here's a little info about John Friend's "Eye of the Tiger" sequence, often called the Tigress Practice.  This link takes you to Christina Sell's blog... she is an Anusara teacher in Texas.  This 4-6hr practice is rockin! :)  On a side note, my friend and yoga student, Jim Peterik (from the band Survivor) wrote the song Eye of the Tiger.  How Auspicious...  ;-)

http://christinasell.blogspot.com/2007/12/eye-of-tiger-back-story.html