Pronation of the foot

Last updated October 27, 2023

Pronation is a natural movement of the foot that occurs during foot landing while running or walking. Composed of three cardinal plane components: subtalar eversion, ankle dorsiflexion, and forefoot abduction,^[1]^[2] these three distinct motions of the foot occur simultaneously during the pronation phase.^[3] Pronation is a normal, desirable, and necessary component of the gait cycle.^[4] Pronation is the first half of the stance phase, whereas supination starts the propulsive phase as the heel begins to lift off the ground.^[5]

Types

The normal biomechanics of the foot absorb and direct the occurring throughout the gait whereas the foot is flexible (pronation) and rigid (supination) during different phases of the gait cycle. As the foot is loaded, eversion of the subtalar joint, dorsiflexion of the ankle, and abduction of the forefoot occur.^[5]^[6] Pronation should not occur past the latter stages of midstance, as the normal foot should then supinate in preparation for toe-off.^[7]

Abnormal pronation occurs when a foot pronates when it should supinate, or overpronates during a normal pronation period of the gait cycle. Approximately four degrees of pronation and supination are necessary to enable the foot to propel forward properly. In the neutral position, the foot is neither pronating nor supinating. If the foot is pronating or supinating during the stance phase of the gait cycle when it ought to be in the neutral position, a biomechanical problem may exist.^[3]

Although varying definitions exist as described by Horwood and Chockalingam,^[8] for choosing appropriate footwear, pronation could be described in three simple terms: neutral pronation, overpronation, and underpronation.^[9]

Neutral pronation

Some pronation, also called eversion, is natural in the body's regular movement. Neutral pronation occurs when the foot experiences a normal, healthy amount of pronation instead of overpronating or underpronating. In healthy movement, more of the toe area will be used when pushing off than an unhealthy movement.^[10] In neutral pronation, the weight distributes fairly evenly among all of the toes with a slight emphasis on the big toe and second toe, which are better adapted to handle more of the load.^[9]

Overpronation

Those who overpronate tend to push off almost completely from the big toe and second toe. As a result, the shock from the foot's impact does not spread evenly throughout the foot and the ankle has trouble stabilizing the rest of the body. Additionally, an unnatural angle forms between the foot and ankle and the foot splays out abnormally. It is common even for people who pronate normally to have some angle between the foot and the ankle, but not to the extent seen in those who overpronate. In normal pronation, the weight distributes evenly throughout the foot.^[9]

Causes

There are many possible causes for overpronation, but researchers have not yet determined an underlying cause. Hintermann states, “Compensatory overpronation may occur for anatomical reasons, such as a tibia vara of 10 degrees or more, forefoot varus, leg length discrepancy, ligamentous laxity, or because of muscular weakness or tightness in the gastrocnemius and soleus muscles."^[10] Pronation can be influenced by sources outside of the body as well. Shoes have been shown to significantly influence pronation. Hintermann states that the same person can have different amounts of pronation just by using different running shoes. “It is easily possible that the maximal ankle joint eversion movement is 31 degrees for one and 12 degrees for another running shoe."^[10]

There has been some speculation as to whether arch height has an effect on pronation. After conducting a study at the Rose-Hulman Institute of Technology, Maggie Boozer suggests that people with higher arches tend to pronate to a greater degree.^[11] However, the generally accepted view by professionals is that the most pronation is present in those with lower arch heights.^[9] To complicate matters, one study done by Hylton Menz at the University of Western Sydney-Macarthur suggests that the methods for measuring arch height and determining whether someone is “flat-footed” or “high-arched” are unreliable. He says, “For this reason, studies investigating the relationship between static arch height motion of the rearfoot have consistently found that such a classification system is a poor predictor of dynamic rearfoot function.”^[12]

Effects

Overpronation may have secondary effects on the lower legs, such as increased rotation of the tibia, which may result in lower leg or knee problems. Overpronation is usually associated with many overuse injuries in running, including medial tibial stress syndrome,^[13] or shin splints, and knee pain.^[10] Hintermann states: “Individuals with injuries typically have pronation movement that is about two to four degrees greater than that of those with no injuries.” He adds, however, that between 40% and 50% of runners who overpronate do not have overuse injuries. This suggests that, although pronation may have an effect on certain injuries, it is not the only factor influencing their development.

