How do the shoe stiffening inserts work?
The purpose of the shoe stiffening inserts made from a thin rigid carbon fiber plate is to restrict motion in the foot. If flexion of the toes is painful, then these rigid plates restrict movement of the metatarsophalangeal joint to help with those symptoms.
When we are walking and the foot is on the ground, in order to move forward we have to lift the heel up off the ground. As the heel comes off the ground the toes stay flat on the ground and the foot bends at the metatarsophalangeal joints to allow that forward movement to happen. In a number of disorders that movement of the joint can be painful. These conditions include things like, for example, osteoarthritis of the big toe joint (often called hallux rigidus), Freiberg’s disease of the 2nd or 3rd metatarsophalangeal joints in the ball of the foot or Turf toe follow trauma to the big toe joint.
Those who have these conditions often find that they are less painful when they wear a shoe that is rigid across the ball of the foot. A more rigid shoe means that the metatarsophalangeal joints across the ball of the foot do not need to bend as much as the heel comes of the ground. The purpose of the rigid carbon fiber plates is to make the shoe even more rigid or stiff across the ball of the foot, so they do not bend or flex much as the heel comes off the ground.
What the rigid plate makes the foot do is not bend or flex so much across the ball of the foot as the heel comes off the ground when walking. The cause to the weight to come across near then end of the shoe over the toes rather than bend at the ball of the foot.
