Navigating the Pain Trail – Tissue Sensitivity, Defusing the Threat

Stay the CourseBack again for more pain! Here’s a quick primer on what we discussed in our first article on running pain:

  • Pain is information. Specifically, it is any information the brain (or “Board of Directors”) deems threatening. It should be neither feared nor ignored.
  • Pain is a brain output based on sensory inputs, not only from peripheral nerves, but all of our senses.
  • Pain correlates poorly to actual tissue damage.

In this article, we’ll expand on those concepts to address chronic pain and how it develops and persists, in spite of our best efforts.

The Board of Directors, Revisited

Last article we discussed the concept of “The Board of Directors” or the accumulation of various parts of the brain that accumulates and interprets all sensory information. It uses previous experience and personal values to make decisions: “Sticks don’t hurt. Snake bites do.” Or, “Quad soreness doesn’t hurt, but low back pain does.”

Based on that threat assessment, the Board makes decisions and takes action, both conscious and unconscious, to protect us.

But what happens when that information is no longer credible? Or if the Board becomes overly cautious?

Pain Management and Central Sensitization

Physiologists and researchers in pain describe chronic pain as the result of central sensitization: the notion that the central nervous system becomes overly sensitive to information.

When tissue damage occurs, various sensations are registered: tissue strains cause leakage of intracellular chemicals onto nerves. This signals chemical, pressure, and temperature receptors to send information to the brain. This registers (usually) as pain.

Pain management concepts – e.g., a “RICE” approach of Rest, Ice, Compression, Elevation – when appropriately applied, invariably results in healing. Different tissues have varying but well-established healing times:

  • Soft-tissue inflammation (muscle, skin, minor tendon strains): 10-21 days
  • Bone fracture and moderate tendon strains: 4-6 weeks
  • Cartilage, major tendon or muscle strains (ruptures) and surgical repairs: 2-6 months

So how is it, then, that many injuries – despite several months if not years of healing time and copious rest – still cause severe pain?

When tissue healing is poorly managed, or when threat value is high, the brain continues to produce pain. Inputs and interpretations cause the Board to decide, “Hey! We need to pay attention to this!” When this situation persists for weeks (or for some, months and years), real physiological changes occur to the information system that keep us in pain, and often make it worse:

1. Nerve tissues become more sensitive to information

With prolonged pain outputs, the Board determines that, “The information from Left Leg is constantly worrisome. We need to keep tabs on this situation! Rather than getting five reports a day, let’s get ten.”

Based on that response, the central and peripheral nerve will generate a greater number of nerve receptors. Receptors are cellular structures that, when activated, will trip a nerve to fire. Nerves have different kinds of receptors that will respond to:

  • Pressure
  • Temperature
  • Chemicals/Inflammation
  • Light Touch
  • Stress and Anxiety!

Chronic, prolonged pain will cause a greater number of receptors and make them easier to trip. Moreover, current research demonstrates that stress and anxiety are the primary receptor types that “grow” on nerves in states of chronic pain. For a runner trying to overcome injury, this may mean that their foot or back pain may occur at one mile, instead of two. Or one meter. But there is no actual tissue damage; rather, the nerve is now more sensitive.

2. The brain becomes more receptive to information

While the peripheral nerves are becoming more sensitive, changes occur in the spinal cord as well! The peripheral and central nerves meet at a junction in the spinal cord (for legs, in the low back, for arms, in the neck). At this junction, there are several “interneurons” that serve to relay information. One cell, in particular, serves as mediator of information. He takes a look at all the reports coming from the legs and helps decide what’s worth letting in, and what can be ignored. He’s “The Bouncer.”

In chronic pain, the Board will determine that it needs all the information it can get, and it will deactivate (and, based on some research, actually destroy) “The Bouncer,” which allows a free flow of any and all stimuli from the body to flow into the brain.

