The technique known as 'circular breathing' is required for Sequenza XII.
The player breathes in through his/her nose and forces the air into the
instrument with the cheek muscles.  I don't remember exactly where this
technique originated, but for some reason I'm thinking it's origins lie
in jazz--I could easily be mistaken though.  Berio's requirement of this
technique and the extremely slow glissandi that occur throughout the piece
limits it's current available performers to a mere handful.  This is the
same situation that Sequenza I was in when it first appeared--only a few
performers could handle it---now it's standard fare for university players!
Could this mean that circular breathing will become a standard technique
among bassoonists? I would say it is doubtful--the bassoon Sequenza is less
overtly flashy (and a little too lengthy) to become a standard recital
piece, in my opinion.  But who knows what the future holds?

Cheers,

Marcus