Navigating the Pain Trail – Concepts of Pain Physiology in Running Injuries
A runner glides along trail in the high-desert country, enjoying the sights and sounds, the fresh air, and the compacted singletrack beneath his feet, when he suddenly feels a “THWACK” of impact on his ankle. “Ouch!” It stings, but he doesn’t break stride. Thinking it nothing but a stick, he finishes the run… only to find himself bitten by a venomous snake. He makes it to the hospital in time to avoid mortal results.
A year later, the same runner glides along the same high-desert trail, when he suddenly feels a “THWACK” of impact. This time, he collapses immediately, intense pain up and down his leg. He looks back.
It was a stick.
Why the difference in pain response? Shouldn’t have the snake bite created more pain than the stick?
Pain is an integral part of life: it protects you and alerts you to dangerous forces, usually before tissue injury. And, as we’ve discussed before, it’s an integral part of running: it makes you behave (and move) differently, avoiding danger.
Runners have a love-hate, yin-yang relationship with pain. Few sports involve such liberal doses of self-inflicted pain. Perhaps that’s why we have such a high injury rate: when things hurt, does that mean “do more” or “do less?”
As a physical therapist (as well as coach and runner), pain is my job. Yet it is distinctly not. As I tell patients, “It is not my job to relieve pain, because pain is too complicated!” Phantom limb pain is an excellent example of pain complexity. Instead, my job is two-fold:
- Take abnormal things (mechanical, neuromuscular, and motor control) and help you make them normal, and
- Be your Pain Manager.
For the former, when you solve those things, pain usually – but not always – subsides. The latter job is equally important. Being Pain Manager helps people interpret the signals they’re receiving from their bodies and their brains, and effectively navigate toward normal function.
The researchers and clinicians at the Neuro Orthopaedic Institute (NOI) have helped us Pain Managers considerably with their work in the physiology – and psychology – of pain. Their book, Explain Pain, is the gold standard in my profession for helping to sort through the complexity of pain, and how we – as runners and people – can effectively navigate the pain experience.
This is the first of a periodic treatment by Stay the Course on pain education, as it relates to running injuries. I will start by introducing some fundamental concepts that we now know to be true about the pain physiology and the pain experience.
According to the NOI group, the most accurate definition of pain is:
“…a multiple system output constructed…whenever the brain concludes that the body tissues are in danger and action is required…” (Moseley)
That said, pain is anything the brain perceives as a threat. No one will argue that an all-out track mile or the last ten miles of a hundred miler aren’t acutely painful experiences. But we do them anyway because, despite the intensity, they aren’t a threat to our safety. However, the mere stab of arch pain for someone with chronic foot pain will stop them in their tracks. Threat value is everything.
Concept: Pain is Information.
With pain so eloquently and thoroughly defined, here is what it is not:
No Pain, No Gain
If it Hurts, Don’t Do It
We’ve all heard these statements; the former from fellow runners (or coaches, or race spectators), the latter from our health care providers. But the truth is, pain is information, nothing more. What, exactly, that information is telling is critical. Often times, the information is “Quit doing that!” But other times – such as during a hard track interval, stretching a stiff muscle, or a soft tissue massage – it is saying, “Oooh! That hurts! I need more!” or “Thank you sir, may I have another?” But sometimes, pain is a gross over-reaction to normal tissue loading.
Therefore, the job of any medical professional is to be a skilled pain manager to help us decipher and interpret what our bodies – and brains – are telling us, and then to develop a plan to work through the pain.
Applied: Patellar tendon pain. Many runners develop patellar tendon pain, often as a result of braking in their running stride (e.g., landing in front of their center of mass) or by a deficiency of knee flexion during their running stride. When the patellar tendon becomes irritated, knee flexion is most painful.
For those who follow the “If it Hurts, Don’t Do It” Rule, their response might be even less knee flexion – with running and walking. This would only make the tissue more irritated, and symptoms worse. In this case, the symptom – the information – is saying, “I’m tight and I need to loosen!”
