Effect of an ultra-distance foot race on the hypothalamic-pituitary testicular adrenocortical axes insulin growth factor levels: distinct patterns of suppression, stimulation and recovery

Background: Physical exercise has a significant effect on the hypothalamic-pituitary-testicular (HPT) axis and testosterone secretion. Testosterone levels can increase or decrease depending on the type, duration and intensity of exercise. This effect is mediated via complex and multilevel mechanisms that involve the activation of the stress system and the hypothalamic-pituitary-adrenocortical (HPA) axis, as well as, the secretion of major anabolic and metabolic hormones, such as cortisol and insulin growth factor-1 (IGF-1). After a bout of exercise, the HPT axis recovers, however the rapidity and magnitude of the recovery are not known. This is particularly important for the assessment of athletes for possible testosterone doping. Methods: In this study, we measured testosterone, LH, FSH, DHEAS, cortisol and IGF-1 levels, in 16 male participants in the 246 Km “Spartathlon” (up to 36-hour continuous, prolonged, brisk exercise) race, at three different time points; before the race (Phase I), at the end of the race (Phase II) and 48 h postrace (Phase III). Results: We found that testosterone, LH, FSH and IGF-1 levels decreased dramatically in Phase II. Testosterone and IGF-1 only partially recovered at Phase III to about half the Phase I values. The HPA axis hormones levels, DHEAS and cortisol increased significantly at Phase II and returned to normal at Phase III. Conclusions: The observed alterations of HPT axis and IGF-1 hormone levels in runners of the “Spartathlon” race, suggest that prolonged exercise suppresses testosterone and IGF-1, which remain partially suppressed for at least 48 hours, even after the HPA axis has recovered. We suggest that each exercise regimen results in a different hormonal response and recovery phase and should be taken into consideration when assessing athletes for doping.