Therefore, this series of events creates a situation where “x” amount of tissue input is interpreted as “10x” or “100x” by the brain. Reality is skewed. The slightest amount of running, walking, or even active or passive joint motion is painful.

Signs and Symptoms of Central Sensitization:

  • Symptoms persist beyond normal healing times (>3 weeks to >3 months or more)
  • Symptom area “grows outward” from original (more pinpoint) injury area
  • Symptoms change, from ache/soreness to stabbing, buzzing, “lightning bolts,” tingling
  • Symptoms occur at rest, or without weight bearing
  • Symptoms worsen at times of stress and anxiety
  • Tissue tolerance (sitting, standing, walking, running) actually worsens…

Sensitization is important in primitive survival: tissue damage is a threat that requires acute monitoring to avoid. But when these changes occur in the absence of any tissue damage, the pain – and the threat of that pain itself – is the sustaining element of the pain cycle:

Tissue damage → threat → pain → sensitized tissue → more pain → more threat → more pain…

Understanding this system is vital to overcoming chronic pain. The realization of, “What I’m feeling right now might not actually be tissue damage… I might just be sensitive!” is critical in taking steps to overcome chronic pain. Moreover, recognizing how our attitudes, beliefs, and stress/anxiety affect pain is vitally important.

This gets us back to the question: “If pain is information, what is mine telling me?”

Based on what we now know, the answer might be one – or all – of three things:

  1. I need rest!
  2. I need more load!
  3. This information is erroneous!

More or Less? Inflammatory versus Ischemic Pain

When tissue damage occurs, it is invariably an inflammatory condition: inflammatory chemical rush to the injury site, the area swells and becomes warm, cells begin to repair. And, usually, it hurts! In acute and sub-acute inflammation (10 days to three months, depending on the tissue), rest is critical for tissues to heal.

When pain persists beyond scientifically-accepted tissue healing times, then rest is seldom the answer. Pain in response to tissue loading might be telling you, “Yikes! That’s stiff! Keep working me!” In those situations, pain is likely ischemic – or due to lack of blood and fluid flow, and overall mobility. Ischemic tissue needs the opposite of inflammation: active and passive motion, blood and fluid flow, and progressive tissue loading.

Think of the different tissue types as meat. Inflammatory tissue is like a medium-rare steak: fresh, warm, soft, fluid-filled, flexible. Hot off the grill, it needs to sit a bit, and cool off. Ischemic tissue is like beef jerky: aged, dry, tough, dysfunctional. To become pliable, it needs heat, fluid, and mobility.

So how do you know what kind of pain you’ve got? Your doctor, PT, or other health care professional can help you determine whether your tissue is inflammatory versus ischemic, but here is a relative comparison:

Inflammatory versus Ischemic Pain*

Age of Injury<3 months, usually <3 wk> 3 weeks or older
Peak SymptomsEnd of the dayMiddle of the night, first in the AM
SymptomsAche, throb, stab that lingersSharpness, immediately subsides w/rest
Pain ReliefColdHot
Treatment ApproachR.I.C.E.Flexibility, relaxed mobility, progressive loading
NSAIDs Effective?YesNo

(*adapted from lecture notes, “Explain Pain”, NeuroOrthopedic Institute, Adriaan Louw, Minneapolis, MN, November 2012)

Escaping the Pain Vortex – Building Tissue Tolerance and “Defusing the Threat”

Freeing oneself of pain – inflammatory, ischemic, and hypersensitivity – requires progressive, patient loading of tissue. Despite where the symptoms come from, they must be respected.

Muscles, bones and joints – while clinically healed – might still be unfit or disorganized. Thrashed quads, weeks after a hard 100-miler, might be fully healed but still dysfunctional and tough, like the beef jerky. A fully healed plantar fascia might only tolerate a full day on your feet, and nothing more. Progressive tissue loading is required to gradually restore the tissue to desired function.

