even know what the proposed guidelines are! And so for now trigger point “diagnosis” is obviously a bit dodgy in practice. Which may or may not matter much. As long as you don’t mind your therapist pretending to know the unknowable.

Diagnostic reliability is still a legitimately open question. It is likely to be poor even if there is a phenomenon to detect, due to poor training and experience, lack of standards, and an inherently difficult challenge. However, there are good reasons to fear that low diagnostic reliability is actually caused by the absence of a palpable phenomenon. We simply do not yet know which explanation is correct.

Trigger point doubt #2: What if trigger point therapy doesn’t work?

If trigger points are real, then trigger point therapy should probably work (and certainly trigger point therapists believe that it does). We don’t need to understand how a treatment works to test if it works. Science can always measure treatment outcomes even if can’t explain the weird biology that powers the results. Changes in pain and function are particularly straightforward things to measure. If trigger point therapy is more than a shot in the dark, then patients should feel better after trigger point therapy. Any massage should generally be effective — assuming any massage has at least some effect on trigger points — while massage that focusses on finding and treating trigger points should produce even more impressive results. Other treatments targetting trigger points — especially dry needling, injections, and stretching — should be supported by promising evidence at least.

Are they? The evidence is limited, weak, and equivocal. Underwhelming with streaks of encouraging, none of which means much of anything without replication. More study truly needed. Surprise surprise.

One of the signature symptoms of quackery is a failure to produce good evidence of efficacy, even after many years. Classic examples of this problem include homeopathy15 and straight chiropractic16 The wheels of science don’t always turn quickly, and it can be logistically and economically difficult to get proper studies done. But the modern era of Travellian trigger point therapy began at least 25 years ago, launched by credible physicians who strongly declared the need for research17 — so it should have gotten off on the right foot, research-wise. And indeed there is a lot of of research. Unfortunately, almost none of it has focussed on outcomes … which is the next problem.

There is a groan that unites men and women, rich and poor, in any nation. These [muscle] pains are “explained” in every culture, but the universal fact of this persistence must mean that no adequate therapy exists.

Professor Patrick D. Wall, FRS, DM, FRCP, in the Foreword to Muscle Pain: Understanding its nature, diagnosis and treatment

Another signature symptoms of quackery is to endlessly emphasize only basic biology and hypothetical treatment mechanisms, instead of treatment outcomes, touting reams of published research about how and why treatment supposedly works before we even know if it actually does.18 The ultimate current example is fascia,19 but trigger point science is sadly similar. There is a lot of trigger point research, but almost all of it is cryptozoological in character: exaggerating the importance of anecdotes, indistinct footprints, and blurry photographs, because more direct and relevant evidence of the monster is curiously unavailable.

So there’s suspiciously little of the right kind of evidence, and the clock of history is ticking pretty loudly. At what point does the absence of evidence become damning? At what point do weakly positive results constitute evidence of absence? And are we there yet?

My opinion is: the deadline is looming, but we are not there yet. Acupuncture crossed the line ten years ago, chiropractic subluxation crossed it twenty years ago, and homeopathy crossed it (at least!) thirty years ago. But trigger point science is still in limbo. Just because a bunch of blind men grab onto an elephant and make amusingly different inferences about the nature of the beast does not mean that there is no beast. Bigfoot hunters have really had their chance and failed.20 Trigger point research is only about a third as old, and it has always been a trickier problem. I wouldn’t have given up on bigfoot in the 1960s, and I’m not ready to give up trigger points yet either. I will do the only thing I can: uneasily wait for more and better evidence.

Trigger point doubt #3: Location, location, location

I have often been troubled by glaring inconsistencies and loose ends in the classic trigger point texts, the “big red books” (Travell, Simons),21 and the more recent and general blue book, Muscle Pain (Mense, Simons).22 The most irritating problem is the puzzle of trigger points that seem to exist entirely outside of muscle. How can you have little pathological contractions in non-contractile tissue?23 What are they? The red text describes them without even attempting an explanation, and the blue book acknowledges the problem … and then refers the reader back to the red!

How unsatisfying!

