Pronation Explanation

For most runners, by the time you've run your first 5k, you've probably heard the term pronation a dozen times or more. It may be the first time a biomechanical term is used to describe your running when getting fitted for a new pair of shoes. What does pronation even mean? It isn't clear if you should be offended, excited, or concerned. In my earlier running days, I'm not sure I was ever told what pronation was exactly, nor any of its implications. 

Gait analyses are performed every day with hundreds of runners or running athletes eventually labeled as pronators, supinators, over-pronators, etc. What's the significance or value of such an appraisal? What's the implication? Is this the best basis for shoe selection? How much pronation is too much, and what does research tell us about it? The answer to these may surprise you. 

My name is Dr. Allan Buccola, PT, DPT, and this post explains pronation and all its amenities. What is pronation, what are the subtypes, and does shoe selection really make a difference. If you are a runner, this article is a must-read, but don't turn away just yet, to all you non-runners. Pronation occurs during walking too and is potentially more relevant to non-running footwear and activity. 

What is pronation? What is supination? 

Pronation is a term describing a set of movements that occur in the ankle/foot from the moment the foot hits the ground to the moment it leaves it. The simplest definition of pronation is 'a transition from the outside of the foot to the inside of the foot during gait.'

Pronation occurs during both heel striking and forefoot striking. The above shows a neutral progression of pronation in both heel striking and forefoot striking individuals. 

Pronation occurs during both heel striking and forefoot striking. The above shows a neutral progression of pronation in both heel striking and forefoot striking individuals. 

Pronation is one of the major ways that the foot/ankle attenuates impact forces during gait. Even in it's mildest form, it is easy to understand this movement during easy walking wherein a heel strike occurs at the outside of the heel and the foot pushes off through force through the big toe. This may not ring true for everyone reading this, so keep reading as variations are discussed below.  

Supination could be considered the opposite of pronation: a transition from the inside of the foot to the outside of the foot during gait. It is far less typical to see a heel strike on the inside of the heel, but it is commonly seen in people who walk/stand with a wide stance,  have weakness and/or joint laxity at the ankle, or in those with flat/rigid archless feet. It also tends to become more prominent as adults age into last decades of life, often resultant of degenertaive changes at the knee and hip joint, or simply due to progressive weakness. 

Supination

Both pronation and supination occur within a wide continuum of movement, but the foot movement considered most 'neutral' would show a mild amount of pronation. Heel strike most commonly occurs at the outer, mostly central part of the heel, and the push-off forces drive through an imaginary line between the first two toes. 

There is a large body of evidence correlating supination and pronation with various injuries related to walking/running, however moving from a correlation to identifying causation has been more difficult and complicated. From a pure biomechanical perspective, as the foot pronates or supinates, it sets the stage for what happens next at the knee, hip, pelvis, and spine.

Be that as it may, posturing and function at the core, pelvis, hip, and/or knee can also change what is going on at the foot and ankle. This is what makes causation difficult at times, and in the presence of  injury or pain, it's essential to discover which end of the system is out of balance. 

'Overpronator': What's the implication?

It is without surprise that foot mechanics have been shown to play some role in certain typical hip and knee injuries. I would argue that this relationship has been overemphasized in the public psyche, hence the knee-jerk reaction to look for a new running shoe when the knee or hip starts to hurt. This would be equivalent to changing the tires on your car, each time you have some engine trouble. 

Several common lower extremity injuries occur simultaneously with excessive pronation. Some examples would be plantar fasciitis, patella pain, iliotibial band pain, and hip bursitis: all correlated (statistically speaking) with 'overpronation.' Whether pronation be the cause, effect, or unrelated is the real question, and likely varies from person to person.  

Unfortunately, it is difficult to quantify exactly how much pronation is too much, especially between two individuals. It is also unfortunate that humans have such great variety in hip joint and ankle joint alignment, as it makes it difficult to study these things and find a universal recommendations for running/walking form that will work for everyone. Many athletes have 

Not all pronation is created equal 

As mentioned above, pronation is a movement that takes place throughout the ankle and entire foot, however, human movement experts may find value in isolating the movement to a singular part of the foot. This can often be a critical component in determining how to address this issue with a patient and how likely they are to respond to different interventions. Let's take a look at those now.

Rearfoot Pronation:

Rearfoot pronation refers to pronation at heel strike specifically. The heel hits the ground with greater pressure on the instep of the heel than the outstep. In the textbook progression of the foot during movement, heel strike occurs in moderate to high levels of supination (hitting the ground at the outside of the heel), hence even a mild shift to the central portion of the heel can be problematic. This is often easily seen in excessive shoe sole wear on the instep of the heel. 

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Rearfoot pronation reduces the natural, typical supinated heel strike that is so critical in attenuating impact force during running. It is often related to a lack of ankle dorsiflexion range, weakness in the ankle dorsiflexors like tibialis anterior/posterior, and is commonly found in patients complaining of plantar fasciitis.

