Pronation and supination are commonly heard terms, often in association with fallen arches, high arches, flat feet etc. This article explains the meaning of these terms and looks in particular at the problem of over-pronation. You will read about the following:
1) What do the terms Pronation and Supination mean?
2) What exactly is over-pronation?
3) What are the consequences of over-pronation?
4) What can we do to fix the problem of over-pronation
What do the terms 'Pronation' and 'Supination' mean?
To understand the terms 'Pronation' and 'Supination', firstly we need to look at the gait cycle - that is the way we walk, or our 'walking pattern'.
The gait cycle is broken down into 3 different phases:
1) Contact phase: Firstly the outside of your heel hits the ground. This is entirely normal and it's the reason why most people's shoes wear out faster on the outside heel area of the soles. Just after the heel strikes, pronation occurs. I.e. the foot flattens out and the ankle rolls inwards. At the same time, your lower leg rotates inwards from the knee down. The pronated foot is flexible and loose, allowing it to adapt to the ground you've just stepped on. Pronation is your natural 'shock-absorbing mechanism'.
This contact phase continues until the foot is completely flat on the ground.
2) Midstance phase: The foot is flat on the ground and in this part of the gait cylce your body weight passes over your foot as the body comes forward. This is where your foot supports your body weight. The midstance phase is the part of the gait cycle where an abnormally functioning foot such as an over-pronated foot (fallen arches) or an over-supinated foot (high arch foot) will manifest its problems.
This phase ends as your body weight passes forward eventually forcing your heel to rise off the ground. At this stage supination occurs and the opposite to pronation happens: the muscles tighten and the foot becomes a rigid lever for the leg muscles to pull against. Rigidity in the foot should occur as the foot is propelled forward towards the next step. With supination, the foot rolls outwards and the lower leg rotates externally.
3) Propulsion phase: this is where the foot pushes off the ground to propel the body forward. Body weight is picked up by the ball of the foot and lastly the weight is absorbed by the big toe as you push off with that foot.
It is important to understand that both pronation and supination are part of a normal, healthy walking pattern! Pronation (rolling inward) acts as a shock absorbing process and supination (rolling outward) helps to propel our feet forward.
What exactly is over-pronation?
Over-pronation occurs when we pronate too deep and for too long, not giving the foot a chance to 'recover' and supinate. The foot stays flexible at all times. Over-pronators use a lot more energy when walking. Worse, over-pronation causes an imbalance throughtout the entire body, putting excessive strain on the feet, legs, knees and lower back.
Other terms for over-pronation are 'fallen arches', 'dropped arches' or 'collapsed arches'. The term 'flat feet' is also often used. However, a true 'flat foot' is very rare. In fact, less than 5% of the population have completely flat feet (Pes Planus) with no arch present whatsoever. Most of us (90%) have a normal to low arch and only 5% have a high arch. People with a high arch (Pes Cavus) are also called 'over-supinators'. This means that the foot stays rigid at all times and lacks its natural shock-absorbing mechanism.
It's important to appreciate that you don't have to be flat-footed to suffer from over-pronation! In fact, the vast majority of people with a 'normal- to-low arch' suffer from over-pronation. Interestingly, the arches may appear quite normal when sitting (or even standing up-right), but when we start to walk the problem of over-pronation becomes evident...with every step we take the arches collapse and the ankles roll inwards.
Over-pronation can be caused by a number of factors. Weak ankle muscles, being over-weight, pregnancy, age or repetitive pounding on hard surfaces (like pavements and concrete floors) can all lead to over-pronation. Over-pronation is also very common with athletes, especially runners.
What are the consequences of over-pronation?
Whether you have a true flat foot or have a normal-to-low arch and suffer from over-pronation (like 70% of the population), in both cases your poor walking pattern may contribute to a range of different complaints.
Many people over-pronate, however there are no clear symptoms, no aches or pains or complaints - especially in younger people (under 40's).
When people reach 40 or 50, poor foot function will start to show and over-pronation will take its toll. Many years of over-pronation will result in wear and tear in the feet, ankle and knee joints and lower back. People will simply accept these common aches and pains as a sign of ageing. Very few people realise these complaints have a lot to do with their fallen arches!
So what are the most common complaints related to over-pronation?
Plantar Fasciitis is a very common condition caused by over-pronation. As the feet flatten, the Plantar Fascia (fibrous band of ligaments under the foot) is being overly stretched, leading to inflammation in the heel, where the fascia attach to the heel bone. Plantar Fasciitis causes chronic heel pain and sometimes a heel spur develops (bony growth at the heel bone).
With over-pronation the foot continues to roll inwards, when it should be pushing off and outwards. When the foot rolls inwards the lower leg will follow and rotate internally and stay in this position (instead of rotating externally with supination).
This puts a lot of strain on the leg muscles (especially the calf muscles), causing aching legs and shin splints. Also, the twisting of the lower leg displaces the patella (knee cap). The knee is a hinge joint, designed to flex and extend (like a door, if you like). It's not designed to rotate!
Furthermore, when the legs rotate inwards the pelvis is forced to tilt forward. This results in constant strain and stress on the lower back muscles.
What can we do to fix the problem of over-pronation?
There is no real cure as such for over-pronation, however a lot can be done to prevent it. The most effective way to minimise over-pronation and its effects on the body is by wearing orthotics inside the shoes.
An 'orthotic' (orthotic insole, shoe insert or orthosis) is a device placed inside the shoes with the purpose of restoring our normal foot function. Different types of foot orthotics are available, from special custom-made devices (prescribed by a Podiatrist) to so called 'off-the-shelf' orthotics which can be purchased from pharmacies, good quality shoe stores or specialty websites.
Orthotics correct the problem of over-pronation and they re-align the foot and ankle bones to their neutral position, restoring our natural foot function. In turn, this will help alleviate problems not only in the feet, but also in other parts of the body!
In addition to wearing an orthotic, it is recommended to wear supportive shoes with some degree of built-in 'motion control'.
Motion control shoes incorporate support features into the shoe. Shoes with adequate arch support and firm heel counters help control over-pronation and will stabilise the heel and ankle during walking. Some shoes also have side posts for extra lateral support. Firm midsoles reduce pronation and protect the ankles and knees from lateral stress. The inner side of the midsole may be made of a denser material (dual density midsoles) to reduce the amount of pronation. A heavy person who overpronates will need a heavier, more supportive shoe than a light person with the same degree of pronation.
Too many shoes these days are using soft materials all-around the shoes and are very 'floppy' giving no support or stability whatsoever. In summer, many people wear open footwear such as sandals and flip-flops which are even worse in biomechanical terms.Over-Pronation, Fallen Arches and Flat Feet
Peter Van Dyke is a Dutch foot specialist and orthotist with a special interest in heel pain , heel spurs, Plantar Fasciitis and orthotics. He gives advice on effective remedies to help relieve aching feet and prevent further problems. He also works closely with a number of large orthotics manufacturers in Europe, the USA and Australia.