A tendon rupture is a separation of a tendon from a bone or muscle, or a complete tear in the tendon itself. Bone and muscle separations are the most common tendon ruptures.
Cause
Tendon ruptures are usually the result of sudden violent contractions. They occur in sprinters, handball players, weight lifters, and athletes in other sports where sudden bursts of speed are required. When an athlete ruptures his tendon, you generally can hear a pop. The pain is so severe that the athlete usually writhes in pain and holds the affected muscle in a contracted position.
Treatment
If a tendon rupture is suspected, consult a physician immediately. In the meantime, apply RICE.
Achilles Tendon Stretch
Stand about three to four feet from a wall or post. Lean forward so that you're at an angle of your heels are raised. Gently push your heals toward the ground.