Dorsiflexion, inversion, eversion explained
Dorsiflexion is the movement of the ankle so that the angle between the top of the foot and the front of the leg is decreasing.
A minimum of 10 degrees of dorsiflexion off the horizontal is required to run. Many physical therapy reports indicate 20 degrees dorsiflexion off the horizontal under manual pressure and 43 degrees under full weight is needed to reduce risk of injury. The American Journal of Sports Medicine says less than 36.5 degrees dorsiflexion is considered restricted ankle dorsiflexion.
Inversion is a movement in which the plantar surface (sole) of the foot rotates towards the mid-line of the body. Another way to describe this movement is to say that the plantar surface (sole) of the foot turns medially, i.e. turns inwards. Simply stated, the big toe is higher up than the little toe when on an inclined surface. Also noted as varus foot position.
Eversion is the movement of the sole of the foot away from the median plane. Inversion is the movement of the sole towards the median plane. For example, inversion describes the motion when an ankle is twisted. Simply states, the big toe is lower than the little toe when on an inclined surface. Also noted as valgus foot position.