Regional Interdependence - Why you need to think beyond the site of pain

As mentioned on this blog previously, it is increasingly common to see athletes reinjure themselves following discharge. Commonly this stems from the status quo in the world of rehabilitation, which is unfortunately commonly solely focused on the specific area of pain, with little or no consideration of the musculoskeletal anatomy that lies above and below. It is imperative that we as physiotherapists consider that there is interdependence on the whole region.

We use the term 'regional interdependence' to acknowledge that, in the human body, everything is related to everything. Regional interdependence refers to the concept that seemingly unrelated impairments in a remote anatomical region may contribute to, or be associated with, the athlete's primary complaint. I will highlight this concept by describing a classic and common example that I come across in my day-to-day practice.

I've lost count of the number of client's I have seen with a chronic right-sided lower extremity injury - be it an Achilles tendinopathy, plantar fasciitis, 'Runner's knee,' etc., with a concurrent restriction through their opposite thoracic spine - i.e. they present with limited mobility when turning their torso to the left. In simplistic terms, if we follow the fascial lines of the posterior oblique chain, we can trace the orientation of the muscle fibres of the right-sided gluteus maximus as they progress superiorly and medially (i.e. up and towards the midline of the body), connecting to the thoracolumbar junction (you can think of the thoracolumbar junction as a sturdy supporting structure in which a whole heap of muscles and tendons attach to). Continue in this direction and you will find yourself now on the left-sided latissimus dorsi muscle, which wraps around your thoracic spine, finishing at your left shoulder (see picture below).

Why is this important? When you make initial contact with the ground with your right foot whilst running (hopefully landing with your foot directly underneath - NOT in front - of your body), your pelvis is rotated in an anti-clockwise direction. To counteract this motion, your upper torso (thoracic spine) must rotate in the opposite direction (clockwise) to ensure that you project in a forward direction - and not deviating towards the left. Hence, a restriction in the amount that your thoracic spine can rotate will allow more rotation towards the left through your entire right-sided lower extremity when it is in contact with the ground. Running is a uni-planar sport - meaning that you essentially only move in one direction - forwards. Any extra rotation (or 'torque,' in biomechanics terms) through your lower extremity is going to place far more stress on the bones, ligaments, muscles, tendons, and cartilage than needs to be - eventually resulting in an overuse injury further down the track (no pun intended). If we look at the knee - it is primarily designed to bend and straighten (although, a very small amount of rotation can occur - but that is irrelevant in the current discussion). If your thoracic spine cannot counteract the rotation that occurs through your pelvis when running, your knee will bend on a slight angle. You can liken this to the analogy of a door on hinges. If you open and close the door normally, there is no issue. However, if every time you open the door, you grab onto the top of it and hang off it as it opens, the hinges are going to bend each time - eventually breaking. This is what is essentially happening every time you run if you have a restriction or limitation through your thoracic spine.

So what does this all mean, and what are the implications for us as physiotherapists as we move our profession forward in the near-future? I think we need to put much greater emphasis on the basic principles of screening our clients and athletes for pain, restricted mobility, stability and asymmetries in areas away from their presenting injury. In fact, this principle can be applied to athletes pre-injury. It's funny in the way that we go to the dentist every 12 months for a routine check-up, visit the GP every 6 months for a standard blood test - hell we even get our motor vehicles serviced annually - however, most people come to visit a physiotherapist once they have already sustained an injury. The take home message here is that most overuse running-related injuries are totally preventable, and can be identified sub-clinically (i.e. prior to the onset of pain) via a comprehensive physical examination coupled with a thorough patient history. Tools such as the Functional Movement Screen (FMS) and Selective Functional Movement Assessment (SFMA) are movements towards the right direction in challenging the status quo of the rehabilitation world from a 'cure' mindset to a more cost-effective 'prevention' approach. If something doesn't feel right - don't hesitate to make an appointment with a physiotherapist (preferably someone who likes to think 'outside of the square'), before a little 'niggle' turns out to be a full-blown injury sidelining you for months.

Wednesday medium long run

What a massive relief that was!!! 20km (4 laps of Queenscliff to Shelly Beach and return) holding sub-4:00 minute/km pace feeling great! This was on the back of a horrible day previously as the cynic in myself predicted a worse case scenario of a right-sided fourth metatarsal stress fracture. I could barely walk following Tuesday's run, the dorsal surface of my outer foot was swollen like a balloon, and I had focal point tenderness right on top of the bony shaft of the metatarsal. Experience tells me that one way to differentially diagnose between a metarsal stress fracture vs. a lower grade bone stress response or metatarsalgia is to determine how the symptoms play out up one attempting to run. If the pain 'warms-up' and improves as the run progresses, the latter is more likely. Alternatively, if the pain deteriorates, a stress fracture could be 'on the cards.' Luckily for me today, the pain on my right foot disappeared (almost) completely after the first 5km. Surprisingly, I was limping less post run than on Tuesday - which is encouraging.

