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Postural laziness is what people picture when they think of poor posture. Thanks to the Puritans.
Most people are at least dimly aware that sexual uptightness is a Puritan thing, that the Puritans bequeathed England and her colonies with the notion that pleasure is evil … and what’s more pleasurable than sex? (Possibly massage, and I doubt they liked that either.) Few people know that the Puritans also gave us the idea that rigid posture implies moral righteousness and strength of character. Postural laziness is a great moral failing in the Puritanical world view, which still pollutes the cultural DNA of modern civilization to a shocking degree. People still exaggerate the value of “good posture” for this reason, mostly unconsciously.
This is a brief excerpt from Does Posture Correction Matter? Posture correction strategies and exercises … and some reasons not to care or bother, Footnote #9. Years after writing that passage, along comes this to illustrate it:
Pain is a lot like this — it is warped by our expectations and point of view. Unlike a clever model, though, we can’t turn it around to see what’s really going on. And trying to see through the illusion, trying to believe that there’s nothing much actually wrong with our tissues (often true), is even more difficult than seeing through these illusions.
Nevertheless, that is what therapy and rehab are all about: trying to change our expectations and point view with interesting new sensations and movements.
Aside from the analogy to pain, these are just fantastic illusions. Thanks to Nick Ing of Massage & Fitness Magazine for pointing out the video. For more about the slippery weirdness of pain perception, see 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.
I got some interesting gripes when I posted last week that “correlation kinda does imply causation.” One Facebook commenter said he’d only ever heard that correlation doesn’t “equal” causation; another skeptic thought it was “not a very helpful explanation”; and Dr. David Colquhoun tweeted at me: “Hmm dangerous”; and of course several smartypants were quick to remind me of the many amusing examples of spurious correlations that can (and have) been mined from data.
All of this points to an inescapable conclusion: I probably screwed something up. But not this bit…
The common wording was not what I screwed up. The standard phrase does indeed employ “imply.” Although “equal” does get used occasionally, “imply” is the more common usage for sure. Also, try the Google search autocomplete results for “correlation does not ____.”
I should have made this super clear on the first try, so allow me to overcompensate today:
The human knack for inferring causation is fantastically unreliable and our failures in this department are legion and disastrous. By far the most important thing anyone needs to understand about the relationship between correlation and causation is that **A** did not necessarily cause **B** just because **B** followed **A**, and making this mistake is one of the Greatest Hits of human thinking glitches.
This problem has been emphasized ad nauseum by so many smart people for so long that I personally just kind of take it for granted, and so I wrote my post last week without bothering to make it clear enough. As it probably should be every time correlation is discussed, because, as Barker Bausell put it (Snake Oil Science), we have a problem with “confusion between correlation and cause on an industrial scale.”
It was just some intellectual musing on my part. My griping about “imply” was not original. I was paraphrasing Edward Tufte, an American statistician who made the same point quite a while ago. So I’m in good company. Tufte suggested that a good informal re-wording would be, “Correlation is not causation but it sure is a hint.” I just wanted to make that same point, and I should have cited him, but I was in a hurry (penny wise and pound stupid, because now this is all taking me three times as long as if I’d just done it right in the first place).
I was mostly keen on the curious mental phenomenon of causality inference. It’s fascinating how aggressively the human mind infers causality from adjacent events… and how often we get it right about simple things. Exactly how much we get it right depends totally on the context and domain. We get causality right constantly when the variables are simple and readily observable; we get rarely get it right in health care, or any other complex endeavour, where the variables counts are high and many are subjective or otherwise murky.
I also wrote about this last week because I wanted to separate two things that are often mixed up: the inference of causality and the attribution of mechanism. General versus specific causes, basically. We can and routinely do correctly detect causes when correlation gives us a strong enough hint, but we routinely screw up exactly what caused what.
Most people will assume that when a very stubborn old pain goes away during a one-hour acupuncture session that the experience must have caused the relief, because the relief followed the experience. And that assumption is probably correct. The appearance of relief probably isn’t a coincidence, probably not just regression to the mean (too quick).
