Part 2 - Why Things Hurt

Pain is not just a reflection of what is happening in your body; it's a complicated and sophisticated protective resolve managed by your nervous system. To help understand why pain can persist after an injury has healed, we need to look at the 'messengers' involved, which this blog post will expand on in detail.

Pain isn't a simple reflection of what's happening in your tissues; it’s a sophisticated protective response managed by your nervous system. To understand why pain sometimes persists long after an injury has healed, we first need to look at the 'messengers' involved and a very special kind of guard dog that lives within your nerves."There are many different types of nerves in the body that detect different types of stimuli.

See the table below for a quick overview the different 'messengers' in your body

Type of Nerves	What They Detect
Nociceptors	Threat and danger
Mechanoreceptor	Mechanical forces (touch, stretch, pressure)
Thermoreceptors	Temperature changes
Chemoreceptors	Chemical changes (hormones, pH levels)
Photoreceptors	Light (in your eyes)

Notice that nerves don't create sensations, rather, they respond to the environment around them and relay these messages to your central nervous system, which is then responsible for your perception of various sensations such as feeling hot, cold, itchy, pain etc.

The most relevant nerve to those with chronic pain, are nociceptors. These are often sensitised and play a large role in ongoing pain.

Analogy of the Guard Dog

The Balanced Dog:

Imagine a guard dog that is calm and resting – like how your nociceptors should be.

If an intruder were to jump over the fence and make a lot of noise, the dog would wake up and start barking – this would then alert you to an actual threat, and if the intruder fled the scene, the dog would then stop barking, and the pain would stop. In this sense, pain is a completely normal mechanism that your body uses to warn you that something is wrong, and you need to do something about it.

The Sensitised Dog:

Now lets take the same guard dog, but this time, imagine that the dog is agitated, overstimulated and highly stressed. Not only will this dog bark at intruders, it'll start barking at butterflies, shadows or children playing across the road. In this scenario, the barking is no longer doing its job of altering you to danger as the bark doesn't represent a real threat.

This is the essence of chronic pain. Your nerves have become hypersensitised. Your body tells you something is wrong even when you are resting in bed and your medical tests have shown no physical damage.

Important note: imaging often shows normal age-related changes such as osteoarthritis and degeneration, which do not always explain your symptoms.

Why Does This Happen?

Nociceptors are distinct from other senses. While you might "tune out" sensations like the feeling of your socks or the hum of a refrigerator, nociceptors do not become accustomed to pain. With pain, the situation is different – the longer a pain signal is present, the more efficient the pain pathway becomes at transmitting that signal.

There are several factors act as "fuel" for sensitisation:

• Anxiety and fear

• Catastrophisation

• Avoidance of movement

• Stress

• Poor sleep

• Persistent tissue irritation

• Work stress and life pressure

Breaking The Cycle of Fear

As someone who has experienced chronic pain after a knee injury, I understand how the 'unknown' regarding your pain can be incredibly unnerving. Thoughts such as:

• "Is this going to last forever..."

• "I'll never be able to do ... again"

• "Why did this happen to me..."

  
  

These thoughts keep your "guard dog" in a state of high alert. It's the equivalent of holding your breath whilst waiting for medical results – your entire system stays braced for impact.

The good news? the same way the dog became sensitised, it can also be "retrained" to feel safe again, this is called neuroplasticity. By reading about pain science and understanding why your body is overreacting, you move from the passenger seat back into the drivers seat. Knowledge is the first step towards lowering the alarm.

How to Retrain Your Guard Dog

The next post will be coming soon...