Good Luck, Edward, I prepare for competitions by doing a lot of cardio exercises to build my stamina. I do a lot of running apart from repeated punching, kicking and technique practice.
However, I also found a very interesting response to a similar question by Professor Gary Lee in Martialcafe.com
you can view his response by clicking on this link:
http://www.martialcafe.com/quest/quest_view.php