Hackney, A.C. Testosterone and reproductive dysfunction in endurance-trained men. In: Encyclopedia of Sports Medicine and Science, T.D. Fahey (Editor). Internet Society for Sport Science: http://sportsci.org. 20 Sept 1998.
Endurance training can result in dysfunction in the reproductive system of humans. Research within the sports medicine community has primarily focused upon reproductive dysfunction associated with athletic women. Not until recently have studies seriously addressed the question of how exercise training affects the male reproductive system. Research findings in this area have led some investigators to suggest that the effect of exercise training on the male reproductive system may be comparable to some degree to that found in women. For example, endurance-trained athletes of both sexes have abnormally low levels of the major sex hormones: testosterone in men, and estrogen in women.
The objective of this paper is to present an overview of how endurance exercise training affects testosterone and other aspects of the male reproductive system. The material is divided into four major sections. The first section deals with the basic endocrinology and physiology of testosterone in the male. The second section deals with physiological and methodological issues surrounding the interpretation of research on hormones. The third section covers the changes in testosterone in response to exercise training and acute or prolonged exercise bouts. Finally, in the fourth section the physiological impact of the changes observed in testosterone levels associated with endurance training are discussed.