If you put your foot in a fire, you will feel pain. In order to feel pain, all you need is three things – the body part, damage to the body part and the brain. Pain is pretty straightforward, right? Well, not really. You only need one of those things – the brain. That is correct, we don’t need the damage to the body part, nor do we even need the body part at all! All we need to feel pain is the brain. What if I went a step further and told you we don’t even “feel” pain? Pain isn’t actually a sensation, but rather it’s an interpretation by our brain.
Fear and threat could be the biggest factors that people need to overcome when it comes to pain and also to athletic performance. The fear could be a conscious thought to avoid movement or exercise, or it could be a faulty perceived threat by the brain deeper in the subconscious
This may be a lengthy post, but I’ll try and keep it as interesting as possible because I think this is a topic most people need to read. Whether you are in pain or not in pain, it’s important. I have made some links here so you can skip ahead to the chapters you want to read if you want:
On to the Fun Part…
Before this gets started though let’s get through some premable, things to keep in mind, warnings etc., etc.: This post is not trying minimize pain. Please don’t misinterpret this post as me saying pain is made up, exaggerated etc. and I am certainly not discounting the role that biomechanics and tissue damge play in the etiology of pain and injury. This is merely some musings and things to think about if you are in chronic pain, or are suffering through an Ironman, marathon or even a 5K. If you have pain, please seek out professional expertise. (BTW, I’m not sure what ‘preamble’ means or if what I said qualifies as ‘preamble’, but it sounded scholarly)
Concept #1: Pain is not a sensation. Pain is a perception. There aren’t nerves that tell our brains something hurts – it’s only our brain that gets input from nerves and then extrapolates that information as being pain. Until our brain goes through a very complicated procedure of determining if a certain sensation is a threat, we won’t feel the pain.
While that may seem abstract initially, there are many examples of how our brain can suppress pain, such as a soldier getting shot on the battlefield but then not realizing it until after the battle – at which point the pain becomes severe. Another example could be an endurance runner who just can’t run anymore due to pain and fatigue, yet they manage to dramatically pick up the pace once they see the finish line. Did their tissue damage miraculously heal, or did their brain perform a layered, complicated calculation and determine that the distance to the finish line is achievable and the disagreeable incoming signals from the body are no longer a threat?
Concept #2: Tissue damage does not cause pain, nor do we need tissue damage to feel pain. For example, I have a few patients whose low backs look like they got hit by a truck on an MRI. The discs are herniated, the spinal cord is compressed, there is severe arthritis, yet they tell me their low back pain is only annoying, not painful, nor does it affect their quality of life. Meanwhile, some other patients with severe, chronic low back pain have no evidence of tissue damage on MRI. Another example is tendon problems. It is well documented that imaging tendon damage does not correlate with pain [1,2]. In addition, structural abnormalities seen in tendinopathy are no different when people are in pain compared to when their symptoms go away .
Again, I’m not saying tendinopathy or low back pain is being exaggerated or made up. What I am saying is that very often, the pain may be interpreted as tissue damage and that the tissue damage is a threat to the person’s well-being. These thoughts end up magnifying pain and leading to fear of movement or activity. This fear of movement ends up causing the person to avoid exercise and movement, causing a greater impact on their lives than the pain itself ever did.
Concept #3: You don’t even need a body to feel pain. OK, now you’re thinking I’m way out on the edge of sanity, but most people have heard of “phantom limb pain.” Phantom limb pain is the sensation of pain in a body part that isn’t there. For example, many amputees (50-90% of them) or even people born without a limb report feeling pain, cold, sweaty, itchy etc. in the limb that is not there . Therefore, we don’t need a body to feel pain, just a brain.
Why Am I Telling You All of This?
