Imagine a world with no hard, flat, or concrete floors; or workers not having to keep extended hours while standing around greeting customers with unyielding non-supportive shoes. Keep in mind that originally, man had sandy beaches and grassy plains to walk on. What a wonderful feeling! Sand between our toes and soft grass comforting every step. The foot was able to do what it needed to do naturally and without effort or painful results. Now with man-made hard flat floors, grueling schedules and fashion shoes, the foot must accommodate to the hard flat surfaces instead of the soft adaptable ground yielding to the foot. Mother nature did not have this in mind when the foot was designed.
As a result, we all work much harder doing what should be the easiest, most natural activity, walking and running. As our feet go into contortions to meet the solid, stiff, and rigid ground, unhealthy pressure is imposed back to our joints in the foot, ankles, knees, hips, back and neck, creating poor posture, bad body mechanics, as well as stress and pain all up and down the body. OUCH!
Why does this happen? The answer lies in the problematic motions of the feet. These motions that become abnormal are termed PRONATION AND SUPINATION.
The Problem: Too Much or Too Little Pronation and Supination
Throughout my podiatric medical career covering over 50 years, I have always been interested in identifying, diagnosing, and then treating the root causes of foot problems that are most commonly seen, not only in my own practice, but for that matter, any medical office involved in treating feet.
The most common painful foot problems that people seek help for are:
- Plantar Fasciitis
- Heel Spur
- Neuroma Pain
- Bunion deformity
- Hammertoe Deformity
- Painful Ingrown nails
Well guess what? The most common denominator to all these painful foot problems is a form of motion sickness…. No!!! Not the kind of motion sickness where one gets dizzy. What I am talking about is a problem with the motions of the foot where there is too much or too little pronation and/ or supination. This destructive abnormal motion is initiated when the foot hits the ground and is programmed to be abnormal throughout the gait cycle. This abnormal motion triggers a posture of the whole body that attempts to compensate for the imbalance that results from these abnormal foot movements; and hence abnormal firing of the small muscles in the feet as well as the larger muscles that attach to the feet and the rest of the body.
The net effect of this abnormal motion is that it creates stress in all the weight bearing joints up and down the whole body (throughout the kinetic chain); and this compensation is responsible for irritation of structures and causes imbalance and pain. Thus, it is easy to see, how abnormal pronation and supination turns out to be critical in the development of these most common painful foot problems, not to mention its contribution to ankle, knee, hip, back, neck and shoulder complaints. It is interesting to note that it works the same way if part of your body north of your feet is off balance, it is likely to cause this abnormal pronation or supination.
Before we explain more about this destructive motion sickness, of the feet, if you will, let us exact a more definitive definition of PRONATION AND SUPINATION.
Definition Of Pronation
Pronation: This is a normal and natural movement of the whole foot, and also the joints inside the foot, when undergoing a weight-bearing activity such as walking or running. These movements take place because of motion at key joints in feet, such as the subtalar joint and the midtarsal joints, which in turn affects the motions of the whole lower extremity. This takes place at specific parts of the gait cycle, (or a person’s stride), causing the foot to move in three different directions simultaneously:
- Eversion, or movement which moves the sole of the foot outward,
- Abduction, or movement that forces the foot at the ankle to point outwards away from the midline of the body and
- Dorsiflexion, which is movement that drives the foot and toes to point upward.
This technically is called closed-chain pronation when the weight-bearing forces a resistance to the ground. (Open chain pronation is when you are not weight-bearing and there are no ground forces to resist and is not relevant to this conversation.)
When Do We Pronate?
In the normal gait pattern, we pronate after the heel hits the ground and this motion lasts until the foot is almost hitting the ground flat. A normal foot does not pronate beyond this contact phase.
Definition Of Supination
Supination: This is also a normal and natural movement of the whole foot, and also the joints inside the foot, when undergoing a weight-bearing activity such as walking or running. This movements take place because of motion at key joints in feet, such as the subtalar joint and the midtarsal joints, which in turn affects the motions of the whole lower extremity. This takes place at specific parts of the gait cycle, (or a person’s stride), causing the foot to move in three different directions simultaneously:
- Inversion, which moves the sole of the foot inward toward the midline of the body,
- Adduction, which is a movement that forces the foot at the ankle to point inwards toward the midline of the body and
- Plantarflexion, which is movement that drives the foot and toes to point downward.
