Pain: Frozen Peas & Rubbing it Better

1 Dec 2017

What is pain?


Firstly, we need to establish what pain is…


Pain is an unpleasant sensory and emotional experience arising from actual or potential tissue damage

(Thomas, 1997; Aronson, 2002)


Read that again. 


The key here, is that pain is not an entity in itself; it's an experience.  It does not mean damage has necessarily been done, but is an indicator of potential damage.

How does it happen?


Here comes the science bit...


The science of pain is far from fully understood but the 'pain gate theory' goes someway to explain it.  The theory is based on the fact that some messages are sent quicker than others and can interrupt those others from reaching the brain and being recognised. 


We'll start with the science and then I'll apply it to an analogy that makes a bit more sense!


Types of Fibres:


-  'C' fibres are thin, slow firing fibres that transmit pain messages to the brain

-  'A-Beta' fibres are relatively thick (myelinated), fast firing fibres that are non-nociceptive (don't send pain messages) and transmit other messages such as changes in heat or pressure / touch to the brain


Pain Perception



For this next bit, take a look at the diagram above and keep referring back to it as you go...


The projection neuron is responsible for sending any message it receives, to the brain; projecting it to the brain for recognition. 

If 'C' fibres are fired, then the inhibitory interneuron cannot fire and therefore cannot stop the projection neuron from firing, thus sending the message of pain to the brain (Kandel et al., 2000).




But, when the 'A-Beta' fibres are fired (image below), the inhibitory interneuron is activated, making it less likely that the projection neuron will fire.  Even when the projection neuron does fire, the faster firing rate of the 'A-Beta' fibre means the message it sends to the brain is more likely to be the one they carry (temperature or pressure change for example) than the pain message carried by the slower 'C' fibres.  Only one message can get through at a time and therefore we feel the change in temperature or pressure and not the pain (Wall & Melzack, 1962; Melzack & Wall, 1965; Aronson, 2002).




An Analogy 


Picture it like British Bulldog.  Yeah, I know... bear with me here.

In the game of British Bulldog, the attacking team aims to run from one side of the playing area to the other, much like pain messages travelling from the site of pain to the brain.


The defending team starts in the middle of the pitch and aims to stop them from getting from side 'A' to side 'B'.  In our above explanation this would be equivalent to the inhibitory interneuron stopping the transmission of pain messages from the site of pain to the brain.


Still with me? 


Good, now let's pretend there is a third team who's only job is to tap the defending team members on the shoulder to allow them to defend, or in reality allow the inhibitory interneuron to stop the pain messages from reaching the brain.  However, they only play on cold days (when ice is applied).


The cold weather is the catalyst that allows the defending team to stop the attacking team reaching the other side.




The application of ice is the catalyst that allows the inhibitory interneuron to stop the pain messages reaching the brain.


Congratulations, you now understand pain and how to manage it!

How can we hijack the system?




When we apply ice to an injured area we are relying on stimulating local thermoreceptors ('A-Beta' fibres).  These fast firing fibres, activate the inhibitory interneuron, stopping the projection neuron from sending the message of pain to the brain, instead we receive a message that sounds something like "THIS IS COLD!"




Similarly, when we apply pressure, through massage or joint mobilisations for example, we are stimulating mechanoreceptors ('A-Beta' fibres). and this has the same effect.  Thats why rubbing your knee when you walk into a chair works! So keep doing it!

Pain & Injury


In my experience, pain is rarely the limiting factor in returning to activity; it's usually, strength or functional defects that limit my athletes towards the end of their rehabilitation.


That said, pain is often the first thing we notice when we get an injury, in fact it's usually the only thing that makes us realise we have an injury, and therefore, we consider it the most important symptom.  


How many times have you thought, 'Oh, my range of motion is reduced' after getting a bad bruise on your leg? 


It will have decreased, but you're seldom worried about this while your leg is hurting.  This, however, does not mean that pain is the only problem! 

Worryingly, I have heard stories of patients ending their rehabilitation process when their pain has reduced, only to return in a matter of weeks when the pain inevitably returns and more damage has been done.  


Obviously, there may have been many other factors that caused the cessation of treatment, and don't get me wrong, reduced pain is a good thing in injury rehabilitation! The problem is that people often do not allow for the treatment to correct the cause of the injury, they see the pain as the injury and the injury as the pain.


Our Sports Injury Rehabilitation sessions will often start by minimising pain, before moving onto the crux of the problem, usually whatever damage the pain was highlighting.


I find the key to protecting athletes from returning with similar or recurring injuries is by working on the factors that influence their function, be it in sport, or daily life. 

Self-Management Tips


For acute injuries, ice (frozen peas, or any other veg you fancy), works a treat, specific durations of application vary depending on the location of the injury so please get in touch if you want further information on specific injuries.

Don't forget our sports massage sessions stimulate pressure sensors to reduce pain, and you can book online right now!

That said, if you're in pain, it may be that you have done, or are on the verge of doing some damage (see pain definition).  Our Injury Rehabilitation sessions include a full assessment of the area as well as injury education, treatment and rehabilitation.

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Aronson, P.A., 2002. Pain theories - A review for application in athletic training and therapy. Athletic Therapy Today. 7(4), pp. 8-13.


Kandel, E.R., Schwartz, J.H. and Jessell, T.M., 2000. Principles of Neural Science. 4th ed. New York, NY: McGraw-Hill, pp. 482-486.


Melzack, R. and Wall, P.D., 1965. Pain mechanisms: A new theory. Science. 150, pp. 171-179.


Thomas, C., 1999. Therapeutic Modalities for Athletic Therapists. 18th ed. Philadelphia: F.A Davis.


Wall, P.D. and Melzack, R., 1962. On nature of cutaneous sensory mechanisms. Brain. 85, pp. 331. 


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1 Dec 2017

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