Impaired gonadotropin responses to gonadotropin-releasing hormone stimulation in endurance-trained women

Abstract

The effects of endurance running on body composition, menstrual cycles, and gonadotropins were studied in 19 healthy, young, regularly menstruating women. Midfollicular plasma concentrations of unstimulated and gonadotropin-releasing hormone (GnRH)-stimulated luteinizing hormone and follicle-stimulating hormone were examined at baseline and after each subject's weekly mileage had increased 30 miles (delta 30) and 50 miles (delta 50) above baseline. Mean +/- standard error of the mean unstimulated luteinizing hormone and follicle-stimulating hormone did not change significantly. GnRH-stimulated luteinizing hormone was 76.3 +/- 22.0 micrograms/min/ml at baseline and declined to 20.2 +/- 4.5 micrograms/min/ml at delta 50 (P less than 0.02). GnRH-stimulated follicle-stimulating hormone was 28.4 +/- 7.0 micrograms/min/ml at baseline and declined to 9.6 +/- 2.1 micrograms/min/ml at delta 50 (P less than 0.02). There were no significant correlations between changes in body composition and changes in gonadotropin responses. Eighteen subjects developed oligomenorrhea.