The dominant theory of trigger points is that muscle tissue contracts excessively, generates a lot of metabolic waste products, which poisons the tissue and perpetuates a vicious cycle. Trigger points are by (this) definition found not only in muscles alone, but in the hearts of their bellies, at their motor end plate zones, where nerves meet the muscles. Travell and Simons believed this to be the precise scene of the crime, on the basis of a few lines of evidence:

The critical trigger point abnormality now appears to be a neuromuscular dysfunction at the motor endplate of an extrafusal muscle fiber.24

Much depends on that sentence. Although they called it a “hypothesis,” they used it more like a fact: it is stated repeatedly with considerable confidence in both texts, old and new, and is then used freely as a major premise for other lines of reasoning. If the motor end plate is really where the dysfunctional action is, that would certainly be an anatomically definite guide to treatment: motor end plates mark the spot. And indeed both texts go to some trouble to explain exactly where motor endplates are in various types of muscles, both explaining and showing with a series of nice diagrams:

Understanding the location of motor end plates is important for the clinical diagnosis and management of myofascial trigger points. Since the pathophysiology of trigger points is intimately associated with the end plate, one expects to find trigger points only where there are motor end plates. End plates in nearly all skeletal muscles are located near the middle of each fiber, midway between its attachments. (p 234)

It’s cut and dried: the conscientious reader of the trigger point bibles, old and new, will take home the message that trigger points are in muscle middles. The theory actually requires it.

Theory, meet practice: trigger points without muscle

As every clinician knows, people seem to have trigger-point-like sensitivity and pain anywhere and everywhere … often far from any motor point. Our subjective experience of body pain includes many examples of focal sensitivity to pressure on tissues, particularly tendons and bony outcroppings. Furthermore, these often appear to respond to treatment just like trigger points: there is little functional difference. All without touching a muscle fibre, never mind a motor point.

And here’s where things get really interesting: Travell and Simons knew this too. For instance, just one paragraph in Muscle Pain is devoted to this problem, short but precise and clear:

Nonmyofascial trigger points. Trigger points that refer pain may also be observed in what appears to be normal skin, scar tissue, fascia and ligaments, and the periosteum. The reason for sensitization of nociceptors at these sites needs to be clarified but must be different from the trigger point mechanism that relates to dysfunctional motor end plates. These nonmyofascial trigger points are considered in detail elsewhere. (pp 231–32)

Must be different? That’s an understatement!25 The paragraph concludes with an endnote, presumably referring me to a source that considers nonmyofascial trigger points “in detail.” Great! I thought. Maybe something I’ve missed all these years! Maybe an answer to the puzzle! I flipped eagerly through the references, feeling that pleasant intellectual buzz one gets when flirting with a revelation. But my heart sank when I arrived at the endnote: a reference to Travell and Simons! Which doesn’t have any answers either.26

How big a problem is it?

I have two distinct kinds of clinical and personal experiences — which I trust equally well, or equally poorly, but equally — and they cannot both be explained by the same conventional wisdom. So something is almost certainly seriously wrong with this picture. But … how wrong?

There’s nothing about the clinical phenomenon of nonmyofascial trigger points that means that the conventional wisdom is actually incorrect. To use cryptids as an example again, there could be many distorted and dishonest reports of monsters and real monsters as well. So too there could be trouble at motor end plates and [insert some other kind of trouble] in non-muscular tissues. Indeed one of the main reasons almost everything about this topic is difficult is that there are probably many overlapping mechanisms for body pain.

Nevertheless, it’s a helluva loose end, and I’m hardly the first to notice it. (Even Travell and Simons and Mense noticed it — they just didn’t explain it.) It must be dealt with, sooner or later, one way or another. It is exactly the kind of thing (one of many) that led Dr. John Quintner to criticize the energy crisis hypothesis 20 years ago, and propose a completely different explanation for what trigger point pain really is — one that did not fall apart when it doesn’t seem to be coming from inside a muscle.27

Whether Quintner’s idea was correct or not is beside this point: what’s important is that he was arguing (20 years ago) that the focus on muscle theory “has directed attention away from other possible explanations,” and it simply can’t account for all the symptoms we observe in the wild. It couldn’t then and it still can’t now. That simple inconsistency packs more skeptical punch that anything I’ve discussed so far. It’s hard to have clinical confidence in hunting for trigger points at motor points when it’s so clear that something else is going on. If extremely trigger-point-like phenomena can occur right next door in ligament, tendon, periosteum, and skin, then it seems silly to place your bets on the motor points: they are not the thing, just a thing, maybe.