But then most people will then (carelessly or self-servingly) move on to another assumption: that the treatment caused the relief because acupuncture works as advertised. (It doesn’t.)
We can be right about the causality in a wide view — somehow or other, that appointment really did lead to feeling better, so yay — but still be hopeless wrong about what specifically caused what. Most people will ignore the possibility that the true mechanism of relief was not the efficacy of acupuncture, but the efficacy of a caring professional promising aid and performing fascinating rituals that reek of implied potency: the power of “surely no one would do this if it didn’t work!” These factors are wildly underestimated by most acupuncture patients. And acupuncturists.
Causality inference is a potent defining feature of human intelligence. It serves us well in many situations. Our ability to suss out how things work is largely based on this “one weird trick” that our brains can do. Flick the switch, light turns on: probably causally related! Touch fire, get burned… throw rock, break window… eat too much, get sick. There are countless simple correlations like this that we master effortlessly before we can even tie our shoes. We see A follow B and we just kinda get it that A caused B, just like humans somehow understand pointing, but most dogs will just lick your finger.
But we also constantly get it wrong, unfortunately.
There’s a famous rule: “correlation does not imply causation.” Unfortunately, it’s wrong, *as normally stated.
It’s missing an important word. It really should be: “correlation does not necessarily imply causation.” Because correlation actually does “imply” causation, and many (if not most) events that occur in sequence that appear to be causally related are in fact causally related. Human brains are dazzlingly good at correctly inferring causal relationships from observed correlations: clapping makes noise, braking stops cars, hot coals burn fingers. This mental super power served us well as we grew up as a species.
The problem is that we’re so good at it, and it’s such an essential mental skill, that we tend to overdo it and perceive causation in all kinds of situations where causality detection is much harder… like evaluating the results of medical treatments.
Complex causal relationships are as tricky to infer from simple observations as simple ones are easy. And we are just pathetically bad at figuring out exactly how events are causally connected — “mechanism of action.” Because of all the unknown variables. What’s really going on in a casual relationship almost always turns out to be different and waaaaay more complicated than we thought.
Nature: defying “common sense” since the dawn of intelligence.
But humans are causality bloodhounds: we smell it everwhere, even when we don’t understand what’s really going on (which we usually don’t). For instance, if someone who’s been limping and grimacing for days walks out of a massage appointment with a grin and a light step, then, yeah, massage probably did cause that result, one way or another.
When movement is limited by pain for too long, could the pain become a conditioned response to the movement? Rather than an accurate indication of the tissue state? Like Pavlov’s dogs salivating in response to a bell instead of food.
This article by Ben Cormack of Cor-Kinetic explores the potential to “recalibrate” painful movement by gradually breaking the association between the movement and pain with the “5 R’s of Rehab”:
I’m fascinated by this idea and think it has a lot of value, but I also wonder if the case for a primarily conditioned painful response is a bit overstated. Is that really a thing? I don’t doubt that it is POSSIBLE, but is it COMMON? I have clinically witnessed (and personally experienced) many chronically painful movements that probably were NOT just a conditioned response persisting long after the resolution of any problem in the tissue. I think a stubborn source of tissue-driven pain (nociceptive pain) is highly plausible in many cases.
Just thinking out loud here.
The bite of one tarantula species, Heteroscodra maculate, doesn’t just hurt: it hurts in a whole new-to-science way.
Sensory “transduction” is the conversion of a stimulus into a nerve impulse (action potential), which zips up to the brain, and then the brain decides what it means. And it usually means “OW!” in the case of this spider bite.
There’s some serious biological voodoo involved in transduction, but most noxious stimuli are converted to nerve impulses by members of the same family of ion channels in nerve cell membranes, the “Nav” channels (Nav1.7, Nav 1.8, Nav 1.9, etc). New members of this family of channels are still being discovered, and Heteroscodra maculate venom targets a Nav channel no one knew about until now. Ars Technica:
Two venom toxins from the tarantula species Heteroscodra maculate cause piercing pain sensations by targeting an ion channel in neurons not previously linked to pain, researchers report in Nature. In further experiments in mice, researchers found that these specific ion channels may underlie chronic abdominal pain in patients suffering from irritable bowel syndrome.
