INTRODUCTION
IRON DEFICIENCY
Iron deficiency (ID) is one of the most common contributing factors that may affect sports performance, although screening, diagnosis, and supplementation have not yet been standardized related to athletes. Compared to the general population, athletes have a higher demand of oxygen transport and energy production, in which iron plays a key role.The main causes of ID are the higher iron demand and loss with lower intake and absorption. In athletes, all these four mechanisms are pronounced due to extreme physical burden and the special nutrition habits (intake of supplements, vitamins, and minerals).The present randomized placebo‐controlled study aims to assess the prevalence of ID and the effect of 3‐month oral iron supplementation in young, male basketball players. We focus on the laboratory parameters, the body composition, and the cardiopulmonary exercise testing (CPET) results before and after the supplementation. We hypothesized that due to the higher iron demand of athletes, the 100 μg/L ferritin cut‐off may be appropriate to determine the IDNA status. On this basis, we investigated whether a 3‐month oral iron supplementation improves laboratory and performance parameters in these young, male athletes with IDNA.