However, like any overuse injury - the essence is to determine the underlying cause - or the 'culprit.' If you have been following my blog, you would note that I have recently completed the majority of my speed work around an anti-clockwise circuit at Passmore Reserve. This means that for the majority of these sessions, my stride length is longer on my right side. This, I believe, put an excessive amount of stress through my peroneal muscles (the muscles on the outside of your lower leg and ankle). In a subconscious attempt to unload these tender muscles, which are responsible for subtalar eversion (i.e. turning your ankle to the side so that the sole of your foot faces away from your body) - and therefore allow you to push off the ball of your foot when running ideally off your first and/or second metatarsal (i.e. closer to the big toe) - my central nervous system compensated by forcing myself to push off on the outside of my foot to propel myself forward. This would likely cause a significant increase in stress towards the outside of the ball of my forefoot - leading to a likely bone stress reaction through my fourth metatarsal bone.

Now that I am aware of this, I ensured that I resumed to the ideal biomechanics of pushing off through the inside of the ball of my right forefoot (like how I always have, and similar to my left side). This obviously relieved the excessive loading through my poor fourth metatarsal!

Who said running related injuries are boring! No two injuries are ever the same, and this is why it is vital to take a comprehensive patient history backed up by a thorough physical examination that considers every single factor that may have played a part in the current clinical presentation.

One possible reason to account for the high rate of injury recurrence amongst distance runners

It's a shame to say that one of the single biggest risk factors for sustaining an overuse injury amongst endurance athletes is whether they have sustained the same (or similar) injury in the past. This suggests one of two things - either our athletes have some unidentified genetic predisposition to sustaining the same injury to a specific anatomical landmark, or that we in the medical and health professions are short-changing our clients by not addressing all of their clinical deficits resulting from their injury. Unfortunately, the latter appears more viable. Throughout my training as a physiotherapist, we were drilled to ensure that following any injury, a pre-requisite range-of-motion and level of strength had to be met prior to returning to their chosen sport. Whilst these guidelines are important, they do not encompass all of the specific areas that are compromised as a result of the initial injury. Consequently, it appears that we may be discharging patients too early.

One specific component of the injured athlete paradigm that is vastly gaining further exposure in the research literature is that of neuromotor coordination. Note that this is very different to 'strength.' In essence, 'strength' can be defined as the amount of force (typically measured in Newtons) that a muscle can generate by either shortening, remaining still, or lengthening. Strength is important, as it provides the foundations for two paradoxical components of fitness - both power and endurance. Both of these variables are simply derived from the equation: force over time - with the value of the denominator being far greater in the latter (endurance). Strength allows our bones and joints to move quickly, powerfully and/or for a long duration in whatever direction we desire. The muscles that are best suited for this role are those that are located more superficially (I like to call these the 'mirror' muscles, as these are the muscles that gym junkies like to spend a lot of time conditioning so that they look impressive when out on the tune); in scientific terms, these are classified as 'global' muscles. In essence, these muscles are mostly under our conscious control; hence we can chose when to activate them, along with controlling the amount of force which we choose to apply. Fundamentally, we condition these muscles by generically applying the '3 sets of 10 repetitions' principle in order to improve their force output (i.e. strength). 

Conversely, 'local' muscles are situated very close to our body's joints, and hence are not as easily seen as they are covered by our global system. These differ fundamentally from global muscles in that their primary role is not that of force output, it is merely to activate in a fast and coordinated manner in order to centrate and stabilise our joints so that our global muscles have a solid platform for which they can exert their force output from. Furthermore, they differ neurophysiologicaly in that they function below the level of our conscious control - in other words, they activate automatically in a feed forward manner in that we do not need to actually devote our attention towards. I am going to state this now (prior to elaborating further on a future post regarding the arguably flawed status quo of our therapeutic/corrective exercises) - local muscles do not respond to strength training principles of '3 sets of 10 repetitions.' This is why you will never see me prescribe internal and external rotation exercises with a thereband to clients with a rotator cuff injury, or 'clamshells' in order to 'activate' someone's gluteals.