Nonmyofascial trigger points are a serious problem for the conventional wisdom. Although it might just mean that the energy crisis hypothesis is merely incomplete, and we need an entire another mechanism just to deal with those other trigger points, my personal hunch is that it’s worse: whatever is going on around motor end plates is just one facet of a deeper, more general problem which has still not been clearly identified. I doubt that trigger points will ever be correctly, meaningfully described as a disease of neuromuscular junctions. It’s either wrong, or too incomplete to be considered more than a slice of the truth.

Insert more here! There are many more specific concerns about trigger point science to report on. All of the above was just an introduction and doubt #1 about diagnostic reliability! There are also doubts numbers 4, 5, 6 and more to cover. I am publishing this article in chunks over a large span of time. It is now roughly 40–50% complete. No telling when it will be updated next — it is an important project, but one of many.

But there is one more section. Many people have written to ask me what I think is “really going on” if trigger points are not what they seem. Obviously, I cannot settle this. I cannot explain a mysterious, intricate human experience that has defied the best efforts of generations of experts to explain without a controversy. I wish! But I do have a working theory that almost everyone can probably agree to (not that consensus is a goal, but it would be a nice perk). I do have a way of explaining what happened with my wife’s uncle’s shoulder (the anecdote at the beginning of this article), which I hope is a little more satisfying than chalking it up to placebo, but it will also fall short of claiming to know what was actually wrong with him in the first place. It’s not “trigger point science” — it’s just speculation. So, for the record, here’s my best guess to wrap up the article for now…

So what is going on? My best guess

There are a lot of questions I have no answer for. Is there a pathological entity? Is there a source of nociception? Is there something wrong with tissue that is ever, in any sense, to any degree, “fixed” by a mechanical intervention, a real effect on tissue? Where there is sensory smoke there must be tissue fire? I still tend to suspect that there must be a pathological, peripheral process, because some experiences seem awfully hard to explain without it. But I have become super cautious about saying it or believing it, or concluding that it happens in muscle, considering that the search for that thing has been mostly a failure for decades now, and there isn’t even one theory that isn’t full of problems, festooned with pseudoscience, and failing to produce a reliable therapy. Maybe it’s just a damned difficult thing to identify (nature is full of things like that). Or maybe there is no “it,” and the pain really is all just a bunch of sensory smoke. Or maybe the truth is in the middle: there is an obscure physical process, but therapy has no “real effect” on it, just sensory tuning.

No matter what is or is not really going on in tissues, here is what I can say with a little more confidence:

“Trigger point therapy” consists of a combination of good story and vivid sensation. This is often helpful to patients regardless of what the story is, or the sensation, so long as they reinforce each other and there’s a net effect of reassurance.

Manual therapists (and acupuncturists) are storytellers and, particularly, sensation-makers. Both story and sensation are powerful ingredients. Both are present in nearly all therapeutic interactions. Therapy consists of telling a patient nearly any story about what is going on, and then providing any kind of strong or novel sensory experience to validate the story. “Wow, that’s such a strange, potent feeling that it must mean that the therapist has found something important and is fixing me! Yay!”The more consistent the sensation is with the story, the better (“Magic hands” impress people). It’s more than placebo28 and less than medicine.29 The narrative and sensory input give people’s brains what they need to “reconsider” the meaning of their symptoms.

How much the quantity and quality of each component matters is unclear and variable, but the combination is probably much more likely to work rather well at times than either one alone. And I’m guessing that sensation is probably the more active ingredient, the special sauce that makes manual therapy interesting and better than placebo. In a few modalities (those that produce less or gentler sensation), the story is probably the major active ingredient. But in many others (strong massage, needling), the sensations probably eclipse the narrative. Sensation alone can communicate a lot. It alone, or nearly alone, can tell the story. Even with no other cues, the patient may think: “Wow, that’s such a strange, potent feeling that it must mean that the therapist has found something important and is fixing me! Yay!” And lo, they actually feel the heck better. Because that’s how pain works. (Remember: pain is impressively modulated by Mr. Brain’s pre-conscious threat assessments.)

