Pronation is the natural movement of the foot that occurs during a foot landing while running or running. Consisting of three cardinal components of the cardinal: subtalar eversion, ankle dorsiflexion, and front foot abduction, these three leg movements occur simultaneously during the pronation phase. Pronation is a normal, desirable, and necessary component of the gait cycle. Pronation is the first half of the founding phase, while supination begins a propulsion phase as the heel begins to lift from the ground.
Video Pronation of the foot
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The normal biomechanics of the feet absorb and direct the forces that occur throughout the gait cycle, while the legs are flexible (pronation) and stiff (supination) during different phases of the gait cycle. When the foot is loaded, the eversion of the subtalar joint, dorsiflexion the ankle, and kidnapping of the forefoot occurs. Pronation should not occur past the last stage of the midstance, because the normal foot should then stop in preparation for doing the to-off.
Abnormal pronation occurs when the foot is prone to rise, or overpronation during the normal pronation period of the gait cycle. About four degrees of pronation and supination are required to allow the legs to push forward properly. In a neutral position, the legs do not protrude or accumulate. If the foot experiences pronation or supination during the attitude phase of the gait cycle when it should be in a neutral position, biomechanical problems may be present.
For ease of selecting corrective shoes, three types of pronation are recognized: neutral pronation, overpronation, and underpronation.
Neutral pronation
Some pronations, also called eversions, are natural in the body's regular movement. Neutral pronation occurs when the foot experiences a normal and healthy amount of pronation rather than overpronation or underpronating. In a healthy movement, more areas of the toes will be used when pushing than unhealthy movements. In neutral pronation, weight is distributed evenly between all toes with slight emphasis on the big toe and the second toe better adapted to handle more loads.
Overpronation
Those who overpronate tend to push almost completely from the big toe and toe second. As a result, the shock from a leg collision does not spread evenly across the legs and the ankle has difficulty stabilizing the whole body. In addition, unnatural angular shape between the legs and ankles and legs breaks out abnormally. This is common even for people whose pronation usually has some angle between the leg and ankle, but not as far as it is seen on those who overpronate. In normal pronation, weight is distributed evenly across the legs.
Cause
There are many possible causes of overpronation, but researchers have not determined a single cause. Hintermann states, "Compensatory overhaul may occur for anatomical reasons, such as tibia vara 10 degrees or more, front leg varus, leg length difference, ligament ligitude, or due to muscle weakness or stiffness in gastrocnemius and soleus muscles." Pronation can be influenced by sources outside the body as well. Shoes have been shown to significantly affect pronation. Hintermann states that the same person can have different amounts of pronation just by using different running shoes. "It is very easy that the maximum ankle eversion movement is 31 degrees for one and 12 degrees for other running shoes."
There is some speculation as to whether the height of the arch has an effect on pronation. After doing research at the Rose-Hulman Institute of Technology, Maggie Boozer points out that people with higher curvature tend to ply to a greater extent. However, the generally accepted view by professionals is that most pronations are present in those with lower curved altitudes. To complicate matters, one study conducted by Hylton Menz at the University of Western Sydney-Macarthur showed that a method for measuring the height of the arch and determining whether a person is "flat-footed" or "high-curled" is unreliable. He said, "For this reason, studies that investigate the relationship between the static high arch moves of rearfoot have consistently found that such classification systems are a poor predictor of the dynamic rearfoot function."
Effects
Overpronation may have a secondary effect on the lower leg, such as an increase in tibia rotation, which can cause problems in the lower legs or knees. Overpronation is usually associated with many excessive injuries in running including medial tibial stress syndrome, or shin splints, and Hintermann's knee pain states, "Individuals with injuries usually have pronation movements that are about two to four degrees larger than those who are not injured." He added that between 40% and 50% of runners who overpronate do not have excessive injuries. This suggests that although pronation may have an effect on certain injuries, it is not the only factor affecting its development.
Prevention/treatment
Orthotics
The principles of foot orthosis design are based on anatomical functional foot knowledge. Pronation of the foot is triplanar. The axis of rotation in the foot joint is not perpendicular to any of the cardinal (sagittal, horizontal, frontal) fields of the human body. The triplanar movement of the foot postulates that blocking one component of the triplanar movement in a single cardinal plane prevents movement in the other two planes as well. This all-or-none rule is the premise for post or orthotic clamp.
Orthotics advocates inside the shoe are generally applied methods to treat many of the common walking injuries associated with excessive pronations. The advantage of orthotics is that they often allow runners to continue participating in athletic activities and avoid other treatment options that can potentially cost and time. Seventy-five percent of the injured runners were successfully treated with prescription orthoses. Orthotics is the most effective treatment for symptoms that develop from strange biomechanics in the body such as overpronation, resulting in major improvements or total healing of injuries in about half the cases.
Shoe type
Foot pronation tends to increase in runners as the mileage also increases, potentially increasing the risk of injury. Motion control shoes are a special type of running shoes designed to limit excessive foot movement by reducing the amount of plantar strength (the power generated by excessive pronation). Motion control and stability shoes have improved medial support that can improve stability in the legs and feet and decrease the amount of pronation in the foot.
Instead, extra pads in shoes are the best way to correct underpronation.
Recording
Certain methods of foot and foot taping have also been shown to be effective in preventing overpronation. In a study conducted at the University of Queensland, a recording procedure known as the LowDye recording technique proved effective in controlling pronation during movement and standing.
Shoe-hitting pattern
The special pattern of running shoes also reduces pronation. Pronation significantly decreased when the highest number of fish eyes in the shoe was used to tie the shoelaces and the shoes tied as tightly as possible,
Barefoot running
Some studies show that running barefoot can decrease the pronation on foot impact with soil. This is presumably because running shoes have extra weight for the pads on the heels of shoes, causing runners more often to strike, which in turn results in increased pronation during the move. According to researchers at the Biomechanics Laboratory of the Swiss Federal Institute of Technology, "The least amount of pronation occurs when running barefoot."
Supination
Supination is the opposite, and occurs when the foot affects the ground and there is not enough "inward roll" in the foot movement. Body weight is not transferred at all to the big toe, forcing the outside of the foot and the smaller toes that can not handle stress as well to take most of the excess weight instead.
The Runner world countries, "[Underpronators] do their best in neutral cushioned boots that encourage more natural foot movements." Because the underpronator's legs do not roll over in like overpronators, support is not required to improve supination due to correct overpronation.
Maps Pronation of the foot
References
See also
- The term anatomical motion
- Comparison of orthotics
Source of the article : Wikipedia
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