Achilles tendonitis is an overuse injury that causes inflammation of the Achilles tendon, which connects the calf muscles to the heel bone. It commonly occurs in athletes and individuals who engage in activities that involve repetitive strain on the tendon, such as running, jumping, or dancing.

Symptoms of Achilles tendonitis include pain and stiffness along the tendon, particularly near the heel, swelling, and difficulty walking or performing activities that require ankle movement. The pain may be more pronounced in the morning or after prolonged periods of inactivity and may improve with light activity but worsen with more intense exercise.