Causes

Achilles tendinitis is caused by repetitive or intense strain on the Achilles tendon, the band of tissue that connects your calf muscles to your heel bone. This tendon is used when you walk, run, jump or push up on your toes.

The structure of the Achilles tendon weakens with age, which can make it more susceptible to injury — particularly in people who may participate in sports only on the weekends or who have suddenly increased the intensity of their running programs.