I make my living off of evaluating biomechanics and correcting movement patterns so that there is less stress and strain applied to various body parts. The three concepts I just mentioned would seem counterintuitive to my expertise. However, I have this conversation often in my office mainly for two reasons:
Reason #1: Once people understand these three concepts, it can dramatically improve their symptom resolution. Most patients have something called “fear avoidance behavior”, meaning they are afraid to move a body part out of fear that they will damage it. In many cases (not all), movement can be therapeutic and end up lessening pain. Sometimes, I prescribe exercises that hurt and I want people to understand that’s OK. Hurt does not equal harm. More on this later.
Reason #2: The “nocebo” effect. Most people have heard of “placebo” which is the idea that if you tell someone that swallowing a benign pill or putting colorful stretchy tape on their skin will help reduce their pain, it usually will have that effect. The “nocebo effect” is the exact opposite. Nocebo implies telling someone that some pill, activity or movement will create pain and it ends up doing just that. I can’t tell you how many times people come into the office for a pain and tell me they avoid doing some activity because some orthopedic surgeon, physical therapist or chiropractor told them that if they ran, they would destroy their knees, or if they bent over the wrong way, they may herniate a disc. I love this one, “Mrs. Jones, you’re only 37, but your spine looks like a 76 year old.” How do you think that makes that patient feel? These poorly thought out words create fear in the patient and magnify their pain. This creates a self- fulfilling prophecy where the patient is afraid to drive a car, exercise or even pick up their children. Physicians and therapists have to be careful with their words. They can do a great deal of help, or they can harm. There are many chiropractors and therapists who read this blog and get this newsletter, so yes, I’m talking to you.
The Fun Part of the Post:
OK, so up to now, this has been fairly abstract in its meaning and interpretation. Let’s look at some research that has been done to try and shed some light on what I’m talking about. After a brief summary of each paper, I will extrapolate what this means in the real world.
Study #1: The Cold Probe Study. Researchers used a -20 °C probe to touch the hand of the subjects. There was a light on the table and in some cases, the light was red and in some cases the light was blue. However, it was always the same probe, at the same temperature. When the probe touched the back of the subject’s hand, they reported significantly higher pain levels when the light was red, even though it was the exact same probe.
Real World Meaning: When presented with the exact same incoming signals from the hand, the brain interpreted more pain when it also saw the red light. To most people, red means danger and it means hot. The study highlights the idea that pain is a perception. If the brain interprets a threat (red, hot, danger) it will magnify pain. Similarly, if I tell you that you have a degenerated disc and that is a big problem (even though it usually isn’t)your brain will then interpret low back pain as stemming from the degenerated disc and perceive this as a threat. I have done you a disservice by telling you you have pain coming from a degenerated disc (which is hard to prove) and yet there is nothing that can really be done about it. Would I be lying if I told you the degenerated disc wasn’t a problem? No, I wouldn’t because there is ample evidence that degenerated discs are highly prevalent – just as prevalent in subjects with no pain.
Study #2: The Anticipation of Pain Study. It is well accepted that pain in a joint can inhibit muscle strength and control around that joint. This has been shown in studies where subjects try and generate a force by pushing and that force is measured. The researchers then inject noxious chemicals into the joint and have the subjects try and push again. There is less force generated because the muscles are inhibited by the pain in the joint.
This particular study that I am highlighting did the same thing – having people try and extend the knee against resistance, thus measuring the quadriceps force output. However, instead of injecting the knee, they used random electric shocks on the knee and compared the results with injecting a noxious injection into the knee. Sometimes the subjects were electrically shocked and other times they weren’t. The result was that the subjects generated less force when they were shocked AND when they weren’t shocked. In other words, the quadriceps muscles were inhibited just as much when the subjects anticipated they were going to feel pain from the shock compared to when they were injected with a painful chemical in the knee. Many of these changes in movement lasted after the experiment. I’m not sure who signs up to participate in these studies, but there you have it.