Rearfoot pronation is typically found in people that are obese, have a high degree of general flexibility, and those who frequently utilize a stance width wider than their hips. This is often related to laxity or alignment issues in the ankle joint, especially when on both sides, and can respond well to medial wedging (medial wedging) when done properly.

Midfoot pronation

Midfoot pronation is probably the most typical type of pronation seen across populations. It can present in a few different ways, but for the purposes of this post can be though of as arch collapse. You may see it referred to as 'medial collapse' which is a phenomenon that includes the entire leg (ankle/foot/knee/hip included) collapsing medially (inward) with each step. 

Medial collapse is common but not exclusive to individuals with higher arches. It is often mediated by weakness in the ankles, often tibialis posterior, but weak peroneals and/or calves can also play a strong role. Individuals with limited mobility in the ankle may selectively perform medial collapse as a means for moving around a stiff ankle restriction.

Pronation in this part of the foot demonstrates some greater global effects because as the arch collapses, it causes the tibia to rotate one direction and the femur to rotate the opposite. This can contribute to a number of knee and hip injuries, including meniscus tears, ACL ruptures, IT band syndrome, and trochanteric bursitis. 

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Midfoot pronation is likely not abated to any significant extent by a 'pronation control' shoe. Be that as it may, pronation control shoes may reduce some of the pronatory stresses that translate to the knee and hip, but the evidence on this is mixed and long-term effects unclear. 

A more traditional approach to addressing this is to provide some arch support to physically support the arch, either through an off-the-shelf orthotic, a custom orthotic, or specialty footwear. This too has not been shown to consistently be an effective strategy in the research. This may partially be related however to another study that shows a drastic contrast between practitioners in orthotic prescription. In other words, when several professionals looked at the same foot, their recommendations were all completely different. 

Although there may be some benefit to using an orthotic insert to address pain often related to this excessive midfoot pronation, it may not be as expensive an option as one might think. One study  actually found that prefabricated orthotics are just as effective as custom ones, which is good news for your wallet, but given overall modest success rate, orthotic inserts still might not be enough for resolving your pain.

Many patients I work with report orthotic inserts with arch support to be quite uncomfortable, especially as a first-line treatment for plantar fasciitis. In the setting of problems propagated by excessive midfoot pronation, I almost always start with strengthening these muscle groups. This may sometimes be combined with some insole modification. Once strength is acquired, motor control training is often the next step. If an orthotic insert is included, the goal is for it to be assumed a temporary device with strength is being developed. 

For patients whom strengthening may not be immediately successful, an orthotic insert can provide some much needed assistance, or even some temporary relief during the strengthening phase. Typically, an orthotic insert is not something that I look to place patients in for the rest of their days, unless there is some anatomical limitation that would warrant that (surgical fusion or athrofibrosis) or a progressive neurological disease. 

Forefoot pronation

Forefoot pronation is a movement taking place in the ball of the foot and toes during the push-off or 'toe-off' phase of gait. A neutral push-off demonstrate the foot rolling off of an imaginary line between the 1st and 2nd toe. Forefoot pronation occurs when excessive toe-off occurs through the big toe and/or the joint behind it. 

forefoot pronation

There can be several precipitating factors that lead to this, including arch weakness, ankle weakness, weakness in the glutes, and many others. If a person tends to walk with and excessive amount toes pointing outward, this further adds loading to the inside of the foot, although this is not always problematic in the setting of adequate strength and appropriate level of activity. 

Recently I have had a great deal of patients with excessive levels of forefoot pronation that was playing a role in plantarfascia pain, as well as bunion development, and hallux rigidus, a painful condition wherein the first metatarsal joint becomes stiff and painful. 

When is Pronation Excessive? 

This is a difficult clinical question to answer. In the gait of a developing child, pediatric specialists tend to see excessive pronation/supination as part of a disease process, often neurological. In this situation, the emphasis lies in restoring neutral alignment as much as possible for the healthy, natural development of bones and joints for growing kids. There may also be a goal to improve mobility and pain in these patients. 

In uninjured or pain-free runners, gross asymmetry can sometimes be a good indicator that excessive pronation is related to some dysfunction. It is not always advisable to correct an asymmetry in the absence of localized pain, however if adjacent tissue injury is involved, excessive pronation may warrant correction. These decisions are best left to trained human movement experts.

There are situations where excessive pronation can be directly traced to weakness at the ankle, hip, or knee. In these cases, excessive pronation isn't the primary concern, but rather indicative of some breakdown in the kinetic chain above. These secondary biomechanical changes can often be assumed to become more exaggerated over time unless these strength deficits are addressed. Addressing this pronation exclusively at the level of the foot may be part of the solution but failure to address the deficits above will prove futile. 