This model of therapy does not need to (and can’t) respond to or “fix” a specific pathological or dysfunctional entity in order to kinda, sorta work. There might be a source of nociception, or there might not. And it could work with virtually any relatively minor or non-ominous source of nociception — anything that can be safely poked, basically.30 The results of such a treatment are also going to be modest, variable and temporary, and yet occasionally rather impressive … which is just what we see in the wild, regardless of the specific story told, and regardless of the specific sensations induced. Most manual therapies produce roughly the same results, pretty much no matter what’s wrong.

By offering an explanation a little beefier than “just placebo” I am hoping to satisfy readers and myself, and I do think that induced sensory modulation is kind of a big deal and should not be underestimated. It may actually possess the “power” that mere placebo is often given too much credit for. Sensory modulation often is severely underestimated. It seems to me that a therapist who can artfully induce substantial sensory modulation, with artful sensory input, is probably doing something much more interesting than just talking a patient into feeling a bit better for a while.

If my best guess is right, then the stories and sensations that are the most pleasing and vivid and non-threatening should generally perform well... which is probably why massage generally seems to be one of the strongest contenders and actually has a bit of an edge in the research. It’s also why I don’t feel too badly that I’m still selling a book that tells a particular story and a safe, cheap method of producing sensations that reinforce the story.

About Paul Ingraham

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

I am a science writer, former massage therapist, and assistant editor of I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook and Google, but mostly Twitter.


  1. The colorful history of medicine and quackery is overflowing with people who “swore by” treatments that were bizarre and dangerous. Bloodletting was popular almost until the 20th century, despite being relentlessly harmful. Some of the most lethal “cures” in history were inspired by the discovery of radiation. People happily drank metals like mercury and silver. Even drinking urine had near fad status for a while! They tried to purge disease with sulfuric acid, and stimulate their vitality (and virility) with powerful electric shocks. Women were sold Lysol as a douche … and women actually went along with it for a while. Voluntary lobotomy may be the craziest of them all: it was a popular treatment for all kinds of psychiatric disorders, and at least fifty thousand people volunteered to have their brains lanced.

    All of these terrible treatments, and many more obscure examples, had many fans and enthusiastic testimonials. People paid for them, believed in them, loved them, swore by them — that is how misleading testimonials can be. People believe what they want to believe.

  2. PS Ingraham. Does Fascia Matter? A detailed critical analysis of the clinical relevance of fascia science and fascia properties. 14343 words. Many massage therapists are selling “fascial therapy” to patients. The main idea is that fascia — sheets of tough connective tissue found throughout the body — can get tight and restricting, and needs to be “released” by pulling on it. Fascia science is considered an exciting frontier in manual therapy. Unfortunately, although some fascia biology is interesting, the stuff does not seem to have any properties that are actually relevant to healing and therapy. Key examples of fascia research either fail to support fascial therapy or actually undermine it. Enthusiasm about fascia seems to be an unjustified fad. BACK TO TEXT
  3. [Internet]. Wolfe F. Travell, Simons and Cargo Cult Science; 2013 Feb 19 [cited 15 Mar 5]. BACK TO TEXT
  4. Co-opted or corrupted evidence-based medicine is a familiar problem, and I’ve written about it for years: see Why “Science”-Based Instead of “Evidence”-Based? For a definition of pseudoevidence-based-medicine, Wolfe quotes Smith: PEBM is medicine in which “falsehoods result from corrupted evidence” or “evidence that has been suppressed, contrived from purposely biased science, or that has been manipulated and/or falsified, then published.” BACK TO TEXT
  5. Unsurprisingly, when I first published this, I got some questions from customers wondering if my book is still worthwhile. For instance, one massage therapist reader asked, “Would you say that trigger point techniques are still useful even if we have to concede that the theory may be wrong and the underlying mechanism is unknown? Or are you challenging it to the core?” Yes, certainly the book is still worthwhile — I’m improving and correcting it, not burning it. This would be a rather different article if I actually thought that all of trigger point therapy needed to be chucked. My challenge to the idea of trigger points will be mainly an academic exercise, with mostly subtle clinical implications. I don’t want to diminish my point too much by saying that — details really do matter, the correctness of the underlying theory matters — but it is a matter of details. The main change in my book is the theory and the science, and not the practical recommendations. Agnosticism about technique has always been baked right into the book anyway. I’ve never seen much reason to believe any particular technique was superior in the first place, so I never really committed to any school of thought that I now regret or have to change. BACK TO TEXT
  6. I have always been careful about this. For instance, I think: • some fascia science is worth knowing • some biomechanical bogeymen are real • some things chiropractors do are fine with me • there are some good reasons to stretch. And so on. I try not to be absolutist — because few things are absolute, of course. There are a couple of exceptions. For instance, I have nothing good to say about acupuncture. BACK TO TEXT
  7. PS Ingraham. Pain is Weird: Pain science reveals a volatile, misleading sensation that is often more than just a symptom, and sometimes worse than whatever started it. 9367 words. BACK TO TEXT
  8. Andersen H, Ge HY, Arendt-Nielsen L, Danneskiold-Samsøe B, Graven-Nielsen T. Increased trapezius pain sensitivity is not associated with increased tissue hardness. J Pain. 2010 May;11(5):491–9. PubMed #20015697. BACK TO TEXT
  9. Wolfe F, Simons DG, Fricton J, et al. The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease. J Rheumatol. 1992 Jun;19(6):944–51. PubMed #1404132.

