Clarinet exercises?

Question:I have played clarinet for 4 and a half years. I am in high school and we just got a march. It is just under 4 pages (after all the repeats). It moves pretty quick and there and the longest period of rest is 2 beats. By the 3rd page my mouth (the corners) is killing me and air starts leaking out. After that it goes down hill pretty quick. What are some exercises that can improve how long I can play with out falling apart. p.s. when I try to close the corners, they just won't close and my mouth feels tense. Usually I would loosen my mouth during rests, but there really isn't any time in this piece.

Best Answer - Chosen by Asker: I have played clarinet for 4 and a half years. I am in high school and we just got a march. It is just under 4 pages (after all the repeats). It moves pretty quick and there and the longest period of rest is 2 beats. By the 3rd page my mouth (the corners) is killing me and air starts leaking out. After that it goes down hill pretty quick. What are some exercises that can improve how long I can play with out falling apart. p.s. when I try to close the corners, they just won't close and my mouth feels tense. Usually I would loosen my mouth during rests, but there really isn't any time in this piece.

There arent really any excercises Its just tiredness. Gradually increase your practice time so your mouth gets used to playing for a while! You may have excess tension in your mouth thats making your mouth more tired then it should be. So use your right hand thumb to support your clarinet rather then trying to 'ang on to it' in your mouth!