Inflammation of a tendon or the tissue surrounding it is called tendinitis. You may feel pain when you move your ankle or when your heel shifts from side to side. The achilles tendon and peroneal tendons are common sites for tendinitis, typically caused from repetitive stress to the tendon. Tendinitis in these sites is often seen following an significant increase in activity or new beginning a new exercise.

The Achilles tendon is the largest tendon in the body. It runs along the back of the leg, connecting the calf muscles to the heel bone. The peroneal tendons run along the outside of the ankle just behind the shin. Inflammation of these tendons typically results in pain along the back of the leg near the heel.

achilles tendon

Diagram of the Achilles tendon