Plantar fasciitis develops due to repetitive or prolonged activities that place strain on the plantar fascia. The arch of the foot is three dimensional. It is formed by (1) the bones in the foot (metatarsals), from the ankle to the toes. (2) The medial arch (on the inside of the foot) runs from the inner heel to the big toe. This is the arch that is decreased if you have “flat feet”. Then you have (3) a lateral arch (on the outside of the foot) that runs from the outer heal to the little toe. The transverse arch connects the medial and lateral arches from the big toe to the little toe. The plantar fascia supports these three arches, like a dome from below.
You are at greater risk to develop plantar fasciitis if you are on your feet for long hours or walk long distances. People who work in health care (nurses), construction and sales especially. Sports that involve repetitive stress to the bottom of the foot on hard surfaces, like hockey, cricket, hiking and marathon running, can also cause plantar fasciitis. Long-distance runners and dancers are more prone to develop plantar fasciitis due to the excessive range of movement that is needed during these activities. Tight calf muscles cause more load through the plantar fascia and may lead to inflammation. Unsuitable shoes that do not cushion the foot sufficiently, or support the arch, or place the fascia in a stretched position (all heels, ladies!) are one of the main factors that lead to plantar fasciitis.
In some cases the pain may develop suddenly due to a high force going through the plantar fascia like a sudden push off out of the starting blocks or falling from a height and landing on your feet. Mostly the inflammation builds up because of repetitive strain. Being overweight or a sudden increase in weight (training or pregnancy) increases the tension on the plantar fascia and may lead to inflammation.