The human individual responds as an entire organism to the effect of endurance training. Exercise physiologists have long documented cardiovascular, musculo-skeletal and metabolic effects of conditioning. Only recently are we beginning to understand that there are hormonal and hypothalamic changes which occur with conditioning. These hormonal changes probably serve similar adaptive functions as do the other conditioning responses. Careful controlled studies need to be performed of individuals prior to, early in conditioning, and following extended periods of conditioning looking at hypothalamic function, body morphometric characteristics, psychiatric and psychological testing and menstrual cycle data in order to better understand hormonal conditioning. When hormone changes occurring with endurance training are approached in this light, the complex inter-related alterations will begin to form a pattern. Further studies are needed to document the dynamic and reversible nature of these hormonal adaptations.