This is the opposite of the movement that place in pronation. This technically is called closed-chain supination. (Open chain supination is when a person is not weight-bearing and there are no ground forces to resist and is not relevant to this conversation.)
When Do We Supinate?
In the normal gait pattern, we supinate with the onset of when the whole foot is in contact with the ground, in the middle of the walking cycle (called the midstance phase of gait) and continues until just before the toes leave the ground. The foot remains supinated throughout the swing phase of gait.
The Normal Foot
How Should The Foot Work? Mother Nature’s Design
The normal motion of the foot is delivered through a dynamic process that starts when the foot hits the ground, and the body weight is distributed from the heel to the toes as the gait cycle progresses. The Gait Cycle consists of the following phases of walking for each foot: Heel Contact, Midstance, Toe Off and Swing. (See Figure 1)
It’s important to note that there are 26 bones to the feet and when all the bones fit together and are in their anatomic “jigsaw puzzle position”, (the neutral position of the foot), and as the foot hits the ground, the bones self-lock together much like that of the parts of a jigsaw puzzle when put together. The foot is very stable when this happens and this stability allows for very efficient functioning of the foot. The textbooks call this the Stable Lever Effect. To further understand this let us review a few terms and concepts.
First off, it should be pointed out that the health of the walking pattern is proportional to how the foot adjusts through the different phases of gait. That is, how the motion of the foot is distributed over the course of the time your foot is on the ground and if the stable lever mechanism is activated or the foot is just a bag of bones which in turn will determine if someone has a healthy pain-free gait. It should be emphasized that pronation and supination are movements that takes place in the foot that are intended to absorb shock, allow for ground terrain changes, establish equilibrium and balance as well as translate the various motions from the body and leg to the foot. The motion begins as soon as the foot hits the ground. This is called the Heel Contact Phase, (See Figure 2) where the foot begins to pronate; and then goes into its neutral position and then starts to supinate at the Midstance Phase, where the bottom of the foot comes in contact with the ground. The health of all the joints impacted by walking, (called the Kinetic Chain i.e. the ankle, the knee, the hip, the back, the shoulder and neck) is dependent on the proper functioning of this mechanism. For instance, the inability of the lower limb to convert these dynamic pressures into productive motion, can be very destructive to the whole body.
When Can Pronation and Supination Be Harmful?
The Cause Of Over and Under Pronation, Under and Over Supination
Depending on the shape of the foot, the angle at which the foot hits the ground, (determined by the shapes and angles of the leg, knee, thigh, hip, spine and neck) the ability of the joints inside the foot to move, i.e., stiffness from arthritis, inherited limitations of the joints, results of trauma, or inherited anatomy, this will determine how aptly the foot is able to meet the ground and compensate for any imbalance or pressure. A major consideration here, is that the amount that the foot needs to move in order to meet the ground (to balance all the aforementioned factors), must equal the amount of movement the foot can healthfully provide. For instance, if the heel of the foot hits the ground at 12 degrees tilted, but the foot can only pronate 6 degrees, this struggle will adversely affect the rest of the foot hitting the ground and cause stress, strain, and pain.
In a different scenario, if the heel is able to come to the ground properly but the rest of the foot is still tilted or a body imbalance needs to be compensated for, then the foot will over pronate. Likewise, too much or too little supination can happen with different postures of the foot traveling through the gait cyle. Thus explains the causes and reasons for over and under pronation and supination.
How Does Over And Under Pronation And Supination Translate To Causing Common Foot Problems
There are basically three pathways this cause these problems
Over and under pronation and supination means that the joints that are designed to dissipate pressure and shock are not functioning optimally and therefore not absorbing the pressures of the foot hitting the ground correctly.