As we remember that pronation is a normal movement pattern use to attenuate impact forces during gait, it should come as no surprise that have too little or none at all can also cause some problems. For runners that tend to spend more time on the outside of the foot (excessive supination), an additional set of problems may come to follow, including stress fractures along the 4th and 5th metatarsals. 

The Role of Running Shoes and Orthotic Inserts

The application of running shoe type to specific gait style has been the standard retail intervention for years now. This move as a first line of defense is so ubiquitous that upon emergence of pain, most novice runners automatically assume that the shoe is the precipitating factor. Not often enough are professionals like PTs consulted to assess biometrics such as strength, flexibility, joint mobility, etc. 

The ability of research science to identify a running shoe's ability to manipulate biomechanics has been limited. There is good evidence to support the notion that fitting a runner to a specific shoe type has no effect on reducing injury incidence. So why do runners have such strong preferences for shoes? There may be something more to comfort than once previously thought.

Research findings are full of apparent contradictions but the devil is in the details. It can be difficult to connect laboratory parameters with real-world scenarios. Another problem is that there are more than 100 name brands of running shoes, without any standardized definition of 'neutral cushioning,' 'motion control,' or 'pronation control.' These labels offer some indication of what the shoe is designed to do, but to what degree is questionable. They arguably exist to more to assist sales persons more than actual runners. 

Even within a single brand there may exist 5 different models of pronation control shoes that are vastly different and between 2 different brands it becomes difficult to compare the differences and similarities. What is more perplexing is that in spite of technological advances in the running shoes of today compared to those of our parents' and grandparents' generations, relative rates of running injury remain essentially unchanged since the 1970's when data was first collected.

The prescription of running orthotics has been equally disappointing. Aside from the wide variety in opinion in what type of orthotic is ideal, the ability of manipulative footwear inserts to change running/walking biomechanics has been mixed at best in the laboratory. The limitations in this area warrants a dedicated blog post. 

The most common errors I see when I have a new patient presenting with an older orthotic insert can be simplified down to two common ones. Often the orthotic has been made with a poor choice of materials, typically a foam that is too soft to create any desired effect during the high loading forces of walking or running.

The second error stems from the orthotic being designed with the intent to control too much of the foot from arch support. In many cases, arch support alone is not the best approach at controlling pronation at the forefoot or at the rearfoot. In attempts to more adequately use arch support in this way, excessive arch support must be created which causes additional problems for the patient and is often uncomfortable. 

The purposes of this article does not include gratuitous detail about orthotics. Be that as it may, the topic of pronation cannot be discussed without an honorable mention. I tend to view orthotics in the same light as a neck brace: a temporary tool to provide some structure, support, and feedback during movement, but only while the strength, mobility, and motor control of the system are being rehabilitated.

When a patient sustains a neck injury, never are they asked to wear a neck brace for the rest of their life. There are instances wherein the patient may require a surgical intervention to immobilize joints in the neck, but even these patients often require some rehabilitation to restore movement and function in the system. In a similar light, there is a small minority of patients for whom lifelong orthotic use might be warranted.

Making the Right Choice

The human brain is notoriously efficient, almost to a fault. When it comes to performing a task, the brain always tries to take the path of lease resistance, the highest level of economy. In running this is especially true. Once a motor pattern has been developed over hundreds to thousands of miles, any deviation from this pattern means additional effort both neurologically and mechanically. 

It is from this foundation that some researchers propose the mechanism for shoe preference may emerge: the shoes that 'feel best' are the ones that create the least resistance to one's established running motor patterns.  The question that has yet to be answered is whether this is protective against injury, but I can say with confidence that when I meet a patient who has run in the same shoe for multiple years, making a shoe change is typically last on my list of interventions. 

In your running endeavors, be mindful of your shoe selection and your successes, but also be aware that bodies change over time. What once was not a problem may now be the straw that breaks the camel's back. Follow these tips for the utmost success in shoe selection:

1. Use the experts at your local running store to properly fit your feet for a shoe that is appropriate.

2. Consider the use of an off-the-shelf orthotic as needed for minor complaints, but those that do not resolve warrant detailed evaluation to assess any larger underlying issues. 

3. When you are consistently having difficulty with foot pain or shoes, seek the guidance of a physical therapist or other qualified human movement specialist. A good PT will assess the structure of the foot, but also the function of the foot, and the rest of the kinetic chain. 

4. Be weary of any solutions offered by providers who do not thoroughly evaluate your walking/running gait, strength, and joint alignment. A failure to be thorough often leads to prolonged pain and wasted money. 

5. Don't believe the hype. There are many tall tales out there about magical therapies that are a cure-all for persistent problems: lasers, needles, injections, etc. All of these modalities are palliative at best, but rarely are they the sole solution to any particular problem.

Always remember that there is no substitute for an in-depth examination, and the best solution often requires the problem being addressed from a couple of different angles. You may need to change up your training, or modify your activity, but ultimately, time is a much needed and often forgotten component as well. 

Until next time: don't stop moving! 

-Allan