The finding—if validated in human studies—may help scientists unravel the complexity of pain perceptions and point to new ways to block the debilitating sensation. More specifically, the data suggests that finding a drug that could block this ion channel “represents a novel therapeutic strategy for diminishing the chronic pain in IBS and perhaps other pain conditions associated with mechanical sensitization, including migraine headache,” the authors conclude.
Oops! I thought the science of this big tendon and its movements was settled! Specifically, I had high confidence that it does not move back-and-forth across the side of the knee (causing IT Band syndrome). My confidence was based on compelling evidence that it can’t move like that — an anatomical impossibility, or near enough. And so debunking “friction” in runner’s knee became one of the mythbusting pillars of my extensive writing on that topic.
It all seemed so clear! I really never expected any controversy on this topic.
And yet there is. Science seems determined to be perpetually unfinished!
At the 23rd Cochrane Colloquium Vienna, Dr. John Ioannidis said this:
The main utility of systematic reviews has been to reveal how miserably unreliable biomedical evidence is.
It was the first point on this really great slide:
And here’s the text of that slide, more legibly rendered:
More recently, Dr. Ioannidis has commented thoroughly the hijacking of evidence-based medicine:
As EBM became more influential, it was also hijacked to serve agendas different from what it originally aimed for. Influential randomized trials are largely done by and for the benefit of the industry. Meta-analyses and guidelines have become a factory, mostly also serving vested interests. National and federal research funds are funneled almost exclusively to research with little relevance to health outcomes. We have supported the growth of principal investigators who excel primarily as managers absorbing more money. Diagnosis and prognosis research and efforts to individualize treatment have fueled recurrent spurious promises. Risk factor epidemiology has excelled in salami-sliced data-dredged articles with gift authorship and has become adept to dictating policy from spurious evidence. Under market pressure, clinical medicine has been transformed to finance-based medicine. In many places, medicine and health care are wasting societal resources and becoming a threat to human well-being. Science denialism and quacks are also flourishing and leading more people astray in their life choices, including health. EBM still remains an unmet goal, worthy to be attained.
Grim stuff. See ScienceBasedMedicine.org for some more good perspective from Dr. David Gorski:
This is why we at SBM frequently refer to the “blind spot” of EBM. From our perspective, EBM has indeed been “hijacked.” I, for example, agree with Ioannidis that industry has to some extent hijacked EBM, but we also add that advocates of quackery have also done so…
The opioid crisis has been in the news a lot this year. Today I’m just doing my bit to spread the word, making sure my readers know about this. My position is a reflection of what most official guidelines now say: although opioids have their uses, no one should take them for chronic musculoskeletal pain, because…
Plainly stated, the risks of opioids are addiction and death, and the benefits for chronic pain are often transient and generally unproven.
~CDC Director Tom Frieden, press briefing in March
This is brilliant:
Not every reader is going to fully appreciate the humour in the doctor’s thoughts. I’ll explain some examples that some might find cryptic:
What’s a “bottom up understanding of back pain,” and why’s that bad? It’s the idea that back pain comes primarily from backs (bottom up), when in fact we have really strong evidence that back pain severity and chronicity is powerfully by the brain (top down).
“Greater disability scores associated with MRI utilization.” One of the most common ways of measuring the badness of back pain is “disability” as determined by a very carefully designed questionnaire. And disability gets worse (higher scores) when MRI is involved in the assessment of back pain, probably because it “medicalizes” and dramatizes. This is a nocebo effect (opposite of placebo). Basically, looking for things wrong with people’s spines makes people fear their spines, which makes them more hesitant. MRI also almost always finds problems that look bad but aren’t actually significant, which of course is even more of a problem. MRI is nearly useless for most back pain.
“Reduced sense of well-being following exposure to MRI.” Very similar to the previous item! “Well-being” can be high even when you have a bunch of back pain … or it can be low. When back pain is over-medicalized — too much fancy diagnosis, scary treatment options bandied about — people feel worse about their situation. More worried! Understandably.