What is Pain?


As a physiotherapist, the majority of work we do is centred around reducing pain. Yes, we also look to improve movement, strength, balance, coordination and general function, but all this is usually linked to trying to reduce pain as a primary goal. As a therapist then, it helps a lot to understand what pain actually is. A short answer might be anything that causes you to say “ouch!”, or anything that simply causes suffering. Pain on the most basic level is just a warning system alerting us to danger, but looking deeper, it is a much more complex phenomena that I think warrants a better, more thorough explanation.

History Lesson. Stay with me.

Throughout history pain is something that has baffled many a deep-thinker. In the very old days (this article probably won’t win any historical accuracy prizes) pain was thought of as something external, that happened to us as a punishment from God. In the centuries after that a chap called René Descartes came up with a new theory; that pain was something you experienced internally. This theory evolved over time into the idea that we had an independent sense of pain. Pain was felt through ‘pain receptors’ which sent signals to the brain telling us when we’re injured. The intensity and type of pain was thought to be directly linked to size, location and severity of the injury. Seems like a perfectly logical explanation? Well, not quite.


Not everything is quite as it seems..

In more recent times scientists have recognised that the level of pain experienced is not always proportional the the injury sustained. To use an example, if you imagine a boxer being punched repeatedly in the face, the damage being done, and how they are able to continue to function and focus with seemingly little pain response. Compare that to stubbing your toe on your bedside table whilst walking to the loo in the night, the boxer is probably sustaining far more tissue damage but the pain response from your big toe could seem far more intense!

How we perceive the intensity and severity of pain is to do with how the brain interprets the signals it receives from the sensory nerves. How the brain interprets the signal depends on a whole host of factors such as our internal biochemistry, the external environment, our past experiences and expectations.

One of the most prominent researchers of pain science in modern times, the very eloquent and witty Lorimer Moseley, explains this far better describing his experience with pain whilst out walking in the outbacks of Australia. The TEDx presentation he did a few years back (link here) is his story, which brings you nice and unto date with how we currently understand things.



Persistent pain

Persistent (or chronic) pain is the most interesting (and perhaps the most debilitating) part of this topic that we deal with as therapists. Lorimer Moseley touched on it at the end of the youtube video, pointing out how pain can change over time. This is because the nerve pathways are ‘plastic’, meaning the more a pain signal gets passed through a nerve, the stronger and more efficient that signal can become. I like to think of it as upgrading a rickety old set of train tracks with an old steam engine into a high speed railway with a bullet train running down it. The end result can be stronger pain signals that get set off much more easily. On top of this, our ‘threshold’ for pain can also become lowered, meaning we experience pain in response to a stimulus that normally would cause no problems. As a result, things such as cold metal on the skin or even light touch could become excruciatingly painful.

“Pain is experienced in the person, not just the brain”

With all this work into pain science being focused on the brains involvement, its important to not get too carried away and think its ALL about the brain. Mick Thacker, another prominent figure in the world of pain science, tells us that pain is something the person experiences more generally, and its not just isolated to the brain and associated nerves. Changes and reactions can occur through a number of the bodies systems including the immune system which can all influence our pain response.



Sleep and Stress

Following on from the idea that pain is part of the person as a whole, lifestyle factors such as sleep and stress can influence our pain levels. Not getting enough of restorative (deep) sleep can influence the hormone balance in our bodies and effect recovery. If we are fatigued due to lack of sleep, our perception of pain may also be greater. This may become a vicious cycle where pain affects sleep, which makes you feel worse, which then affects sleep more, and so on. This dysfunctional pattern can be something that contributes to the persistent pain mentioned above.

Acute stress should be considered a normal part of life, and can be helpful in certain situations, but chronic stress (sustained stress over long periods of time) can have a more negative effect on our hormones and increase our sensitivity to pain. Stress (like sleep) can be a significant factor in persistent pain, so monitoring pain levels and seeing if that relates to a stressful period at work for example, can be useful.



Understanding the subtleties of pain can help us as physiotherapists get the most out of the people we see. Being aware of, for example, someones past experiences of injury, can help us provide a more individualised treatment program set at the right level. Knowing to keep an eye out for factors such as stress and poor sleep, and having the tools to deal with them, means we can deliver a much more thorough treatment for those people that need it.

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