The previous post about contests had me thinking more about rehearsing, which is always recommended as a way of overcoming stage fright. (Advice on how to rehearse appears in this previous post).
Before a contest it is tempting to rehearse repeatedly. When should you stop? At the Boise State University library I found a book by Stewart Gordon called Mastering the Art of Performance: a primer for musicians. Musicians have problems similar to contest speakers, so the book has a whole chapter on overcoming stage fright. On page 107 Mr. Gordon says that it is is time to “give it a rest” and pursue a diversion when you have any of the following symptoms:
“Your concentration becomes fuzzy and forced.
You are prone to making mistakes that you don’t usually make.
You become irritable or temperamental.
You feel physical pain as a result of tension (headaches, neck or back pain).
You are consistently getting results that you know are below par for your present level of ability.”
You can read most of this book chapter on stage fright by putting the keyword “diversion” in the "search in this book" box on the top right corner of the page at Google Books, and then choosing page 107.