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Orthotics for Athletes: New Research provides important information about human biomechanics.
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Every athlete understands that foot function is a very important part of their sport. Scientific literature, in the field of human biomechanics has documented the relationship, between placement of the foot and function of the entire body, for more that 20 years. Ultimately both optimal performance and chronic medical conditions have been related to the biomechanical movements of the foot, knee, and spine during weight-bearing activity.
Even though the importance of this functional relationship associated with placement of the foot during athletic activities, is clearly identified by science, medicine, and virtually every athlete, only two or three biomechanical researchers currently understand the mechanical forces involved.
The problem is somewhat complex, it involves the anatomical relationship of the lower extremity and the mechanical forces that result during closed kinetic chain function.
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Ulitmately the cause of less than optimal function is one of angles.
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Intrauterine development of the human fetus, results in a frontal plane angular deformity of the tibia at birth. Interestingly this varus (inward) curvature of the leg, is present in most everyone, and is the cause of excessive pronation of the foot, with internal rotation of the leg and knee, observed during ambulation. This angular deviation of the lower leg, requires pronation of the foot , to place the foot on the supportive surface. Twenty degrees of curvature in the leg, identified in most all human beings, demands 20 degrees of compensatory pronation in the foot.
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Orthotics create a varus wedge between the foot and the supportive surface.
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Basically the varus wedge present in all functional orthotics, brings the ground up to the foot, and compensates for the angular deformity in the leg. When this wedge is used during weight bearing, the foot no longer needs to pronate, and internal rotation of the leg and knee does not take place. Orthotics supinate the foot, and externally rotate the leg and knee, as we walk, stand and run.
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Function of this varus wedge is determined by the change in angle of support.
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For every degree of varus wedge, applied during foot function, one degree of pronation, and one degree of internal rotation of the leg is stopped. When the full 20 degrees of angular deformity present in the tibia is compensated for by the wedge, optimal alignment of the knee, with optimal biomechanical function occurs. Improved performance and decrease symptoms associated with chronic irritation to the anatomy is observed clinically.
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Placement of the wedge determines how it functions during gait.
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Compensation for the angular deformity in the leg, with a wedged orthotic, is complicated additionally by the type of weight bearing activity. During normal walking and standing, when both heel and ball of the foot are flat on the ground, a rear foot wedge placed in the center of the arch will change the angle of the supportive surface.
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Propulsive stage activity, requires a wedge placed directly under the metatarsals.
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Athletes require a forefoot wedge, under the metatarsals, to treat excess pronation.
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