The specific aims of the current study were: 1) To determine the prevalence of IDNA in a sample of female rowers at the beginning of a training season; 2) To determine how IDNA affects endurance training and performance at the beginning of a training season; 3) To determine how iron supplementation affects iron status, training and performance in IDNA female collegiate rowers. The researchers hypothesized that IDNA affects endurance performance in female collegiate rowers both in and outside of the laboratory, and that iron supplementation of IDNA rowers will improve iron status, and consequently, training quality via increased energetic efficiency.