If you're getting dizzy spells you're likely to be using an arch in the back of your tongue(arching the front third of the tongue can be helpful, but arching the back can force pressurized air up into the delicate nasal sinuses, thus causing dizziness, nosebleeds, and injury to the delicate tissues there)....
An alternative is that you may be tensing the muscles of the neck/throat, and pinching the artery there, thus causing a diminishing in the blood supply to your brain(also not a good thing to practice on a regular basis<G>)....
Isometric work can help, as can exercises such as you'll find in books by Allan Colin(Range Extensions), Eddie Lewis(Trumpet Pyramid) and Clyde Hunt(Sail the 7 C's), and flexibility studies, done carefully, using the mentalis muscles and proper air support....
Also work on Clarke Technical Studies, as is and 8va, in a range of dynamics....
Hth, let me know if you'd like more details....
Roger Mann wrote:
> I play in an amateur B. Band which has recently lost its lead player. By
> default, I found myself playing the 1st book in rehearsals. Doing OK, maybe
> needed the incentive. However, I need more range. Requirements are modest,
> D as a secure performance range. This would cover all but about 6 of our
> 80+ charts. Have started to pop out a few nice Es but with short dizzy
> spells, which can't be right. My only theory is inadequate embouchure
> strength, but would like any advice on what needs work. I don't want the
> last thing I hear before the stroke to be that high note I was going for,
> if you know what I mean!