The windlass is that apparatus that are used by the mariners on yachts to wind the rope about to help to make it less difficult to maneuver the boom. In the foot there exists a mechanism that is known as the windlass mechanism that gets its name from this apparatus used on boats. There is a ligament like structure beneath the foot called the plantar fascia which is at one end connected to the underside of the heel and at the other end to the great toe or hallux. When we are walking and the heel bone comes off the ground, the foot moves around the big toe or hallux where this ligament is connected, tensing the ligament as it winds around the windlass of the first metatarsal head. This is the windlass mechanism of the foot. It is a very important functionality as the plantar fascia is the thing that supports the arch of the foot, therefore it must function correctly and quickly for normal foot biomechanics. This is the foots natural arch support mechanism.
There are a number of disorders involving the windlass mechanism not working correctly. When the windlass doesn't work, then the arch of the foot will collapse from this lack of support and a range of conditions may develop as a result of that for example bunions and plantar fasciitis. The cause of the windlass not functioning correctly can be multiple like the force needed to establish it simply being way too high, so the body has to work harder to make the windlass function. If that hard work can make it work, then that is a greater energy cost which might be very fatiguing. Podiatrists use different design characteristics in foot supports to improve the windlass mechanism and also to make walking easier and more efficient. In the event the windlass can be established easily during walking or running is not going to need so much and the foot will naturally support its own arch.