The human foot is remarkably ‘plastic’ and the habitual use of poorly designed or ill-fitting shoes can have a dramatic effect on the form and function of the human foot. The ‘unshod’ human foot (a foot that has never worn shoes) typically has a broad, flat forefoot and toes that are spread out and aligned with the metatarsal heads to give the foot a ‘fan-shape’.
The habitually shod human foot (always in a shoe) has begun to adapt to the footwear being worn and has become ‘shoe-shaped’. A shoe-shaped foot has a narrow forefoot relative to the rear-foot, meta- tarsal heads that are no longer aligned horizontally and toes that are cramped together, twisted and elevated from the floor.
Therefore, the first and foremost criteria to consider when choosing shoes, is that it should be foot-shaped.