As we walk the foot strikes the ground slightly on the outer side of the heel. Turning forces encourage the foot to roll towards the inner side. This natural movement causes the inner arch to lower and the heel to lean inwards. This movement is called pronation.
In some feet this leaning of the heel is excessive and can cause strain on the supportive ligaments and joints of the foot; notably the calcaneo-cuboid and talo-navicular joints (mid tarsal joint). Supportive posture is lost, painful symptoms develop in the foot or ankle and leg (due to associated internal leg rotation). Lower back symptoms and loss of core stability may occur.
In order to prevent this from occuring the heel should remain vertical, the medial arch must be supported and pressure through the forefoot should be evenly distributed.
The majority of symptoms caused by poor foot posture result form excessive valgus rotation of the heel. This occurs as a consequence of pronation. Whilst different foot types manifest pronation in a number of different ways the most common associated finding is failure to recover from this valgus position.