Blackberry Thumb: Text Messagers Trendy Malady

"Yes, you can peck out text messages with any finger. But users of popular wireless devices such as the Blackberry type much faster by pecking out messages with their thumbs. Many people soon learn to type 40 words a minute.

Whatever your thumb-typing speed, lots of messages mean lots of repetitive thumb motions. And that could mean trouble, says Alan Hedge, PhD, director of the human factors and ergonomics research group at Cornell University in Ithaca, N.Y."