Tendinitis is inflammation of a tendon, an overuse injury usually due to repetitive stress activities such as running and jumping. In chronic cases, the tendon composition changes over time, causing a thickening known as tendinosis. In severe/chronic cases, microtearing can occur and increase the risk of tendon rupture.
Heel or arch pain is known as plantar fasciitis. It is an inflammation of the plantar fascia or irritation at its attachment on the medial (big toe side) aspect of the calcaneus (heel) often related to excessive weight-bearing.
Tendonosis is also known as chronic tendonitis, or chronic degeneration, of a tendon. It usually does not involve inflammation, the primary sign of tendonitis. Tendonosis is often the result of failed healing or repetitive trauma to a tendon. This may result in loss of strength and risk of further injury.
An overuse injury caused by repetitive impact is a stress fracture. It is caused by an overload of stress on the bone, resulting in a crack in the bone. This most often causes pain with activity and some swelling and tenderness at a certain spot.