Comparison of estradiol and testosterone levels during and immediately following prolonged exercise in moderately active and trained males and females.

Estradiol (E2) and testosterone (T) levels were compared among 28 subjects, ages 21-30, classified as male controls (MC), male runners (MR), female controls (FC) or female runners (FR). Serial blood samples were drawn from an indwelling venous catheter during rest (2 hrs), treadmill exercise (1 hr at 60% VO2max), and immediate recovery (15 min). Two-way ANOVA resulted in expected sex differences (p less than .01) in resting levels of E2 (M = 43.2 +/- 26.4; F = 142.4 +/- 72.8 pg/ml) and T (M = 4.8 +/- 1.2; F = 0.6 +/- 0.4 ng/ml). Significant (p less than .01) percent (%) and absolute (ABS) increases in E2 were observed in all subjects. Exercise increases in T were only significant in the MRs. ABS and % changes were compared among groups during exercise and during recovery. Training-related differences were found in the nature of the steroid responses. Runners exhibited greater ABS and % increases in T and E2 during recovery while the controls' greatest increases occurred during exercise. It was concluded that the greater (and more rapid) exercise responses of E2 in the MCs and T in the FCs as compared to the MRs and FRs, respectively were due to increased adrenal stimulation. The greater (and more delayed) recovery responses of the runners were due to gonadal production or differences in gonadal blood flow dynamics immediately post-exercise. The significance of this training difference may be relevant for steroidal induction of anabolic processes that lead to training adaptations.