Are you a bodybuilder? If so, you have a sworn nemesis and you may not even know it... Hes been scheming against you behind the scenes, working to undermine your bodybuilding gains at every turn... Every time your girlfriend picks a fight with you, hes there fanning the flames of passion... Every time your boss makes you work late so you have to skip a meal or shorten a workout, he is there, siphoning away your muscle.

His name is Mr. Cortisol and he is the one who has sworn to derail your bodybuilding gains... But he can only hurt you if you let him! 

Rather than being an evil super villain with a really cool costume and a fascinating story of betrayal and revenge, cortisol is actually a hormone produced in your brain that is manufactured every time you are subjected to stress... This chemical is released every time you worry about something, experience fear or anxiety, or lift something heavy in the gym... All types of stress  emotional, mental, and physical  cause cortisol to be produced... Cortisol levels being elevated result in muscle tissue not receiving protein, which stunts your progress in the gym... Theres a fine line which exists between just enough stress (adequate heavy training) and too much stress (overtraining and external stressors unrelated to bodybuilding)...
 
For many years, bodybuilders believed a steroid stack containing 400 to 800 mg of a testosterone ester was adequate for lowering cortisol levels in a very meaningful way... It was believed that steroids worked by lowering blood levels of cortisol. While this may occur to a very minor degree, research is beginning to show that a very flimsy relationship actually exists between the amount of testosterone injected and present, and the levels of cortisol in the body. It turns out that much of the success that bodybuilders see as a result of using anabolic ..steroids occurs completely independent of wherever the cortisol levels lie...
 
This may not ring true for natural bodybuilders.. For them, there is a strong likelihood that elevated cortisol levels may depress natural testosterone production or shuttling in the body, which would certainly limit gains... However, the chemically assisted bodybuilder has the gift of artificial testosterone levels which exist completely independent of natural production. This doesnt go to say that the non-natural bodybuilder should invite more stressors into his life. Any unnecessary stress can negatively affect gains in one way or another... Training will be less than 100%, or the appetite may be decreased... There are a number of functions which may limit muscle gains for the non-natural bodybuilder... It just appears that elevated cortisol levels are not one of them...
 
Keep an eye on Cortisol as you look to make gains in the gym... Hes a good indicator of the negative influences attempting to derail your training... Hes not all bad he does arise as a result of training  but youd like to see as little of him as possible.

Your body is in an elevated anabolic state when on cycle. If you are eating properly, training properly and getting plenty of rest I wouldn't stress out to much about your cortisol levels. Stress increases cortisol also so do what you can to reduce it. When you enter PCT is when I would start to be more concerned about cortisol levels because you are no longer in your elevated anabolic state from the AAS and your hormones are also going to be out of whack for awhile which is stressful on the body and will increase cortisol levels. Some compounds that reduce cortisol levels are clenbuterol and your SARMS such as ostarine. These compounds could definitely aid in reducing cortisol levels and may be something you might consider using in your PCT.

you can not completely block cortisol, it does serve a good function. when muscle breaks down you need some inflamation, which releases cortisol, cortisol is what signals the repair of muscle tissue. there is some good and bad to it. but you do need some. because with out it your muscle dont get the signal to repair, thus regenerate and grow

from memory, Schwarzenegger once advocated taking 1000mg of vitamin c a day to block cortisol.