Relationship between circulating cortisol and testosterone: influence of physical exercise.

Human research has shown the administration of cortisol into the circulation at rest will result in reduced blood testosterone levels. Many researchers have used these results to imply that physical exercise induced cortisol increases would perhaps result in subsequent reductions in circulating testosterone levels. Our purpose was to examine this concept and determine what, if any, relationship exists between circulating cortisol (C) and testosterone (T) in men (n = 45, 26.