Every day the feet carry our weight through a series of activities. Standing and moving on our feet puts a tremendous amount of stress and strain on each foot. As we walk, run and move, the bones and joints of the foot and ankle complex must be stable when the foot hits the ground and pushes the body through space.
Gait mechanics involve the rigidity of the foot and ankle when the foot hits the ground and at toe or push off and the foot’s ability to become somewhat supple at mid-stance to absorb stress of the body weight. The mid-stance position enables the foot to protect the lower extremity from impact type injuries. The problem arises when the foot is unable to transition from the mid-stance, flat foot position to the rigid, heel off the ground push off position.
A person with a “flat foot” is diagnosed with excessive pronation. The person that has a “high-arch” is categorized as a “supinator”. Both conditions can cause pain within the foot, ankle and entire lower extremity if they are not controlled.
The foot and ankle are constructed in a way that stability is intrinsic with the design. The ability to push off one’s entire body weight with one foot is dependent upon many factors. The lower extremity muscle strength is the primary factor, but the transition from a supple mid-stance to a rigid push-off or toe-off is greatly aided by the plantar fascia.
The plantar fascia is a thick, leather-like band of connective tissue that spans the bottom or plantar surface of the foot. The band attaches to the heal bone (calcaneus) and stretches across the mid-tarsal bones to the ends of the metatarsals. The plantar fascia inserts into the flexor tendons of the toes. When the toes are moved into a dorsiflexed position (movement toward the shin bone) the plantar fascia is “wrapped” around the metatarsal heads. The Great toe or Big toe is the primary site of this occurrence. This “wrapping” is referred to as the windlass mechanism of the foot. The term is taken from the sailing world because the winch mechanism wraps the rope around a drum to move the sail.
The windlass mechanism in the foot enables the foot to support the body weight and move it through space. When the foot transition from mid-stance to toe off, the toes move from a plantar flexed or neutral position to a dorsiflexed position. The dorsiflexion of the toes produces the windlass mechanism utilizing the plantar fascia. The “wrapping” of the plantar fascia around the metatarsal heads “pulls” the calcaneus towards the toes. The mid tarsal arches raise up off the ground and the foot transitions from a supple, pronated position to rigid, supinated position. The rigidity of the foot is needed to become a lever that is capable of propelling someone as they walk.
