Why Do Physical Treatments Reduce Pain?(Hint: Probably Not for the Reason You Think)

A person who walks into a physiotherapy clinic with pain will usually be given, as part of their treatment, exercises to strengthen and activate the area. Physical exercise is among the first recommendations for almost any musculoskeletal pain problem, and the literature backs this up. A huge review published only recently pooled over 2,500 controlled trials and more than 220,000 participants, and found that physical exercise reduces pain across a wide range of pain conditions [1].

But the interesting question is — why does this happen?

That same person in the clinic will usually hear from their physiotherapist that the goal of the exercises is to "strengthen the area," to "strengthen a weak muscle so it can take more load," and that this will make the pain go away. The logic is simple — there's weakness, you strengthen it, and the pain drops. In other words — it hurts because there's weakness. But it turns out this intuitive explanation isn't quite accurate. A new editorial published in the British Journal of Sports Medicine, one of the world's leading medical journals, calls on us to rethink it [2].

The Gap Between Outcome and Mechanism

There is indeed plenty of evidence that exercise reduces pain, even if modestly. On the other hand, there is far less evidence for how it does so (that is — what is the mechanism?). A recurring finding in pain research is that different types of physical activity have a similar effect on pain [1,3]. This strengthens the assumption that the change in pain is not necessarily related to the physical effect of the exercise (such as improved strength, endurance, or flexibility), because if that were the case we would consistently see certain types of activity being more effective than others. If pain is relieved to a similar degree after general strengthening exercises, walking, tai chi, or Pilates (activities with very different physical effects on the musculoskeletal system), that strengthens the assumption that the change is related to a more central mechanism, which all types of activity influence.

In their paper, Powell et al pooled examples from several studies on knee pain, Achilles tendon pain, and shoulder pain that examined the specific effect of getting stronger on pain [2], and found no relationship between the strengthening of muscles and tendons (as a result of the exercise) and the improvement in pain that was observed. In other words, some people got much stronger and their pain improved only slightly, while others got only a little stronger and their pain improved a lot — and through relatively simple statistical analysis the researchers identified that the strengthening itself did not affect the pain.

In short — strengthening exercises really do reduce pain. But this probably doesn't happen because we got stronger.

So If Not Strength, Then What?

The authors propose several possible mechanisms through which strengthening exercises reduce pain, chief among them a positive psychological effect (reducing fear and improving confidence and self-efficacy); and a reduction in markers of inflammation that exercise can contribute to. There is consistent evidence that improving these factors actually is associated with improvement in pain and function. The authors essentially bring us back to the biopsychosocial model, which approaches pain treatment holistically and does not view it as a purely biomechanical problem.

In fact, the understanding today is that beneath pain (acute or chronic) there always lie neurophysiological mechanisms — abnormal activity of the brain's pain network (or what is called the "danger mechanism"). These processes are influenced by the biomechanical state of the body (abnormal load, injury, inflammation …), by psychological factors (fear, avoidance, confidence …) and social ones (social support, belonging, relationships …). There is no such thing as "structural pain," exactly to the same degree that there is no "psychological pain." All pain is created by abnormal activity in the nervous system and the brain, and the important questions are which factors in the biopsychosocial triangle are more dominant in their influence on the pain, and which of them we can influence in treatment.

From here a fuller perspective opens up — even "purely" physical treatment (such as strengthening exercises) can have an enormous psychological effect, one that expresses itself as a change in the nervous system and a reduction in pain. Research consistently shows that physical activity of various kinds has a positive effect on (almost) everything: on pain, heart and vascular problems, cancer, and even PTSD. Specifically in pain conditions, physical activity regulates the central nervous system by reducing sensory sensitivity, releasing molecules such as endorphins and serotonin that inhibit the activity of the "pain network," and activating the immune system in a way that helps lower inflammation levels in the blood [4,5].

The Same Story Is True for Manual Therapy

There is a wide range of therapeutic techniques that fall under the term "manual therapy" (various massages, joint manipulations, treatments for fascial tissue, and more). The original aim of these techniques is to make some kind of change in the tissue on which they are performed — "correcting alignment," "releasing adhesions," "creating joint space," "putting the disc back in place," and so on — and to bring about an improvement in the patient's condition: in pain, range of motion, movement, and so forth.

Sounds nice, and indeed studies show that these treatments really do have a positive effect on pain, although usually in the short term and not as a standalone technique. The problem begins with the fact that studies fail to confirm the physical explanation for the question "why does manual therapy work." That is, there is no real "joint spacing," no "release of adhesions" (are there even adhesions?), no incorrect alignment that needs correcting (and even if there were, it is probably a normal finding that does not explain persistent pain, and the treatment does not correct it), and so on and so forth [6].

