Heel pain is one of the most common forms of foot pain in adults. It often occurs as a result of daily activities and exercise. The heel bone (calcaneus) is the largest bone in the foot and the heel is the first part of the foot to contact the ground during walking.
Two structures located on the bottom (sole) of the foot are primarily associated with heel pain: the plantar fascia, a band of fibrous connective tissue, and the flexor digitorum brevis muscle, which supports the arch and flexes the four small toes.
Normally, as the foot absorbs the weight of the body during walking, the arch begins to flatten and the plantar fascia and the flexor digitorum brevis muscle maintain the arch and stabilize the foot.
Gait abnormalities can cause inflammation of the structures attached to the heel bone, resulting in heel pain. Inflammation of the plantar fascia, called plantar fasciitis, is the most common cause of heel pain.
Plantar fasciitis often causes pain that is more severe following a period of rest (e.g., after sleeping). This condition is also called post-static dyskinesia, which means "pain after rest."
Sometimes, muscle strain and tension (usually on the flexor digitorum brevis) pulls a piece of bone away from the calcaneus, causing a heel or bone spur. Heel spurs can irritate nerves and cause pain.