    Four experts on myofascial pain syndrome (MFP) performed trigger point examinations and 4 experts on fibromyalgia performed tender point examinations on 3 groups of subjects (7 patients with fibromyalgia, 8 with MFP, and 8 healthy persons) while blinded as to diagnosis. Local tenderness was common in both disease groups (65-82%), but was elicited in a greater proportion of MFP experts' examinations (82%). Active trigger points were found in about 18% of examinations of patients with fibromyalgia and MFP, but latent trigger points were rare in all groups. A more liberal definition of trigger point, however, resulted in a 38 and 23% positive rate among patients with fibromyalgia and MFP, respectively. Taut muscle bands and muscle twitches were common (50 and 30%, respectively) and noted equally in all 3 diagnostic groups. Problems with reliability were identified for taut bands, muscle twitch, and active trigger points. Our data are exploratory and tentative, but suggest that attention to definition and reliability are required to advance our knowledge of these common syndromes.

  10. Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N. Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature. Clinical Journal of Pain. 2009 Jan;25(1):80–9. PubMed #19158550. BACK TO TEXT
  11. Myburgh C, Larsen AH, Hartvigsen J. A systematic, critical review of manual palpation for identifying myofascial trigger points: evidence and clinical significance. Arch Phys Med Rehabil. 2008 Jun;89(6):1169–76. PubMed #18503816. BACK TO TEXT
  12. [Internet]. Chabris C, Simons D. The Invisible Gorilla; 1999 [cited 13 Apr 11].

    Description and video of a classic mind-blowing psychology experiment that demonstrated “inattentional blindness” — such as not noticing a gorilla walk through a group of people you’re watching.

    Chabris & Simons book is excellent read: see The Invisible Gorilla.

  13. French SD, Green S, Forbes A. Reliability of chiropractic methods commonly used to detect manipulable lesions in patients with chronic low-back pain. J Manipulative Physiol Ther. 2000 May;23(4):231–8. PubMed #10820295.

    I do enjoy reliability studies, and this is one of my favourites. Three chiropractors were given twenty patients with chronic low back pain to assess, using a complete range of common chiropractic diagnostic techniques, the works. Incredibly, assessing only a handful of lumbar joints, the chiropractors agreed which joints needed adjustment only about a quarter of the time (just barely better than guessing). That’s an oversimplification, but true in spirit: they couldn’t agree on much, and researchers concluded that all of these chiropractic diagnostic procedures “should not be seen … to provide reliable information concerning where to direct a manipulative procedure.”

  14. Gerwin RD, Shannon S, Hong CZ, Hubbard D, Gevirtz R. Interrater reliability in myofascial trigger point examination. Pain. 1997 Jan;69(1-2):65–73. PubMed #9060014.

    This paper describes a failed initial attempt to confirm that the diagnosis of trigger points is reliable, and then goes on to report on greater success with practitioners who were more thoroughly trained. Unsurprisingly, the authors conclude that some diagnostic signs are more difficult to reliably detect than others, and some trigger points are harder to diagnose in some muscles than others.

