There are many reasons why your muscles won't grow or why your muscle growth is retarded. One main culprit for your muscle tissue to in a catabolicNO2 Maximus and not in an anabolic state is the stress hormone called cortisol. This stress hormone, cortisol, is produced by your body when you are under stressful situations. Yes, any type of stress, whether they are mental stress, physical stress or just emotional stress will trigger off an increased in the production of cortisol hormones. A high level of cortisol is always a bane for bodybuilders and that in itself, is creating more stress.