Hi Sheryll - Here's just my personal experience:  My exercise-induced migraines seemed to be related to blood flow in the head.  That is, I would always turn bright red in the face and it seemed like my head was pumping full of blood.  I would take a dose of Fiorinal or Fioricet right after (as soon as I got to the locker room or the car - I think taking it before or during exercise would have thrown off my balance).  I think the effect of the caffeine in those has some relation to blood dilution of vessels in the brain...?  In any effect, in those instances I would usually feel better in about an hour or two.  Also, I would drink a TON of water, but make sure not to throw off my salt content.  I like smartwater (I get it at target) b/c it has electrolytes in it, but just tastes like plain, pure water, not like a flavored sports water.  Best of luck!