Overpronation is one of the most frequently used terms I hear in fitness. This is from both trainers and clients. The plethora of pronation control shoes has plucked the word from the world of anatomy and physiology and biomechanics into everyday terminology.

Although the word is widely used it is not widely understood. Overpronation can happen in many ways and for multiple reasons but is generally used as a generic term and no more attention is paid to it.

Lets first define pronation. It is the triplane action of dorsiflexion, eversion and abduction at the rearfoot.  These joint motions are relative to the bone motion of the talus which is the primary moving bone in a closed chain scenario. This rearfoot motion will also create relative forefoot dorsiflexion, inversion and abduction. The forefoot can have quite an impact on rearfoot pronation that we will talk about later in the blog!

Now lets look at the different ways in which we can overpronate.

1. Range-I think this is the "classic" definition of overpronation. The amount of distance that the joint goes through. Obviously far too much range places stress on the joint and muscles all through the kinetic chain of the lower limb. The associated tissues have to work hard to control the excess range. Common problems that can arise are posterior tibialis syndromes, Achilles problems and ITB problems.

2. Rate-Along with range goes the rate or speed/acceleration of pronation. The larger the range, the more distance to accelerate into. This again causes problems for the muscles/tissues that have to decelerate this increased acceleration.

3.Sequence-This is the most overlooked element of overpronation. Pronation should occur at initial heel strike and be followed by supination. If the range and rate are excessive then the foot is unable to reverse the motion in time to go into supination. This means that someone may pronate through midstance and also through the propulsive phase of gait. If any of the motions associated with supination are restricted it may also lead to a return to pronation late in the gait sequence.This can also be because of the instability created by the pathomechanics of different foot types. This can lead to plantar fascia problems and HAV bunions as the foot remains in its unlocked mobile state rather than becoming the rigid propulsive unit that the supination process creates.

The question most often overlooked when it comes to pronation problems is WHY??           A good knowledge of foot dysfunction is required to really answer this question. The most overlooked area in my opinion that causes pronation problems is ontogenic (developmental) forefoot positioning relative to the rearfoot. However I am also really interested in the spatial location of the STJ (subtalar joint) axis. The medial  deviation of the STJ will increase the moment arm of GRF (ground reaction forces) associated with pronation and decrease the moment arm of the supinatory muscles. It will also increase the area of the foot laterally to the STJ that  cause pronation to happen when force is applied. The lateral deviation will do the opposite with more internal muscular supinatory force and decreased GRF pronatory force occurring and increased medial area of the foot that will cause supination.

Anyway, back to the forefoot!! An inverted or varused forefoot position will be compensated for at the rearfoot by excess pronation. Another scenario is that the foot is able to get into supination but the extra instability of the varused forefoot causes a pronation response to get the forefoot on the ground and create stability. This would happen late and out of sequence in the gait cycle. This means that just controlling the longitudinal arch as many pronation control shoes do, does not gain quite the control anticipated.

Many times I also see short or half foot orthotics. These orthoses have arch control but do not provide stability at the forefoot. This is done by bringing the ground up to the foot, to stop the foot trying to search out the ground. Without the forefoot control I see the foot unable to pronate to compensate because of the arch control, instead using the transverse plane to rotate the foot and tip onto the forefoot. This maybe a reason behind a medial heel whip!! A similar thing can happen when the STJ axis height is high and favours transverse plane motion over frontal. The STJ axis height should be around 42 degrees from the transverse plane, slightly favouring frontal plane motion.

I realise this a bit of a big post, but is also a really big subject. Much more complicated than many give it credit for, so thanks for reading. Until next time....

Ben Cormack

I have read so much recently about barefoot training/running and the amazing ability of the foot. While a lot of what I read tends to have many elements of scientific truth to them I don't think the people writing them always have an understanding of the foots effect on the system as a whole.

Barefoot training seems to be heralded as a "one size fits all" fix to whatever problems people have. Suddenly shoes have become the pariah of human function. Understanding the function of an area of the body is important however we seem to do this only in an "ideal" sense. If A + B = C, then everything would be fine, we could take our shoes off and never have any problems ever again. If we look back however at every other amazing resolution that has been thrown at us over the last 10 years and take stock, we still have people with the same problems seeking help.

Maybe a key to this is understanding dysfunction. Only by having knowledge of the many things that can affect the foot to disrupt its success can we truly find an answer. Lets look at an example. On a localised level the foot will create an environment that makes it successful. This however may not be successful for the system as a whole. A Varus deformity of the forefoot will 99% of the time cause the foot arch to collapse, if it is able to compensate then the forefoot will stop the body having a top down influence on the foot (which will also cause a bottom up inhibition!). This creates a success of stability at the forefoot but will reduce motion elsewhere in the functional chain. Now the question is will taking my shoes off help this??

The are a few points to the answer of this question (which I am not totally sure I have the answer to!!). Firstly a shoe might limit the range the STJ goes through to get the Forefoot to the floor improving joint start position, motion and systemic influence. Much has been made of the cushioning affect of footwear on proprioception.  While this maybe true, in the example of the Forefoot Varus however, a reduction of force maybe advantageous to a system that cannot attenuate force through muscular deceleration because of joint position or osseous restriction. This can lead to shin splints, stress fractures and forces being absorbed by structures further up the functional chain. A point going one step beyond would relate to more sophisticated interventions such as orthosis. Now by creating tailored stability to enhance the success of the system we will improve the environment around the foot that barefoot training cannot do. This is because the dysfunction of the foot will not allow it. If I could simply tell people to run and train barefoot and all these problems would go away then believe me I would!!! We need to go back to the principle of individuality that tells us that no one thing will work for all. Only by individual assessment and also understanding of why and how things go wrong can we find the appropriate cure.

This brings me on to my favourite quote by Betrand Russel:

"The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt"

Now I would not regard anybody as stupid in the context of the topic of this blog but sometimes those that lack an understanding of dysfunction can tend to make bold or "cocksure" statements regarding "cure all" methods of training!

This brings me on to my second topic in this rambling blog. This relates to a conversation I had recently with a very intelligent Osteopathic friend of mine. We were talking about dysfunctions in the system and the use of interventions such as orthosis. He did not seem convinced about the need for such things. I do certainly agree that the body has the ability to "heal" itself to some degree. However my belief is that when we factor in scenarios such as short legs (a favourite topic of mine) that the body in certain cases (generally people with problems) cannot overcome them. Factor in changes in training e.g. running a marathon, and this tends to become to much for the system to deal with leading to pain. Now the demand on the tissue has become to great and keep up with change in function we need to create a better environment for the body or cease the increase in activity.

I suppose the real question is can we as practitioners create a systemic change that is able to cope with the structural deformities presented to us through manipulation and exercise. Of course the answer maybe yes in some examples, then the question would be how long would that take and what level of activity could they continue to do. Many times I believe the answer is no, foot deformities being a good example, the localised problem can cause to big an influence on the chain reaction of the system that cannot be "compensated" for anymore or allow us to increase demand such as training on the system. We cannot change bony orientation or length and the muscles and connective tissue cannot cope with the demand any longer, this is why we have many cases that are chronic (for years even) until we can find the problem in the system that is causing various chronic problems. Many time the only way to solve these structural problems is to add in a structural intervention!!!!

I am sure this will be controversial but I believe good debate is something we can all learn from if we are less "cocksure" at the risk of sounding cocksure of course!!!