This is an inflammation of the large tendon behind the ankle. If the problem lingers, it may become a chronic condition which is much more difficult to treat quickly. Often the Tendonitis becomes Tendonosis ( which means chronic irritation and inflammation that could develop into an intra-substance tear) . If the muscles that make up the Achilles tendon are tight or weak, if the foot over pronates, or the hip and core muscles are weak, there is a predisposition to this injury. Early on the symptoms may include warmth and swelling, and can be very stiff in the morning, upon arising, or during or immediately after exercising. Many people will exercise or run through this to later complain of significant soreness later. This is not a good sign. Early aggressive and conservative treatment is important as it may take a long time to rehabilitate and treat.