The combination workout, or brick, is a great way to prepare for Multisports racing. A workout that combines two or more disciplines into one training session pays big dividends, providing physiological as well as psychological training for the stresses of race day. In large part, this is due to the very sport-specific nature of the combination. Many athletes use the “same old brick” as a staple in their training plan, however, workouts can be combined in an infinite number of ways and should be structured to make them suitable given a variety of factors that should be considered.
[Extract from: http://www.ipmultisports.com/topicpage.php?linkid=462]