The relationship between long-distance running, plasma progesterone, and luteal phase length.

The chronic effects of long-distance running upon the menstrual cycle were studied in a healthy, ovulatory 30-year-old woman. Luteal phase plasma concentrations of follicle-stimulating hormone, luteinizing hormone, 17beta-estradiol, and progesterone were compared during a control and a training cycle. The luteal phase was shorter in cycles of greater mileage. Mid-luteal phase plasma progesterone concentrations were significantly lower during training.