“You can’t put fitness on dysfunction.” – Physical Therapist, Gray Cook
Injury prevention and injury therapy are both shifting from focusing on regional anatomy to more of a global movement appraisal and correction. For example, if a patient suffers from tennis elbow, treatment used to focus on the elbow. Up to date clinicians these days will focus more on appraising and correcting faulty movement patterns that may be happening in different part of the body (in the shoulder and thoracic spine for example) which may be the reason the tissues in the elbow became overstrained. This article focuses in on how pain can cause dysfunctional movement and how dysfunctional movement can cause pain. The central nervous system’s role in this cannot be understated. Below, I have given a few of the very interesting studies and examples that are emerging.
Ok, here’s a little 3 question test:
- Guess what the best predictor of low back pain is? Weak abdominal strength? Being slightly overweight?
- Guess what the best predictor of hamstring strains is? Leg length difference? Short, tight hamstrings?
- Guess what the best predictor of running injuries is? Lack of orthotics? Running on hard surfaces? ‘over’pronation?
If you answered “yes” to any of those, sorry, but you’re way off. I actually put those up there because those are all factors that have been shown to NOT be risk factors, or very weak risk factors at best. Nope, the biggest risk factor for low back pain is: Previous low back pain . The biggest risk factor for a hamstring strain is: Previous hamstring strain . The biggest risk factor for a running injury is: Previous running injury .
What that ultimately means is that the underlying cause of the injury has persisted in each one of those situations I listed above and recurrences become the norm.
Why am I telling you this? Two reasons I suppose:
- First, our current method of applying treatment to the area of pain is incomplete, narrow minded and simply doesn’t work because it doesn’t help fix the underlying problem and will likely lead to recurrences.
- Second, and more importantly, because I’m trying to bring some awareness to the idea that pain leads to dysfunctional movement and dysfunctional movement leads to pain. This is a peek into the mechanism of recurrent injuries.
As an illustration, let’s look at just one example: Recurrent ankle sprains. Guess what the biggest risk factor is? If you guessed previous ankle sprain, you’re right .A 2006 study  found that people who suffered from chronic ankle sprains also exhibited weakness in the hip muscles on the same leg as the chronic ankle sprains. There is nothing new to this. We know from many different studies that individuals with ankle sprains also suffer from poor motor control in the hip [6,7,8,9,10]. The link between faulty hip movement and ankle sprains has been well established, but what is the significance?
I think you have two options:
- There is an inherent motor control problem in the hip which results in poor motor control for the leg and ends up with recurrent ankle sprains, or…
- The person suffered an ankle sprain which set off a chain reaction of neurologic/movement compensations and resulted in poor motor control of the hip and pelvis.
More succinctly, the two options are: 1) Did the poor motor control in the hip cause the ankle sprain, or 2) Did the ankle sprain cause the hip problem?
Researchers aren’t really sure of the answer yet, but we have some clues. With the use of EMG, researchers can measure exactly when muscles turn on and off and thereby map out the brain’s strategy for moving a limb. We can call this the “muscle firing pattern”. When laying face down and asked to lift the leg upward (see figure 1), normally we would expect to see the low back muscles, glutes and hamstrings do the work in lifting the leg. The exact order of which muscles fire in the pattern is not consistent between people, but should it should be consistent in the same individual?
A recent study looked at the muscle firing pattern of healthy people performing this test. Serendipitously, 10 weeks following the test, one of the subjects sprained her ankle while “leaping into a camping tent filled with children”. When she came into the clinic 2 weeks later for treatment of her ankle sprain, the researchers had her perform the prone leg extension test again. They found that the low back muscles fired much earlier in this subject than they had before she sprained her ankle . 8 weeks later, when her ankle was healed, they did the test again and the low back muscles fired even earlier than they had 2 weeks after the ankle sprain.
In other words, following the sprained ankle, her brain changed its strategy for hip extension. The timing is laid out in Figure 2.
Figure 2. Times are in milliseconds and are listed relative to then the hamstrings contracted. Positive numbers indicate the muscle contracted after the hamstrings, negative numbers indicate the muscle contracted before the hamstrings
So, what does this teach us? Well, frankly not much because it was only one subject, so we can’t start making blanket statements. However, it is one example showing that pain can lead to altered movement strategies and those altered movement strategies can persist after the pain is gone. It’s an example of how the brain can “re-map” a motor pattern.
Moving on, we can look at another article published in 2012 which reviewed all previous research on the most common running pain: patellofemoral knee pain. In this review article, the researchers determined that in people suffering from this type of knee pain, there was consistency in the research showing delayed and shorter duration contractions of the gluteus medius muscle in the hip compared to people without the knee pain . Again, this doesn’t show a cause and effect, just a relationship. However, it once again shows that pain and dysfunctional movement patterns are interrelated.
There is one last study I would like to highlight and this one is on knee extension and anticipation of pain. I think most people would agree that your brain will likely alter the movement strategy for the muscles that move a painful joint. In other words, if you have pain, you will recruit muscles differently than if you didn’t have pain. Unfortunately, researchers have also proven that when you ask people to generate an extension force with the knee, the brain recruits muscles in a particular order and intensity that is the same whether the person feels pain or even if they anticipate pain . In other words, in a non-pain vs. pain situation, we move differently, but in a pain vs. anticipation of pain situation, we move the same. That means that all you have to do is convince someone that they will feel pain in a joint and “presto”…they will now move differently simply by anticipating pain.
This has huge implications for rehabilitation because it becomes so much harder to get patients to move correctly when they have had chronic pain. Even if the painful source is eliminated, the brain can still be capable of anticipating pain and so the patient has a hard time overcoming the movement problem. Not overcoming the faulty movement pattern may lead to altered loads on the rest of the body and possibly persistent or recurrent pain.
To summarize, our neuromuscular system is more complex than we give it credit for. When you suffer from recurrent hamstring strains, tennis elbow, low back pain etc., there is a reason for it. It’s not just weakness. It’s not just tightness. It’s not just a build up of adhesions and scar tissue. It’s not just trigger points. Our motor control, timing, coordination, movement patterns, stability and a host of other factors play a role in determining how we move and why we get injured. An appraisal of how you move is the bare minimum of what your should expect from your health care provider and if they are focusing only on the site of pain, don’t expect fantastic outcomes.
“He who treats the site of pain is lost.” – Karl Lewit
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