The best prescription for patellar tendonitis (besides gait analysis to reduce any braking forces) is to increase knee flexion and perhaps (gasp!) speed up. This runs counter to the “Don’t Do It” mindset that drives most people’s pain response.
Concept: Pain is a Brain Output Based on Sensory Inputs.
In November, I attended a two-day workshop on pain physiology, put on by the NOI Group. The instructor, Adriaan Louw – a prominent researcher on the subject – related the concept of pain as thus:
Information from all parts of the body is relayed continuously to the brain – like different “departments” in a large company. The various parts of the brain act as a “Board of Directors.” There are representatives from the muscles and joints, the intellect, the emotions, the immune and endocrine systems, and more. These Board of Directors pour over that information, and they – as a collective – decide what to pay attention to.
Based on the quality of the information – and the specific experience, beliefs and values of the board – they decide how to respond. Inconsequential information – like the shirt on your back – which you felt when you put it on in the morning – no longer registers. But the dull ache of a long run, or the sharp stab of your foot arch on a stone – garners more attention. Information that the board determines is threatening must be acted upon. Based on the information – and qualities of the board – it takes action to protect you.
This action could take any forms:
- The muscle system might increase tension to protect (as we discussed in the Achilles column),
- The endocrine system can secrete adrenaline and cortisol (stress) hormone to protect against the threat,
- The central nervous system might secrete inflammatory chemicals to “heal the tissue,” and
- The intellect could send the message to “Stop Running!”
In most cases, this system is highly-effective in protecting us from threats to our system. However, the response to the threat is only as good as:
- The information coming in: which is relayed by sensory peripheral nerves, and modulated by interneurons (“bouncer” nerves) in the spinal cord – and these nerves are sensitive to many different factors and subject to manipulation.
- The Board of Directors: how effective it is at accurately interpreting the information and responding rationally, as well as the other demands that it is dealing with at that moment (work, family, life stresses, other illnesses, previous physical or psychological trauma).
Heavy stuff? Perhaps, but incredibly important stuff to consider when navigating pain. Because, what if the information absorbed from the peripheral nerve is over-blown or inaccurate? What if other factors beyond tissue irritation are impacting the Board of Directors and how it responds to those sensations?
Applied: The Stick vs. The Snake. The difference between the trail runner who finished the first run yet immediately collapsed in the second run was the brain. Sticks are not threats. Snakes are. Therefore, snake bites hurt, and sticks do not. The brain incorrectly interpreted the snake bite; thus, when a similar sensation came along, it over-reacted in order to protect.
Sharp joint pain, very often random impulses from nerves, or microscopic tissue releases, are often perceived as threats; chronic, dull joint ache – the cardinal sign of developing osteoarthritis – is often not. This is the challenge of overcoming pain, especially in a sport where pain is an accepted part of the experience.
Concept: Severity of pain correlates poorly to actual tissue damage. If you accept the concept that pain is an interpretation of information – from the peripheral nerves, by the Board of Directors – then you might accept that what we perceive as pain might not accurately depict actual tissue damage.
However, if that information is deemed to be threatening, it will hurt. Period. And the more important running is to our lives, the higher the perceived threat. The higher the threat, the more the Board of Directors will do to mobilize against that threat – more pain, more inflammation, more tensing and protecting.
There’s the rub.
In Part II, we will analyze this concept further, addressing both the physiology and the psychology behind pain versus tissue damage. Until then, a…
Call for Comments
However, rather than simply relating specific injury tales, I encourage commenters to examine their injury experiences under the microscope of these concepts:
- What are your experiences with “Sticks versus Snakes”? Severe pain that was actually nothing serious, or severe injury that – at the time – registered very little pain.
- How have you struggled with – or triumphed over – the erroneous Pain Rules: “No Pain, No Gain” versus “If it Hurts, Don’t Do it?”
- What have you noticed about how your “Board of Directors” behaves with pain information? What about Running Pain versus Non-Running Pain?
Bibliography: Explain Pain, Butler & Moseley. Orthopedic Physical Therapy Products; 1st Ed. ( 2003)