Glucocorticoids
are a group of steroid hormones that have catabolic effects on muscle -
they break down muscle tissue, the opposite of androgenic effects.
During times of stress, the glucocorticoids are secreted from the
adrenal gland ( hence, it's a "stress" hormone ).
Too much of glucocorticoids can cause an
excess breakdown of muscle tissue and is sometimes used as an indicator
( measured by high levels in the blood ) of overtraining.