I am going to give you a bit of information that is often overlooked by doctors.

A certain group of antibiotics given for urinary tract, kidney and upper respiratory, and skin infections can damage tendons.
These drugs are fluoroquinolones, (Cipro, Avelox and Levaquin).
They distrupt DNA in cells and have specific damage potential for tendons. Often the tendons become damaged a year or more after the use of these drugs for simple reasons. They are still commonly given by doctors when other drugs could suffice. People will rupture or strain tendons because of these drugs so doing any severe lifting or sports extensions of the limbs, can damage the already damaged tendons.

Here is the FDA warning about this:
http://www.fda.gov/NewsEvents/Newsro.../ucm116919.htm

Often much time passes from the use of these drugs for treatment of common infections, and the development of the tendon damage. Often the doctors just see an physical strain as the culprit, when in fact the problem could have been brewing for a long time after treatments with these drugs.

People who have used these drugs should be very careful therefore and NOT push themselves physically to do things that might further rip or strain the tendons further.