(HealthDay News) -- The Achilles tendon is what joins the muscles in the calf to the heel bone. When it is overused or injured, it becomes inflamed -- a condition called Achilles tendonitis.

The American Academy of Orthopaedic Surgeons says common causes of Achilles tendonitis include:

• Among runners, rapidly running much faster or for longer distances.
• Changing your exercise regimen to include running up hills or climbing stairs.
• Beginning to exercise again too soon after a rest period.
• Very strenuous exercise of the calf muscles, such as during a final sprint.
• Overusing the calf muscles.