Coming back to the original question - it is well established that our neuromuscular control is altered immediately post injury. The central nervous system adopts a compensatory strategy following an injury in attempt to off-load the injured structure, providing it with the best possible environment to allow it to heal. An example of this occurs when you sprain your ankle - without realising, you will rotate your entire lower extremity of the injured side outwards in order to reduce the amount of stress that would otherwise be applied to the outer ligaments of your ankle. Whilst this provides an extremely effective short term strategy, the body does not spontaneously default back to its original posture once the pain and swelling has subsided. As a result, your body is likely to adopt this posture into all of its normal activities of daily living. Running with an out-turned foot impaires stabilisation of the entire lower extremity, allowing the knee to cave inwards during midstance - which is a biomechanical cause of a vast array of common injuries including plantar fasciitis, Achilles tendinopathy, and runner's knee to name just a few.

Nevertheless, it is important to consider that this is simply one factor that may contribute to your current running-related injury, and the relative weighting of this past history is going to differ vastly from client to client. Factors such as training errors, running technique, basic mobility and stability are all imperative variables to consider when attempting to determine the underlying causes of any running injury. As I commonly say to my patients, no two running injuries are ever the same, meaning that if I had 10 current clients with the clinical diagnosis of Achilles tendinopathy, I would have 10 very different treatment protocols based on the relative contributions of the above-mentioned variables that each client uniquely presents with. 

So next time your medical practitioner asks you 'what injuries have you experienced in the past,' hopefully you will better understand the significance of such information and how it allows them to tailor their treatment plan to your own unique presentation.

Why do I insist on making sure people can touch their toes?

As a number of my client's will attest to, I am always adamant on ensuring that people can touch their toes from a standing position. "What has this got to do with my sore knee" is a common question I get asked when exposing this fundamental limitation in one's movement pattern repertoire. You see, our current knowledge of how the body works is growing exponentially. It is now widely acknowledged, thanks to the ground breaking work of pioneers in the field such as Gray Cook and Lee Burton, that the brain and the central nervous system does not tend to activate individual muscles in isolation when performing a designated movement - this would be simply inefficient and require an expansive amount of work and energy. Rather, the brain relies on movement patterns (or patterns of movement if you like). These movement patterns are developed on a hierarchical model, and are actually learnt through growth and development. As a newborn, you are lying supine. One of the first movements that your perform is cervical spine flexion and rotation (i.e. lifting your head up off the floor and looking left or right). This movement pattern then evolves into rolling left to right, as you learn to bring your arm across your body to faciltate this movement. Next, you are on your stomach - you prop up onto bent elbows and learn how to creep. This then becomes crawling. Before you know it, you can sit. Standing is the next progression. This forms the building blocks for walking, which progresses to running, etc. This is a drastic oversimplification of neurodevelopmental kinesiology - but the overarching theme here is that you need to develop one movement pattern to a proficient standard prior to progressing to the next milestone. Have you ever seen someone progress from sitting to walking bypassing standing in the process?

What does this all have to do with touching your toes??? The most common explanation I get from clients who cannot touch their toes is that their hamstrings are 'tight' and they need to stretch more. Whilst this can be true for a small minority of people, anecdotally, I find that the issue is not that of a lack of muscle length or flexibility - it's simply a 'software' issue where the client is not reflexively (i.e. automatically) engaging their core in a feed-forward manner. This causes the brain and central nervous system to adopt a compensatory strategy to ensure equilibrium when one attempts to touch their toes from standing in order to prevent them face planting into the ground. A common strategy that is employed is to activate the hamstring and calf musculature to act as 'brakes' to prevent this from occurring. The way to address this 'dysfunctional' movement pattern is remarkably simple (I will post a common strategy very soon). In essence, the client is not engaging their core quick enough (note that it is not a lack of core 'strength' - which is one of the most common myths out their today, witnessed by the number of people who implement core 'strengthening' into their exercise routine; rather it is simply a timing and coordination issue - which we refere to as 'motor control.' No amount of planks, sit-ups, crunches, etc. will get your core muscles to engage in an anticipatory manner - which is the essence of their functional role).

Now, if we reconsider the above mentioned concept of a neurodevelopmental hierarchy, the client has a core 'timing' issue whilst standing. Remember that standing forms the building blocks to walking, which is imperative prior to running and other higher level activities. Put simply, if your core is not engaging properly with both feet statically on the ground in standing, there is no way in hell it will be working properly when running - which is much higher up the movement pattern chain thanks to its dynamic alternating single-leg support nature with a plyometric flight phase between.

Take home message here: touching your toes in standing is essential for a normal, healthy and functional movement pattern repertoire. Rarely is stretching the answer (in fact, I would controversy say that stretching will likely cause you far greater harm than not stretching in this situation) - fixing the 'software' issue of a mis-firing core is the first step, prior to reintegrating this function back into your more complicated movement patterns higher up the movement tree.