Besides the one study that I just referenced, there are other studies that have shown movement adaptations due to anticipation of pain based off memory. For example, every time we move a limb, we need to make postural adjustments. One study measured the postural adjustments when subjects moved their arm in a particular way. They then experimentally produced painful stimulation of the low back whenever the subjects moved their arm in that particular way. The postural muscles of the back contracted differently in that scenario. When the experimental painful stimulus was removed and the subjects were asked to move their arm again, most subjects returned to their normal muscle activation pattern…but some subjects didn’t. They maintained their altered motor pattern in a manner that stiffened the spine. The authors concluded that this protective strategy would predispose the subjects to spinal injury if maintained long term.
Real World Meaning: These studies highlight the idea that our movement patterns and motor control can change when we simply anticipate pain. All you have to do is convince someone that something is going to hurt, and they will move differently. That means that if someone does have a knee injury, shoulder injury low back pain etc., their movement strategies may change in a way that becomes detrimental. Even when the pain goes away, our movement patterns are different. This makes it very difficult as a clinician for a few reasons. First of all, we know that the #1 risk factor for hamstring strains, ankle sprains, low back pain etc. is whether you’ve had the pain before. When the pain goes away, many people feel treatment is done, and they can stop doing their rehab. Unfortunately, movement patterns often need to be re-learned, so the absence of pain should not mean that rehab is over. Secondly, due to the anticipation of pain, fear of movement becomes overwhelming for many people, so they stop using the body part, which results in increased joint pain and muscle disuse so the problem becomes a self-fulfilling, snowballing problem.
Study #3: Mirror Training Studies. As I mentioned earlier, phantom limb pain is experienced by 90% of amputees. A mirror box is a contraption which fools the patient’s brain into thinking that they are moving their real (but amputated) limb simply because they are seeing a reflection of their opposite limb moving. This has been shown to be highly effective in reducing phantom limb pain.
Real World Meaning: Mirror training is not only effective in amputees, but also in people with inexplicable limb pain or low back pain. Once a person has been in pain, their brain’s sensory maps for that body part are altered. This altered mapping has been seen in trials where subjects with hand pain are unable to quickly recognize pictures of the side of their body that the pain is on. For example, if you have a painful right hand and are shown random pictures of right and left hands in different positions, you would most likely be less quick and less accurate in identifying pictures of a right hand compared to the left. If you don’t understand what I’m talking about, go to around the 2:00 minute mark of the video below.
In order to figure out if the hand in the picture is a right or left hand, we must mentally move the hand into a position we can recognize. People with chronic pain are less able to do so on the side with the chronic pain . This could mean that a contribution to ongoing pain in the absence of tissue damage could be due to incongruence between motor intention (the way you want to move) and proprioception (your brain’s perception of spatial orientation and position of your body parts). In other words, incongruence between motor commands and sensory perceptions.
Again, this may sound abstract, so let me give a couple examples. People with chronic low back pain have impaired proprioception of their back (they have poor positional sense of their back) [6, 7, 8, 9], however, it has been shown that this impaired positional sense is not present in people prior to suffering from low back pain . In other words, the impaired positional sense is an effect of the low back pain, not the cause. By using mirrors, researchers have been able to help this impaired positional sense and thereby significantly reduce pain. They did this by having low back pain patients go into two different rooms where they were instructed to make 10 pain producing repetitions of movements with their low back. In one room, they were able to see their back moving via a system of mirrors and the other room they weren’t. The group that saw their spine moving ended up having significantly less pain with movement after the intervention. Why did they end up having less pain when they were able to see their back moving?
Unlike the mirror “illusion” therapy used in the phantom limb pain, this study merely allowed the patients to improve the congruence between their intent to move and the way their back actually moved. In other words, it helped their brain “map out” the spatial orientation of their back. The other possibility is that by seeing the spine moving normally in the mirror may reduce the “perceived threat” in the brain. This is backed up by studies that show subjects perceive less pain if they watch the moving painful body part, thereby (potentially) reducing fear of movement and the perceived threat associated with using the body part .
