The Achilles tendon is a large band of tissues connecting the muscles in the back of your lower leg to the heel bone. The Achilles tendon is the largest tendon in the body and is used anytime you walk, run,jump or rise up on your toes. While this is the largest tendon in the body and can withstand forces up to 1,000 pounds, it is also ruptured more frequently than any other tendon and this overuse injury is possible for athletes of all calibers. Achilles tendonitis occurs when the band of tissues that composes the tendon become irritated and or inflamed.