The achilles tendon is the large cord-like structure at the back of the heel. It connects the calf muscles (gastrocnemius and soleus) to the heel bone (calcaneum). It is an engineer’s nightmare – not only does it take the entire force of the body during walking or running (in fact it is required to withstand 4 to 5 times the weight of a person during activities like jumping or sprinting) but it has an extremely poor blood supply.Image Hence when the achilles tendon sustains an injury (this may be the small micro-trauma that results from prolonged or repetitive use of the tendon or more substantial tendon tearing as a result of rapid, resisted calf muscle contraction) the poor blood supply to the tendon is often insufficient to produce normal tissue healing.