Laura,
Nothing in the iTread library that I have is strictly BFL (1 min at successively higher intensities and then cycle again...).
But if you are willing to stretch the principle to say vary intensity progressively up and then a short recovery before upping intensity, these 20 minute iTreads may work iTread Set 1 or Set 20. The first song on iTread 1 is one of my favorites. I havent heard it on nany other iTrains.
~* Vrinda *~