Pain and the Brain part 1
Pain is in the brain 100% of the time. Let me say that again with several dramatic pauses. Pain, is in the brain, 100% of the time. This statement isn’t meant to offend or call anyone “crazy.” Well, given the level of self-inflected torture that most of us put ourselves through we are likely a little off somewhere. But that is a different conversation for a different day. This statement comes from Lorimer Moseley one of the leading researchers in a field of study that is commonly referred to as neuroscience. Dr. Moseley and David Butler have spent the vast majority of their careers trying to understand the complexity of pain and how it has such a wide variance amongst people. Pain is a very normal experience that often occurs as a protective response to some type of stimulus to our bodies. Sprains, strains, broken bones and sore muscles can all signal a cascade of events in our bodies that create the pain experience that is ultimately registered in our brains. This highly complex, primitive process, is designed to alert us to what the brain perceives as a threat and to get us to take action to protect itself. The concept of pain and pain management is a widely studied area of medicine and can get very dense very quickly. I will do my best to keep the “nerdiness” to a minimum but provide you with a solid idea of how we generate pain, how that impacts performance and what you can do about.
The types and stages of pain
Cuts to the hand, muscle tears and low back injuries all share one thing in common, they hurt! Although they are all described by the term pain, the way in which the body has generated the pain signal is significantly different. To better understand pain and how this relates to us as athletes we need to define several key components. Pain is a very general term. Everything from a sprained ankle to a paper cut is often referred to as being “painful.” But the process to generate a pain response is unique based upon the type of stimulus and structures that are involved. Nociceptive pain, neuropathic pain and visceral pain are all terms used to describe the types of pain we experience. Acute and chronic reference the amount of time pain has been present.
Nociceptive Pain is generated by stimulating specialized nerve endings called nociceptors. There are two subgroups of nociceptive pain, somatic and visceral. Somatic pain is a type of nociceptive pain response that is common with injuries such as a sprained ankle or a muscle strain. Visceral pain is brought on by stimulation of nociceptors in organs and can be described by aching and squeezing.
Neuropathic Pain is often the result of nerve damage or irritation. Symptoms are often described as burning, tingling, electrical and stabbing. A true case of sciatica, irritation to the sciatic nerve, is an example neuropathic pain.
Acute, subacute and chronic pain is defined in terms of duration. While some authors will vary on their definitions, it is mostly accepted that acute pain is 0-3 months in duration and anything greater than 3 months is considered chronic. Subacute pain will sometimes be referenced as a subset of acute pain and is defined as anything greater then 6 weeks but less then 3 months.
The Pain Process
Our bodies are equipped with a vast neural network that serves very unique roles and functions. Chemical, thermal and mechanical stimuli can trigger the millions of tiny sensors that line a nerve. In order for a nerve to be stimulated a specific threshold needs to be exceeded. That means that the nerve needs to receive a sufficient amount of a particular stimulus in order to be trigger. To see this in action, picture a ten-pound kettle bell resting on your foot. Uncomfortable yes, but not enough mechanical stimuli to generate a pain response. Now, same kettlebell dropped onto your foot from only a few inches up. What happens? The weight of the kettle bell stimulates a ton of these mechanical sensors that activate the nerve that will produce a signal that travels to the spine and then up to the brain. Now here is where it gets really “groovy” as Dr. Mosely likes to put it.
The stimulus from your foot alone is not enough to generate a pain response. Once the signal has reached our brain, it will go through an incredibly detailed process to determine an appropriate response. Within milliseconds your brain will take in information about the situation from your eyes, nose and ears. It will recall past experiences that may be similar in nature. Even our current mood, state of stress and perception of the situation is factored into the equation. There is no “pain center” in the brain so this process requires rapid communication amongst various parts of the brain. Ultimately your brain will need to come to a decision about the situation and if the experience warrants a pain response or not. If the answer is yes, a painful response is produced and action is taken. In this case it will likely be a quick jerk of the foot followed by the not so graceful “walking it off” limp. If the brain doesn’t feel the situation requires any significant type of response then there is no pain and the kettle bell rolls to the floor.
Sounds simple enough right. I drop something on my foot, foot hurts, I move foot and curse wildly. Well not exactly. Did you catch the part about perception, mood and stress influencing the pain experience? The amount of pain you experience doesn’t always reflect the amount of tissue trauma. A key element to what we feel is dependent on how we perceive the situation. We have all heard of stories of military personal returning back to base after taking enemy fire only to then realize they had been wounded. But how is that possible? Didn’t those mechanical and chemical nociceptors produce a pain signal that went to the brain? They sure did and lots of it. But the brain, in its infinite wisdom, recognized that there were more pressing issues at hand (an understatement) and produced a response that diminished the pain response to allow the soldier to attend to what was necessary at that moment in time.
Another way to think about this concept is with the idea of hurt vs. harm. During any given day we will find a variety of things that we would say hurt. Work activities can hurt, stretching can hurt, even therapeutic exercises can hurt. That doesn’t mean any tissue trauma has occurred though. Harm is when we see trauma occurring to a region of our body and this is what we want to avoid. That is why it is vital as an athlete for us to have a good sense of what is going on with our bodies and seek quality information about any injury or physical issue. A well trained physical therapist, coach, chiropractor or athletic trainer can not only help you better understand what is going on but can also limit your Google searches which can lead to misinformation or inappropriate treatment.