For runners, building tissue tolerance should be a familiar concept: it’s training! We all know that just because we could run four-hour long runs six months ago, doesn’t mean we can automatically do so, today. Even when healthy, we lose tolerance when we rest. It must be gradually rebuilt.

Injured tissue is no different. It requires gradual building-up of load over a prolonged period of time to strengthen and toughen.

The system that most needs gradual loading is the nervous system. The Board of Directors, after months and years of pain, is, indeed, “nervous.” And just because pain perception might be due to erroneous information, doesn’t mean the pain response is fake. It is, indeed, real, and must be respected.

Thus, to desensitize the nervous system is paramount: to progressively load tissue, just enough to convince the systems that it is “okay” and “Sore but Safe”, to defuse The Threat.

People who can accomplish this feat – progressive tissue loading, desensitization and threat defusing – may do so quickly, and will often report “miraculous” cures, because they finally give their tissues what they need: blood flow, flexibility, and relaxed, confident function!

Tissue Tolerance and Desensitization: A Case Study

I’ve experienced this “miracle” firsthand:

Before my first Western States 100 in 2011, I experienced a knee injury. I strained it in early April, yet by the end of May (nearly two months), severe pain persisted: it hurt with the slightest movement, walking was painful, biking was intolerable, running was out of the question.

Threat value was sky-high: I was running my first hundred, I was unprepared, I had a dozen friends and family committed to helping. Moreover, I was mentally catastrophizing: “If I cannot walk without pain, how could I possibly run a hundred miles?”

At the end of May, critical things occurred:

1. I determined that there was no severe tissue damage.

A simple x-ray ruled out any bony pathology. The absence of swelling ruled out ligament or cartilage pathology, and it confirmed that tissues were healed.

2. I recognized how my own attitudes, stress, and anxiety impacted my pain.

Stress, anxiety, and threat caused two things: abnormal (protective) movement patterns – not letting it relax and bend normally, as well as increased muscle tension and decreased blood flow to the area. The knee tissue was ischemic, not inflammatory.

3. I began to progressively load and defuse threat.

Recognizing the physiological reality, the impact of my mental state on the tissue function, and rationalizing that I’m “Sore but Safe,” I began to gradually load the tissue.

Starting Memorial Day Weekend:

  • Pre-Friday: Zero running for over a month.
  • Friday: 35 minutes of running, one minute on, one off. I was “Sore but Safe” – pain during the run, but none immediately after. I was relaxed and positive about the progress.
  • Saturday: Walked from Michigan Bluff to a mile past Last Chance… then ran back nearly the entire way (26 miles, total – 13 of it running). “Sore but Safe!” More excited…
  • Sunday: Ran from Michigan Bluff to Rucky Chucky, 23 miles, total.

What a miracle, right? Or did I finally give my knee exactly what it needed? Relaxed, normal motion, and progressive (albeit, aggressive) loading. I was sore as heck after that weekend – general muscle soreness everywhere – but I had no knee pain. Race day was similar: loads of body pain, a safe knee, but most importantly, a Silver Buckle.

Recognizing what pain is telling you is like learning a new but important language. You need not be fluent, but simply gaining understanding of the impact of our brain and nerves on pain and injury will help defuse the threat, and get you back on the trail!

Call for Comments

  • Have you experienced Central Sensitization firsthand? An injury that took far longer to heal, that created abnormal, hyper-sensitive symptoms? How did you “escape”?
  • Describe your experience with “miracle cures.” What happened, how did you emerge, and how might that relate to sensitivity and tissue loading?


