I have been watching a show called Switched at Birth. Many of the characters (and actors) are deaf. American Sign Language is featured very prominently on the show. One of the characters named Regina could no longer sign because of an injury that she acquired. I looked it up and it was a case of art imitating life. The actress who plays her began to have tendon problems from learning ASL as an adult. Is this inevitable or are they ways to condition your tendons? What exactly is the issue? Is it flexibility or something else?