Francis, here is a link to an article I posted a few weeks ago on coritsol and how to deal with it:

Muscle Breakdown: Is Cortisol Leading You Down the Catabolic Pathway?

In a nutshell cortisol results from stress placed on the body. This can be emotional stress or physical stress. When dealing with exercise it is the result of the physical demands placed on the body to perform. A controled increase in insulin after a workout will help to neutralize it's effects. As will taking your anti oxidants (Vits C & E, green tea).

If you try a search on this website using the search tool on the right upper corner of every page you should find more information

HTH
Nat