  15. A couple centuries and counting with nothing but evidence of no effect. I reviewed homeopathy pretty thoroughly for my homeopathic arnica article. BACK TO TEXT
  16. “Straight” meaning the original, subluxation-based spinal manipulation as a replacement for internal medicine — a little over a century and counting with no evidence for that. Because it’s pre-scientific nonsense. See Organ Health Does Not Depend on Spinal Nerves!. BACK TO TEXT
  17. Travell and Simons may not have been perfect. Travell in particular may have succumbed to guru-ism, with all of its mental blinkers. But both Travell and Simons were extensively on the record encouraging research, and not just in general up-with-science way: they made many specific suggestions, in ink, about which hypotheses and assumptions needed to be checked and why. Whether they would have actually been able to accept evidence that challenged their hopes and beliefs is unknowable, but that is no way to judge the matter. Many scientists have ended their careers unable to accept new evidence. BACK TO TEXT
  18. This is the cart-before-horse problem in alternative medicine. “We need some science to prove how treatment modality X works!” No! No no no! That is bass-ackwards. It’s a terrible inspiration for doing science, guaranteed to dial confirmation bias up to 11. BACK TO TEXT
  19. A faddishly vibrant area of research which doesn’t even achieve clinical relevance, let alone demonstrate that any patients are actually helped by any therapeutic method informed by fascia science. See Does Fascia Matter? BACK TO TEXT
  20. Loxton D, Prothero DR. Abominable science! Origins of the Yeti, Nessie, and other famous cryptids. Columbia University Press; 2012. I challenge any sane person to read up on the history of Bigfoot without coming to the conclusion that the whole business is utter nonsense. BACK TO TEXT
  21. Travell J, Simons D, Simons L. Myofascial Pain and Dysfunction: The Trigger Point Manual. 2nd ed. Lippincott, Williams & Wilkins; 1999. BACK TO TEXT
  22. Mense S, Simons DG, Russell IJ. Muscle pain: understanding its nature, diagnosis and treatment. 1st hardcover ed. Lippincott Williams & Wilkins; 2000. BACK TO TEXT
  23. To answer a likely question: no, the contractility of fascia does not solve the puzzle. Yes, connective tissue is marginally contractile (Schleip 2006, but the phenomenon is wholly inadequate — too slight, too gradual — to plausibly power trigger points of the same character as that which allegedly exist in muscle bellies. BACK TO TEXT
  24. Muscle Pain, p240.
    Our current understanding of trigger points results from the convergence of two independent lines of investigation, one electrodiagnostic and the other histopathologic. Sitting together the lessons from each leads to an integrated hypothesis can explain the nature of trigger points. It is now becoming clear that the region we are accustomed to calling a trigger point or tender nodule is a cluster of numerous microscopic loci of intense abnormality that are scattered throughout the trigger point or nodule. This would make myofascial pain caused by trigger points a true neuromuscular disease.
  25. The reason many fish walk or fly must be clarified, but must be different from swimming…. BACK TO TEXT
  26. The big red books acknowledge and describe nonmyofascial trigger points in some detail, but this only deepens the chasm. No effort was made to actually account for them, or integrate them into their integrated hypothesis of trigger points. BACK TO TEXT
  27. Quintner JL, Cohen ML. Referred pain of peripheral nerve origin: an alternative to the "myofascial pain" construct. Clin J Pain. 1994 Sep;10(3):243–51. PubMed #7833584. PainSci #54775.
    The construct of MPS, as proposed to explain chronic, deep, aching, poorly localized pain, not only lacks internal and external validity but also is epistemologically unsound. The emphasis on the primacy of the TrP phenomenon has directed attention away from other possible explanations. By contrast, there are anatomical and physiological grounds to suggest that the phenomenon of the TrP … is better understood as a region of secondary hyperalgesia of peripheral nerve origin.
  28. Placebo is an effect of belief. Artfully imposed sensation is an actual input that can meaningfully change experience. BACK TO TEXT
  29. An input that has a measurable biological effect. BACK TO TEXT
  30. As a thought experiment, imagine how treatment would go if the source of nociception was a serious lesion or infection. In such cases, the nociception is just too great and relentless, and of course manipulation could actually make it worse. Under such circumstances, the brain will — clever thing — continue to correctly believe that the situation is threatening, and therefore painful. BACK TO TEXT