In addition, studies on manual therapy show that there is usually no difference in the effect on pain between different types of techniques — specific or general massages, manipulations ("cracks" in the back), "fascial release" — and no meaningful difference between them and "sham treatment" [7]. It appears that the mere fact of the therapist's hands touching the patient in a compassionate way is enough to bring about improvement.

And indeed, this may be exactly what happens: a new (and highly comprehensive) review recently published in the journal PLOS ONE summarizes a large body of research on the bodily mechanisms that manual therapy affects — that is, what actually happens in the patient's body in response to the treatment [8].

And the conclusions are nothing short of astonishing — the strongest evidence shows that manual therapy does not work through a physical change in the tissue on which it is performed (as the original assumption held). Instead, it appears to work mainly on the central nervous system — through changes in the cerebral cortex, regulation of stress levels, the release of neurotransmitters that promote calming, a rise in the neural threshold for pain, and more.

"What Does It Matter Why It Works, as Long as It Improves My Pain?"

The treatment helps, and that's what matters! On the bottom line, that's true. But there's another layer to consider here — the possible negative effect of physical explanations and treatments over the long term (or — the nocebo effect).

When I'm told that if I strengthen my muscles the pain will decrease, the belief that something in the body is weak, fragile, or unstable takes root. When the therapist "releases" my back, I receive a message (even if unconsciously) that this is a problem too big for me to handle, and that I'll need expert help to cope with it in the future. These messages and beliefs can nest within us unconsciously and keep activating the "danger mechanism," and with it the pain.

If it's a new, localized pain, this is probably fine and won't cause harm. But if it's persistent pain, related to increased sensitivity of the nervous system and of the brain's "danger mechanism" (nociplastic pain) — this can already be far more problematic. In such a case, even if the treatment provides short-term relief, it can contribute to the persistence of pain and disability over the long term. And indeed, many patients with chronic pain can spend (sometimes years) going to various treatments focused on "fixing the body" that provide only temporary relief. By contrast, understanding that these treatments don't fix a "broken body" but rather help me calm a sensitive nervous system ("turning down the volume") may reduce negative beliefs and increase confidence and self-efficacy.

Of course, there is no need or intention to throw all manual therapies or strengthening exercises in the trash. On the contrary! — physical activity is a critical factor for a healthy life and well-being, and touch is a basic, irreplaceable biological and human need. The problem is the hidden negative message that accompanies the treatment. But that message can absolutely be reduced:

For example —

• Instead of strengthening, stretching, or movement exercises specific to the painful area (which may reinforce a negative focus on the area and perpetuate a belief of bodily damage) — you can do general physical activity that involves that area indirectly. For example, with back pain — activities such as walking, swimming, yoga, and general gym workouts also engage the back excellently, have also been proven effective, and also carry less of a "fixing" message.
• Instead of going to manual therapy in a mindset of "fixing" the back (or the painful area) — go with the goal of reaching calm, feeling comforting touch, giving yourself a pleasant experience. As a patient once told me: "The massage is for the soul, not for the body."
• If movement or touch in the painful area is impossible because of increased pain — you can activate other areas that don't hurt first. The physiological effect of the activity can be achieved even without engaging the painful spot. The same principle applies to manual therapy — massage or treatment of body areas far from the pain can have a significant effect, because they too influence the nervous system and the brain.

It's important to note — physiotherapy (which combines physical exercises and manual therapy) is probably the best treatment available today for most acute musculoskeletal pain. So the first line in these cases is, of course, to go to a physiotherapist. If the pain persists for a long time and did not improve after "conventional" physiotherapy (and of course a medical workup was done that ruled out a serious medical problem) — you can move on to Neuroplastic Recovery Therapy, which includes diagnosing the source of the pain (by a qualified medical professional) and a treatment that focuses directly on the nervous system and on changing the patterns that maintain the "danger mechanism" and, through it, the pain.

In Summary

As therapists, it's time to change our explanation for why treatment works. To stop telling patients fairy tales about the weak muscle that, if only it gets stronger and "takes more load," the pain will drop — or about what our hands are doing (as if we were sculpting clay or building with Lego) — and to start talking about the nervous system (and the brain), which is the system that transmits pain and controls muscle tension, movement, and sensation. It's time to dismantle the outdated separation between "body" and "mind," because in pain they were never really separate.

To those suffering from pain, I want to make it clear — I'm not saying stop getting stronger. Quite the opposite — train, get strong, run, dance, and do any activity that feels good to you! But don't think the pain stems from a weak, fragile body (because it most likely doesn't). Strength is important for health, function, and longevity. It's just worth updating the story we tell ourselves about why exercise helps pain.

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Further watching & listening:

• The Pain PT — YouTube channel (Jim Prussack) — an American physiotherapist specializing in pain.
• On physiotherapy and chronic pain — an interview with physiotherapist Charlie Merrill.

Disclaimer: The information in this article is for educational enrichment; it is not personal medical advice and is not a substitute for it. If you are experiencing any health problem, please consult a qualified health professional to evaluate it.

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