Training zones (1)

Im having a difficult time trying to determine the percentage for the 5 training zones. im following the gale bernhardt plan for half ironman.

there are charts in the book but i dont see where the LT zone corresponds to each zone, unless the zone 5a is the LT zone.

Is there anybody familiar with this plan or are there standard percentages of the LT for each zone I can use to mathmatically figure out each zone?

Thanks

Tom

Diff formulas exist. Start herehttp://www.digifit.com/heartratezones/training-zones.asp