Most common cause of inseional tendonitis of tendoachilles is:

Overuse Ref: see below Achilles inseional tendonitis describes an inflammatory process affecting the tendon-bone interface. Achilles tendonitis typically occurs as one of two types of tendonitis: inseional and noninseional, with the former involving the tendon-bone interface, and the latter occurring just proximal to the tendon inseion on the calcaneus in or around the tendon substance. All the first 3 options given are causes of inseional tendinitis, but we think that 'overuse' is the most probable answer. See the below quoted texts in suppo. "Inseional tendonitis is inflammation at the tendon's bony insetion, which can result from overuse or acute injury."- A thletic training and spos medicine By Robe C. Schenck, American Academy of Ohopaedic Surgeons p133 "Achilles tendonitis in high-level athletes is usually a sign of faulty training, improper running techniques, or overuse."- Current diagnosis & treatment in spos medicine By Patrick J. McMahon 1/e pill "Achilles tendonitis is the most common form of overuse tendonitis seen in athletes. .... Causes of Achilles tendinits include overuse, excessive forced dorsiflexion, an inflexible gastrocnemius-soleus comples, and hyperpronation."- Management of common musculoskeletal disorders: physical therapy principles By Darlene Heling, Randolph M. Kessle p599