Hormone levels of world class cyclists during the Tour of Spain stage race

Objectives-To evaluate the hormonal response to strenuous endurance exercis e performed by elite athletes. Methods-Nine professional cyclists (mean (SD) age 28 (1) years; mean (SD) V O(2)MAX 75.3 (2.3) ml/kg/min) who participated in a three week tour race (V uelta a Espana 1999) were selected as subjects. Morning urinary levels of 6 -sulphatoxymelatonin (aMT6s) and morning serum levels of testosterone, foll icle stimulating (FSH), luteinising hormone (LH), and cortisol were measure d in each subject at t(0). (before the competition), t(1) (end of first wee k), t(2) (end of second week), and t(3) (end of third week). Urine samples of aMT6s were also evaluated in the evening at t(0), t(1), t(2), and t(3). Results-Mean urinary aMT6s levels had increased significantly (p<0.01) duri ng the day after each stage (1091 (33) v 683 (68) ng/ml at t(1); 955 (19) v 473 (53) ng/ml at t(2); 647 (61) v 337 (47) ng/ml at t(3)). Both morning a nd evening aMT6s levels decreased significantly during the study. A similar pattern was observed for morning serum levels of cortisol and testosterone . Conclusions-The results suggest that the basal activity of the pineal gland , adrenal glands, and testis may be decreased after consecutive days of int ense, long term exercise.