The 'transition' period is a recovery period and occurs after a race and at the end of the season. The transition period will last between one and six weeks. One week after a standard distance triathlon say or six weeks having finished your last race of the season.
The 'preparation' period sees you preparing to train. This period will allow you to work on rehabilitation of an injury, strengthen areas of weakness, improve flexibility in areas of relative inflexibility getting your body ready for the demands of endurance training. The preparation period will last three to four weeks but may be longer (Principle of Individuality!) if you need it.
The 'base' period lasts between eight and twelve weeks. During this period you work on the basic abilities of endurance, strength and speed skills. Training intensity remains relatively low while training volumes gradually increase.
The 'build' period lasts six to eight weeks. During this period training intensity increases while training volumes remain relatively high. This period might also include low priority races used as preparation for your priority race(s). In this period the advanced abilities of muscular endurance, anaerobic endurance and power may be trained depending on the athletes needs. Training is starting to mimic the demands of racing.
The 'race' period lasts for 1-3 weeks. This is the period in which you will race in your priority race or you may have a number of priority races within a three week period. It is difficult to hold peak form for more than three weeks.
Let me give you an example. Say your priority race for the year is the London Triathlon Olympic Distance race on August the 8th. The two weeks prior to this starting July 25th would be your 'peak' period. The eight weeks prior to this starting May 30th would be your 'build' period. This can be split into two four week blocks where the fourth week in each block is a recovery week when training volumes are reduced. The eight weeks prior to this starting April 4th would be your 'base' period (this could be up to twelve weeks). This again can be split into two four week blocks where the fourth week in each block is a recovery week when training volumes are reduced. The four weeks prior to this starting March 7th would be your 'preparation' period. Prior to this you would have your 'transition' period that may vary in length from one to six weeks depending on what you have been doing in the off-season.
This is just an example. Someone new to endurance sport or someone that is stepping up to long distance events may have a shorter 'build' period or no 'build' period at all. Instead the 'base' period will continue up until the 'peak' period begins in order to really establish the basic abilities of endurance, force and speed skills or the 'build' period may only be four weeks long. You may also want to compete in more than one priority race in which case you will have to achieve multiple 'peaks' within the season. This is why the ITU World Championship Series is so demanding.
Reference: The Triathlete's Training Bible 3rd Edition by Joel Friel.
If you need a little motivation click on this link to watch the ITU World Championship promo video for 2010.
See ya! Tim (LFTC Coach)