Pain Explained


IMG_8560These past 2 weeks, I had to sit down with an old patient of mine and explained why he had bad back pain for the past couple of years. It took 2 sessions to go over this material and prepare him for the rehab process.

This guy is young, pretty fit and has played basketball and other sports. I had seen him for shoulder injuries and knee injuries before and all he needed was a bit of treatment, a bit of rehab, lots of reassurance and he was fine. In fact, you could say that he was a bit anxious and I have always dealt with that by minimizing the extent of the injury and the “don’t worry about it” approach. This has worked for him for over a decade that I have known him.

2 year years ago, he hurt his back. The knee and shoulder injuries didn’t really bother him but his back was a real shock to the system. He had a young family now, working hard, a mortgage…you get the picture. I saw him once at his home. He was so bad one day, he paid the home visit fee for me to see him. I didn’t think his back was that bad physically but he was obviously in pain. I did what I could for him and because my new workplace was further than before, he asked me to refer him somewhere more local to home…easily done. Fast forward 18 months. I hadn’t heard from him. He was doing well with my friend who I sent him to see but the pain was still a problem. He came to see me for a review because it has flared up.

The picture you see is what I drew for him to explain some aspects of his pain. I have been telling this story for a looooong time now. David Butler and Lorimer Moseley are Australian Physiotherapists, researchers and educators who specialise in chronic pain and wrote a great book called “Explain Pain”.

Anyway, let me tell you this story of how pain can work…it is not complete or technical but it will get main ideas across for you.

1. Pain is 100% from the brain. Pain is an output we get from the brain. There are receptors called nociceptors that tell the brain that something potentially noxious is triggering a response but the brain then does a whole bunch of unconscious things to decide if it is pain.
2. Some of these unconscious things are:
a: Context – what is going on right now in your life? Were you expecting something to hurt you? Are you in danger or safe? The list goes on. Basically what else is going on in your life that your brain has to consider.
b: Current situation – similar to context, what is going on RIGHT NOW?
c: Previous history – has something like this happened before? If you had a brother or sister scare you from behind a cupboard door, how do you think you would feel if you were opening that door again?
d: Hormones and your body’s automatic functions. Are you fatigued? Pregnant? Perimenopausal? Just come off a stressful job like a deployment to Iraq? Been working long hours under lots of stress? These things can affect you.
e: Beliefs – this is huge. So much of what we believe in everyday life is actually not quite accurate, at least in relation to our bodies. If you believed that bending over when you have a disc bulge in MRI will result in you being possibly paralyzed, do you think you will move differently compared to people who don’t care? Every day I get people telling me they should do this or that to help whatever problem they have and are surprised when I help them get better without touching them.
f: The Body – inputs from your body (from nearly every cubic cm of your body) is reporting to the brain all the time. The brain then accepts these and then decides on what to tell you about.

Your conscious self also delivers inputs to the brain.

Try this example:

Ask someone who is a friend but not your partner to do the following if you want (don’t do anything you don’t want to do!). Ask them to stroke the outside of your thigh gently near the knee. How did that make you feel? Now repeat roughly the same place (near the knee) but on the inside of the thigh. For most people it feels different. Why?

So the context and current situation is that you know and have given consent to someone touching your leg. You therefore should feel safe. Hopefully there is no previous history of weirdness between the two of you…if so, choose someone else! Your hormonal state should be the same 10secs apart. Your beliefs may have been modified by reading this. And hopefully they touch you in the same way for the outside thigh and the inside thigh.

Why does it feel weird? Quite simply, more things touch your outside thigh than the inside thigh. Your brain is used to getting input from there from chairs, tables, walls, bumping into people and things etc etc. The inside thigh though, only your loved one touches you there generally. Therefore the brain perceives touch there differently.

How does this relate to pain?

Well, contrary to popular beliefs, not all people who have pain have a physical injury after a certain period of time. That is why the scans come up empty but you are still in pain. Sure, you might have a disc bulge or a scarred muscle but after 6 weeks or so, they tend to heal up. What you are left with is a brain that now has a past history of injury and pain and maybe some sensations coming from that area (or other areas) that the brain is misinterpreting as pain.

You see, what the brain does is it takes the I out from the body, compare it to your past history, taking into account the context and current situation as well as your beliefs (I will have a bad back for life now because the Physio said it will never be the same :/), and how you are feeling and then give you an output. If your brain feels your body is threatened, you may feel pain.

Why is this important?

Sometimes, when I can’t find something physically stopping you from doing something, I have to help you get back to normal by using graded exposure (CBT techniques) and explaining pain to you.

Ever wondered why physios give you lots of exercise to do? Well I give them because I want you to experience lots of different types of movement and I want them to be essentially pain-free. Then we progress with lots of reps and your brain gets used to it and calms down a lot of the responses you get.

A lot of what I do each day is teach people to move differently. Sometimes it is because I think there is a good biomechanical reason but mostly it is because I just want your brain to experience pain free motion and develop hope. Having said that, good technique is really helpful in sharing the load/input around.

So pain is not a simple thing. There are lots that goes into it. Whilst pain is 100% from your brain, you aren’t “making it up”. Sometimes we just need to turn the volume of the warning systems down a bit 😁

What about my patient?

Well, this guy is going to do well. He understands where we are going. He has already benefited from seeing some of the work in action and will be slowly but surely breaking down the barriers he has been using to protect himself from the pain (fear avoidance behaviors). He will be squatting, lunging, hanging, pulling, pushing, twisting and bending with me. We will progress slowly so his brain doesn’t freak out and he will relax more in general. This should be fun 🙂


About Antony Lo
Antony Lo is an APA Musculoskeletal Physiotherapist based in Sydney. His website is He specializes in the management, treatment and prevention of pain and dysfunction, particularly of the pelvis and ribcage. His sub-specialties include Crossfit and Exercise Performance Optimization, Ante-Natal and Post-Natal Care and difficult cases that have failed treatment elsewhere.

9 Responses to Pain Explained

  1. jerryhenderson says:

    Antony… Really great post. Best explanation of pain for a layman I have read in a long time explaining the mysteries of pain. Bravo!


  2. Wildland firefighter to DPT student says:

    This is awesome, thank you for sharing!


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