I have scream parts in several jazz songs my band is playing that go up to double Fs and Gs. My endurance is weakening after so many practices. Night after night has taken its toll. How can I improve my endurance.

Long tones and lip slurs! don`t try any of those books that claim to teach you how to play high because you have to do only one the book says and nothing else for about 6 months and if you don`t it won`t work

Im going to go with Derek on a previous post about larger mouthpieces. I am pretty sure that my endurance is from learning how to play high on a larger mouthpiece then working my way back to smaller mouthpieces. Last time i checked my endurance it was after a 12hour rehearsal for drum corps and when i checked my range i had an a above high c at forte. One i learned to play for long periods of time on a large mpc(1.5c) at hi dynamics and range endurance stopped being a problem. Now for me the game is all mental, if i dont use the same form to play the instrument on a smaller mouthpiece it will usually kill my endurance(found this out as of last night`s jazz rehearsal) But anywho moral of the story is work your hi and low dynamics, and if you use a smaller mpc(5cish to 7cish shallow) I suggest getting a bigger cupped mpc(you dont really need to change the rim or inner diameter keep the same) to practice those on. Oh mirrors are good too!