prolonged exercise or repetition of exercise on several consecutive days, would be responsible for decreased LH release and decreased sensitivity of Leydig cells to LH, hence production Of Strength Muscles. Elevation of endorphins and CRF (Corticotropin Releasing Factor resulting from stress. An increase in endorphins and CRF in the central nervous system decreases the release of pituitary gonadotrophins. This increase, resulting from prolonged exercise or repetition of exercise on several .