Achilles Tendinopathy is typically an overuse injury. It can cause your Achilles tendon (the tendon which attaches your calf muscles to your heel bone) to become painful and sometimes cause a small lump to form in the tendon. Tiny micro tears can appear in the tendon and, as a result of these repeated micro tears, Achilles tendinopathy can occur. The Achilles tendon can withstand great stresses and this is why it is prone to tendonitis. Tendonitis, to be simplified is the inflammation of a tendon.