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Why Does it Hurt? The Science Behind Pain

Woman on abdominal painThis is a question I am asked on a daily basis. While I try to simplify it as much as possible, the real answer is quite more complex. To really get an understanding of why it would be best to start with understanding how essentially our brain and nervous system works. The complexity of pain makes it a very difficult thing to treat and work with. On a positive note, it also means that some factors are more treatable or manageable than others, but only if you have a true understanding of how pain really works.

We have sensors called nociceptors that respond to a stimulus. These sensors then send warning signals from the body to the spinal cord via nerves. The signals from the nerves within tissues alert that there is a potential for tissue damage. The nociceptors then send that signal to the spinal cord for further processing. Your spinal cord is like a middle man who can decide to send the signal up to the brain or to leave that nociceptive alert at the spinal cord. This means that there could be potentially something “dangerous” going on, and you have no clue!

So now that you have a little more understanding of the system that takes place, now it is time to change our mindset when we first think of “pain” or when we even feel “pain.” We really need to stop thinking of pain in terms of causes or cures: “It’s all coming from the ____, I know it!” Sadly, and I am sure most of you have experienced it with me – It almost never is.

We have many non-specific sensitivities to pain. Pain is purely an alarm. It is a very unreliable sign of what’s really happening. Is it a fire? It is the carbon monoxide detector? Is it the neighbor’s alarm? We have no idea!

We have assumed for a very long time that the most common cause of musculoskeletal pain, such as a “structural” or biomechanical problems, like a slipped disc, or a short leg is the root cause and only explanation. These poor explanations for pain that have been told over and over again for the last 20-30 years are also evidence that there is a lot more to pain than just screwed up tissue. I find a lot of patients are often given the alarming idea that the slightest crookedness/ “out of place” joint is “serious”. I think as humans – we are designed to compensate. We are designed to figure out how to go about our days with no concept or feeling of pain so we can survive. Did you know the world record holder for the deadlift has idiopathic scoliosis! (Lamar Gant in 1974!) If humans weren’t designed to compensate and not be “perfectly” aligned, would a 123 lb human with scoliosis be able to deadlift 524.5 lbs?

Also, some statistics that make this “structuralism” as the answer to our pain more questionable:

  • 96% of athletes younger than 22 will show changes on an MRI that some people call “abnormal”. But since everyone has them how “abnormal” can they be? (Rajaswaran 2014)
  • 37% of 20-year-olds with NO PAIN have disc degeneration in their spine (Brinjikji 2015)
  • 57% of 20-50-year-olds with no hip pain will have cartilage and ligament tears (Tresch 2016)

The other common cause of the pain I seem to hear a lot is: “inflammation” or “tissue damage.” Damage can certainly be a contributing factor in pain but it is not the only factor. And you don’t need to have damage to have chronic pain. Your nervous system can become sensitized. This sensitivity can come from a number of areas in your life. Depression, anxiety, fear of movement, a low sense of self-control, the loss of meaningful activities are factors that might influence your sensitivity and chronic pain.

To understand injuries and pain problems and to recover from them more effectively, we need to stop thinking about the body as a machine that is inevitably going to break down and start thinking about the body as one big crazy system of neurology and biochemistry, and even crazier psychology and lifestyle factors. When you throw in curveballs like poor dietary habits, medication side effects, exhaustion, emotional distress, smoking/pollutants, and being really out-of-shape or having inefficient biomechanics: these are all the more important factors for pain than any “structural” issue. The body is strong and truly adaptable. You just need to give it the right stuff! Sleep, water, good nutritious food, movement, etc. All the things you really need.

The bottom line is, pain is much more about sensitivity rather than injury. Any information that convinces your brain that you might need protection or that increases your danger alarm can contribute to your pain. This is why we say pain is more about sensitivity than damage/injury. We need to teach ourselves how to be more resilient to the external factors that most of the time beyond our control.