My daughter is an up-and-coming star baseball pitcher. She's had to fight being with boys and has gotten to a high level for her age. The problem is now, her coach says she can't pitch a full game if it goes beyond a certain number of pitches and she can't pitch two games in a row unless there's a week between them. He said it's to protect her arm. What's this all about?

Every time your daughter throws a pitch, she is putting a large amount of sudden and forceful stress on her elbow. Repeated stresses like this can damage her ulnar ligament, a ligament that helps move the elbow.

Studies have shown, as has real life, that athletes who throw things at such a level are at high risk of injuring this ligament. If the ligament is torn, it causes pain and elbow instability and the athlete can no longer play at that sport or in that role without surgery. Even with surgery, 20 percent of the athletes can't return to their previous level of competition.

Studies have also shown that by limiting the amount of pitching that growing children and teens do also limits the damage they can do to their elbow. This limit of a certain number of pitches per game and a minimum amount of time between games is to protect your daughter from hurting - and perhaps ruining - her elbow.