Achilles tendinitis is inflammation of the Achilles tendon, which is the tendon that connects the calf musculature to the heel bone. Inflammation can occur in this tendon after a sudden injury or can occur over time based on the demands placed on the tendon. Risk factors for developing Achilles tendinitis include a tight hamstring or calf muscles (gastrocnemius or soleus) or a tight Achilles tendon, abrupt changes in activity level such as increasing running mileage too quickly or walking further distances than normal, changing running surfaces such as trail running or including hills, or starting new activities that involve sprinting, jumping, or changing directions quickly.

Achilles tendinitis may present with pain, tenderness, and stiffness along the tendon. This can occur directly over your heel bone or higher up towards your calf muscle. You may also notice swelling in the area. The calf may also feel weak. Numbness and tingling are not typically associated with this condition. Often times, the first few steps after sitting are more painful or you may only notice pain after participating in walking, running, or jumping activities.