Prevention/treatment

Orthotics

The design principles of foot orthoses are founded on knowledge of the functional anatomy of the foot. Pronation of the foot is triplanar. The axis of rotation in the foot joints is not perpendicular to any of the cardinal planes (sagittal, horizontal, frontal) of the human body. The triplanar motion of the foot postulates that blocking of any one component of triplanar motion in a single cardinal plane prevents movement in the other two planes as well. This all-or-nothing rule is the premise for orthotic posting or wedging.^[14]

Supportive orthotics in the shoe is a method commonly implemented to treat many common running injuries associated with excessive pronation. Orthotics are the most effective treatment for symptoms that develop from biomechanics within the body such as overpronation, resulting in either great improvement or complete healing of the injury in about half the cases.^[15]

Shoe type

Foot pronation tends to increase in runners as mileage also increases, potentially increasing the risk for injury.^[16] Motion control shoes are a specific type of running shoe designed to limit these excessive foot motions by reducing the amount of plantar force (a force generated by excess pronation). Motion control and stability shoes have increased medial support which may increase stability to the foot and leg and lower the amount of pronation in the foot.^[10]

Taping

Certain methods of taping the foot and leg have also been shown to be effective in preventing overpronation. In a study conducted at the University of Queensland, a taping procedure known as the LowDye taping technique was shown to be effective in controlling pronation during both movement and standing.^[17]

Shoe-lacing patterns

Specific patterns of lacing running shoes also reduce pronation. Pronation significantly decreases when the highest number of eyelets in the shoe is used for lacing and the shoes are tied as tight as possible,^[18]

Closeup of a person running barefoot 06patriotsrun5.jpg — Closeup of a person running barefoot

Barefoot running

Running barefoot has been seen to decrease pronation on the foot's impact with the ground. A studies investigations show that this is connected to a large torsional movement between forefoot and rearfoot which can be influenced by the shoe sole construction, with the heel pitch placing the foot into a slightly plantar flexed position, which can result in increased pronation during the pre-swing phase. According to researchers at the Biomechanics Laboratory of the Swiss Federal Institute of Technology, “The least amount of pronation takes place when running barefoot."^[19]

Supination

Supination is the opposite, and occurs when the foot impacts the ground and there is not enough of an “inward roll” in the foot's motion. The weight of the body is not transferred at all to the big toe, forcing the outside of the foot and the smaller toes which cannot handle the stress as well to take the majority of the overweight instead.^{[ citation needed ]}

Runner's World states, “[Underpronators] do best in a neutral-cushioned shoe that encourages a more natural foot motion."^[9] Since underpronators' feet do not roll inward like overpronators', support is not necessarily needed to correct supination as it is to correct overpronation. ^{[ citation needed ]}

Related Research Articles

The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.

Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity. The term running can refer to any of a variety of speeds ranging from jogging to sprinting.

<span class="mw-page-title-main">Human leg</span> Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The human leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.

A bunion, also known as hallux valgus, is a deformity of the joint connecting the big toe to the foot. The big toe often bends towards the other toes and the joint becomes red and painful. The onset of bunions is typically gradual. Complications may include bursitis or arthritis.

Pes cavus, also known as high arch, is a human foot type in which the sole of the foot is distinctly hollow when bearing weight. That is, there is a fixed plantar flexion of the foot. A high arch is the opposite of a flat foot and is somewhat less common.

A gait is a manner of limb movements made during locomotion. Human gaits are the various ways in which humans can move, either naturally or as a result of specialized training. Human gait is defined as bipedal forward propulsion of the center of gravity of the human body, in which there are sinuous movements of different segments of the body with little energy spent. Varied gaits are characterized by differences such as limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in contact with the ground.

Achilles tendinitis, also known as achilles tendinopathy, occurs when the Achilles tendon, found at the back of the ankle, becomes sore. Achilles tendinopathy is accompanied by alterations in the tendon's structure and mechanical properties. The most common symptoms are pain and swelling around the affected tendon. The pain is typically worse at the start of exercise and decreases thereafter. Stiffness of the ankle may also be present. Onset is generally gradual.

