As a neurologist, I am aware of the problems of patients withe exertional headaches.
I cannot exactly oversee your specific problem, but can give you some suggestions :
1. Try taking Dextrose tablets before and - when training for a long time - also
during sporting activities. Take a sandwich directly after exercising.
2. You could try taking paracetamol or aminoacetophen about 30 minutes before the
start of the exercises.
I really hope these suggestions will do you some good; if they do, please send me a
Joop Kuster, neurologist, The Netherlands
kuster at euronet.nl