Explain Pain, Butler & Moseley. Orthopedic Physical Therapy Products; 1st Ed. (2003)

Joe Uhan

is a physical therapist, coach, and ultrarunner in Eugene, Oregon. He is a Minnesota native and has been a competitive runner for over 20 years. He has a Master's Degree in Kinesiology, a Doctorate in Physical Therapy, and is a USATF Level II Certified Coach. Joe ran his first ultra at Autumn Leaves 50 Mile in October 2010, was 4th place at the 2015 USATF 100K Trail Championships (and 3rd in 2012), second at the 2014 Waldo 100K, and finished M9 at the 2012 Western States 100. Joe owns and operates Uhan Performance Physiotherapy in Eugene, Oregon, and offers online coaching and running analysis at

There are 28 comments

  1. Phil Jeremy

    4 weeks before an ultra I pulled up with a severe calf strain. Having had them before I started panicking as they often return. I rested then ran and the pain returned, rested again and ran, pain again.One week before the race I couldn't run at all due to the pain, not even 500 metres. On race day I figured I'd get about a mile and that would be it….I ran the whole race with no pain at all and have not had it since! Great post Joe, I think I need a CEO to overide the Board…or something like that:)

    1. Ron LaPoint

      Same here! I overloaded on some speedwork after a 100 miler late last year and developed quite the angry knee (never had any problems before). I put in a good amount of rest over the holidays, then had some serious hill work to do before a very hilly ultra this spring. This led to a pretty painful calf strain. I couldn't run more than a mile without pulling up in a straight-leg limp. I almost blew off a 50K last weekend because of it, but decided to just go out and see what happens. Long story short, calf strain hurt the whole race, the knee pain came back FULL FORCE, but the next day, both my calf AND my knee were pain-free. I have never experienced anything like it.

    2. OOJ

      Phil & Ron,

      Thanks for sharing your experiences!

      Good examples, indeed, of the notion of "ischemic" tissue – tissue that's healed, but still stiff and dysfunctional.

      I definitely do NOT recommend that people simply go run an ultramarathon as a "cure" for injury. But, these are examples of what can happen with gentle, relaxed, prolonged "tissue remodeling" – what you often get when you run trail ultras.

  2. Luke Garten

    I have chronic siatic nerve pain in my right leg. The pain is worse around the Piriformis muscle usually giving my hamstring a lot of pain. After a very fast paced long run or after a race it goes away for at least a few weeks. Not sure if it is the increased blood flow or the increased range of motion at the very fast pace. The more active I am the better the sciatic nerve feels

  3. Digger

    Very timely article for me, Joe. I have had pain in my right big toe for two months, I assumed it was turf toe (from soccer)that still hadn't healed. Your description of ischemic pain sounds like my pain to a "T".

    I'm going to change my self treatment from R.I.C.E. and NSAID's to heat and some massage, and try to stretch it out a little more.

  4. Guy Smiley

    Great article. I learned from trial and error the difference between ischemic and inflammatory pain. I've treated calf strain and plantar fasciitis with more running.

    I find deep stretching pre and post run (especially in a hot shower) really helps to alleviate ischemic pain. My RMT pointed out that for problematically tight muscles, holding a stretch for 60 seconds or longer can be very beneficial.

    It helps that I have a high pain tolerance and generally hold pain in contempt…

  5. Eric

    Really interesting and timely article. I have a question — I used to be fairly flexible and "fast" (by my own standards at least), and over the course of the past 5 years have been repeatedly injured (mainly muscle strains and tendinitis issues). Over this time I have lost almost all my flexibility (and my speed — 10/min miles is a "good" pace now whereas 7/min miles was my old comfortably hard pace) — doctors/PTs/etc. have joked that I'm the most inflexible person they've ever seen — worse than 90 year old patients! Anyway, I now feel enormously abnormally tight even when walking on flat ground or up/down stairs — I never feel severe "pain" but always feel the threat of an imminent pulled muscle or knee pain if I "push" myself and attempt to open up my stride or quickly walk up/down stairs. This sounds exactly like what you're describing — the body goes into over-cautious hyper-sensitive mode to protect itself due to past injuries, despite old injuries being 100% healed and their recurrence unlikely (by doing such normal things as walking quickly or up/down stairs). It's extraordinarily frustrating and I can't seem to shake it — after 5 years it seems like the new normal. What would you suggest to get through this? My best guess is to "force" these normal motions and do my best to ignore the false signals/pain I'm feeling to retrain my brain, and to do flexibility/strength work — it's just really tough when I keep receiving these false threats as if re-injury is imminent — I guess my main issue is deciphering between false threats and real threats, since I've been out of whack for so long. Thanks for reading such a long post!

