The windlass is that gadget which are used by the mariners on yachts to wind the rope around in order to make it less difficult to maneuver the sails. Within the foot there exists a mechanism that is known as the windlass mechanism that gets its name from this equipment used on boats. There is a ligament like structure under the foot called the plantar fascia which is at one end connected to the bottom of the heel and at the other end to the big toe or hallux. When we are walking and the heel comes off the ground, the foot moves around the big toe or hallux where this ligament is attached, tensing the plantar fascia as it winds around the windlass of the first metatarsal bone. This is the windlass mechanism of the foot. It is a very important functionality as that ligament is what supports the arch of the foot, so it needs to function properly and quickly for normal foot biomechanics. It is the foots own natural arch support system.
There are a variety of conditions involving this windlass mechanism not functioning properly. In the event the windlass mechanism does not work, then the arch of the foot will collapse from the lack of support and a variety of conditions may develop as a consequence of that for example bunions and plantar fasciitis. The cause of the windlass not functioning correctly can be multiple like the force necessary to establish it simply being too much, so the body needs to work harder to make the windlass function. If that effort does make it function, then that is a greater energy cost which can be very fatiguing. Podiatrists use several design characteristics in foot orthotics to improve the windlass mechanism and also to make walking less difficult and more effective. In the event the windlass can be established easily during walking won't require so much energy and the foot will naturally support its own arch.