Along those same lines, there is evidence that people with chronic pain will perceive more pain in a painful hand by moving the hand while looking at it through a magnifying glass. Not only will they feel more pain, but the swelling can actually increase . Conversely, they can reduce their pain by viewing the painful hand moving while looking at it through a minifying lens.
Once the brain perceives that the body part is in pain, infering that there is tissue damage and thus is a threat, the brain map changes for the involved body part. Very often, we prescribe exercises where the patient uses the painful body part in a non-painful way which “convinces” the brain that the body part is not a threat and it can use the body part without threat. Teaching a patient to utilize the body part in a non-painful way can help the brain overcome fear of movement with that body part.
Study #4: The Sadomasochism Study.
Pain is felt differently according to social and personal contexts and how the brain interprets the threat. One need not look any further than sadomasochism, self flagellation, cutters etc. In this video below, “Mind and its Potential”, one of the leaders of pain research, Lorimer Moseley, talks about a study he conducted on sadomasochists. In this study, they recorded actual brain activity as well as the response of the subjects. In the study, the sadomasochist subjects had a hot poker put on their leg in two different circumstances. Circumstsance #1 was when Dr. Moseley’s recorded voice was saying “Now, I am putting a hot poker on your leg” and in circumstance #2, there was a mistress’ voice saying the same thing. The subjects brain activity was similar in both circumstances, but the experience reported by the subjects moved from pain in the first circumstance, to pleasure in the second circumstance. He goes on to say “these people don’t find pain pleasurable, but they do find noxious stimuli in that context, pleasurable. They’re not hurting, because they are in pleasure“. I highly recommend you watch this video if this subject is at all interesting to you, or you are in chronic pain. He is really entertaining and funny.
This type of situation is observed quite frequently in the office. When we perform soft tissue treatment on runners or bodybuilders or other athletes, they frequently say, “ya, that hurts right there.” When I respond with “Do you want me to back off?“, the answer is usually, “No, it kinda feels good.” Contrast this with some other folks, where the response to my “do you want me to back off question“, is a very angry, “Yes, I want you to back off!” The athlete is very accustomed to pain and often associates enduring some pain as being necessary to achieve improvements in physical strength, endurance etc. The context of feeling pain is entirely different for more sedentary folks who perceive the pain as a threat.
This has been researched and shown that athletes can handle pain better than non-athletes. After reviewing many studies, the authors of this particular review concluded, “regular physical activity is associated with specific alterations in pain perception.“
Real World Meaning: The “No Pain, No Gain” mantra is very well known amongst athletes. I have known many ultra distance runners who have told me they did a long, grueling race and their legs “hurt so bad!” and they finish up their statement with, “the pain felt great!!” The ability of endurance athletes to go into the “hurt locker” or the “pain cave” is what sets some great athletes apart. However, while some athletes seek out the pain, most try and simply endure the pain with mantras in their head, or counting steps etc. Some athletes endure the pain, whilst others seek it out.
This gets really interesting when researching endurance running. I will hopefully do a follow up post soon on the “central governer” theory of fatigue in endurance running. In the meantime, we must all remember to distinguish the difference between “normal” and other pain signals. As I said at the beginning of the post – pain is a subjective output of the brain, but it is usually there to tell you something and should not be ignored.
- Pain is an opinion of the brain. Usually, tissue damage fires nerves that tell the brain something happened. It is up to the complex, layered processes of the brain to figure out what to do with that information. If it perceives the information to be a threat, it is interpreted as pain.
- Very often pain leads to altered movement patterns which can perpetuate the problem. Very often, we prescribe exercises where the patient uses the painful body part in a non-painful way which “convinces” the brain that the body part is not a threat and it can use the body part without threat.
- Chronic pain leads to changes in the brain that fundamentally change the way the brain perceives the painful body part. There are various methods that can be employed to change this perception