    1. Eric

      One more thing to add — I'm in my early 20's so it's not like I'm 75 and moving slower as a result of age — this is highly abnormal!

    2. OOJ


      Thanks for sharing. I can't give out specific medical recommendations without seeing you, but what I like to do with folks who have significant:

      – stiffness

      – poor pain tolerance/weakness

      – sensitivity

      is get them in a pool. For the runner who is returning from injury (either acute or chronic), doing actual, shallow water running works wonders to simulate the real thing with 50% less weightbearing and "safety" and comfort of warm water.

      For those more acute/stiff, I will commonly recommend deep water running, where one could work through the full range (hip/knee/ankle flex/extend) with a very fast turnover w/out resistance or worry of impact stresses.

      1. Eric

        Thanks a lot for the response — this is great advice. If I can get access to a pool, I will definitely try to do this in addition to everything else.

  6. Rod

    Eric, take this comment for what it is worth. What else is going on in your life? Not everything in life needs to be hunted down and killed. If you are one of those(us)people who constantly vibrates at a higher level it will benefit you to learn how to manage it. Calmness is a useful tool for the mind and body. Ok, now back to regular programming.

    1. Eric

      Thanks for the advice, Rod! I am quite a busy person at the moment, and the tension/pain increased at the same time I began this hectic/stressful period in my life. The two are certainly related to some extent, but I'm fairly good at managing it and relaxing. I think I need to specifically face my fears head first by working through them and making myself uncomfortable, so the abnormal activity becomes normal again. Much easier said than done though.

  7. JenE

    I'm trying to figure out how this applies to dealing with "runner's knee" (with no torn tissue and clean x-ray). The most common advice I hear is to stop running or at least run less. When it first started, I used modified RICE (R.I.I. = rest, ice, ibuprofin), but the problem persisted beyond a few weeks… stabbing pain when going down stairs and running was out of the question. Eventually I resorted to the elliptical machine which I had no trouble with. I was SO excited, and even more excited that I was able to transition back in to running again after about a month of elliptical. Why did the elliptical help so much? I feel like it had more to do with form than ischemic pain because the pain was always the same. It either hurt intensely or it didn't; there was no stage where it "kinda" hurt.

    1. OOJ


      My professional values are that nearly ALL running injuries are mechanics-related: the better the mechanics, the higher our tolerance to volume and intensity, and vice versa. Runner's knee is no exception.

      Elliptical might've helped for two reasons:

      1.) Desensitization and progressive loading of knee tissue.

      2.) Run mechanics retraining. Some elliptical trainers can facilitate better run efficiency by encouraging glut push and a more compact leg action. Prolonged "practice" on the elliptical may have carried over into minor but pain-significant stride changes.

  8. Ryan

    Very informative article. I thought I had researched everything possible regarding piriformis syndrome. 14 months later the pain in the foot (mostly small toe) and ITB is still persistent. I was wondering why consistent but not overly aggressive exercise helped to keep the pain in check. Ischemia. Although I'm perplexed as to how to completely eliminate the pain. Sometimes too much stretching seems to aggrevate the nerve/piriformis symptoms.

    1. OOJ


      Thanks for the comment. While these pain concepts play a crucial role in chronic pain, the fundamental issue is "making the abnormal, normal". Again, mechanics: is your stride efficient, or is it causing lumbopelvic and leg stress. If so, desensitization and progressive loading will likely NOT completely eliminate symptoms.

