There are fibrous bands of tissue, including the arch ligament and planter aponeurosis, that run from the heel bone and attach into the ligaments of the toes that we call plantar fascia. When the heel is lifted during the push off phase of running or running up a hill, the angle between the heel and the toes increase so the band of tissue is stretched. If the tissues are too tight or overused, it is at these times when the toes are bent and there is load going through the foot that the plantar fascia is vulnerable to injury. It can be caused by a fast change of direction or a sudden take off in a run that can cause damage to the plantar fascia. If the foot is over pronating there will be more chance of an overuse injury or tear.
The result of over pronation is a stretched arch of the foot and spread toes adding to the strain on the plantar fascia. There is usually pain around the heel or arch of the foot especially in the mornings when it is stiff. Achilles tenderness and tightness can also be associated with plantar fasciitis. You must ice and rest as much as possible and stop any activity that causes strain on the plantar fascia like running and walking uphill. Stick to activities such as cycling and swimming. You can use taping to unload the area and apply heat after the acute phase is over.