<span class="mw-page-title-main">Flat feet</span> Deformity in which the foot arches contact the ground

Flat feet, also called pes planus or fallen arches, is a postural deformity in which the arches of the foot collapse, with the entire sole of the foot coming into complete or near-complete contact with the ground. Sometimes children are born with flat feet (congenital). There is a functional relationship between the structure of the arch of the foot and the biomechanics of the lower leg. The arch provides an elastic, springy connection between the forefoot and the hind foot so that a majority of the forces incurred during weight bearing on the foot can be dissipated before the force reaches the long bones of the leg and thigh.

<span class="mw-page-title-main">Tarsus (skeleton)</span> Bones of the foot

In the human body, the tarsus is a cluster of seven articulating bones in each foot situated between the lower end of the tibia and the fibula of the lower leg and the metatarsus. It is made up of the midfoot and hindfoot.

Foot drop is a gait abnormality in which the dropping of the forefoot happens due to weakness, irritation or damage to the deep fibular nerve, including the sciatic nerve, or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. Foot drop is characterized by inability or impaired ability to raise the toes or raise the foot from the ankle (dorsiflexion). Foot drop may be temporary or permanent, depending on the extent of muscle weakness or paralysis and it can occur in one or both feet. In walking, the raised leg is slightly bent at the knee to prevent the foot from dragging along the ground.

Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative to the anatomical position of the body parts involved. Anatomists and others use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing unique movements such as those of the hands, feet, and eyes.

Unequal leg length is where the legs are either different lengths or appear to be different lengths because of misalignment. Leg length inequality is very common; small inequalities in leg length may affect 40%-70% of the human population. It has been estimated that at least 0.1% of the population have a difference greater than 20 mm (0.79 in).

The Ponseti method is a manipulative technique that corrects congenital clubfoot without invasive surgery. It was developed by Ignacio V. Ponseti of the University of Iowa Hospitals and Clinics, US, in the 1950s, and was repopularized in 2000 by John Herzenberg in the US and Europe and in Africa by NHS surgeon Steve Mannion. It is a standard treatment for clubfoot.

<span class="mw-page-title-main">Cuboid syndrome</span> Medical condition

Cuboid syndrome or cuboid subluxation describes a condition that results from subtle injury to the calcaneocuboid joint and ligaments in the vicinity of the cuboid bone, one of seven tarsal bones of the human foot.

Comparative foot morphology involves comparing the form of distal limb structures of a variety of terrestrial vertebrates. Understanding the role that the foot plays for each type of organism must take account of the differences in body type, foot shape, arrangement of structures, loading conditions and other variables. However, similarities also exist among the feet of many different terrestrial vertebrates. The paw of the dog, the hoof of the horse, the manus (forefoot) and pes (hindfoot) of the elephant, and the foot of the human all share some common features of structure, organization and function. Their foot structures function as the load-transmission platform which is essential to balance, standing and types of locomotion.

<span class="mw-page-title-main">Orthotics</span> Medical specialty that focuses on the building and designing of artificial legs

Orthotics is a medical specialty that focuses on the design and application of orthoses, sometimes known as braces or calipers. An orthosis is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are professionals who specialize in designing these braces.

Locomotor effects of shoes are the way in which the physical characteristics or components of shoes influence the locomotion neuromechanics of a person. Depending on the characteristics of the shoes, the effects are various, ranging from alteration in balance and posture, muscle activity of different muscles as measured by electromyography (EMG), and the impact force. There are many different types of shoes that exist, such as running, walking, loafers, high heels, sandals, slippers, work boots, dress shoes, and many more. However, a typical shoe will be composed of an insole, midsole, outsole, and heels, if any. In an unshod condition, where one is without any shoes, the locomotor effects are primarily observed in the heel strike patterns and resulting impact forces generated on the ground.

Children's feet are smaller than those of adults, not reaching full size until the ages of 13 in girls and 15 in boys. There are correspondingly small sizes of shoes for them. In poor populations and tropical countries, children commonly go barefoot.

Running injuries affect about half of runners annually. The frequencies of various RRI depend on the type of running, such as speed and mileage. Some injuries are acute, caused by sudden overstress, such as side stitch, strains, and sprains. Many of the common injuries that affect runners are chronic, developing over longer periods as the result of overuse. Common overuse injuries include shin splints, stress fractures, Achilles tendinitis, Iliotibial band syndrome, Patellofemoral pain, and plantar fasciitis.

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