      Your collective symptoms (lateral foot, ITB, piriformis) are suggestive of either an overstride and/or lateral foot strike. Check out the trunk alignment post from September (

      And stay tuned for next month, where we will post an article on foot strike patterns and how they affect leg and back pain.

      1. Ryan

        Thanks for the advice. I thought it might be from a muscle imbalance. Years of biking and not much hamstring work. I've noticed that lightweight squats before a run helps. I've been mindful of stride length, but I do have a lateral foot strike. Thanks again, looking forward to next months' article.

  9. kristy

    Hi there, really enjoyed this article. i have had lateral knee pain for nearly 2 years. havent ran in that time as havent been able to walk pain free at all. i have had 3 mris's ct scans, bone scans (which showed that i had a hot spot on lateral tibial plateau) and then even arthroscopic surgery in which nothing was found and i am still in pain. over the past 2 years i have been on crutches non weight bearing for 2 months, done nothing for a whole year, tried biking, walking, tins of physio exercises, have seen numerous physios, osteopath, chirpractor, and no one can give me an answer. my knee is alot better with a brace on and it is not really sore at rest, just weight bearing, it is better in the morning and alot worse by late afternoon, it is a dull, pulling, pinching pain, not a stabbing or tingling pain. i found it diffiuclt to bend my knee when walking so have been walking with a straight leg for a couple of years, i have been working hard not to do that.i really want the pain to go so i can get on with my life does this sound like ischemic pain or the real deal? hoping that nothing was missed on my scan or scope surgery. if you could be of any advice that would be greatly appreciated.

    1. OOJ


      Thanks for the post, and I'm very sorry to hear of your troubles. A very complicated case, indeed.

      I will say, but two things:

      1. We limp because we're in pain; we're in pain because we limp. We use our knee abnormally because we're in pain; we're in pain because we use our knee abnormally. Is there ANY reason, anymore, to: 1.) wear a brace, or 2.) walk with a straight knee? Is there any remaining pathology? Might the "Pathology" be from not using your knee normally?

      2. You absolutely MUST read this book:

      3. Find a healthcare professional who has advanced education in pain management (non-surgical, non-pharmacological), preferably one who is familiar with the "Explain Pain" work (

      Good luck!

  10. kristy

    thankyou for your reply i will try and find someone to help, im in new zealand. in my mind it still feels like pathology has been missed as i cant seem to shift it in daily activities and i guess the Marjory of your article is running with pain, maybe i have been foucsing so much on trying to find out what it is, i haven't realised that maybe it is healed, i guess that it has never been dignosed is why i think there is somehting there to dignose, as so one has ever said "oh well you strained your lcl but it has healed now so what you are feeling isnt real pain". hmmm i dont really know. thanks so much for your reply

  11. bnak

    Great article. I had come to this conclusion that ischemic pain needs stimulation to properly restructure and condition tissues following the initial tissue damage. (although I did not realize ther was a name for it). It was nice to see there is some science to validate this theory. I find that after the injury recovery time recommended in the article, I begin running gently to get back into running for a couple weeks, then I throw in a hard 5-10k. This often seems to work out the remaining lingering pain. Perhaps it alleviates that lingering anxiety that one may carry when coming back from a nagging injury.

  12. Luke

    This is provocative stuff. Reading your description of ischemic pain I can't help coming back to most people's experience with plantar fasciitis, and how many of the standard treatments are contrary to the concepts you lay out here (and are often seen as ineffective). Do you have any thoughts on this particular ailment, and the wisdom of treating with immobilization?

  13. Espi walmsley

    Very informative and educational! My case is I have stubborn plantar fascitiis for over a year. I tried conventional treatments icing, stretching/strengthening exercises, custom and prefabricated orthotics, night splint, shockwave therapy to no avail.

    Any thoughts or suggestions will be greatly appreciated.

    I look forward to hear your input.

    Thanks for your courtesy of areply.

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