This article was first published in Ryding2Health Magazine in 2011 and is the first time it has been on my blog. I've made some small edits which I never had the chance to do first time round, so hopefully it reads better!
As always please feel free to comment.
Pronation is a subject close to many a podiatrist’s heart and traditionally the focus of treatment in many biomechanical pathologies.
Patients regularly tell me that they “pronate too much” or that they “overpronate” and that their feet are “flat”. In my experience, the main group of patients who consider pronation more than many other groups are runners.
I suppose the question is; is pronation really a bad thing?
Let’s begin with identifying exactly what pronation is, and when it occurs.
Pronation is a three-dimensional movement occurring at the subtalar joint in the foot. Sounds simple enough, but don’t be lulled into a false sense of security; podiatrists undertake three years of study to understand it and relate it to an individual’s biomechanics and that’s just the beginning!
Now before I get inundated with corrections, I know that pronation also occurs in the arm too; but I’m a podiatrist and I only really get to play with feet and legs. For more information on the arm you’ll need to talk to your local physiotherapist.
When pronation occurs, it allows the forefoot to abduct (move away from the midline of the body) upon the rearfoot, dorsiflex (or lift upwards) in relation to the rearfoot, and evert or flatten the arch of the foot. The overall view of a foot in pronation is that of a “flat foot”.
The opposite of pronation is supination and when the foot becomes more supinated it takes on a “high arched” profile.
The diagram shown above (taken from Michaud (1997)) shows both pronation and supination movements.
Now, both of these movements are essential and we use both as part of normal “gait". As a general rule, when walking the foot strikes the ground in it’s supinated form, becomes pronated to shock absorb the body forces upon the ground, and the becomes supinated again prior to lifting of the ground so as to provide a rigid leverage force to move to the next step.
So is pronation bad?
On the whole pronation is not a bad thing; it’s a necessary movement required for normal ambulation, be it walking, running or your activity of choice. Interestingly there have been many studies examining the link between pronation and injury and most show that there is little relationship between injury and pronation (those which do show a link are pretty weak).
Pronation is key in providing shock absorption as the foot makes contact with the ground and then body-mass continues in a downward direction. These movements require a very complex interplay between joints, ligaments, muscles and the forces acting upon these structures.
Often this will become imbalanced when the forces cannot be controlled or opposed by the body, leading to compensation and then injury.
My role is to examine areas of compensation and injury and identify the causative factor. This involves looking at the forces acting upon the foot from internally (muscles, ligaments, joints, etc) and externally (footwear, the supporting surface, orthotics) to ensure that a balance is struck. There are a number of tests that we use clinically to look at how easy (or hard) it is to move the foot from a maximally pronated position to a supinated position.
These forces change when different activities are undertaken; running, has much greater forces affecting the foot and leg in comparison to walking.
When it comes to pronation, the movement isn’t such a bad thing, it’s the forces that hurt and cause damage. My treatment involves the reduction of these pathological forces and this can involve the use of exercises, footwear, orthotics and mobilisation.
So what about running shoes?
Okay, you were always going to ask. Running shoe design, prescription and personal choice is based on the idea of levels of pronation. And while this is flawed it is really all we have. However, this will change in the future with some interesting and potentially game changing designs coming from Asics and other companies.
A very experienced and knowledgeable Sports Podiatry colleague, Ian Griffiths, wrote an excellent blog regarding running shoe prescription and I would urge you all to go and have a look. It surmises the issues and research perfectly. You can find the blog post here http://www.ransacker.co.uk/running-shoes/goings-on/what-running-shoes-should-you-wear-the-myths-busted/.
This article is a designed to be a quick look at a very complex subject and in essence doesn’t cover everything. Contemporary research is continuing to challenge current and past dogma leading ultimately to a greater understanding of lower limb biomechanics. Personally, I think it's a very exciting time for anyone working in biomechanics.
Michaud, T (1997) Foot Orthoses and other forms of conservative foot care. Newton, Massachusetts.