There are many different types of forces and pressures at work here. Basically, however, there are 3 types of pressures that must be dealt with here and are negatively affected by abnormal pronation or abnormal supination. They are
- Direct pressure, that is the pounding pressure or blunt force that develops mainly in the heel, merely from the body weight when the foot hits the ground. This is responsible for a lot of bone pain in the heel and also a common type of callus that exhibits a core, called a nucleated keratoma.
- Shearing pressure, that is the tearing motion which exists when one part of the foot, usually the forefoot is planted firmly while another part of the foot moves to establish balance. Shearing forces occur between the internal body structures and skin tissues typically moving in opposite directions and may lead to deep tissue injury. In the foot Shearing is a primary cause of some calluses on the bottom of the feet called dispersive calluses.
- Friction pressure, that is injury that takes place when one surfaces rubs against another, in the case of the foot the injury is to the skin, and usually shows up as redness, irritation or blister. The Blister is a friction injury that occurs when the epidermis or top layer of skin separates from the dermis or bottom layer of skin. This type of pressure also exacerbates any other callus formation.
The Stress Put on the Foot Through Abnormal Pronation and Supination
When the foot moves forward from when the heel and foot hits the ground until it leaves the ground and swings forward, the bones move in such a way that they are not moving in concert each other with the other and causes abnormal movement and stress inside of the foot. This results in such problematic developments such as bunion deformity, hammertoe deformity, plantar fasciitis, heel spurs and neuroma and other nerve problems.
The Stress Put on the Whole Body Through Abnormal Pronation and Supination
There used to be a popular song written in 1928 called Dem Bones, and has been well-known throughout the years. It speaks of the bones are connected to one another all the way from the foot to the head and neck. This describes most assuredly and unintentionally, the Kinetic Link Principle, which states that movement of one segment affects segments both proximal and distal to the first segment. The kinetic chain of the lower extremity includes the toes, feet, ankles, lower legs, knees, upper legs, hips, pelvis, and spine; and when standing or walking, the movement of each can affect the others. It follows then that abnormal pronation and supination affects the movement and function of each segment of whole kinetic chain of the lower extremity. It works the other way around as well. A problem anywhere along the kinetic chain of the lower extremity can have a negative effect on the foot.
Solutions To Problems Of Too Much Or Too Little Pronation Or Supination
Stay In Balance
The solutions may be simple but for most not easy.
There Are 7 Steps To A Healthy Walk
- Control of Abnormal Pronation and Supination — That is instead of allowing the foot to meet the ground, put the ground up to the foot to avoid that damaging balancing act of the foot. In the majority of cases with the majority of foot complaints this would require an orthotic insert that hugs the foot closely while being flexible enough to move with the foot changing positions throughout the walking cycle.
- Correcting Any Situation Where One Leg Is Longer Than The Other — This can be accomplished with lifts inside the shoe.
- “Riding On Good Tires” — That is you have to wear shoes that work with your orthotics. Good Shoes are as important as the correct foot orthotic insert.
- Muscle Flexibility and Strength — Make sure that the muscles that are involved with walking are in shape, that is strong yet flexible. This involves in particular the small intrinsic muscles of the feet and the larger muscles in the back and front of the leg and thigh.
- Having Strong and Healthy Core Muscles — Healthy walking involves the whole body and having strong core muscles is certain critical to that end.
- Postural Health that involves a healthy spine of the back and neck.
- Generalized Good Conditioning Practices.
Pronation and Supination are normal and important mechanisms to absorb the shock when we walk or run. It where imbalance occurs that forces us to over or under pronate or supinate.
In this report, I have tried to make a complicated subject understandable. It may appear to be a difficult concept at first but once you get it, the solutions are easy if the will is there.
Basically the takeaway message is that the foot is attached to the rest of the body and Controlling the destructive abnormal movements of the foot ( that is too much or too little pronation and/or supination ) involves
- putting the ground up to the foot through an orthotic insert instead of allowing the foot to meet the ground,
- having good shoes to work with the orthotic insert and
- healthy conditioning of the rest of the body.
If we all pay attention to prevention, we will enjoy good feet-ness!
Dr. Kenneth Rehm
America’s Own Podiatrist